Cattle Practice 8.2

Cattle Practice APRIL 2000 Volume 8 Part 2

CONTENTS Strategic Analysis of the British Beef Industry 71 S Mead The Future of Cattle Practice: Possible Solutions 75 P G Orpin The Effects of Sub-Clinical Parasitism on the Growth Performance 79 of Spring-Born Suckled Calves During their First Grazing Season K L Cutler Overview of Coccidiosis - Recent Obsevations 83 A Holliman Chronic Peri-Weaning Diarrhoea - The Clinical Syndrome 89 R W Blowey Peri-Weaning Diarrhoea Syndrome - A Farm Perspective 91 R Laven Peri-Weaning Calf Diarrhoea Syndrome: Findings to Date and Further Investigation 93 J R Jones Clinician's Approach to Neurological Disorders in Young Cattle 97 P R Scott The Calf Pneumonia Complex - Current Thoughts on Aetiology 103 D G Bryson Calf Pneumonia Costs! 109 A H Andrews Mycoplasma Infections in Growing Cattle 115 R Nicholas Tuberculous Pneumonia and BVD in Housed Calves 119 R J Monies Building Designs to Optimise Health 127 J F Robertson Pneumonia: Identifying the Causal Agent 131 G L Caldow The Calf Pneumonia Complex - Treatment Decisions 135 D C Barrett Skeletal and Other Disorders Associated with Inadequate Dietary 139 Mineral and Vitamin Supplemention in Growing Cattle I H Davies Miscellaneous "Locomotor" Disorders in Young Cattle 145 S Borsberry Bovine Spongiform Encephalopathy (BSE) and Variant 151 Creutzfeldt-Jakob Disease (vCJD) R Bradley Workshops The State Veterinary Service Inspection 155 K Kirk Batch Recording in Veterinary Practice 159 R Vernon Regional Meetings 2000 Caesarean Section in the Bovine 161 D Bee Calvings and Caesars 163 G Singleton Laminitis & Lameness: Putting Science into Practice! 165 D N Logue Control of Digital Dermatitis 179 R Laven

Treating Bovine Mastitis 183 M J Green Machine Milking and Mastitis 185 I Ohnstad Suckler Cow Nutrition: I. Management by Condition Score 187 K D Sinclair Suckler cow nutrition: II Minerals and vitamins 193 N F Suttle Other Papers Cattle News 1999 Parts 4-6 201 D C Barrett Clinical Forum 207 Letters to the Editor 208 Some Useful WebSites Worth a Visit 209 Classified Adverts 210

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 INTRODUCTION A Strategic analysis of the British Beef Industry cannot be done in isolation to the wider issue of meat, nor indeed can it be separated from the whole issue of consumerism, but for the sake of simplicity, the scope of the paper is limited. Classic analysis techniques of PEST, SWOT and assumption definition have been presented for the period to the middle part of this decade. The conclusions for the industry and or the Veterinary Profession have not been presented, the former is available within the MLC Corporate Plan document and the author is not qualified to comment on the latter. Individual business competitive advantage is gained by the separate and distinct tactical implementation of solutions. This paper and the subsequent presentation will seek to clarify both the global and home agricultural and economic influences upon the beef sector. PEST ANALYSIS FOR MEAT Table 1. Pest Plus Analysis For Meat Generally: Political. 1. The agreement on Agenda 2000 will be phased in, which will impact directly upon beef production, and less upon pig and sheepmeat production 2. EU enlargement will influence future development of policy 3. There will be greater emphasis on the consumer, food safety and the environment 4. There will be less direct support for meat production 5. The Food Standards Authority will be established during the period 6. Slow recovery in Russian and Far East economies 7. Greater volatility on International Markets, leading to less stable trading conditions. Table 2. Pest Plus Analysis For Meat Generally: Economic. 1. Lower economic growth in the early part of the period (GDP forecast at around an average of 2.5% pa over the period as a whole) 2. Inflation 2 - 2.5%pa 3. UK's entry to Economic and Monetary Union is only at the end of the period at the earliest. Table 3. Pest Plus Analysis For Meat Generally: Social/ Consumer 1. Declining proportion of income to be spent on food. 2. Continued growth in eating-out/take-home meals. 3. Increasing demand for convenience, stimulating growth in prepared and processed products. 4. Continuing competition from all substitute products for meat. 5. Need for greater choice demands new product development. 6. Food safety concerns, animal welfare and the impact of high profile issues high on consumer attitudes. 7. Continuing consumer awareness of diet and nutritional content of food. 8. Continued distancing of consumers and school children from cooking and meat. 9. Continuing investment by major retailers strengthening their influence on consumer purchasing patterns. 10. Demand for naturalness may conflict with developments in some production systems and the drive to improve competitiveness. 11. Genetically Modified Organisms and biotechnology etc. are seen as a route to achieve these improvements. Table 4. Pest Plus Analysis For Meat Generally: Technical 1. Food safety continues to be a key issue. 2. The value/costs of animal by-products continue to impact on the meat supply chain. 3. Capabilities of biotechnology grow, but so do consumer concerns. 4. Continuing threat of downward pressure on consumption from diet, health and animal welfare concerns. Table 5. Pest Plus Analysis For Meat Generally: Trade. 1. Strong £ supporting imports/hindering exports in the early part of the period. 2. Increasing range of imports as WTO frees up trade. 3. Retailers demanding more traceability and assurance on behalf of consumers. 4. Increasing need for greater and faster information flows as consumers become more sophisticated and the trade looks for competitive advantage. 5. The beef export ban is lifted prior to the start of the period, although conditions remain difficult. 6. Some recovery is possible in by-products trade. Table 6. Pest Plus Analysis For Meat Generally: Wider Issues 1. The impact of EU legislation grows. 2. EU and UK Government policy broadens from agriculture to the rural agenda. Strategic Analysis of the British Beef Industry Mead S., Head of Beef Strategy, Meat and Livestock Commission, PO Box 44, Winterhill House, Snowdon Drive, Milton Keynes, MK6 1AX.

CATTLE PRACTICE 3. Structural adjustments to the industry continue to occur. 4. Better animal identification, record keeping and traceability demanded. 5. Waste disposal and pollution issues increase in importance. 6. Scottish, Welsh and English industries develop their own strategies. BCVA 2000 3. Meet the growing demand for quality food products. 4. Maximise meat's share of the growing catering market. 5. Capitalise on the growth in interest in 'Local'/known links to product by sensible exploitation of points of difference. 6. Influence schools programmes to benefit industry. 7. Develop marketing & NPD expertise as the basis of brand development. 8. 'Lead the world' on issues of traceability. D. Threats 1. High profile industry open to attack especially on health issues. 2. Vociferous opposition to meat eating among some opinion formers. 3. Downward pressure on demand from unbalanced medical opinion. 4. Growing interest in standards linked to the raw material and to industry practices. 5. Increasing cost pressures, including abattoir waste disposal and environmental legislation. 6. Industry structures adjusting too slowly. 7. Fragmented industry, not speaking with a single voice in crisis. SUMMARY ASSUMPTIONS FOR BEEF INDUSTRY A. Consumer 1. Retail sales as a proportion of total beef sales decline. 2. Processing and catering beef sales grow. 3. Supermarkets increase their proportion of retail sales. 4. The demand for new product development will accelerate. 5. High profile issues continue, but the scale of the vCJD epidemic remains at the lower end of 1997/8 estimates. 6. Food safety issues remain high in the public consciousness. 7. Without new product development or improved price competitiveness, beef consumption will continue to decline. B. Processing 1. Continuing low slaughter levels exacerbate abattoir over capacity. 2. Over capacity and other costs put further downward pressure on the whole industry margins. 3. Beef exports occur by the end of the period at a low level. 4. Over Thirty Month beef comes back onto the market by the end of the period. VOL 8 PART 2 Table 7. UK Consumption of Meat ( 000 tonnes) 1987-2003. 1987 1997 1999 2000 2001 2002 2003 Total meat 2,754 2,507 2,531 2,514 2,548 2,467 2,487 of which:- Beef/veal 1,154 850 895 894 879 854 843 Mutton/lamb 371 351 391 382 358 357 350 Pigmeat 1,229 1,295 1,287 1,238 1,311 1,306 1,294 Table 8. Market share for different meats (%) 1987-2003. 1987 1997 1999 2000 2001 2002 2003 Beef/veal 41.9 34.1 34.8 35.6 34.5 33.9 33.9 Mutton/lamb 13.5 14.1 15.2 15.2 14.1 14.2 14.1 Pigmeat 44.6 52.0 50 49.2 51.5 51.9 52.0 SWOT ANALYSIS OF THE BRITISH MEAT INDUSTRY A. Strengths 1. Important as part of a healthy balanced diet. 2. Range of flavours, texture and formats of meats (particularly compared with poultry). 3. Traditional part of meals. 4. Comprehensive safety controls in place. B. Weaknesses 1. Very limited resources for promotion/ communication. 2. Viewed as expensive compared to poultry and most non-meats. 3. Relatively difficult to cook/prepare. 4. Perceived as inconvenient, and relatively unhealthy (fatty) 5. Source of product still has image problems with consumers e.g. welfare. 6. Not 100% Farms or output Quality Assured. 7. 'Unsophisticated' traceability. 8. Limited marketing/New Product Development (NPD) expertise by many suppliers. 9. Still some 'fringe' companies operating at barely minimum standards. 10. Lack of brands (other than retailer). C. Opportunities 1. Overcome unhealthy image by explaining health benefits 2. Use meat's versatility to exploit product opportunities through NPD

CATTLE PRACTICE C. Production 1. About 200, 000 calves pa are slaughtered as bobby calves. 2. Introduction of sexed semen increases proportion of beef production from dairy herd. 3. EU support will emphasise extensification and environmental issues. 4. No calf deliveries to other EU countries within the period. 5. Breeding sector remains fragmented. 6. Finishing sector rapidly consolidates. BCVA 2000 4. British beef production costs remain high compared to imports and other foods. 5. Some parts of the slaughter sector remains weak nor generate sufficient margins to support investment and innovation. 6. Low or nil returns for the fifth quarter. 7. Lack of integration, communication and trust in the supply chain. 8. Agenda 2000 moves production away from the market. C. Opportunities 1. BSE very low level by 2003. 2. Industry image boosted by strict UK BSE controls. 3. Opportunities provided by the lifting of the export ban. 4. Opportunities created by quality assurance and traceability measures. 5. Increasing opportunities in the catering sector. 6. Displace imports with competitively priced home product. 7. Develop 'added value ' sector for beef. D. Threats 1. Food poisoning, particularly E Coli, has the potential to damage the image of beef. 2. Use of hormones in imported beef, and biogenetics raises consumer concerns. 3. Competitively priced imports. 4. Persistence of Intervention beef coming back to the market disrupts prices. 5. Lower EU consumption and capped exports increase EU competition. 6. Waste disposal throughout the supply chain adds costs. 7. Compulsory EU labelling regulations add costs and hinder recovery in export markets. 8. Cereal based white meats, particularly poultry meat. 9. Rigorous legal compliance of EU and specific UK legislation relative to other EU countries. VOL 8 PART 2 Table 9. Forecast beef and veal balance sheet. 1987 1997 1999 2000 2001 2002 2003 Slaughter: '000 head Prime cattle 3,074 2,263 2,207 2,304 2,331 2,440 2,455 Other *1 969 20 190 278 243 220 220 *1Entering the food chain 1987 1997 1999 2000 2001 2002 2003 Production 1,099 694 680 709 714 747 753 Imports 239 226 200 180 180 170 150 Exports 192 0 5 15 25 35 50 Consumption 1,154 850 895 894 879 854 843 SWOT ANALYSIS OF THE BRITISH BEEF INDUSTRY A. Strengths 1. Nutritional benefits of beef. 2. The British consumers historical perception of beef. 3. The demand for steaks and other cuts. 4. The reputation of the Minced Beef Quality Mark. 5. Scotch beef as a brand. 6. Industry able to meet a range of specifications. 7. Good technology base available for production. 8. Electronic data base and passport system in place. B. Weaknesses 1. The processed beef sector has not fully recovered. 2. The range of alternative products grows quicker than for beef. 3. A low return for forequarter beef.

CATTLE PRACTICE BCVA 2000 VOL 8 PART 2

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 INTRODUCTION In the last 18 months milk price has dropped by as much as 8 pence per litre, further falls in milk price are expected. A collapse in calf and cull cow sales has further reduced farm incomes. A rationalisation of both the agricultural and veterinary sector is bound to occur and the purpose of this paper is to outline some possible options for cattle practices to consider in evaluating what direction to pursue. The paper is not intended to be prescriptive and ultimately what will happen will depend on the local situation. POTENTIAL CHANGES TO THE FARMER CLIENT BASE Farm numbers will decline and the actual numbers of cows may decline as yields per cow increase. Small or inefficient units may cease milk production. Farms left in the industry will be cost and value conscious and demand a high quality of expertise and service. The net result will be fewer, larger units and the veterinary service will have to change to meet these challenges. The bigger client will be more focussed on overall cost control and profit generation. This has not always been an overwhelming priority for every farmer client until recently. Many farms may have been able to operate at lower levels of efficiency with higher levels of output prices. This is no longer the case. There is an opportunity for vets to market profit generating services to a more knowledgeable and responsive client base. The needs of this future client will be different. He/she will focus on reducing overall costs to improve profits. The challenge will be to demonstrate that the vet can deliver a positive cost benefit. The total vet spend per cow may reduce; the vet may have to be responsible for a larger number of cows. Should stock values remain low and a veterinary service for the individual animal not be a major requirement, the geographical area covered by any one practice can be increased. To survive in the agricultural sector the vets will need not only to have the skills and knowledge required by the client but have an understanding of farm economics, spreadsheets, be effective communicators and good business people. WHAT ARE THE POTENTIAL REQUIREMENTS OF YOUR CLIENTS? Every practice will be different. Individual practices will have to ascertain by survey or face to face contact the needs of their key clients. 80% of income generally comes from 20% of your clients ( Pareto's principle) and time spent identifying future client needs is time well spent. Retaining the focus on the long-term clients is imperative before any major decisions are made. These clients would typically value expertise in preventive medicine, health programmes, farm assurance, education and training and at a competitive price. The fee structure will have to be fair for both parties and orientated to suit the client type. Attempting to have a fee structure that fits all clients from one cow to 500 cows may be futile. The ultimate aim would be to develop a health partnership with these key clients focussing efforts at reducing levels of disease and boosting farm profitability by good veterinary practice. The BCVA Herd Health Plan forms the basis of this good health monitoring and practice. WHAT IS THE IMPACT OF THESE MARKET FORCES ON TRADITIONAL VET PRACTICE? Most farm practice is based around delivering a 24 hour service with rapid response to local farms who have traditionally always used the nearest practice. In most areas farm skills and knowledge have increased and the demand for basic fire brigade work has decreased. More of the vet's time is devoted to herd health work. The Future of Cattle Practice: Possible Solutions Orpin P.G., The Park Veterinary Group, 82-84 High Street, Whetstone, Leicester. LE8 6LQ. ABSTRACT Cattle practice is changing as agricultural incomes fall. Farm numbers decline and income from agricultural clients has reduced by 10-30% in many practices. The cattle practitioners will have to be efficient, professional and make the right strategic decisions to maintain their role in the farming industry. Practice size, structure and service are central to the future of cattle practice. KEYWORDS: Practice, management, future.

CATTLE PRACTICE Increased use of vaccinations and reduced manual tasks on farm has led to a situation where more turnover is derived from preventive medicines and drug treatments than from services. This is an inevitable consequence of larger farms and preventive medicine. This is not necessarily a failure in veterinary service but more a reflection of technological change, farm size and farmer education. This will only be reversed by changes in client outlook: organic farming, disease eradication or technological advancement (in line milk progesterone assays, alternatives to dry cow therapy) In many areas and practices the challenge will be to retain the critical mass of vets to deliver both the onerous 24-hour commitment and to retain the specialist veterinary skills required by the focussed farmer client. Unless a minimum of 3 vets can be allocated in whole or part to farm work it is difficult to see how professional development and the holistic service can be provided. Indeed, in many areas there may be insufficient clients left to justify the existing levels of veterinary service with a prolonged agricultural recession. This is already posing problems for farmers and vets in areas of low stock density where it is not easy to provide the service on business grounds. A conundrum exists: providing a 24 hour service from a smaller team of vets with skills of value to the client, over a larger area, at reduced cost! WHAT ARE THE OPTIONS? • Evaluate your own clients and your own vets aspirations. • Is there a business opportunity to continue to provide a service? • Do you have vets that wish to continue with farm work? If not, it may be better to get out and specialise in other areas than attempt to provide a service for no better reason than nostalgia or interest. There is no point in delivering a service which is uneconomic and unsustainable. • If there is a will and knowledge to provide the service and there is sufficient work for 3 vets then invest in CPD, evaluate your clients needs and seek to develop a practice that is focussed on satisfying the needs of your clients. • If there is insufficient clients to produce an economic unit but a commitment to providing a large animal service then expansion by merger, cooperation or growth are the possible options. It is beyond the scope of this paper to examine these options in detail but the aim must be clear. To provide BCVA 2000 an economic service with the necessary skills and personnel to deliver a quality service. Unless this can be achieved, the best option is to sell the business or contract out aspects of the work to other practices that can. Simply to increase the practice size may not bring automatic economies of scale unless the practice can be structured correctly to have the right mix of expertise and management skills. Any amalgamation must be synergistic, making the larger practice better and more profitable than the original smaller units. The major cost of large animal practice is the cost of employing the vets and this is the key area where efficiency savings should be directed. SHORT TERM COPING STRATEGIES In many instances the decisions may not be clear-cut as how to go forward. The priority will be focussed on how to maintain turnover in a distressed market. Possible options are:- • Reduced fees and margins. In a non-specific way. This is unlikely to achieve anything but reduced profitability for the practice and no major economic gain for the client. Veterinary costs are a less than 4% of total costs to a dairy farm and reduced costs at expense of service will not deliver long term returns for the client. • Reducing costs. This may mean reducing the number of vets allocated to farm work by redirecting their skills to other areas or "downsizing". Other options, which may be explored, are reduced drug costs by direct purchasing from manufacturers rather than wholesalers. • More active promotion of existing services. This may expand your total sales and deliver better health onto farms. Reduced fees for advisory or practical work at times of down time will benefit both parties as long as this is carefully structured . An ideal opportunity to get BCVA Herd Health Plans on farm, which in turn will have other long-term benefits. • Packaging of products or services. Products and services are offered at a lower margin in return for a commitment to purchase more products or services from the practice. More total sales to client: better prices for client. Farmers helping vets: vets helping farmers. Effectively volume discounts passed onto clients. • Health partnerships. Based on key commitments from the farmer to purchase key products and services from the practice. Again the motivated client and vet working together to generate better animal health. A separate fee structure could be set up for these clients that is fair to both parties. Possibly this could be structured on a monthly payment plan. • Promoting the need to invest in health. Ensuring that existing farmers do not take the easy option and abandon key health plans to satisfy current financial VOL 8 PART 2

CATTLE PRACTICE concerns. Robust reminder and contact systems are needed together with rudimentary computer databases or paper records. This is basic marketing. However, if the decision has been made to provide a system of vaccinations, we have an obligation to ensure that the client does not forget to use them. • Expanding the total number of professional services. Diversifying the portfolio of options. Mastitis control is a good example as cell count penalties are ever increasing. The list of possibilities is endless. Careful evaluation of both profit potential and client needs is required before developing new systems. • Loyalty schemes. Increasing market share of services and sales by rewarding clients with credit points on their invoices. This means that any incentives offered are kept within the practice turnover. • Developing paraprofessional links or services for clients. Foot trimming is a good example where the link with the foot trimmer can be used to increase herd health and advisory work with lameness. PRACTICE STRUCTURES Ultimately the practice structure will develop as the market dictates and in the long-term more radical solutions may be required or considered. In addition to the traditional mixed practice there may be options to develop a more specialist or alternative options more suited to the current agricultural climate. This may be within private practice or via incorporation. HIGH STOCK DENSITY/LARGER PRACTICE Client base The clients will have to accommodate to a service from either further afield or at a reduced response time. Much of the current cost in providing a veterinary service is the requirement for vets on standby for emergencies. This has potential welfare implications and these will have to be managed within the requirements of farm assurance and professional ethics. As cows per vets increase and cows per square mile reduce then the area required for the ideal practice will be bigger. Growth, merger or co-operation with sharing of skills would increase this larger client base and possibly increase the density of clients reducing non chargeable travelling time. Personnel The vets and support staff will need to be highly motivated and willing to embrace change and opportunity. The market place is more volatile and the service must change with demand. BCVA 2000 Continued professional development (CPD) will be a pre-requisite of success together with a good system of internal dissemination of knowledge and ideas within the practice. This is a common rate-limiting step of technology transfer. The practice must make it a priority for personnel attending courses to debrief others and put in place new initiatives gained from the meetings. Acumen will be also required in business development, personnel management and marketing as the practice will have to be well run to maintain motivation. This may be more easily produced from a professional manager. A career structure will have to be in place to afford opportunities and advancement. At least 4 tiers of professional staff will be required from student through to consultant vet. Further postgraduate qualifications or equivalent experience will be necessary to provide the level of expertise within the practice. A basic minimum of 3 vets will be required and this together with the client base will ultimately determine the level of service provided. Team work is the key with all the vets working to a common aim referring work within the team as required. INFRASTRUCTURE AND FACILITIES The practice centres need not be based at one site but adequate space must exist to train staff, store products and medicines and administer the practice. This may or may not be linked to a small animal practice but the phones and entrances ought to be dedicated according to client type. Avoiding over investment is crucial, as the service must be cost effective. Clinical Service The practice must provide the highest possible service at all times and have excellent lines of communication with the clients. Work requires to be pre-planned and the fee structure based around creating this culture to minimise cost to the practice. In years to come more sophisticated systems of charging may develop. Contract payments, different levels of fees according to service requirements and farm size may evolve in this harsher economic climate. Similarly, visit fee structures may need to be altered to encourage planned and zone visit work to reduce non-chargeable travel time. Computer support, advisory and consultancy work, paraprofessional and related services would be essential ingredients. The practice will provide a full professional service at a cost that the practice and client can afford. Integrating the flow of information and data from client to vet and vice-a-versa is essential to provide meaningful quantifiable advice. VOL 8 PART 2

CATTLE PRACTICE Paraprofessional services The practice should provide the full range of services and work closely or employ relevant paraprofessionals to expand the total turnover of the business. This would facilitate better health care and job satisfaction. Nutrition and farm consultancy advice is best integrated with the overall health care of the farm. This could be achieved by employment of individuals in areas of high stock density or by closer links and contracts with self employed operators in smaller practices. Pharmaceutical sales The practice should be the focus of advice and knowledge for all pharmaceuticals irrespective of classification. This would ensure the best use of medicines and deliver competent and specific advice. This would be integrated into the health plans. The size of the practice may confer better terms of business and an increase in sales of products may occur as other smaller retailers go out of business in times of economic hardship. Alternatively, fee base advice may be an option for some clients. This could be provided on a fee for service basis or part of a health partnership or contract. Ownership This type of model may be adopted by the merging of partnerships or more likely via incorporation. The key to success will be the retention and motivation of staff and the overall costs and efficiency of the business. THE LOW DENSITY/SMALLER PRACTICE ALTERNATIVE In areas of low stock density the provision of a veterinary service may be more problematic. As senior vets retire taking their experience with them many practices may simply give up the large animal work. This poses problems for those left behind as travel distances will be greater and creating a core of 3 vets to facilitate holidays and CPD will be more difficult. Co-operation or merger will become more attractive. More experienced vets may periodically visit to provide consultancy work and be a source of knowledge for the possibly less experienced local vet. This is a model operated by pig vets but it is difficult to envisage a vet from 200 miles away providing a full service to the farm. A joint venture would be more likely with co-operation between consultant and local vet. The costs of veterinary care will be higher to reflect the increased cost of providing the service. BCVA 2000 CONCLUSIONS Predicting the future is not an exact science and there will be great variation in approach depending on the client and vet mix. This paper is not intended as a blueprint for change more a collection of possible options for BCVA members to consider. The agricultural recession and consequential restructuring of the industry will provide great challenges for the farmer and related service industries. The priority for the veterinary surgeon is to make rational adjustments in approach and working arrangements in order to ensure that the practice structure can support the large animal vets required to provide for the fewer farm clients. The current level of service is largely dependent on the knowledge and commitment of the individual practice. In many practices the provision of the service is not strictly cost effective and relies on cross subsidy from other areas of the practice. In time these practices may decide to stop providing a farm animal service. In areas of high stock density there is logic in cooperation and mergers between practices to continue to provide a highly cost effective service for the farmer at a time of reduced demand for services. This may become an imperative as many practices face reductions in farm sales of 10-30%. Alternatively, by applying more focus and expanding the amount of services offered, and reducing costs, the practice may survive without radical restructuring. In areas of low stock density it is uncertain how large animal practice will survive if stock levels drop further. Significant cross subsidy from other parts of the veterinary business or government support such as the Highlands and Islands scheme may be essential. In such circumstances co-operation between practices is central to providing a workable solution, as the critical mass of vets needs to be maintained. Whatever the eventual outcome, the wise veterinary surgeon would benefit from considering all options and making measured decisions rather than hoping the situation will get better. It may not. Forewarned is forearmed. ACKNOWLEDGEMENTS To Dick Sibley and Chris Watson for critical appraisal and colleagues and BCVA members for many of the ideas. VOL 8 PART 2

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 INTRODUCTION The benefits of controlling sub-clinical internal parasitism in weaned and adult cattle at pasture have been well documented ( Ryan et al 1997, Weech et al 1995) however, there is a lack of published evidence on the subject in beef suckled calves at pasture with their dams. Anecdotal reports from farmers in the UK suggested that there was a benefit to be gained from giving an anthelmintic treatment to suckling calves from the middle of the summer grazing period. Epidemiological studies by Michel. (Michel et al 1972) and Agneessens. (Agneessens et al 1997) showed that the level of parasitic gastro-enteritis in spring-born suckled calves was likely to be low and thus of minimal danger to these animals. Nevertheless it was demonstrated by following faecal nematode egg output that worm burdens were acquired by these calves at pasture and, although they appeared to be low, these burdens peaked towards the end of the summer grazing period. The purpose of these studies was to examine the effect of these apparently low worm burdens on the growth performance of single-suckled calves. MATERIAL AND METHODS A total of 334 spring-born suckled calves of both sexes and a minimum of 3 months of age were included in studies conducted over three successive years (1997, 1998 & 1999) and included four different farms. Calves included in the trial weighed between 100 and 279kg at the beginning of the study. As was normal farm practice, in each study calves were grazed extensively together with their dams on natural pastures. No parasite control was given to the dams either in the weeks leading up to or during the study. In each year and at each location the calves were ranked by initial weight within sex, paired according to rank and then within each pair randomly allocated to either of two treatment groups. Group 1 animals were treated with an ivermectin sustained-release (SR) bolus (IVOMEC® SR Bolus, Merial) in July and Group 2 animals remained as untreated controls. Weights were measured at allocation and again at housing. A representative number of faecal samples were taken from calves and their dams at allocation and at housing. These samples were examined by the local VLA laboratory for the presence of nematode eggs using the McMaster method. (sensitivity ref.) RESULTS Results are presented separately for male and female calves and for each farm in each year (Tables 1-2). Combined analysis of all the results indicate that on average female calves treated with the ivermectin SR bolus gained 8.9kg more than untreated controls Cutler K. L1., Rice B. J2., Forbes A. B2. 1Endell Veterinary Group, 49 Endless Street, Salisbury, Wilts. SP1 3UH. 2Merial Animal Health Ltd., Sandringham House, Harlow Business Park, Harlow, Essex, CM19 5TG. The Effects of Sub-Clinical Parasitism on the Growth Performance of Spring-Born Suckled Calves During their First Grazing Season ABSTRACT To evaluate the effect of sub-clinical parasitism on the growth performance of spring-born single suckled beef calves, calves treated with an ivermectin sustained-release (SR) bolus were compared with untreated controls. The studies were carried out over three successive years and included a total of 334 spring-born suckled beef calves weighing between 100 and 279kg at the start of the studies. The animals were grazed extensively on pastures naturally infected with nematode larvae. In each year and at each location the calves were ranked by initial weight within sex, paired according to rank and within each pair animals were randomly allocated to either of the trial groups: an untreated control group and a group treated with the ivermectin SR bolus in July. The calves in both trial groups, and their dams were grazed together on a single pasture until weaning and housing. The calves were weighed at allocation and housing. The adult cows were not treated during the study. With the exception of one farm during 1999 when only female calves were available, both male and female calves were included in the study. Female calves treated with the ivermectin SR bolus in mid-summer gained an average of 8.9 kg bodyweight more during the grazing period from treatment to housing than the untreated control heifers, an average of 90g more per day. Males calves treated with the ivermectin SR bolus gained an average of 8.5 kg more (91g more per day) than the control males. The differences in mean weight gain and average daily gain between treated and control groups was statistically significant (p<0.02) for both female and male calves.

CATTLE PRACTICE (p<0.01) and treated male calves gained 8.5kg more than untreated controls (p=0.0121) during the trial period. Expressed as average daily weight gains the differences in favour of treated female and male calves were 90g/day and 91g/day respectively (p<0.02 in both cases). BCVA 2000 Table 3. Arithmetic mean faecal egg counts (eggs per gramme) for animals sampled on Day 0 and at housing. Group 1 animals treated with an ivermectin sustained-release bolus on Day 0; Group 2 animals untreated controls. VOL 8 PART 2 Table 1. Weight gain (kg) of the calves at each farm. Group 1 animals treated with an ivermectin sustained-release bolus on Day 0; Group 2 animals untreated controls. Farm & Year Group 2 Group 1 Difference (Gp1-Gp2) Females Farm 1 - 1997 84.4 93.8 9.4 Farm 2 - 1998 101.9 101.6 -0.3 Farm 3 - 1998 50.1 58.5 8.4 Farm 4 - 1998 120.6 133.0 12.4 Farm 2 - 1999 95.6 101.2 5.6 Farm 3 - 1999 46.6 63.1 16.5 Farm 4 - 1999 120.0 130.5 10.5 Males Farm 1 - 1997 98.1 111.5 13.4 Farm 2 - 1998 96.8 99.6 2.8 Farm 3 - 1998 55.1 60.7 5.6 Farm 4 - 1998 120.8 125.5 4.7 Farm 2 - 1999 130.3 138.7 8.4 Farm 3 - 1999 51.3 67.4 16.1 Table 2. Average daily gain (grams per day) of the calves at each farm. Group 1 animals treated with an ivemectin sustained-release bolus on Day 0; Group 2 animals untreated controls. Farm & Year Group 2 Group 1 Difference (Gp1-Gp2) Females Farm 1 - 1997 760 845 85 Farm 2 - 1998 796 794 -2 Farm 3 - 1998 748 873 125 Farm 4 - 1998 874 964 90 Farm 2 - 1999 810 858 48 Farm 3 - 1999 575 779 204 Farm 4 - 1999 992 1079 87 Males Farm 1 - 1997 884 1004 120 Farm 2 - 1998 864 889 25 Farm 3 - 1998 823 906 83 Farm 4 - 1998 1172 1218 46 Farm 2 - 1999 1113 1185 72 Farm 3 - 1999 634 833 199 Results of faecal nematode egg counts (FEC's) indicated that in all cases worm burdens were low in mid summer and ranged from means of 0 to 83 eggs per gram for both calves and their dams. These egg counts had increased by the time of housing to means ranging from 100 to 325 epg in the untreated calves. A nematode faecal egg count of 50epg was detected in only one calf that had been treated with the ivermectin SR bolus, the remainder of the animals sampled showed no evidence of worm burdens. Day 0 All Housing Ivermectin SR Bolus Controls Farm 1 - 1997 21 - - Farm 2 - 1998 9 0 100 Farm 3 - 1998 83 0 250 Farm 4 - 1998 42 0 119 Farm 2 - 1999 0 0 110 Farm 3 - 1999 67 12 325 Farm 4 - 1999 33 0 167 Table 4. Arithmetic mean faecal egg counts (eggs per gramme) for dams sampled on Day 0 and at housing. Day 0 Housing Farm 1 - 1997 17 - Farm 2 - 1998 83 0 Farm 3 - 1998 17 0 Farm 4 - 1998 0 - Farm 2 - 1999 0 - Farm 3 - 1999 0 - Farm 4 - 1999 0 - DISCUSSION The results from this study clearly demonstrate that spring-born suckled calves are affected by subclinical parasitism in their first season at grass and that there is a production benefit to be gained by treating such calves against such parasitism. It can be noted that animals included in the trial, although still suckling from their dams were at least three months of age and so would be starting to rely on feed sources other than their dams' milk and naturally this would be provided by the grazing. It is therefore not surprising that such calves would acquire worm burdens which in turn could affect their growth performance while at grass. What is of interest however is the scale of the growth benefit obtained in the face of what appeared to be low worm burdens as reflected by FEC's at a level such that many would not even consider intervention necessary. The studies did not attempt to determine the proportion of the calves diets that were obtained from the dam's milk and from grazing either at the beginning or end of the study. This subject has been addressed by previous authors (Boggs et al 1980) where it was shown that in spring-born suckled calves the proportion of the diet taken up by forage in comparison to milk increases from less than 10% in early spring to more than 50% by late summer. (Graph 1).

CATTLE PRACTICE This study demonstrates that worm burdens have already been acquired by three months of age (when forage intake still accounts for a relatively low proportion of feed intake) and that these had a negative effect on growth rates over the remainder of the grazing season. In these studies the calves were weaned at housing and the untreated controls were treated with an endectocide, an additional housing treatment not BCVA 2000 being necessary in calves treated with the ivermectin SR bolus in mid-season because the bolus would have still been active at that time. The latter point, i.e. that an additional housing treatment is not needed, provides a further argument in support of treating suckled calves in mid-season and would play an important part in determining the cost benefits of such a treatment. REFERENCE Ryan W.G., Crawford R.J., Gross S.J., Wallace D.H., (1997) Assessment of parasite control and weight gain after use of an ivermectin sustained-release bolus in calves. JAVMA Vol. 211 No. 6, 754-756 Weech B.L. 1972 and Whittier J.C., 1995. Effect of anthelmintic on follicular development and response to estradiol challenge in prepubertal beef heifers. J. Anim. Sci. 44: 165 Michel J.F., Lancaster M.B. & Hong C., The Epidemiology of Gastro-intestinal Nematode Infection in the Single-suckled Calf. Vet. Rec. 91: 301-306. Agneessens J. 1997., Dorny P., Hollanders W., Claerebout E., Vercruysse J., Epidemiological observations on gastrointestinal nematode infections in grazing cow-calf pairs in Belgium. Veterinary Parasitology 69: 65-75 Boggs D.L. 1980, Smith E.F., Schales R.R., Brent B.E., Corah L.R. and Pruitt R.J., Effects of Milk and Forage Intake on Calf Performance. Journal of Animal Science Vol. 51, No 3, 550-553 VOL 8 PART 2 Graph 1. Relative milk and grass intake in springborn suckler calves (Boggs 1980). 20 40 60 80 100 %

CATTLE PRACTICE BCVA 2000 VOL 8 PART 2

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 INTRODUCTION Eimeria species of coccidia are considered to be one of the most important causes of diarrhoea in sheep and cattle in temperate areas of the world. The only data we have in this country for the incidence of coccidiosis in cattle is based on VIDA (Veterinary Investigation Diagnostic Analysis) figures and these suggest that the incidence of disease is on the increase. Some of the possible reasons for this increase will be discussed in this paper. oxygen, the oocysts sporulate within a matter of days and only now become infective. The cycle continues following emergence of sporozoites from the sporulated oocysts within the gut of the host. However, without re-infection, disease is usually self-limiting as a fixed number of asexual reproduction cycles occur and infection terminates with oocyst shedding. Those species invading the small intestine generally produce less pathogenic effects as the absorptive function can be compensated for, to some extent, by the large intestine. Conversely there is no compensating effect from other gut regions for large intestinal damage and, in addition, the rate of cellular turnover here is much less, consequently the pathology is more severe. BOVINE SPECIES OF IMPORTANCE Species of coccidia recognised in cattle:- Overview of Coccidiosis - Recent Obsevations Holliman A., Veterinary Laboratories Agency, Penrith, Merrythought, Calthwaite, Penrith, Cumbria. CA11 9RR. Age 0-1month over 2yrs 6mths-2yrs 1-6months The first and only publication on the occurrence of different coccidial species in cattle in the UK appeared in 1966 based on a study carried out in the South West of England (Joyner et al, 1966). Very little original work has been done in recent years. Perhaps we need to find a zoonotic form in the hope of generating sufficient funding!! Nonetheless, a wealth of useful, relevant and practical information is available in the literature and I would like to try and bring this together in this paper and explore one or two aspects of the disease itself, its treatment and control, which may have changed. THE PARASITE Most coccidia are intracellular parasites of the intestinal tract. At least 13 different species are known to infect cattle, all localised to the intestine (Taylor et al, 1994). Each species is usually localised to a specific location within the tract and each may invade different cells within each location. Even the location within each host cell may vary. Adaptive evolution par excellence. The typical life cycle of bovine coccidia usually involves 2 generations of asexual reproduction (schizogony) before a stage of sexual reproduction (gametogony) which releases resistant oocysts into the faeces. In the presence of warmth, moisture and Vida Figures 1990-1999 Species Prevalence Virulence E. bovis frequent ++ E. zuernii frequent ++ E. aubernensis frequent +(a) E. ellipsoidalis frequent +(a) E. alabamensis ? +(a) E. canadensis infrequent ? E. cylindrica infrequent ? E. illinoisensis infrequent ? E. brasiliensis infrequent ? E. wyomingensis infrequent - E. bukidnonensis rare - E. pellita rare - E. subspherica rare - a - Large numbers of oocysts administered experimentally may cause disease. The 2 main pathogenic species of cattle, in the UK and other parts of the temperate world, Eimeria bovis and Eimeria zuernii both affect the large intestine. First generation schizonts of E.bovis and E.zuernii occur in the lower small intestine, but second generation schizonts and gamonts are located in the caecum and colon, where they attack crypt cells (Taylor et al, 1994). The large endogenous stages induce both local and more extensive lesions, and are capable of killing stem cells, thus impairing cellular repair. (Fox 1985, Radostits et al, 1980, Taylor et al, 1994). Following 2 asexual generations a single oocyst can produce 24 x 106 second generation merozoites and ultimately many millions of oocysts; and an

CATTLE PRACTICE infection of only 1,000 oocysts would lead to the destruction of 24 billion host intestinal cells!. Interestingly, the greater the infecting dose the lower the number of oocysts/oocyst ingested, a phenomenon known as the "crowding effect". Eimeria auburnensis and Eimeria ellipsoidalis are thought to be of minor pathogenic significance, but a fifth species, Eimeria alabamensis is becoming increasingly recognised as a cause of diarrhoea. The endogenous stages of E. alabamensis occur within the nuclei of the epithelial cells of the small intestinal villi. Long thought to be non-pathogenic, work in Germany in the 1970's (Grafner et al, 1982) and in Scandinavia, particularly Sweden, in the 1990's (Svensson et al, 1994) confirmed a pathogenic role for this species. The remaining 8 species are thought to have minimal or no clinical significance. The pre-patent period of the 2 main pathogenic species is 15-20 days, and the patent period about 11 days. However, E.alabamensis has a pre-patent period of only 8 days and a patent period of 5 days. A feature of this latter species are the many millions of oocysts present in a faecal specimen. PATHOGENICITY The pathogenicity of any species depends on:- i)Location of parasite within intestinal tract, eg. ileum, colon, caecum. ii)Number of host cells destroyed/infecting oocyst, which in turn depends on:- (a) number of merozoite generations. (b) number of merozoites/generation. (c) location of parasite within the cell. iii)Size of the infecting dose. iv)Degree and time of re-infection. (v)Immunity. Even pathogenic species may elicit no pathology in an immune host, but immunity to some species may be only partial. Stress may render an immune host susceptible. THE DISEASE Up to 95% of infections may be sub-clinical, and the consequent reduction in food intake and daily liveweight gain often goes unrecognised. Such animals may shed oocysts in low numbers for months or years without ever showing overt clinical signs. The significance of this in relation to the perpetuation of infection on a farm will be discussed later. Coccidiosis may be seen anywhere, at any time; it is both sporadic and unpredictable; age, season and system, both indoors and out, pose no barrier to infection with this parasite. Symptoms may range from chronic, low-grade to acute, severe and often fatal. Clinical signs, when present, appear during the gametogenous phase and are typically seen between BCVA 2000 3 weeks and 6 months of age, although cattle up to 2 years of age, and occasionally older, are increasingly presenting with overt disease. Acute and chronic forms of disease associated with E. bovis and E. zuernii infection may occur. Acute coccidiosis One or more of the following signs are always present:- • diarrhoea • catarrhal enteritis • dysentery • tenesmus • anaemia • pyrexia • dehydration • a range of secondary infections Although dramatic when present, neither dysentery nor tenesmus are present in more than 50% of acute episodes. The acute phase of infection lasts 3-4 days and, if the animal survives, recovery begins at 7-10 days. A post-mortem examination at this time would reveal erosion of colonic mucosa with diphtheritic membrane formation, focal and diffuse haemorrhages, sub-mucosal oedema and semi-fluid bloody content (Stockdale 1977). The extensive colonic epithelial destruction results in a dramatic loss of absorptive function and may result in extensive blood loss. In the United States a nervous form of the disease has been described, with muscle tremors, staggering, convulsions and blindness and a fatality rate of up to 50% (Radostits et al, 1980, Julian 1976). However, no associated gross or histological lesions in the CNS have ever been demonstrated and the exact significance of these signs remains unclear. Similar signs in young cattle in the UK are rarely attributed to coccidiosis and the reason for this discrepancy is not clear. Chronic Coccidiosis A more chronic form of infection is described. Diarrhoea is usually present in the form of pasty faeces and the calves appear weak and listless with drooping eyes and staring coat. This form of the disease tends to be under-diagnosed. Faecal oocyst count is often low or negligible and post-mortem evidence is usually lacking because the overall mortality rate is low. Disease results from continual re-infection in a heavily contaminated environment with a partial immune response barely holding the parasite in check. Chronic intestinal pathology ensures a protracted recovery period. This may be relevant in relation to the next paper on peri-weaning scour. Reports detailing the role of E.alabamensis in calf VOL 8 PART 2

CATTLE PRACTICE diarrhoea describe a more specific condition (Marshall et al, 1998, Radostits et al, 1980, Svensson et al, 1996). They describe a diarrhoeic condition of calves, with faeces varying from gruel-like to watery, seen 4-6 days after turnout in the spring. Signs include anorexia, listlessness and weight loss and appear to be associated with asexual stages in the small intestine (Long 1989, Svensson et al, 1996). 8- 10 days post-turnout millions of oocysts are present in the faeces. It is thought that over-wintering oocysts represent the main source of infection. Evidence is accumulating that a similar syndrome may occur in the UK. (J Catchpole pers.comm, A Otter pers.comm.) DIAGNOSIS An accurate diagnosis may depend ultimately on a post mortem examination but ante mortem diagnostic aids include:- •clinical history •clinical signs •oocysts in faeces - most coccidial species can be identified by the size, shape and thickness of the oocyst wall, but there is some overlap between species. However, the procedure is simplified following artificial sporulation of the oocyst in potassium dichromate solution - a chemical that would normally be lethal to most parasite eggs! BCVA 2000 animals may shed small numbers of oocysts in the faeces for weeks or months, but the infection remains inapparent - there is sufficient protective immunity to limit but not exclude infection. This will be discussed further under 'Immunity'. (c) In severely affected diarrhoeic calves the main oocyst production phase may have passed, or may not even have started. Oocysts of E.bovis and E.zuernii are usually seen in the faeces on day 16 or 17 after infection (Ernst et al, 1986). Oocyst numbers may be underestimated due to the dilution factor of watery faeces. VOL 8 PART 2 Bovine coccidial oocysts: non-sporulated and sporulated The demonstration of oocysts alone is not diagnostic because:- (a) they may represent a non-pathogenic species, or (b) a pathogenic species in a partially immune host. It is a little recognised fact that of all the bovine coccidial species, E.bovis and E.zuernii occur most frequently and often in the greatest numbers and yet clinical symptoms are not common. Recovered Days - post-mortem examination - typical gross and microscopic pathology. Demonstration of schizonts, gamonts, oocysts in mucosal scrapings. In heavily infected calves almost every epethelial cell in the target areas is infected. TREATMENT Most cases of clinical coccidiosis recover without treatment. However, if calves become anaemic, anorexic, weak or dehydrated, supportive therapy may be indicated. Clinical signs usually become apparent during the late asexual or early sexual phase of the life cycle. The passage of oocysts lags behind the onset of signs and by the time high numbers of oocysts appear in the faeces, the disease has probably run its course. Specific anti-coccidial treatment at this time is unlikely to confer significant benefit. Furthermore, most of the traditional coccidiostats act at the early asexual stage and their use during an acute clinical episode would be a pointless exercise in the individual case. Far better to concentrate one's efforts on prophylactic therapy of in-contact animals and supportive treatment to control secondary infections which are a significant feature of coccidial infections. A depression of immune function is a common sequel to coccidiosis. (Roth et al, 1989). Because of the relatively infrequent use of anticoccidials in cattle, drug resistance has been slow to develop and a wide range of products may, in theory, be used. Number of oocysts

CATTLE PRACTICE Coccidia in the sexual stages of their life cycle, i.e. gametogony, are rarely susceptible to anti-coccidial products, which generally act on the early or late asexual stages. Nonetheless many, if not all, of these products are highly effective in preventing clinical signs, weight loss and oocyst output when used prophylactically, (Conlogue et al, 1984, Emanual et al, 1988, Fitzgerald et al, 1973, Fitzgerald et al, 1989, Fitgerald et al, 1994, Foreyt et al, 1986, Stockdale 1978, Svensson et al, 1996). However, only DECCOX is licensed for use in cattle in the UK, as an in-feed additive, to control coccidiosis. It has been shown to prevent clinical coccidiosis and significantly reduce oocyst numbers (Foreyt et al, 1986). It can be fed continuously for 28 days at 0.5mg/kg or every 2nd day at 1-1.5mg/kg, or every 3rd day at 1.5mg/kg. VECOXAN is given by single dose at 1mg/kg and is widely used in cattle in France. It is highly effective, with a wide safety margin. However, in the UK it is only licensed for sheep. Where in-feed medication is not practical Vecoxan may be used "off-label" via the prescription cascade, for both BCVA 2000 treatment and prevention, provided a 28 day withdrawal period is adhered to. Sulpha drugs run into problems of toxicity, reduced growth rates and only partial efficacy. The ionophore antibiotics, eg. monensin, are no longer licensed as coccidiostats in the UK. However, ROMENSIN G100 is licensed as a growth promoter for incorporation into feed or feed blocks. Amprolium is now available only as "AMPROL PLUS", as a coccidiostat premix in poultry rations. Drugs other than those with data sheet claims should be used with caution because of potential tissue residues and legal consequences. Steroids are strongly contra-indicated. They have been shown to enhance the life cycle and pathogenicity and reduce subsequent immunity (Long 1989). A major change took place in 1998 relating to the use of zootechnical feed additives, implementing Directive 70/524/EC. Zootechnical additives are no longer authorised under the Medicines Act 1968. They can now be marketed only in accordance with the requirements of the Annexes to the Directive VOL 8 PART 2 Drug Trade Name Mode Of Action Life Cycle Stage Against Which Drug Acts Legal Status Uk Licence For Cattle? Diclazuril “Vecoxan” coccidiocidal unknown POM NO coccidiocidal schizogony and gametogony stages Toltrazuril “Baycox” coccidiostatic sporozoites POM NO Monensin "Romensin" G100 coccidiostatic sporozoites and merozoites ZFA NO Lasalocid “Avatec 15% CC premix” coccidiostatic sporozoites and merozoites ZFA NO Decoquinate “Deccox” coccidiostatic sporozoites MFS YES Sulfamethoxy -pyridazine “Bimalong” “Sulfapyrine LA” “Midicel” Sulfadimidine “Bimadine” “Sulfoxine 333” coccidiostatic 2nd generation schizonts (late in cycle) POM YES Amprolium “Amprol Plus” coccidiostatic 1st generation schizonts and merozoites ZFA NO POM = Prescription Only Medicine ZFA = Zootechnical Feed Additive MFS = Medicated Feedingstuff

CATTLE PRACTICE 70/524/EC, as amended. This means that whereas before it was possible for a vet to prescribe such products under the terms of the prescribing cascade, even if they were not authorised for that use, this is no longer permitted. Feedingstuffs which contain veterinary medicinal products, eg Deccox, on the advice of a veterinary surgeon, still require authorisation but are now classified as MFS and require a Medicated Feedingstuffs Prescription which has replaced the Veterinary Written Direction (VWD). Any establishment which handles zootechnical feed additives, medicated premixes or feedingstuffs must be approved by the relevant authority which in England is the Royal Pharmaceutical Society of Great Britain. Some feed-mills may not encourage the use of medicated feed due to the difficulties it can cause them. IMMUNITY There is little or no cross-protection from one coccidial species to another in the same host, and immunity is seldom complete. This applies particularly to E.zuernii where recovered animals are often continuously re-infected, resulting in a light infection and a constant source of further infection to young stock. Most animals are repeatedly infected through oocyst ingestion until immunity is acquired following several infection cycles (Fox 1985). It has been suggested that trickle infection with regular low doses of oocysts will stimulate a better immunity than a single heavy dose (Fox 1989, Long 1989). Resistance acquired as calves continues, more or less, into adulthood. Adults generally show few, if any, clinical signs. A balance exists between the build-up of resistance and the build-up of infection with the result that 95% of infections remain subclinical. Most cattle within a population are thought to be infected at a sub-clinical level. Coccidia are opportunist parasites awaiting the right combination of events to tip the balance in their favour. Immunity may be overcome as the result of an overwhelming infection or in association with a reduction of immuno-competence, usually related to stress. This almost certainly accounts for the occasional cases seen in older animals, even adults, although sometimes such events remain unexplained (Gunning et al, 1996). The incidence and even the severity of coccidiosis outbreaks is often directly related to the level of stress. Several of the associated stress factors have been mentioned already. Weaning and turn-out to pasture significantly depress the immune response, particularly when coupled with adverse weather conditions and are commonly linked to outbreaks of disease. Antibodies do not appear to play a crucial role in protection, immunity being mediated by Tlymphocytes, possibly of the CD4 + series . BCVA 2000 CONTROL Coccidiosis, not surprisingly, is typically, but not exclusively, a disease of management systems with an emphasis on high stocking densities. Sensible control procedures should include some, or all, of the following:- • isolate all affected cases and treat effects of dysentery. • reduce stocking density. • keep feed in troughs to avoid faecal contamination. • avoid faecal contamination of water supplies. • provide extra bedding to reduce oocyst contamination. • minimize stressful management procedures during outbreak. e.g. dehorning, castration, dietary changes including weaning, transport. • mass medication of food or water for 28+ days in the face of disease or in anticipation of stress. • at pasture, move water troughs and feeders regularly. • ensure thorough cleaning and disinfection of buildings with a product effective against coccidial oocysts (see below). New generations of calves are often contaminated at birth, especially suckler calves in winter housing (Mage et al, 1989). Coccidial oocysts are remarkably resistant (Marquardt et al, 1960). They survive temperatures of -5 to -8°C for several months and will successfully over-winter in most UK situations. The repeat use of pasture for calves at turn-out is often linked to disease outbreaks, especially E.alabamensis. The thick double-walled oocyst is able to survive a whole range of harsh disinfectants, chemical agents and pH changes. However one product, "Oocide" (Antec International), claims a high degree of efficacy, with its dual action and release of ammonia. Use of such a product is vital in any control programme, and failure to do so negates much of the good work done in other areas. CONCLUSION There is some evidence to suggest that the incidence of clinical disease in the UK cattle population due to coccidiosis has been increasing in recent years. Whilst E.alabamensis may be playing an important role in outbreaks of diarrhoea in recently turned-out calves, its exact significance remains to be determined. However, the two main pathogens, both here and in other parts of the temperate world, E.bovis and E.zuernii, cause disease whenever and wherever conditions prove favourable for their multiplication. If the evidence is correct and disease incidence is indeed increasing possible reasons include:- VOL 8 PART 2

CATTLE PRACTICE 1. Calves are being more intensively housed/grazed. 2. Recent environmental conditions have been more favourable for parasite survival and sporulation 3. Stockmen are overworked as staff numbers reduce but stock numbers remain steady or even increase, leading to inadequate calf management e.g. bedding, feeding, early diagnosis etc. This in turn is likely to increase stress levels on stock. 4. Greater awareness on the part of investigating laboratories. The development of immune methods of control must be a desirable goal, as seen in the poultry sector, but I do not anticipate rapid developments in this area. Once again, as with so many other diseases, we fall back on the need for good stockmanship at a time when margins are being cut to the bone. Hopefully the ensuing rewards will extend beyond the control of this potentially serious infection. It is many years since a co-ordinated, structured investigation of bovine coccidiosis took place in the UK and I feel that such an approach could provide much useful information which is currently lacking. REFERENCES Conlogue G., Foreyt W.J. & Westcott R.B. (1984). Bovine coccidiosis: protective effects of low-level infection and coccidiostat treatments in calves. Am. J. Vet Res. 45: (5) 863-866. Emanuel C., Bianchi C. & Biolatti B. (1988). Efficacy of toltrazuril in bovine coccidiosis.Vet. Med. Rev. 59: 90 - 91. Ernst J. V., & Benz G. W. (1986). Intestinal Coccidiosis in Cattle. Veterinary Clinic of North America : Food Animal Practice 2: (2) 283-291. Fitzgerald P.R. & Mansfield M.E. (1973) Efficacy of monensin against bovine coccidiosis in young Holstein-Friesian calves.J. Protozool. 20: (1) 121 - 126. Fitzgerald P.R. (1975). The significance of bovine coccidiosis as a disease in the United States.Bovine Practitioner, 10: 28 - 33. Fitzgerald P.R. & Mansfield M.E. (1989). Effects of intermittent and continuous administration of decoquinate on bovine coccidiosis in male calves. Am. J. Vet Res. 50: (6), 961 - 964. Fitzgerald P.R. & Mansfield M.E. (1994). Control of bovine coccidiosis with monensin in non-resistant newborn calves.Am. J. Vet Res. 45: (10), 1984 - 1988. Foreyt W. J., Rice D. H., Wescott R. B. (1986). Evaluation of lasalocid as a coccidiostat in calves: Titration, efficacy, and comparison with monensin and decoquinate. Am J Vet Res, 47: (9), 2031-2035. Fox J.E. (1985). Coccidiosis in Cattle. Modern Veterinary Practice 66: 113-116 Fox J.E. (1989). The epidemiology of subclinical coccidiosis in United States and results of its prevention in the bovine and other ruminants.Coccidia and intestinal coccidiomorphs. Proceedings of BCVA 2000 the Vth International Coccidiosis Conference. Tours (France), 17 - 20 October 1989. INRA publication, 461 - 466. Grafner G., Graubmann H-D, Kron A, Muller H, Daetz H-H, Plotner J, Benda A (1982) Zum Auftreten der Weiderkokzidiose in Jungrinderbestanden. Mh. Vet.-Med. 37: 776-779. Gunning R F & Wessels M E (1996) Clinical coccidiosis in a herd of dairy cows. Vet. Rec. 139: 497-498 Joyner L P, Norton C C, Davies S F M, Watkins C V (1966). The species of coccidia occurring in cattle and sheep in the SouthWest of England. Parasitology 56: 531-541. Julian R J (1976) Nervous signs in bovine coccidiosis. Modern Veterinary Practice 57: 711-718. Long P.L. (1989). Factors affecting the life cycle and development of Eimeria.Coccidia and intestinal coccidiomorphs. Proceedings of the Vth International Coccidiosis Conference. Tours (France), 17 - 20 October 1989. INRA publication, 91: Mage C. & Reynal P. (1989) Epidemiological observations of coccidiosis in suckler calves in France. Coccidia and intestinal coccidiomorphs. Proceedings of the Vth International Coccidiosis Conference.Tours (France), 17-20 October 1989.INRA publication, 457 - 460. Marquardt W.C., Senger C.M. & Seghetti L. (1960). The effect of physical and chemical agents on the oocyst of Eimeria zuernii (Protozoa, Coccidia). J. Protozool 7: (2). 186 - 189. Marshall R.N., Catchpole J., Green J.A., & Webster K.A. (1998). Bovine coccidiosis in calves following turn-out. Veterinary Record 143: (13) 366 - 367. Radostits O.M. & Stockdale P.H.G. (1980). A brief review of bovine coccidiosis in Western Canada. Can. Vet. J. 21: 227 - 230. Roth J A, Jarvinen J A, Frank D E, Fox J E (1989) Alteration of neutrophil function associated with coccidiosis in cattle: Influence of decoquinate and dexamethasone. Am. J. Vet. Res. 50: 1250- 1253 Stockdale PHG (1977) The Pathogenesis of the Lesions Produced by Eimeria zuernii in Calves. Can. J. Comp. Med. 41: 338-344 Stockdale PHG (1978) Treatment of bovine coccidiosis due to Eimeria zuernii Can. J. Ani. Sci. 58: (4) 823 Svensson, C., Hooshmand-Rad, P., Pehrson, B., Tornquist, M. & Uggla, A. (1993). Excretion of Eimeria oocysts in calves during their first three weeks after turn-out to pasture. Acta Vet. Scand. 34: 175 - 182. Svensson, C., Uggla, A. & Pehrson B. (1994). Eimeria alabamensis infection as a cause of diarrhoea in calves at pasture. Vet. Parasitol. 53: 33 - 43. Svensson, C., (1995) Survival of Oocysts of Eimeria alabamensis on Pastures under Different Climatic Conditions in Sweden. Acta vet. scand., 36: 9-20. Svensson, C. & Olofsson H. (1996). Eimeria alabamensis coccidiosis in grazing calves - control by a long-acting baquiloprim/ sulphadimidine bolus. Appl. Parasitol. 37: 168 - 176. Svensson, C., Olofsson, H. & Uggla A (1996). Immunisation of calves against Eimeria alabamensis coccidiosis.Appl. Parasitol 37: 209 - 216. Taylor, M.A. & Catchpole, J. (1994). Coccidiosis of domestic ruminants. Appl. Parasitol. 35: 73 - 86. Uggla A. (Editor) (1993). Report from a Nordic Seminar: Coccidial infections of ruminants - diagnosis, epidemiology and control. Bull. Scand. Soc Parasitol 1: 37 - 47 VOL 8 PART 2

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 INTRODUCTION Chronic peri-weaning calf diarrhoea is not a new syndrome (Blowey 1988), although it does appear to be increasing in both prevalence and severity and would certainly be listed as one of my own "difficult case" categories. The syndrome also causes major problems for feed companies because diet is often implicated. As no consistent infectious organisms have been identified, and no precise clinical description exists, it is difficult to explain to clients why it is not necessarily the recent delivery of calf food which is involved! CLINICAL SIGNS Typical signs are a chronic grey-brown, pasty scour seen in calves between four and ten weeks old and invariably when concentrates are being consumed. Mild cases show little more than increased faecal soiling of the tail. In more advanced cases there is profuse scour, weight loss, depressed appetite and occasionally death. In the terminal stages the calf often develops a pot-bellied appearance, suggesting that the rumen is excessively filled with undigested fibrous material. Although mortality is low, morbidity can be high and individual calves can be left with an unusually persistent scour which is unresponsive to treatment. Many calves continue scouring and remain in poor bodily condition for 4-6 weeks and only slowly resolve. The increase in both prevalence and severity of the syndrome could be associated with increasing group size and the more frequent use of group feeding systems. AETIOLOGY Later papers deal with this in more detail, but the explosive spread of the syndrome through one or more batches of calves would suggest that infectious organisms must have at least some part to play. For many years we have identified "motile protozoa" in fresh faecal samples from affected calves. The protozoa have two nuclear bodies and are most likely to be Giardia species. Giardia has been recorded as a cause of chronic diarrhoea in calves by Rings and Rings (1996) and by O'Handley et al (1999). It is most probable that the syndrome is similar to colitis in pigs: a nutritional disturbance leads to proliferation and overgrowth of otherwise "normal intestinal organisms. Balantidium coli is the motile parasite most commonly seen with porcine colitis. POST-MORTEM As mortality is low, opportunities for post-mortem examinations are rare and even then findings are unremarkable. The rumen is commonly impacted with undigested fibrous material and the colon dilated, with excessively fluid and grey contents. In one of my own recent cases the terminal ileum was thickened and inflamed and histological examination revealed changes typical of coccidiosis. Instigation of improved hygiene and incorporation of decoquinate ("Deccox", Merial Animal Health Ltd) into the concentrate ration at 100ppm appeared to prevent further cases. MANAGEMENT FACTORS Management factors are likely to play a major part in inducing the syndrome, although once the scouring starts it remains difficult to resolve. Although somewhat anecdotal, it is the author's opinion that the following may be involved:- Group housing Calves penned singly until 2-3 weeks after weaning are less commonly affected, or are not affected until they are group housed. Use of pellets rather than coarse mix Calves eat coarse mix more slowly, chew it more thoroughly and therefore salivate more. This could reduce potential rumen acidosis. Digestive upsets, especially those associated with poor abomasal groove closure (Blowey 1994) Group feeding of milk, or feeding through inappropriate or excessively open teats can predispose. Inappropriate concentrates A calf is not a full ruminant until 12 weeks old, its rumen being more acid in the early stages of development. Use of Chronic Peri-Weaning Diarrhoea - The Clinical Syndrome Blowey R.W., Wood Veterinary Group, 125 Bristol Road, Quedgeley, Gloucester, GL2 4NB. ABSTRACT The syndrome of chronic diarrhoea in calves during the early stages of rumen development is increasing in both prevalence and severity, leading to depressed growth and occasional deaths. This paper describes the clinical syndrome and some of the potential management factors involved. KEYWORDS: calves, scour, management, nutrition, protozoa.

CATTLE PRACTICE rapidly fermenting feeds such as maize gluten or wheat, or unsuitable protein sources such as those present in adult dairy concentrates, will predispose to scouring. TREATMENT This is largely symptomatic and includes antimicrobials, anticoccidials and vitamins. Macrolides, for example tilimicosin, have been used and sulphonamides and other anticoccidial agents. Badly affected calves should be returned to a whole milk diet without access to solid food, and possibly fed three times daily. The fairly rapid improvement in such calves would suggest that abomasal function is not impaired. BCVA 2000 REFERENCES Blowey R.W. (1988) A Veterinary Book for Dairy Farmers, 2nd Edition, page 54. Farming Press, Ipswich Blowey R.W. (1994 Cattle Practice 2 375-382 "Calf feeding practices in relation to health". O'Handley R.M., Cockwill C., McAllister T.A., Jelinski M., Morck D.W., Olsen M.E., J. Am.Vet.Med. Assoc. 1999 Feb 1;214 (3) "Duration of naturally acquired giardiosis and cryptosporidiosis in dairy calves and their association with diarrhoea". Rings D.M. & Rings M.B. (1996) "Managing cryptosporidium and Giardia infections in domestic ruminants". Veterinary Medicine 88: 1125-1131 VOL 8 PART 2

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 morbidity is very high and the mortality generally very low, although sudden death of some calves can occur at the beginning of an outbreak. The diarrhoea is usually self-limiting but the associated weight loss can be substantial and the differences between calves can be seen months later. Post-mortem examination of affected calves has demonstrated little of significance, except for one calf which was found on histological examination to have an allergic gastro-enteritis. TREATMENT Initially no treatment was given, except for electrolytes for the calves developing significant dehydration. However, as the disease has developed, the mortality rate has increased (although it is still very low), thus antibiotic treatment is now used at the start of an outbreak. The two antibiotics used have been tylosin and tilmicosin. Because of the selflimiting nature of the disease, it is difficult to assess the effectiveness of antibiotic treatment, but the subjective assessment is that it has reduced the severity and duration of the disease. DISCUSSION The cause of peri-weaning diarrhoea on this farm is unclear. The response to antibiotics suggests that it is at least partly bacterial in origin, although such bacteria could be secondary to the primary cause. Peri-weaning diarrhoea may be dietary in origin, however the change from a proprietary coarse mix to a cheaper dustier home mix does not seem to have increased the incidence. Further research is needed to discover the cause of this disease. Treatment of peri-weaning diarrhoea is currently limited to antibiotics, which are not effective at eliminating the disease. Other potential treatments such as zinc oxide (effective against colitis in pigs which can have very similar clinical signs) or fenbendazole (effective against Giardia which has been a frequent finding in some outbreaks on some farms) may be more effective and should be investigated. Peri-Weaning Diarrhoea Syndrome - A Farm Perspective Laven R., Adas Bridgets, Martyr Worthy, Winchester, Hants. SO21 1AP. Peri-weaning diarrhoea is becoming a significant and increasing disease of calves on many farms, at ADAS Bridgets peri-weaning diarrhoea is a problem that occurs sporadically in batches of calves. The calves are raised in hutches from birth to weaning at approximately six to eight weeks of age, they are then moved to group accommodation. Table 1 summarises the feeding and housing of the calves from birth until after weaning. Table 1. Feeding and housing of calves from birth to weaning Age Liquid feed Solid feed Housing 0-1 week Colostrum twice daily None Outdoor hutches 1-6 weeks Milk twice daily Home-mixed coarse mix Outdoor hutches 6-8 weeks Weaning Home-mixed coarse mix Outdoor hutches 8 weeks + None Home-mixed coarse mix Hay Group-fed straw yards Weaning occurs when a calf is eating approximately 1kg of concentrates per day. Calves are usually fed milk once daily for two or three days before weaning, however because calves are moved to the postweaning accommodation in batches, some calves are weaned abruptly. After weaning the calves are group housed on straw yards on a site remote from the main farm, away from contact with other cattle. It is primarily on this site that the peri-weaning diarrhoea is seen. As yet no milk-fed calves have developed peri-weaning diarrhoea on this farm. The outbreaks of peri-weaning diarrhoea are sporadic, with less than one third of batches affected. Peri-weaning diarrhoea has affected animals up to 20 weeks of age. There is no consistent triggering factor, although one outbreak was associated with regrouping of the calves based on weight. CLINICAL SIGNS Sudden onset of profuse pasty grey diarrhoea (with the consistency of tapioca). The calves tend to be bright and to continue eating, dehydration tends to be moderate when compared to neo-natal diarrhoea. The

CATTLE PRACTICE BCVA 2000 VOL 8 PART 2

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 INTRODUCTION Increasing numbers of cases of Peri-Weaning Scour Syndrome have been reported to Veterinary Laboratories Agency (VLA) Centres since 1997. The problem has been raised in BCVA clinical clubs and a review published (Bidewell C.A. et al 1999). The cause of these scour cases has not been established by routine examinations. The following case definition has been suggested:- • Affects dairy bred calves. • Chronic grey/brown diarrhoea. • Starts between 3 and 10 weeks of age and persists for at least one month. • Appetite unaffected. • Aetiology not identified by routine examinations. • Affects at least 50 per cent of the group, with low case fatality. A small postal survey of practices was carried out in the VLA Langford catchment area and of 17 that replied, 12 reported seeing incidents in the last year that fitted this case definition with an average number of cases per practice of 2.5. Many of the cases appeared to be in South Somerset, Dorset or Wiltshire. In our experience this syndrome causes anxiety and frustration to the farmer or farm manager as often this is on apparently well-managed farms where cattle have previously thrived. INVESTIGATIONS Data was accumulated from twelve farm investigations from 5 VLA Centres. Most cases were in southern England. All cases were in dairy bred calves. Pre-weaning diets varied with most farms feeding milk replacer, a starter pellet and straw. No particular feed manufacturer was involved. Roughage was normally straw but occasionally hay. Post-weaning, various pellets or rearing nuts were fed with normally straw but occasionally hay or silage. There did not appear to be any striking consistencies in the diet fed or in the management of these calves. Six out of 12 farms had experienced this syndrome in previous years. The following possible aetiologies were considered:- Possible aetiologies • Nutrition. • Coccidiosis. • Salmonellosis. • Campylobacter. • Cryptosporidia. • Vitamin and mineral deficiencies. • Mucosal disease. • Giardiasis. • Protozoal infections. Nutrition Farmers reported that they were normally feeding the same or very similar diets as in previous years. They had often reduced the amount of concentrate feed fed by the time of a visit as they felt that the more they fed, the more calves scoured. Many had changed feeds to different brands or different manufacturers without response. Once the animals were affected with this syndrome, dietary changes seemed to make no or very little difference in most cases although 3/11 farms reported a response with one each feeding silage, one feeding sugar beet and one returning the calves to a milk diet. If the cause is dietary, it might be expected for this syndrome to be more widespread. The fact that individual farms are often affected in successive years may also suggest a dietary cause is less likely. Coccidiosis Coccidial oocysts were found in faecal samples from 6 out of 12 outbreaks. Normally this was just a low number of coccidia in one or two animals in the group and was not considered suggestive of coccidiosis. Salmonella No salmonellas were found in faecal samples from any of the12 outbreaks. Campylobacter Campylobacter was isolated from 3 out of 8 outbreaks. The species isolated were Campylobacter Peri-Weaning Calf Diarrhoea Syndrome: Findings to Date and Further Investigation Jones J.R., VLA Langford , Langford House, Langford, Bristol, BS40 5DX. ABSTRACT Increasing numbers of incidents of a persistent scour in calves that begins at around the time of weaning and persists for at least 6 weeks have been reported. The result of investigations to date are described and possible aetiologies and future investigations discussed. The aetiology of this syndrome is unknown.

CATTLE PRACTICE jejuni or Campylobacter hyointestinalis. Campylobacter species are common isolates from healthy and diarrhoeic calves. Although there are publications to the contrary, workers at Compton concluded that Campylobacter fetus subsp fetus and C. hyointestinalis are non-pathogenic in the intestinal tract of the calf and the importance of Campylobacter jejuni is still uncertain but is unlikely to be of major significance in diarrhoea in calves (Morgan et al 1986). Giardia Giardia cysts were demonstrated in faeces from calves from 8 out of 10 outbreaks. Occasionally most of the group tested were positive for giardia cysts but normally it was just the occasional one or two animals in a group. Giardia is thought to be an enteric pathogen causing a similar syndrome in Canada and North America (O' Handley et al 1999, Xiao 1994). On four units, treatment with fenbendazole (Panacur; Hoechst) has been used with no response. Fenbendazole is an effective treatment for giardiosis in cattle (O' Handley et al 1997). The prevalence of giardia infection in healthy cattle in Britain is not known. Rotavirus Rotavirus was demonstrated in 1 out of 12 outbreaks sampled. Coronavirus Coronavirus was not demonstrated in any of the 12 outbreaks investigated. BVD Antigen No persistently infected calves were identified in the 12 outbreaks. BVD Antibody Six out of twelve outbreaks had BVD antibody positive animals amongst them, the remaining six were all sero-negative. Protozoal Infections Motile protozoa have been observed in intestinal smears from calves presented live. It is unclear whether these reflect overflow from the rumen. BIOCHEMISTRY Blood copper, GSH-PX (for selenium) and B12 were within normal ranges. Liver copper levels in calves examined post-mortem were often markedly elevated, but this seems to be a feature of emaciated or ill-thriven calves and may therefore not be related to this condition. BCVA 2000 Some calves have low serum vitamin A or E. Possibly this reflects poor intakes of feed as farmers have restricted concentrate fed or possibly poor absorption of these vitamins. Blood urea levels were low in some but not all outbreaks. This may be a reflection of decreased concentrate intakes or malabsorption. PATHOLOGY Because of the low mortality, post mortem material was only obtained from 4 out of these 12 outbreaks. However, material has also been obtained from similar cases where a farm visit has not been carried out. Gross post mortem examination has not revealed any significant abnormalities. Motile protozoa have been demonstrated on intestinal smears, although the significance of this is not known Histopathology Because of the low fatality rate calves have not been received from most of these outbreaks. When histopathology has been carried out on freshly euthanased calves, occasional calves have shown a purulent abomasitis. Slender filamentous bacteria in the gastric pits of the stomach are a consistent finding in these cases and also in similarly affected unthrifty weaned calves with diarrhoea that have been seen at VLA Langford (Personal Communication R.F. Gunning). Low grade inflammation and crypt abscesses have also been observed. TREATMENTS A variety of treatments had been tried and there was normally a transient response to antibiotics regardless of the antibiotic used. Some vets report a response to boluses containing baquiloprim and sulphadimidine (Zaquilan bolus; Schering-Plough) but in this series of cases, only 1 out of 3 outbreaks improved after administration of this bolus. Tylosin is quoted anecdotally as a treatment for this syndrome and in 1 out of 2 cases there was a transient response only. Sulphamethoxypyridazine (Midicel; Pharmacia and Upjohn) was used on a number of farms without response. The lack of response to treatment with fenbendazole has been discussed earlier. SUMMARY Although no specific aetiology has been determined, the results to date suggest that BVDV rotavirus, coronavirus, salmonella and campylobacter are unlikely to be involved. Further investigation of the cause of the condition is dependent on detailed histopathology of the gastro-intestinal tract and a more detailed case series or case control study. VOL 8 PART 2

CATTLE PRACTICE FURTHER INVESTIGATIONS A proposal has been put forward to identify 20 further outbreaks conforming to the case definition and carry out a case series study examining feeding and management factors in more detail. In addition ten typically affected calves in the early stages of the disease will be obtained for detailed histopathology. Further definition of the pathology underlying the condition will provide a powerful indication of the likely aetiology. Any hypothesis generated can be subsequently tested using the data acquired in any case series/control study. ACKNOWLEDGEMENTS The author acknowledges the contribution of all VLA colleagues who contributed to the results discussed here, and to the practising veterinary surgeons and farmers involved for their help and cooperation. BCVA 2000 REFERENCES Bidewell C. A., David G. P., Gunning R. F., Harwood D. G., Higgins R. J, Jones J. R., Laven R. A., (1999) Persistent periweaning calf diarrhoea. UK Vet 4: 35-37 Gunning R. F., personal communication O' Handley R. M., Olson M. E., McAllister T. A., Morck D. W., Jelinski M., Royan G., Cheung K-J., (1997) Efficacy of fenbendazole for treatment of giardiosis in calves American Journal of Veterinary Research, 58: 384-388 O' Handley R. M., Cockwill C., Mcallister T. A., Jelinski M., Morck D. W., Olson M. E. (1999) Duration of naturally acquired giardiosis and cryptosporidiosis in dairy calves and their association with diarrhoea. Journal of the American Veterinary Medical Association, 214: 391-396 Morgan J. H., Hall G. A., Reynolds D. J. (1986) Proceedings of the 14th World Congress on Diseases of Cattle, Dublin. 1: 325-330 Xiao L. (1994) Giardia infection in farm animals. Parasitology Today 10: 436-438 VOL 8 PART 2

CATTLE PRACTICE BCVA 2000 VOL 8 PART 2

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 INTRODUCTION The brain can be conveniently divided into six areas, each with a recognised neurological "syndrome" however only four cerebral, cerebellar, pontomedullary (brain stem) and vestibular concern the veterinary practitioner. CEREBRAL SYNDROME Diffuse cerebral disease is common in ruminants associated with metabolic disease in adults and bacterial meningo-encephalitis in neonates. The cerebrum is concerned with mental state, behaviour and, in conjunction with the eye and optic (II) nerve, vision. Clinical signs which would suggest cerebral dysfunction would include; blindness, but with normal pupillary light reflex (II, III), compulsive walking, circling, constant chewing movements, severe depression, dementia, yawning, head pressing progressing to hyperaesthesia to auditory and tactile stimuli, and opisthotonus Ipsilateral compulsive circling, deviation of the head (not a head tilt), depression with contralateral blindness and postural deficits are variably seen in animals with unilateral cerebral lesions. CEREBELLAR SYNDROME The cerebellum is primarily concerned with fine coordination of voluntary movement. In cerebellar dysfunction limb movements are spastic (rigid), clumsy and jerky. Initiation of movement is delayed and may be accompanied by intention tremors. Cerebellar disease is characterised by a wide-based stance and ataxia (inco-ordination), particularly of the pelvic limbs but with preservation of normal muscle strength. In addition to the ataxia, dysmetria may be observed with hypermetria the more common form observed in cerebellar disease. Opisthotonus can occur in animals with severe lesions of the rostral cerebellum. VESTIBULAR SYNDROME The major clinical sign associated with a vestibular lesion is that of ipsilateral (to the same side) head tilt. Circling may also be observed. Positional nystagmus may be depressed or absent in animals with a vestibular lesion. Facial nerve paralysis is common in peripheral vestibular disease since both facial and sympathetic nerves fibres pass close to the middle ear. PONTOMEDULLARY SYNDROME As most of the cranial nerve nuclei are present in the brainstem, dysfunction is characterised by multiple cranial nerve deficits. Depression is also a key sign of brainstem disease which is attributed to a lesion in the ascending reticular activating system. Circling, ipsilateral hemiparesis and proprioceptive defects are also common. In diseases affecting the brainstem circling can be observed because of involvement of the vestibulo-cochlear nucleus. Involvement of the facial nucleus results in ipsilateral facial nerve paralysis. Facial palsy is evident as drooped ear, drooped upper eyelid (ptosis) and flaccid lip. Involvement of trigeminal nerve or the trigeminal motor nucleus results in paralysis of the cheek muscles and decreased facial skin sensation. CONGENITAL/ACQUIRED CENTRAL NERVOUS SYSTEM DEFECTS Cerebellar hypoplasia/hydranencephaly The cerebellum is the most common CNS site for inutero insult. The cerebellum is primarily concerned with fine co-ordination of voluntary movement. In cerebellar dysfunction, limb movements are spastic (rigid), clumsy and jerky. Initiation of movement is delayed and may be accompanied by intention tremors. Cerebellar disease is characterised by a Clinician's Approach to Neurological Disorders in Young Cattle P. R. Scott., Easter Bush Veterinary Centre, Roslin, Midlothian EH25 9RG. ABSTRACT A methodical neurological examination allows central nervous system lesions to be localised to specific areas of the brain. The common diseases and conditions which affect those areas of the brain can then be listed and further investigated. The most useful and cost effective ancillary test is cerebrospinal fluid analysis. This methodical approach explores all aspects of the clinical presentation rather than fit the clinical signs to a known condition/disease. KEYWORDS: central nervous system, cerebrospinal fluid, calves.

CATTLE PRACTICE wide-based stance and ataxia (inco-ordination), particularly of the pelvic limbs but with preservation of normal muscle strength. In addition to the ataxia, dysmetria may be observed with hypermetria more commonly observed in cerebellar disease. Opisthotonus can occur in calves with severe lesions of the rostral cerebellum whether the result of an autosomal recessive condition or caused by inutero infection with bovine virus diarrhoea/mucosal disease (BVD/MD) virus. Such calves present in lateral recumbency with rigid extension of the neck and thoracic limbs and flexion of the pelvic limbs (opisthotonus) with clinical signs noted soon after birth. More typically, in-utero BVD/MD virus infection causes cerebellar hypoplasia (clinical signs listed above), and less commonly, hydranencephaly. In addition to the cerebellar signs, calves with hydranencephaly exhibit blindness and depression/ somnolence. Cerebellar dysfunction in young calves may be the first manifestation of active BVD/MD infection in the herd and it is important that these clinical signs are identified such that control measures are introduced to prevent further losses. SARCOCYSTOSIS Congenital sarcocystosis infestation has been recorded as a cause of recumbency in newborn calves. RECUMBENCY IN NEONATAL CALVES Recumbency is a common presenting clinical feature in calves less than one week-old. Among the more important points to establish during the historytaking include:- 1. Details of the birth 2. Whether the calf has ever been able to raise itself and stand unaided? 3. Whether the calf's general demeanour and/or appetite has changed? TRAUMA DURING SECOND STAGE LABOUR Excessive traction of oversized calves in anterior longitudinal presentation may cause, in order of increasing severity, peroneal nerve, femoral nerve, or spinal cord trauma, but only the latter two conditions result in paralysis and recumbency. FEMORAL NERVE PARALYSIS The femoral nerve supplies the quadriceps femoris and injury is not uncommon resulting in the calf's inability to extend the stifle joint and bear weight on that leg. Unilateral femoral nerve paralysis results in BCVA 2000 the inability of the calf to raise itself, but affected calves can stand unaided when assisted to their feet. Gradual return of function may take up to 6 weeks. Bilateral femoral paralysis results in inability to stand and should be differentiated from a thoraco-lumbar spinal lesion. The prognosis for bilateral femoral nerve paralysis is frequently hopeless despite intensive nursing and supportive care. SPINAL CORD LESIONS Spinal cord dysfunction, due to segmental hypoplasia, or related to a traumatic lesion such as epidural haemorrhage, vertebral body fracture or compressive lesion, is relatively uncommon in neonatal calves. Infection of a cervical vertebral body causing tetraparesis is not uncommon in 2 to 4 month-old calves which may be the major clinical presentation of Salmonella dublin infection in the herd. C1 - C6 The ataxia may vary from mild to moderate with the pelvic limbs worse affected. There is a range of muscle weakness extending to complete paralysis. Spinal reflexes are increased. Cervical pain may be present evident as rigidity of the neck with resentment to forced movement of the head. With severe lesions the animal is unable to maintain sternal recumbency but will make frequent attempts to raise itself from lateral recumbency. C6 - T2 Spinal cord lesions involving the brachial intumescence may result in equally severe deficits in both the thoracic and pelvic limbs. There is ataxia and weakness of all four limbs. Thoracic limb reflexes are reduced (lower motor neuron signs) with increased pelvic limb reflexes (upper motor neuron signs). T2 - L3 Calves with a spinal cord lesion caudal to T2, but cranial to L3, have normal thoracic limb function but upper motor neuron signs affecting the pelvic limbs. Affected animals frequently adopt a dog-sitting posture with normal thoracic limb function but with the pelvic limbs extended alongside the abdomen. L4-S2 A lesion involving the sacral outflow results in lower motor neuron signs of the pelvic limbs with superficial sensation loss, paresis, and reduced or absent reflexes. VOL 8 PART 2

CATTLE PRACTICE GROSS EXAMINATION OF CEREBROSPINAL FLUID IN RECUMBENT CALVES (Please refer to later section for methodology). Red blood cell lysis following trauma and subarachnoid haemorrhage may be evident as a yellow discolouration in cerebrospinal fluid (CSF), referred to as xanthochromic change, which may persist for up to four weeks. Localised spinal meningitis results in a marked increase in the lumbosacral CSF protein concentration and a pronounced neutrophilic pleocytosis. CALVES WHICH WERE ABLE TO STAND AFTER BIRTH BUT ARE NOW RECUMBENT Diffuse cerebral disease caused by metabolic disease (acidosis) and bacterial meningo-encephalitis is common in young calves. BACTERIAL MENINGOENCEPHALITIS Bacterial meningoencephalitis most commonly affects calves 3 to 8 days-old with clinical signs of episcleral congestion, lack of suck reflex, weakness, altered gait, depression extending to stupor but hyperaesthesia to auditory and tactile stimuli. Opisthotonus is observed during the agonal stages of disease. Lumbar CSF analysis reveals a large increase in protein concentration with a neutrophilic pleocytosis. Bacteriological culture of lumbar CSF is largely unrewarding. SEPTICAEMIA Calves with septicaemia frequently present with similar clinical signs to bacterial meningoencephalitis as the meninges are simply one site for localisation of blood-borne pathogens. The clinical course of septicaemia is generally peracute and affected calves may be found dead or in extremis within 12 hours. Other sites of infection such as eyeshypopyon, gut - diarrhoea, joints - polyarthritis may be identified. Foci in the lung, kidney, liver and spleen are only detected following necropsy. ENTERIC INFECTIONS CAUSING METABOLIC DISTURBANCES Sequestration of water and electrolytes in the gut lumen, often without overt signs of diarrhoea, caused by the heat stable enterotoxin produced by K99 strains of E. coli, can result in recumbency in one to four day old calves which can rapidly progress to coma and death. Older calves with severe metabolic acidosis secondary to enteric viral infection are weak, unable to stand and depressed with deterioration of BCVA 2000 mental state to stupor. It can prove difficult to undertake a thorough neurological examination, e.g. spinal reflexes, in such depressed or stuporous calves. Treatment with intravenous isotonic saline solution, spiked with 400-600 mEq of sodium bicarbonate, is usually successful with a rapid improvement in demeanour and ability of the calf to stand within six hours of treatment. BRAIN ABSCESS Ipsilateral compulsive circling, deviation of the head (not a head tilt), depression, contralateral blindness and postural deficits (often knuckling of the fetlock joints) are variably seen in older calves with a unilateral cerebral lesion. Approximately 90% of efferent nerve fibres cross at the optic chiasma, therefore animals with a left-sided cerebral abscess are blind in the right eye but the pupillary light reflex is normal. The menace response is not always reliable in cases of unilateral space-occupying lesions and this test can be supplemented with unilateral blindfolding. CEREBELLAR ABIOTROPHY Cerebellar abiotrophy is an inherited condition which has been reported in both Holstein and crossbred calves in the UK. Clinical signs of pelvic limb ataxia especially when turning quickly, wide-base stance and hypermetria appear from around six weeks of age and are slowly progressive leading eventually to recumbency by one year-old. UNILATERAL MIDDLE EAR INFECTIONS/VESTIBULAR SYNDROME Unilateral middle ear infections are not uncommon in growing calves and yearlings and usually arise from ascending infection of the eustachian tube. The major clinical sign in unilateral peripheral vestibular disease is an ipsilateral head tilt of 5° to 10° down to the affected side. There may be loss of balance, leaning, and movement/circling toward the affected side. During the early stages of unilateral peripheral vestibular lesions there is spontaneous horizontal nystagmus with the fast phase away from the side of the lesion. There is often ipsilateral ventral deviation of the eye which is exaggerated when the head is raised. The facial nerve travels close to the middle ear and facial palsy is often seen in conjunction with otitis media. It is important to differentiate vestibular lesions from listeriosis. LISTERIOSIS As most of the cranial nerve nuclei are present within the brainstem ascending infection of the trigeminal nerve by Listeria monocytogenes is characterised by VOL 8 PART 2

CATTLE PRACTICE multiple cranial nerve deficits. Involvement of the trigeminal nucleus results in paralysis of the cheek muscles and decreased facial skin sensation. Facial palsy is evident as drooped ear, drooped upper eyelid (ptosis) and flaccid lip. Occasionally, there may be paralysis and protrusion of the tongue. Depression is attributed to a lesion in the ascending reticular activating system. Circling can be observed with involvement of the vestibulo-cochlear nucleus. Cattle frequently have a "propulsive tendency" and may be found wedged across the front of the cubicle or with the head forced through a gate or under a feed trough. Dairy cows may barge through the parlour under the tail gate and the cows ahead of them; such behaviour leads to mis-diagnosis as bovine spongiform encephalopathy. A moderate increase in CSF protein concentration in the range 0.8 to 2.0 g/l is observed in meningo-encephalitis caused by L. monocytogenes (Rebhun & deLahunta, 1982). COLLECTION OF LUMBAR CSF Collection of lumbar CSF is facilitated when the animal is positioned in sternal recumbency with the hips flexed and the pelvic limbs extended alongside the abdomen. Aversion of the head against the flank may assist in maintaining sternal recumbency during the CSF collection procedure. In adult cattle that are still ambulatory, the lumbosacral CSF sample is collected in the standing animal which must be suitably restrained in cattle stocks. The site for lumbar CSF collection is the midpoint of the lumbosacral space which can be identified as the midline depression between the last palpable dorsal lumbar spine (L6) and the first palpable sacral dorsal spine (S2). The site must be clipped, surgically prepared and between 1-2 mls of local anaesthetic injected subcutaneously. The needle (Table 1) is slowly advanced at a right angle to the plane of the vertebral column or with the hub directed 5-10° caudally. BCVA 2000 concentration. A urinary protein dipstick test is not sufficiently sensitive to determine low CSF protein concentrations and should be relied upon only to estimate CSF protein concentrations greater than 2.0g/l. Calves with bacterial meningo-encephalitis frequently have a CSF protein concentration above 1.0 g/l (deLahunta, 1983) and greater than 2.0 g/l (Green & Smith, 1992; Scott & Penny, 1993). There is also a marked increase in CSF total while cell count in the order of 100 fold and a change in the predominant white cell type from lymphocyte to neutrophil (neutrophilic pleocytosis). VOL 8 PART 2 Table 1: Guide to needle length and gauge for lumbar CSF sampling in ruminants Kg Inch Gauge <80 1 20 Calves 80-200kg 2 19 >200 4 18 + internal stylet LUMBAR CSF RESULTS The lumbar CSF results (median, range) for some common CNS and related diseases are shown in Table 2. A rapid approximation of CSF globulin concentration can be made using the Pandy test whereby one drop of CSF is added to 1ml of saturated phenol solution. A blue/white turbidity indicates a significant increase in the CSF globulin Table 2: Lumbar CSF results (medium, range) for some common bovine CNS diseases Disease Number Specific gravity Protein g/1 White cells (x109 /litres) Control 31 1.007 (1.006-1.011) 0.28 (0.06-0.73) 0.0125 (0.012-0.25) Meningitis 17 1.010 (1.007-1.017) 2.5 (0.5-7.1) 2.0 (0.012-12.6) Listeriosis 12 1.009 (1.008-1.017) 1.69 (0.39-10.4) 0.3 (0.012-1.7) Bovine viral diarrhoea 5 1.007 (1.006-1.010) 0.22 (0.09-0.24) 0.0125 (0.012-0.1) Septicaemia 11 1.009 (1.007-1.011) 0.77 (0.19-2.04) 0.05 (0.01-0.2) Acidosis 5 1.009 (1.007-1.011) 0.35 (0.2-1.3) 0.012 (0.012) TREATMENT OF CNS INFECTIONS Few broad-spectrum bacteriocidal antibiotics are capable of penetrating the intact blood brain barrier although it is commonly assumed that the disruption of the blood brain barrier, which occurs in bacterial CNS diseases, increases the degree of antibiotic penetration (Barlow, 1983). This increased membrane permeability may allow sufficient passage of antibiotics to achieve minimum bactericidal concentrations (MBC) within the CSF. A peak CSF antibiotic concentration 10 to 30 times the effective MBC may be more important than the maintenance of CSF antibiotic MBC (Prescott & Baggot, 1988) and emphasise that intensive intravenous antibiotic therapy is indicated as soon as possible after the onset of clinical signs of bacterial CNS infection. A good survival rate for calves with bacterial meningoencephalitis and marked CSF changes including positive bacterial cultures was reported for calves treated with chloramphenicol (Scott & Penny, 1993). While similar data are lacking for florfenicol, this closely related drug would seem a sensible choice to treat bacterial meningo-encephalitis. Alternatively, trimethoprim-sulpha could be used. Penicillin or trimethoprim-sulpha remain the choice of antibiotic for listeriosis. Oxytetracycline is not considered an appropriate antibiotic choice for listeriosis because of its large molecular size although good results have been claimed.

CATTLE PRACTICE REFERENCES Green S.L. & Smith L.L. (1992) Meningitis in neonatal calves: 32 cases (1983-1990) Journal American Vetrinary Medical Association 201: 125-128 de Lahunta A. (1983) Veterinary Neuroanatomy and Clinical Neurology. Philadelphia. W. B. Saunders Co. Second Edition. Prescott J.F. & Baggot J.D. (1988) In: Antimicrobial therapy in veterinary medicine. London, Blackwell Scientific Publications p78 Rebhun W. C. & de Lahunta A. (1982) Diagnosis and treatment of bovine listeriosis. Journal American Veterinry Medical Association 180: 395-8. Scott P.R. & Penny, C.D. (1993) A field study of meningoencephalitis in calves with particular reference to cerebrospinal fluid analysis. Veterinary Record 133: 119-121. BCVA 2000 VOL 8 PART 2

CATTLE PRACTICE BCVA 2000 VOL 8 PART 2

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 oedema, interstitial emphysema and widespread pneumocyte hyperplasia which is seen in many fatal cases of BRSV pneumonia is believed to have an immunopathological basis involving complement activation, antibody and mast cells (Kimman et al 1989). In lung damage inflicted by Mannheimia (Pasteurella) haemolytica neutrophils play a key role in pathogenesis with lyosomal contents and other products released from neutrophils damaged or destroyed by bacterial leukotoxin making a major contribution to lung damage (Slocombe et al 1985). VIRUSES BRSV remains of major importance and parainfluenza - 3 virus and bovine viral diarrhoea/ mucosal disease virus can also be significant contributors to outbreaks. Adenoviruses, calf coronavirus and bovine herpesvirus 1 (IBR virus) are on occasions demonstrable in outbreaks but less commonly than the three preceding viruses. A serological study was carried out on acute and convalescent bovine sera submitted by veterinary practitioners from incidents of infectious respiratory disease in young cattle in Northern Ireland between 1994 and 1996 (Graham et al 1998). The majority of these would have been of enzootic pneumonia type although a small number of submissions from incidents of pneumonic pasteurellosis and IBR would be included. A total of 564 serum pairs from 145 outbreaks were examined for antibodies to BRSV, PI3 virus, BVD/MD virus and bovine herpesvirus 1. Seroconversion to one or more viruses was found in 88 (61%) outbreaks and in 195 (35%) of the total animals tested. In 47 of the 88 outbreaks (53.4%) seroconversion to only one virus was detected while The Calf Pneumonia Complex - Current Thoughts on Aetiology Bryson D.G., Veterinary Sciences Division, Stormont, Belfast, BT4 3SD. INTRODUCTION Infectious respiratory disease of young calves during their first period indoors continues to be a major source of economic loss and threat to animal welfare. Studies in the North of Scotland involving surveillance and economic assessment of 152 pneumonia outbreaks on beef and dairy farms indicated that the average total loss was approximately £21 per calf at risk and in the most severe outbreak the cost to the farmer was £114 per calf at risk (Gunn et al 1998). In another recent study on pneumonia outbreaks in eight dairy herds and four suckler herds the average cost of pneumonia for each ill dairy calf and suckler calf was £43 and £82 respectively (Andrews 1999, Barrett 1998). Within the UK the most important syndromes are enzootic pneumonia of housed calves and growing cattle, acute pneumonic pasteurellosis mainly seen in older recently weaned single suckled calves shortly after housing and infectious bovine rhinotracheitis (Bryson 1985). The present paper is primarily concerned with enzootic calf pneumonia and associated infectious agents. OVERVIEW OF AETIOLOGY A range of infectious agents together with management and environmental stress factors can all combine to produce severe outbreaks of pneumonia in young calves. Viruses, mycoplasmas and bacteria can all be involved in respiratory tract damage and it is not at all uncommon to demonstrate multiple viral, mycoplasmal and bacterial pathogens in the same incident (Bryson 1985, Otter et al 1997). Mechanisms of lung damage can be complex and varied. For example, the development of severe ABSTRACT Enzootic calf pneumonia continues to be a major source of economic loss and adverse effect on animal welfare. Viruses, mycoplasmas and bacteria can all be involved in respiratory tract damage and adverse managemental and environmental factors can predispose to and enhance the severity of outbreaks. Of the viruses, BRSV remains of major importance and parainfluenza 3 virus and BVDV can also be significant contributors to outbreaks. Multiple viral infections can occur in the same outbreak and this is particularly so in relation to respiratory tract infections with BVDV. The significance of antibodies to influenza A type viruses which have been recently described in some incidents of respiratory disease in young cattle is currently unclear. The role of mycoplasmas is sometimes under- rated. Mycoplasma bovis, M. dispar and Ureaplasma diversum are frequent contributors to the calf pneumonia complex in the UK and of these M. bovis is the most invasive and pathogenic. In addition there are a limited but increasing number of reports of isolation of M. canis from incidents of calf pneumonia. Mannheimia (Pasteurella) haemolytica serotype A1, Pasteurella multocida, Actinomyces pyogenes and Haemophilus somnus are the bacterial pathogens most frequently involved in the calf pneumonia complex and there is an increasing prevalence of M. haemolytica A6 in bovine respiratory disease outbreaks in UK. KEYWORDS: calf pneumonia, aetiology, viruses, mycoplasmas, bacteria, management, environment.

CATTLE PRACTICE in 41 of the 88 (46.6%) there was seroconversion to two or more viruses, in 29/88 to two, in 9/88 to three and in 3/88 to four. The highest incidence of seroconversion detected in serum pairs was to BRSV (19%), followed by PI3 virus (13.7%) and BVD/MD virus (8%). Seroconversions to BHV1 were least common, and were detected in 7.4% of serum pairs. While seroconversion provides evidence only of a temporal association between virus infection and the respiratory disease incident, the above data does give an indication of the continuing importance of BRSV, highlights one aspect of the multifactorial nature of bovine respiratory disease and would suggest that PI3 virus should not necessarily be "written off" as a significant respiratory pathogen. Virulent strains of BRSV and PI3 virus have been shown capable of inducing primary lung damage in susceptible calves (Bryson et al 1979,Bryson et al 1983) and in two extensive longitudinal farm studies both viruses, but particularly BRSV, were identified as important primary viral candidates in the pathogenesis of calf pneumonia (Thomas 1992). Evidence has also accumulated in recent years that both these viruses can cause immunosupression and compromise pulmonary defences by interference with alveolar macrophage and lymphocyte functions (Adair et al 1992, Keles et al 1998) and this is likely to facilitate secondary infection with mycoplasmas and bacteria. The immunosupressive properties of BVDV are well known and this virus has been shown experimentally to enhance infections with other viral and bacterial pathogens (Kelling et al 1996, Potgeiter 1997). The main role of this pathogen in incidents of calf pneumonia may be to facilitate the activity of other viral, mycoplasmal and bacterial pathogens. In the NI study referred to previously (Graham et al 1998) seroconversion to BVD/MD virus was most commonly found in association with other virus infections, which would tend to support this hypothesis. In experimental studies involving combined infections with BRSV and BVDV, there was a greater time lag before an antibody response to BRSV developed, antibody titres were lower and BRSV was detected for a longer period in lung lavage fluids in dually infected calves in comparison with calves infected with BRSV alone (Elvander et al 1998). However, in another study (Graham et al 1998) concurrent infection with BVD/MD virus was not found to adversely affect diagnosis of BRSV infection based on detection of BRSV - specific IgM in serum samples collected at onset of clinical signs and ten days later. Recently, antibodies reacting positively in serological tests to human influenza A type viruses have been detected in dairy cows and young cattle in some incidents of reduced milk yield and respiratory disease (Brown et al 1998, Gunning et al 1999). BCVA 2000 Rising antibody titres and seroconversion has most frequently been seen in association with milk drop incidents in dairy cows sometimes accompanied by respiratory signs (Gunning et al 1999). However, seroconversion has also been detected in outbreaks of calf pneumonia, sometimes with and sometimes without demonstrable presence of other pathogens (Brown et al 1998, Crawshaw 2000). Attempts to culture virus from these incidents, including inoculation of respiratory tract samples into eggs have not as yet proven successful (Crawshaw 2000). The significance of the above findings in relation to the aetiology of bovine respiratory disease is presently uncertain, further clarification would be greatly assisted if the agent or agents concerned could be isolated. MYCOPLASMAS The role of mycoplasmas in calf pneumonia can sometimes be under - rated in comparison to that of viruses and bacteria. Mycoplasma bovis, M. dispar, Ureaplasma sp. and the less pathogenic M. bovirhinis have been associated with pneumonia outbreaks in the UK for many years (Bryson et al 1978, Reilly et al 1993, Nicholas 1997) and it is not uncommon to isolate two or more of these species from calf lungs in a single incident of pneumonia. M. bovis is currently demonstrable in approximately 15% of pneumonic calf lungs at necropsy at Veterinary Sciences Division. Data from Veterinary Laboratories Agency indicates that M.bovis is the most commonly identified mycoplasma from cattle in GB and is mainly isolated from pneumonic calves (Nicholas 1997). Of these mycoplasmas, M. bovis is considered to be the most invasive and the most pathogenic. This organism also possesses a number of strongly immunogenic variable surface membrane lipoproteins (Vsps) which have the ability to undergo rapid changes in expression and structure. While the role of these "variable proteins" remains to be fully elucidated they do play an important role in attachment of organisms to host cells and may also serve to aid the organism in diverting and evading the host immune system (Behrens et al 1994). In studies involving experimental infections of gnotobiotic calves with M bovis (Thomas et al 1986) significant pneumonia was induced which involved up to 30% of the lung surface and was of sufficient severity to cause clinical respiratory disease in some calves. Distinctive areas of coagulative necrosis were sometimes prominent within the induced lesions. Experimental infections of calves with M. dispar and Ureaplasma diversum has also resulted in production of pneumonia but this has often been subclinical with lung lesions more limited in extent (Howard et al 1976). VOL 8 PART 2

CATTLE PRACTICE The appearance of M. bovis has on some farms been associated with increased severity of respiratory disease and increased mortality rates (Gourlay et al 1989). Experimentally, synergism between M. bovis and M(P) haemolytica producing severe exudative pneumonia has been demonstrated (Gourlay et al 1985) and such interactions would also appear common in natural disease (Reilly et al 1993). Characteristic necrotic foci similar to those described in experimental infections and containing large quantities of M. bovis antigen are not uncommonly observed in the lungs of fatal cases of pneumonia from M. bovis associated outbreaks indicating that M. bovis is making a significant contribution to the lung damage in such cases (Reilly et al 1993, Gourlay et al 1989, Rodriguez et al 1996). More chronic mycoplasmal infections involving M. bovis, M dispar and Ureaplasma diversum are often associated with a chronic lymphocytic ("cuffing") pneumonia where there is marked hyperplasia of peribronchial and peribronchiolar lymphoid tissue causing stenosis of airway lumina and compression and collapse of adjacent pulmonary parenchyma (Pirie et al 1975). There are several reports of chronic lymphocytic pneumonia in pathological studies of the lungs of calves with chronic pneumonia in the UK. In some of these studies there were indications of an earlier more acute pneumonia incident involving the affected group, in one report this was identified as BRSV pneumonia (Pirie et al 1975, Pirie et al 1981). In the mid 1990's reports from the Netherlands (ter Laak et al 1993) and UK (Nicholas et al 1995) recorded isolation from pneumonic calf lungs of M. canis, a mycoplasma species more commonly found in the upper respiratory and urogenital tracts of dogs. In the Netherlands M. canis was found to be not an uncommon isolate from the pneumonic bovine respiratory tract and was recovered from 5.5% of 733 respiratory tract samples from calves in 143 herds. Most of these isolations were from the lower respiratory tract of calves with pneumonia. However ,the contribution of M. canis to the respiratory problems was unclear and was not clarified by an experimental study involving endobronchial inoculation of calves with a M. canis isolate (ter Laak et al 1993). In the UK, reports of M. canis isolation from calf pneumonia cases whilst limited are definitely increasing (Nicholas et al 1998). Further studies are ongoing to clarify prevalence and pathogenicity of this organism in the bovine respiratory tract. BACTERIA Mannheimia (Pasteurella) haemolytica serotype A1, Pasteurella multocida, Actinomyces pyogenes and Haemophilus somnus are the bacterial pathogens most frequently involved in the enzootic calf BCVA 2000 pneumonia complex. Recent surveys have shown that M. (P) haemolytica serotype A6 is increasingly prevalent in bovine respiratory disease outbreaks in the UK (Donachie 1999). In our experience in Northern Ireland the majority of calves submitted for post mortem from enzootic calf pneumonia outbreaks will have some degree of bacterially induced lung damage which is usually manifest as suppurative, fibrinous or necrotising bronchopneumonia and this is often extensive and ultimately responsible for the death of the animal(s). Not infrequently large numbers of two or more of the above bacterial pathogens can be recovered from the same pneumonic lungs. While agents such as M. (P) haemolytica A1 and Haemophilus somnus are perfectly capable of inflicting primary respiratory tract damage, their task is likely to be made considerably easier if pulmonary defences have already been compromised by previous viral or mycoplasmal infections. MANAGEMENT/ENVIRONMENTAL STRESS FACTORS In addition to the wide range of pathogens which can be involved, adverse managemental and environmental stress factors predispose to incidence and increased severity of outbreaks. Examples include inadequate feeding of colostrum early in life, co - mingling of different age groups, poor housing standards including draughts at stock level and bad air hygiene, the latter associated with overstocking, poor ventilation and high relative humidity (Webster 1983, Gibbs 1992). The majority of respiratory pathogens previously described have on occasions been described in association with subclinical infections or only mild respiratory signs in groups of calves. This may involve several factors including possible differences in strain virulence, whether or not the infections were primary or reinfections and the overall immune status of the batches concerned. Nevertheless undoubtedly in many instances managemental and environmental stress factors can tilt the balance in favour of severe clinical disease. Whatever the intensity of debate on the efficacy or otherwise of various prophylactic and therapeutic agents, the fundamental and paramount importance of good management must never be overlooked. CONCLUDING COMMENTS Control of calf pneumonia is a difficult problem, a fact which is emphasised by the considerable range and numbers of pathogens which can be associated with lung damage and the major impact of managemental / environmental stress factors. However, hope should not be abandoned and progress is being made in a number of different areas (Bryson 1996). There have been recent advances in VOL 8 PART 2

CATTLE PRACTICE the range of therapeutic tools available for bacterial and mycoplasmal infections and in diagnostic methods for viral and mycoplasmal pathogens. Not all the pathogens mentioned previously in this overview are of equal status in terms of primary pathogenicity for the bovine respiratory tract and there is an increasing and improving range of vaccines available for control of disease caused by key respiratory pathogens such as BRSV and M.(P) haemolytica A1. It is important that optimal use be made of the vaccines currently available as there is still overdependance on antibiotics for control. Unfortunately despite the importance of mycoplasmas in the calf pneumonia complex no vaccines against organisms such as M. bovis are commercially available although some success has been demonstrated in the past with experimental vaccines (Howard et al 1987). No Haemophilus somnus vaccines are currently available within UK. There is still considerable scope for further vaccinal development. This may involve continued development of conventional vaccines and/or increased development of novel biotech type vaccines. In control of respiratory tract infections induction of mucosal immunity is very important and is most likely to be best facilitated by topical administration of vaccine within the respiratory tract. In future development of vaccines for bovine respiratory disease prospects for mucosal immunisation should be kept very much in mind. The latter is also likely to reduce possible risks of maternal antibody interference with live vaccines administered systemically and to facilitate a very rapid onset of mucosal immunity. This is particularly important on those farms where calf pneumonia problems commence at a very early age. In the case of IBR and disease caused by PI3 virus, the ability of intranasal vaccination to protect the upper and lower respiratory tract has been clearly demonstrated (Bryson et al 1999, Frerichs et al 1982). In the human field it is interesting to note that nasal spray vaccines containing cold adapted strains of influenza virus have been used very successfully in USSR in recent years and are due to be licensed for use in USA this year. The calf pneumonia complex causes severe economic loss, impacts very adversely on animal welfare and currently involves extensive use of antibiotics for control. For all these reasons it is important that sufficient research funding is made available for effective progress to be made on prophylactic, therapeutic and managemental aspects of disease. REFERENCES Adair B.M., Bradford H.E.L., Mackie D.P., McNulty M.S. (1992) Effect of macrophages and in vitro infections with parainfluenza type 3 and respiratory syncytial viruses on the mitogenic response BCVA 2000 of bovine lymphocytes. American Journal of Veterinary Research 53: 225-229. Andrews A.H. (1999) Farmers Weekly. September 1999. Barrett D.C. (1998) Bovine Respiratory Disease - A Clinicians Perspective. Cattle Practice 6: 251-255. Behrens A., Heller J., Kirchhoff H., Yogev D., Rosengarten R. (1994) A family of phase and size - variant membrane surface lipoprotein antigens (Vsps) of Mycoplasma bovis. Infection and Immunity 62: 5075-5084. Belak S., Alenius S. (1998) An experimental study of a concurrent primary infection with bovine respiratory syncytial virus (BRSV) and bovine viral diarrhoea virus (BVDV) in calves [1998] Acta Veterinaria Scandinavica 39: 251-264. Brown I.H., Crawshaw T.R., Harris P.A., Alexander D.J. (1998) Detection of antibodies to influenza A virus in cattle in association with respiratory disease and reduced milk yield. Veterinary Record 143: 637-638. Bryson D.G. (1985) Calf pneumonia. Veterinary Clinics of North America 1: 237-259. Bryson D.G., McNulty M.S., Ball H.J., Neill S.D., Connor T.J., Cush P.F. (1979). The experimental production of pneumonia in calves by intranasal inoculation of parainfluenza type 3 virus. Veterinary Record 105: 566-573. Bryson D.G., McNulty M.S., Logan E.F., Cush P.F. (1983). Respiratory syncytial virus pneumonia in young calves: Clinical and pathologic findings. American Journal of Veterinary Research 44: 1648-1655. Bryson D.G., McFerran J.B., Ball H.J., Neill S.D. (1978) Observations on outbreaks of respiratory disease in housed calves - Pathological and microbiological findings. Veterinary Record 103: 503-509. Bryson D.G. (1996) Infectious bovine respiratory disease - emerging issues and progress toward control. Proceedings XIX World Buiatrics Congress. Edinburgh 1996 1-8. Bryson D.G., Adair B.M., McNulty M.S., McAliskey M., Bradford H.E.L., Allan G.M., Evans R.T., Forster, F. (1999). Studies on the efficacy of intranasal vaccination for the prevention of experimentally induced parainfluenza type 3 virus pneumonia in calves. Veterinary Record 145: 33-39. Crawshaw T.R. (2000) Personal communication. Donachie E. (1999) Bacteriology of bovine respiratory disease 8: 5-7. Elvander M., Baule C., Perssan M., Egyed L., Ballagi-Pardany A., Graham D.A., Elvander M., Adair B.M., Merza M. (1998) Influence of concurrent BVDV infection on the IgM response of calves experimentally infected with bovine respiratory syncytial virus. Veterinary Record 143: 198-199. Frerichs G., Woods S.B., Lucas M.H., Sands J.J. (1982) Safety and efficacy of live and inactivated infectious bovine rhinotracheitis vaccines. Veterinary Record 111: 116--122. Gibbs H.A. (1992) Calf pneumonia - The future. Proceedings of the British Cattle Veterinary Association symposium on enzootic pneumonia in housed calves. Ripon 1992 95-97. Gourlay R.N., Houghton S.B. (1985) Experimental pneumonia in conventionally reared and gnotobiotic calves by dual infection with Mycoplasma bovis and Pasteurella haemolytica. Research in Veterinary Science 38: 377-382. Gourlay, RN., Thomas, LH. And Wyld, SG. (1989) Increased severity of calf pneumonia associated with the appearance of Mycoplasma bovis in a rearing herd. Veterinary Record 124: 420- 422. Graham D.A., McShane, J., Mawhinney K.A., McLaren I.E., Adair B.M., Merza M. (1998) Evaluation of a single dilution ELISA system for detection of seroconversion to bovine viral diarrhoea virus, bovine respiratory syncytial virus, parainfluenza -3 virus and infectious bovine rhinotracheitis virus. Journal of Veterinary Diagnostic Investigation 10: 43-48. Gunn G.J., Stott A.W. (1998) Economic losses associated with calf pneumonia. Cattle Practice 6: 259. Gunning, RF., Brown, IH. and Crawshaw, TR. (1999) Evidence of influenza A virus infection in dairy cows with sporadic milk drop syndrome. Veterinary Record 145: 556-557. VOL 8 PART 2

CATTLE PRACTICE Howard C.J., Gourlay R.N., Thomas L.H., Stott E.J. (1976) Induction of pneumonia in gnotobiotic calves following inoculation of Mycoplasma dispar and ureaplasmas. Howard C.J., Stott E.J., Thomas L.H., Gourlay R.N., Taylor G. (1987) Protection against respiratory disease in calves induced by vaccines containing respiratory syncytial virus, parainfluenza type 3 virus, Mycoplasma bovis and M. dispar. Veterinary Record 121: 372-376. Keles I., Woldehiwet Z., Murray R.D. (1998) In vitro studies on mechanisms of immunosupression associated with bovine respiratory syncytial virus. Journal of Comparative Pathology 118: 337-345. Kelling C.L., Brodersen B.W., Perino L.J., Cooper V.L., Doster A.R., Pollreisz J.H. (1996) Potentiation of bovine respiratory syncytial virus infection in calves by bovine viral diarrhoea virus. Proceedings XIX World Buiatrics Congress, Edinburgh 20-27. Kimman T.G., Terpstra G.K., Datie M.R., Westenbrink F. (1989) Pathogenesis of naturally acquired bovine respiratory syncytial virus infection in calves. Evidence for the involvement of complement and mast cell mediation. American Journal of Veterinary Research 50: 694-700. Nicholas R.A.J., Hannam D.A.R., Baker S.E., Weaver C.R., ter Laak E.A. (1995) Mycoplasma canis in a British calf. Veterinary Record 139: 443-444. Nicholas R. (1997) The other M bovis: Mycoplasma bovis. State Veterinary Journal 7: 3-5. Nicholas R., Ayling R., Miles R. (1998) Prevalence of mycoplasmas in respiratory diseases in cattle in Britain. Proceedings of EU COST Workshop on Mycoplasmas of ruminants: pathogenicity, diagnostics, epidemiology and molecular genetics. Vol 3: 94-96. Otter A., Farrer M.E. (1997) Pneumonia associated with five respiratory pathogens in a group of steers. Veterinary Record 140: 187-188. Potgeiter, LND. (1997) Bovine respiratory tract disease caused by bovine viral diarrhoea virus. Veterinary Clinics of North America 13: 471-483. BCVA 2000 Pirie H.M., Allan E.M. (1975) Mycoplasmas and cuffing pneumonia in a group of calves. Veterinary Record 97: 345-349. Pirie H.M., Petrie L., Pringle C.R., Allan E.M., Kennedy G.J. (1981) Acute fatal pneumonia in calves due to respiratory syncytial virus. Veterinary Record 108: 411-416. Reilly G.A.C., Ball H.J., Cassidy J., Bryson, D.G. (1993) First reported isolation of Mycoplasma bovis from pneumonic calves in Northern Ireland. Veterinary Record 133: 550-551. Rodriguez F., Bryson D.G., Ball H.J., Forster F. (1996) Pathological and Immunohistochemical studies of natural and experimental Mycoplasma bovis pneumonia in calves. Journal of Comparative Pathology 115: 156-162. Slocombe R.F., Malark J., Ingersol R. (1985) Importance of neutrophils in pathogenesis of pneumonic pasteurellosis in calves. American Journal of Veterinary Research 46: 2253-2258. ter Laak E.A., Tully J.G., Noordergraaf H.H., Rose D.L., Carle P., Bove J.M., Smits M.A. (1993) Recognition of Mycoplasma canis as part of the mycoplasmal flora of the bovine respiratory tract. Veterinary Microbiology 34: 175-189. ter Laak E.A., van Dijk J.E., Noordergraaf J.H. (1993). Comparison of pathological signs of disease in specific pathogen free calves after inoculation of the respiratory tract with Ureaplasma diversum or Mycoplasma canis [1993]. Journal of Comparative Pathology 108: 121-132. Thomas LH., Howard C.J., Stott E.J., Parsons KA. (1986) Mycoplasma bovis infection in gnotobiotic calves and combined infection with respiratory syncytial virus. Veterinary Pathology 23: 571-578. Thomas L.H. (1992) Causative Organisms: Their relative importance and mixed infections. Proceedings BCVA Symposium on enzootic pneumonia in housed calves. Ripon 11-13. Webster A.F.J. (1983) Environmental stress and the physiology performance and health of ruminants. Journal of Animal Science 57: 1584-1593. VOL 8 PART 2

CATTLE PRACTICE BCVA 2000 VOL 8 PART 2

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 INTRODUCTION It is believed that this is the first multi-site on-farm study of calf respiratory disease costs involving outbreaks on ordinary British commercial farms. The study was commissioned by Pfizer Animal Health and carried out by the National Animal Disease Information Service. Twelve commercial herds were examined in detail at weekly intervals throughout the outbreak of pneumonia until one week after the end of the problem, with a final examination of all affected and control calves one month later. The study took place in the winters of 1997-98 and 1998- 99. The main inclusion criteria were that farms had a history of respiratory disease, vets were notified at the beginning of the new disease outbreak by the farmer, farmers had to be prepared to record even after the end of the outbreak, and that herds were unvaccinated (although one vaccinated herd was included). Three herds examined were in north Devon, five in mid Devon and four on the borders of mid Wales. Four veterinary surgeons, in four different practices, recorded the cases. No attempt was made to influence the treatment or preventive regimes undertaken in each pneumonia outbreak. Eight of the herds consisted of calves from dairy herds and in all but one of these they were predominantly homebred. The calves were either heifer replacements or being reared for beef. The four Welsh farms were suckler herds. An initial visit was made to each farm to start recording at the beginning of the respiratory disease outbreak. A group of apparently unaffected calves was used as a control group. Weekly visits were made to determine the progress of the outbreak and affected calves were weighed either by weighband or by weigh crate. Other visits were made if necessary to treat and control the problem. The routine visits continued until one week after the end of the outbreak and a final visit was made by the veterinary surgeon one month after the last visit when all affected calves and controls were examined and weighed. Most outbreaks occurred in mild moist weather with a high level of humidity. The ventilation was adequate on four farms, but in the other herds it was unsatisfactory. Because of the husbandry systems used and most calves being from their own herds, on all farms different age groups were in the same air space. While all the suckler herds were adequately fed, six of the eight herds with calves of dairy origin had inadequate diets. For analysis the twelve herds were divided into those derived from the dairy herd and those from suckler herds. Calf Pneumonia Costs! Andrews A.H., Acorn House, 25 Mardley Hill, Welwyn, Hertfordshire, AL6 0TT. ABSTRACT The study involved an investigation into the cost of twelve outbreaks of pneumonia (eight dairy-bred herds and four suckler herds) as they occurred on farm. The outbreaks, on ordinary commercial farms, were followed throughout their duration and involved all calves with apparent clinical infection, and some calves without as controls. Calves were examined and weighed at weekly intervals until five weeks after the end of the outbreak. The study took place in the winters of 1997-98 and 1998-99. Most outbreaks occurred in mild moist weather with a high humidity. The ventilation was adequate on four farms, but on the other farms it was unsatisfactory. Because of the husbandry systems used and the fact that most calves were homebred, on all farms different age groups shared the same air space. While all the suckler herds were adequately fed, six of the eight herds with dairy-bred calves had inadequate diets. The cost per ill dairy-bred calf varied from £8.59 to £78.74. These were the two extremes and all the other six outbreaks were within ± £5.00 of the overall average of £43.26. The average cost of pneumonia per dairy-bred calf within the group was £29.58. The overall costs per outbreak were higher in the suckler herds and the average cost per ill calf (£82.10) was nearly double that in the dairy herd and the cost per animal within the group was £74.10 (2.5 times the cost for dairy calves). In the suckler herds the morbidity (90.3%) and mortality (3.9%) were higher than in the dairy herds (68.4% and 1.5% respectively). Looking at the overall costs, those immediately tangible to the farmer, namely veterinary and medicine costs, came to about 40% of the total costs of an outbreak. The remaining costs, which included mortality, weight loss, extra labour and other costs were higher. In all studies, weight reductions or reduced weight gains during the outbreaks were the highest cost in both dairy and suckler herds. The second highest cost was that of medicines. When mortality occurred, it became a major cost input. In the dairy herds, costs tended to increase when the outbreak was protracted and in the suckler herds it was more dependent on the severity of the illness. In many herds the consequences of the pneumonia outbreak were still apparent after the end of the study. KEYWORDS: calves, pneumonia, costs, economics.

CATTLE PRACTICE Calves originating from dairy herds In the eight herds involving calves from dairy herds, most had an environmental component to the disease outbreak. They were seen between January and February 1998 (four farms) and September to December 1998 (four farms). Laboratory investigations, including nasopharyngeal swabs and paired serology, were carried out to determine the cause(s) of disease. The results are in Table 1. Bovine respiratory syncytial virus (BRSV) and Parainfluenza III (PI3) were detected in three and two outbreaks respectively. Pasteurella species were isolated from three outbreaks and in two they were identified as Pasteurella multocida. Mycoplasma bovis was isolated in one outbreak and Aeromonas hydrophila was present in the same outbreak, although the latter is of unknown significance. Thus the pathogens detected were representative of what might be found in most calf respiratory disease outbreaks. Calf pneumonia was seen and treated in 186 of 272 calves at risk (68.4%) (see Table 2) although the morbidity ranged from 41.7% to 90.5%. Mortality was seen in four outbreaks and occurred in 1.5% of calves at risk and 2.2% of those affected and treated. The signs presented by the calves were variable and in a number of outbreaks, those which were severely BCVA 2000 VOL 8 PART 2 Table 1. The main organisms isolated and other potential precipitating factors in the pneumonia outbreaks Organism Study 1 Study 2 Study 3 Study 4 Study 5 Study 6 Study 7 Study 11 Total Pasteurella spp. P. multocida P. multocida Pasteurella spp. 3 Other bacteria Aeromonas hydrophila 1 Mycoplasma bovis + 1 RSV + + + + 4 PI 3 + + 2 IBR - Ventilation Adequate Poor for some Adequate Very poor Poor Poor Very poor Adequate Feeding Could increase Low Low Good Very low Adequate Could increase Low Weather Mild, damp Mild, damp Mild, moist Mild, overcast Variable, wet period Mild, damp Wet, high humidity Mild, damp Different ages Yes Yes + cows Yes Yes Yes Yes Yes Yes All-in all-out No No No Mainly No No No No Own calves 3 herds Yes No Yes No (cows) No Yes Yes Table 2. The combined results of the eight pneumonia studies involving dairy replacement or dairy-bred beed calves Study 1 Study 2 Study 3 Study 4 Study 5 Study 6 Study 7 Study 11 Total Number in group 24 12 21 37 63 15 65 35 272 Number affected 10 6 19 31 42 9 46 23 186 Percentage affected 41.7 % 50.0 % 90.5 % 83.8 % 66.7 % 60.0 % 70.8 % 65.7 % 68.4 % Number died - - 1 - - 2 1 - 4 Percentage mortality 0 % 0 % 4.8 % 0 % 0 % 13.3 % (22.2 %)* 1.5 % (2.2 %)* - 1.5 % (2.2 %)* ill, but responded rapidly, cost less per calf than those problems where animals had a limited degree of illness and did not appear to be at any risk of dying. The costs of outbreaks varied considerably, as did the proportions of the costs within the total expense; therefore each study needed to be looked at separately. The cost per ill calf varied from £8.59 to £78.74 (see Table 3). However, these two were extremes and all the other six outbreaks were within ± £5. 00 of the overall average of £43.26. As so many calves were affected and treated in each outbreak the costs of pneumonia per calf within the group ranged from £3.58 to £47.24 with a mean of £29.58. (Table 4). In Study 1, where calves were vaccinated against RSV, PI3 and IBR, the investigation indicated the sole cause to be Pasteurella multocida, and the costs were the lowest in the whole study by £30 per ill calf and £16 per atrisk calf. In some cases, further costs due to the outbreak were incurred after recording had finished, although these were not included in the study. These costs included vaccines, rearing calves on other farms and further deaths due to chronic pneumonia. With these costs included, the average cost per calf ill with pneumonia came to £119.36 and the cost per calf *( ) Mortality percentage amongst those affected

CATTLE PRACTICE The proportions of the costs attributable to different components within the dairy calf outbreaks varied widely from farm to farm (Table 5). Overall reduced weight, or loss of weight gain compared with untreated cohorts tended to be the biggest expense (average 26.4%). The second most expensive cost was medicines (mean of 22.4%), followed by veterinary fees (average 18.9%). Other costs were labour (11.3%), usually an overlooked cost, mortality (7.1%), materials (7.0%), and other costs (6.8%). There were few deaths in these outbreaks probably because of prompt and thorough veterinary involvement. However, when deaths occurred, they rapidly became a major cost within the outbreak; two calves died in Study 6 and this produced a mortality 13.3% of those within the group and this amounted to 46% of the total costs. When other costs within or after the outbreak were considered in these eight cases they rose to 61.1% of all costs. This was because of the determination of one farmer to stop the pneumonia problem by out-rearing his calves. The other contributory costs in Study 6 were roughly in the same proportions and sequence; reduced weight gain (13.2%), medicines (8.1%), veterinary costs (6.8%), mortality (4.2%), labour (4.1%) and materials (4.1%). The outcome suggests that there are often BCVA 2000 unforeseen consequences of a pneumonia outbreak; for example, those which resulted in the very high cost of Study 6. However, it was also apparent that otherwise, the most costly outbreaks of respiratory disease were those which continued over a long period of time. Although the signs here were not particularly severe, the calves required periodic treatment (e.g. Study 3, 4, 11). Suckler calves These outbreaks were all seen within one practice; one in November 1998 and three in January 1999. The outbreaks involved 139 animals out of a total of 154 (see Table 6), had considerably higher costs, with morbidity levels ranging from 73.3% to 100% (mean 90.3%). Thus treatment costs were higher. Mortality was also higher at 3.9% overall and 4.3% in affected calves. Cases were seen in mild conditions with high humidity (Table 7). Most farms had a more prolonged calving season, so there were several age groups often sharing the same air space. Most herds bought in some replacement cows but not calves. Feeding was good. The majority of the clinical disease tended to be in weaned animals around six months old; having lost passive immunity they would be more susceptible to infection by pathogens which were endemic on the farm. VOL 8 PART 2 Table 3. The costs of the eight pneumonia studies involving dairy herd replacement or dairy-bred beef calves Costs Study 1 Study 2 Study 3 Study 4 Study 5 Study 6 Study 7 Study 11 Total Veterinary £37.17 £60.33 £226.63 £370.88 £260.00 £79.31 £266.00 £218.00 £1518.32 Medicines £46.18 £26.22 £83.77 £286.72 £316.65 £95.48 £552.98 £394.29 £1802.29 Materials £20.00 £268.75 £271.20 £559.95 Labour £2.57 £2.93 £146.85 £96.26 £256.22 £6.88 £284.84 £115.97 £912.52 Mortality £150.00 £325.00 £100.00 £575.00 Weight loss £143.50 £237.00 £507.20 £360.00 £202.00 £624.00 £47.00 £2120.70 Other costs £512.00 £44.85 £556.85 Total £85.92 £232.98 £864.25 £1261.06 £1704.87 £708.67 £2141.42 £1046.46 £8045.63 Table 4. The costs of the pneumonia outbreaks per ill calf and calf within the group Costs Study 1 Study 2 Study 3 Study 4 Study 5 Study 6 Study 7 Study 11 Total Per calf ill £8.59 £38.83 £45.49 £40.68 £40.59 £78.74 £46.55 £45.50 £43.26 Per calf in group £3.58 £19.42 £41.15 £34.08 £27.06 £47.24 £32.94 £24.90 £29.58 Table 5. Proportions of the costs in the pneumonia outbreaks involving dairy replacements or dairy-bred beef calves Costs Study 1 Study 2 Study 3 Study 4 Study 5 Study 6 Study 7 Study 11 Total Veterinary 43.3 % 25.9 % 26.2 % 29.4 % 15.3 % 11.1 % 12.4 % 20.8 % 18.9 % Medicines 53.7 % 11.3 % 9.7 % 22.7 % 18.6 % 13.5 % 25.8 % 37.7 % 22.4 % Materials 2.3 % 12.6 % 25.9 % 7.0 % Labour 3.0 % 1.3 % 17.0 % 7.6 % 15.0 % 1.0 % 13.3 % 11.1 % 11.3 % Mortality 17.4 % 45.9 % 4.7 % 7.1 % Weight loss 61.6 % 27.4 % 40.2 % 21.1 % 28.5 % 29.1 % 4.5 % 26.4 % Other costs 30.0 % 2.1 % 0 % 6.8 % Total 100 % 100 % 100 % 100 % 100 % 100 % 100 % 100 % 100 %

CATTLE PRACTICE BCVA 2000 Laboratory results from naso-pharyngeal swabs showed mixed bacterial growths (or very limited numbers of colonies) rather than pathogenic organisms. In three of the outbreaks two or more viruses were associated with the pneumonia problems. In one study (Study 8) the only organism demonstrated to be present was RSV. Other studies all showed seroconversion to RSV and PI3. In one study, calves had titres rising to IBR and on two farms bovine viral diarrhoea virus (BVDV) was active during or soon after the respiratory disease outbreak. The calves in the suckler outbreaks tended to be much more severely ill than those in dairy-bred animals. However except in one (Study 8) the duration of the outbreak tended to be shorter. All the farms had suffered pneumonia outbreaks of varying severity on their farms in the previous year (1997- 98). The costs of each outbreak tended to be higher than those in the dairy-bred calves (Table 8). The overall cost per ill calf was £82.10 and, because the morbidity was so high, the cost per calf within the group was £74.10 (Table 9). Three herds had costs per ill calf ranging from £59.12 to £77.92, although one herd (Study 12) was considerably higher VOL 8 PART 2 Table 6. The combined results of the four pneumonia studies involving suckler calves. Study 8 Study 9 Study 10 Study 12 Total Number in group 30 33 27 64 154 Number affected 22 26 27 64 139 Percentage affected 73.3 % 78.8 % 100 % 100 % 90.3 % Number died - - 2 4 (+1) 6 (+1) Percentage mortality 0 % 0 % 7.4 % 7.4 %* 6.3 % (7.8 %) 6.3 %* (7.8%)* 3.9 % (4.5 %) 4.3 %* (5.0 %)* *Mortality percentage amongst those affected Table 7. The main organisms isolated and other potential precipitating factors in the pneumonia outbreaks. Organism Study 8 Study 9 Study 10 Study 12 Total Bacteria Mixed growth Mixed growth Mycoplasma bovis - RSV ?+ + + + 4 PI 3 + + + 3 IBR + 1 BVD (+) (+) (2) Ventilation Reasonable Poor one yard Variable in sheds Fair Feeding Good Good Good Excellent Weather Damp, high humidity Mild, damp, high humidity Wet Wet, mild Different ages affected Yes Yes Yes No Own calves Yes Yes Yes Yes Cows bought in 12 / year Occasionally Some No Precipitating factors Worming (£101.55). This was mainly because the severity of the outbreak resulted in larger quantities of medicines being used. There were fewer continuing costs after the end of the outbreaks in the four suckler herds, except for one animal (Study 12) which subsequently died. The average costs of medicines used in these four outbreaks was £25.53 per ill calf which was over 2.5 times that for the dairy- bred calves at £9.69 per animal. Thus it is not surprising that the medicine costs made up 31.1% of the outbreak costs and this was the second most costly component. In the dairy bred calves it constituted 22.4% and likewise was the second most costly item. The effect of the pneumonia on weight gain was variable but there was an influence with calves either losing weight or reducing their daily liveweight gain during their illnesses in all four outbreaks. In two of the studies the performance reductions formed the major cost (Study 8: 76.7% and Study 9: 62.9%) of the outbreak (Table 10). These were the two herds with less than 100% morbidity. All the costings and reduced weight gains were agreed by the farmers and on one farm (Study 12) the owner regularly weighed and so was very familiar with his expected daily liveweight gains.

CATTLE PRACTICE Comparison of the outbreaks between dairy bred and suckler groups Comparing the data between the two types of calves involved in the pneumonia outbreaks must be done with some caution, but can provide useful information when dealing with individual outbreaks on farms (Table 11). Thus, in the whole study, the cost per ill calf was nearly twice (1.9 times) as great in the suckler calves as in the dairy-bred calves. Also, the cost per calf within the group was 2.5 times higher because of the high morbidity in the suckler herds. When the proportions of costs were examined, the main loss was the "hidden" cost of reduced weight gain in both calf types. This was followed by the treatment costs. Veterinary involvement costs were the third most important in the dairy-bred calves, but fourth in the sucklers. Third in the sucklers was mortality and this is a more absolute loss to this production system as it means that the cow producing that calf has been non productive for the year. Other costs were usually less important, labour was fourth in dairy-bred systems and fifth or last in suckler herds, and in the dairy studies there were also costs for materials and other incidental costs which could become considerable following a pneumonia outbreak. BCVA 2000 CONCLUSION The results of these twelve pneumonia outbreaks show that respiratory disease outbreaks are a major cost to a farmer either when rearing calves from the dairy herd or the suckler herd. These costings were "real" and derived from outbreaks on commercial farms. They show that each outbreak does need to be looked at separately, although in general, broad conclusions can be made e.g. vet fees plus medicine costs comprise 40% of total lost for either dairy bred or suckler calf pneumonia outbreaks. In many cases incidental or unexpected direct and indirect costs occurred. While these animals were examined for their final costs a month after the end of the disease VOL 8 PART 2 Costs Study 8 Study 9 Study 10 Study 12 Total Per calf ill £77.92 £61.60 £59.12 £101.55 £82.10 Per calf in group £57.14 £48.55 £59.12 £101.55 £74.10 Table 9. The costs of the pneumonia outbreaks per ill calf and calf within the group. Costs Study 8 Study 9 Study 10 Study 12 Total Veterinary £178.33 £168.34 £241.67 £603.34 £1191.68 Medicine £174.71 £403.00 £323.92 £2651.59 £3553.30 Materials - - - - - Labour £45.83 £86.17 £90.78 £334.57 £557.35 Mortality - - £500.00 £1100.00 £1600.00 Weight loss £1315.40 £944.00 £440.00 £1810.00 £4509.40 Other costs - - - - - Total £1714.27 £1601.59 £1596.37 £6499.50 £11,411.73 Table 8. The costs of the individual pneumonia outbreaks. Table 10. The proportions of the costs in the pneumonia outbreaks involving suckler calves. Costs Study 8 Study 9 Study 10 Study 12 Total Veterinary 10.4 % 10.5 % 15.1 % 9.3 % 10.4 % Medicine 10.2 % 25.2 % 20.3 % 40.8 % 31.1 % Materials - - - - - Labour 2.7 % 5.3 % 5.7 % 5.1 % 4.9 % Mortality - - 31.3 % 16.9 % 14.0 % Weight loss 76.7 % 62.9 % 27.6 % 27.9 % 39.5 % Other costs - - - - - Total 100 % 100 % 100 % 100 % 100 % Table 11. The proportion of costs attributable in each type of respiratory disease outbreak (continuing costs not included). Costs Dairy-bred Suckler Weight loss 26.4 % 39.5 % Medicines 22.4 % 31.1 % Veterinary 18.9 % 10.4 % (4) Labour 11.3 % 4.9 % (5) Mortality 7.1 % 14.0 % (3) Materials 7.0 % - Other costs 6.8 % - Total 100 % 100 % ( ) Ranking of the cost in the suckler herds

CATTLE PRACTICE outbreak, it was found that some losses related to the outbreak continued or became apparent some considerable time after this last visit. All outbreaks appeared to have been partly precipitated by weather changes. However, other management factors were also important; inadequate feeding was a contributory factor in many of the dairy-bred calf outbreaks. Various organisms were present at the time of the outbreaks and viruses were the most commonly associated. It did appear that high mortality made marked differences to the costs. In the dairy herds costs tended to be highest when outbreaks continued over a long period rather than when clinical disease was severe. However, in suckler herds costs were much more related to the severity of the signs experienced and the morbidity levels. The main costs, in both types of calves, were that of reduced weight gain followed by medicine used. While it may surprise farmers, veterinary fees were only the third highest cost in dairy-bred calves and fourth in sucklers. In all outbreaks veterinary BCVA 2000 attention reduced the severity of the disease outbreak and on most farms prevented calves deteriorating or dying, which otherwise would have occurred. In fact in almost all outbreaks (11 farms) ill calves or those needing extra treatment (which had been overlooked by the farmer) were detected at routine weekly veterinary visits. Alterations to management and the environment were made on most of the dairy farms and in some cases this included changes in feeding management. ACKNOWLEDGEMENTS The study was undertaken by the National Animal Disease Information Service (NADIS) for Pfizer Limited. The particular help of Andrew Montgomery, Lesley Peek and Georgia Owen MsRCVS is gratefully acknowledged. The studies were undertaken by Sotirios Karvountzis, Kathy Murray, Charlie Sullivan and Stuart Young MsRCVS. The laboratory investigations were performed at the VLA Itchen Abbas, Winchester. VOL 8 PART 2

BCVA 2000 CATTLE PRACTICE VOL 8 PART 2 INTRODUCTION Respiratory disease causes huge losses to the cattle industry worldwide. In Britain losses are estimated to be as much as £50 million per year in treatment, "set back" costs and deaths in calves (Rebhun et al 1995). A more recent and detailed study concluded that respiratory disease costs more in lost profits than in treatment (Esslemont et al 1998). Pneumonia is a complex syndrome caused by viruses, bacteria and, of course, mycoplasmas. Mycoplasmas are small degenerate bacteria with a typical "fried egg" morphology on solid media. Their major characteristic is the lack of a cell wall which means they are resistant to some antibiotics. They are difficult to grow in the laboratory and are generally host specific. It is generally believed that mycoplasmas have a secondary role in infections by exacerbating preexisting disease and this may certainly occur. Experience has shown that the introduction of Mycoplasma bovis, for example, on to a farm with a history of bacterial pneumonia, initiates calf mortality (Nicholas 1997). Experimental infections have also shown M. bovis to a primary pathogen (Pfutzner and Sachse 1996). Furthermore, farms can be persistently infected with M. bovis as once introduced onto a multi-age site the disease is very difficult to eradicate (P Duff, unpublished results). In a survey by the OIE of over 48 countries, M. bovis was seen as a major impediment to the cattle industry. In a US survey, M. bovis was isolated from one third of over 400 pneumonic lungs. In France M. bovis is involved in 25-30% of pulmonary disease in fattening calves. In Northern Ireland, following its introduction in 1993 the incidence of M. bovis in pneumonic lung samples rose to 23%. M. bovis is also a primary cause of arthritis and keratoconjunctivitis in calves and mastitis and reproductive disorders in cattle (Pfutzner and Sachse, 1996). Other mycoplasmas which have been associated with respiratory disease include M. dispar, Ureaplasma diversum, M. bovirhinis and of course M. mycoides subsp. mycoides SC the cause of contagious bovine pleuropneumonia. Ter Laak et al (1993) isolated M. canis from pneumonic calves but evidence on its role in disease from a survey of healthy and sick calves was not conclusive. A more potent indicator of the importance of mycoplasmas in respiratory disease is the increasing interest of international drug companies in sponsoring antibiotic trials. In Britain, we regularly see cases of calf pneumonia involving mycoplasmas in the absence of other microbial pathogens including mycoplasmas not normally associated with calf disease (Nicholas et al 1999). This paper presents data on mycoplasmas isolated from clinical disease in cattle, the serological prevalence of M. bovis in pneumonic animals in Britain, antibiotic sensitivity of recent strains and clinical and bacteriological evidence that M. canis causes pneumonia in the absence of other pathogens. MATERIALS AND METHODS Mycoplasma tests As the reference laboratory for animal mycoplasmas in England and Wales, VLA (Weybridge) receives mycoplasma isolates from cases of clinical disease from the 12 regional veterinary laboratories. Isolates are typed by growth inhibition, disc film inhibition, immunofluorescence tests (Nicholas and Baker 1998) and, increasingly, PCR specifically for M. bovis using the primers of Johansson (Ayling et al 1997). In addition serum samples are received exclusively from cattle experiencing respiratory disease. This amounts to some 2000-3000 samples a year and now also covers Scottish cattle. Serology An indirect ELISA, using a whole cell antigen of M. bovis from a British field strain (B5/96), is carried out. Briefly a 1/100 dilution of sera was applied to a microtitre plate coated with washed and optimised whole cells of M. bovis. After 60 minutes incubation, Mycoplasma Infections in Growing Cattle Nicholas R1., Baker S1., Ayling R1., Stipkovits L2 1Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey. 2Veterinary Medical Research Institute, Budapest, Hungary. ABSTRACT This report confirms the surveys of others that Mycoplasma bovis plays an important role in respiratory disease in cattle more often with other bacterial pathogens but, frequently as sole pathogen and with high mortality. An in vitro study of the sensitivities of M. bovis to commonly used antibiotics reveals that present isolates are resistant to tetracyclines, tilmocosin, florfenicol, spectinomycin; only danafloxacin showed any significant antimycoplasma activity. In the last five years there has been a large increase in the isolation of M. canis from pneumonic calves. Further experimental evidence is presented here that M. canis can cause severe pneumonia in calves in the absence of other pathogens.

CATTLE PRACTICE plates are washed thoroughly and rabbit anti-bovine IgG peroxidase conjugate was added for 30 minutes. Following another washing, the substrate (3, 3', 5, 5' tetramethylbenzidene) is added and the reaction stopped after 10 minutes by the addition of citric acid. Plates are read by ELISA reader at 450nm. Optical density values of greater than 0.3 are considered positive while values above 0.25 to 0.29 are considered suspect and values below this are negative. In vitro antibiotic assay of M. bovis strains In total, 62 M. bovis isolates, exclusively from cases of calf pneumonia over the last five years, were examined for their sensitivities to a range of commonly used antibiotics using an in vitro method (Ayling et al 2000). Experimental infections of calves with M. canis Eight 4-6 week old calves were infected with 5mls of 109/ml colour changing units of a field isolate of M. canis (17B95) by aerosol administration on two successive days. Controls from the same batch of animals were housed separately. RESULTS Mycoplasma recovered The most frequent mycoplasma isolated from clinicaly affected cattle at VLA over the last decade was M. bovis which accounted for nearly 60% of isolations in 1999. These isolations mainly arose from respiratory specimens but also from a small number of arthritis and mastitic cases and one case of severe conjunctivitis; interestingly, M. bovis was also isolated from a goat showing mild mastitis. As expected the majority of isolations occurred during the winter months from November to March extending into April when most animals are turned out but outbreaks continue in herds where animals are housed throughout the year. The results of serological diagnosis of M. bovis follows a similar pattern. On average the percentage of herds where M. bovis is involved is about 22% and this has risen only a little over the last five years. It is interesting to note that during the summer the percentage of herds affected by M. bovis increase in relation to the total tested. In the vast majority of cases other pathogens such as Pasteurella haemolytica, P. multicoda and Haemophilus somnus are also recovered, but in several incidents where mortality has reached 30%, no other pathogens were implicated. M. bovirhinis is the next most frequently isolated but is clear from ter Laak (1993) and a study from Belgium in 1998 (J Mainil, unpublished) that this BCVA 2000 mycoplasma is found equally amongst healthy and pneumonic calves. Other mycoplasmas also found frequently include M. arginini and A. laidlawii which are both of dubious significance. The infrequent identifications of M. dispar and U. diversum, both capable of causing experimental infection, suggest current media used for primary isolations throughout Britain is not capable for supporting these fastidious organisms. In 1995 we reported the first isolation of M. canis from pneumonic cattle in Britain (Nicholas et al, 1995). Two further isolations were made in 1996 from similar conditions. In 1997 and 1998 there were increases but last year, however, saw 25 cases of calf pneumonia in which M. canis was involved (Table 1). All cases involved animals below the age of 5 months of which half involve some mortality. Most involve other known pathogens such as Pasteurella haemolytica, P. multicoda, H. somnus, RSV or M. bovis. However in a number, no other pathogens were implicated (Table 2). VOL 8 PART 2 Table 1. Isolations of M. canis from calves 1994- 1999. Year No of herds where M.canis isolated 1994 0 1995 1 1996 2 1997 11 1998 13 1999 25 Table 2. Disease data from herds where M.canis isolated. Date Disease Age (months) Number affected Other findings 1/95 Pneumonia 3-5 3/10* H.somnus 4/97 " 1-5 2/10* None 5/97 " 2 3/20 None 7/97 " 1-2 1/? C.perfringans 7/97 " 4-5 10/20 RSV 10/97 " <6 150/150 RSV/Pm/M.bovis 11/97 " 2 ~20 None 11/97 " 3 30/100* None 11/97 " 3 Not known H.somnus/Ph 12/97 " 4 5/10 Ph 12/97 " 2 1 S.typh/Pm 3/98 " 3 2/10* None 3/98 " 5 2/10 M.bovis/H.somnus *mortality seen Ph - Pasteurella haemolytica Pm - Pasteurella multicoda In vitro antibiotic assay of M. bovis strains The results showed that all present strains of M. bovis have developed resistance to tilmicosin; most are resistant to tetracyclines, and about 20% resistant to spectinomycin; only danafloxacin was effective on all strains (Table 3).

CATTLE PRACTICE Experimental infections of calves with M. canis All calves infected with M. canis showed clinical signs of pneumonia including two deaths within two weeks of infection. Post mortem examination revealed lung lesions consistent with pneumonia in all animals. M. canis was recovered from the lungs, liver, blood and kidneys; there was evidence of secondary infection with Pasteurella but no viral involvement. The control group showed no clinical signs and no mycoplasmas were isolated from their organs DISCUSSION This report confirms the surveys of others that M. bovis plays an important role in respiratory disease in cattle more often with other bacterial pathogens but, occasionally and with high mortality, it may be the sole cause of disease although other conditions such as weather and stress may also play a part in the disease process. Evidence over the last five years indicates no great increase in the isolations of M. bovis; however it is clear from the published reports (Anon 1996) that its role is severely underestimated. The finding that resistance has developed in recent British isolates of M. bovis to many commonly used antibiotics is alarming; tetracyclines and tilmicosin are the drugs of choice in infections where mycoplasmas are suspected. With the concern that the fluoroquinalones (danafloxacin) may be prohibited by the EU for use in animals, the options for control are reduced and suggests strongly that vaccines may provide the best approach. The increasing reports of M. canis, although relatively small, represents a real increase rather than greater surveillance because the mycoplasma grows readily in most media. So far three countries (Canada 1974, Netherlands 1993, Britain 1995) have reported its isolation and there may be others which have not considered the organism significant. It is possible that surveillance is not extended to this mycoplasma or that it has been misidentified as other glucose fermenters most likely M. bovirhinis. Biochemically BCVA 2000 the two are similar apart from the inability of M. canis to reduce tetrazolium salts but immunologically they are quite distinct. Experimental evidence is presented here that M. canis can cause severe pneumonia in calves in the absence of other pathogens. This confirms field investigations where in several cases this organism is the only significant pathogen involved in respiratory disease. Early reports suggested that close contact between dogs and calves may be responsible for the appearance of M. canis in cattle. The widespread distribution of M. canis seen in this report provides evidence that this mycoplasma may be considered to be part of the pneumonic mycoplasma flora of cattle. Further work will examine the prevalence of M. canis in healthy and pneumonic cattle using culture and serological techniques. We will also examine the relationship of canine and bovine isolates for evidence of their origin. ACKNOWLEDGEMENTS We are grateful to the Ministry of Agriculture, Fisheries and Food, England and Wales for financing this work. We wish to acknowledge the excellent assistance of Emma Wood. REFERENCES Anon (1996) Veterinary Investigation Diagnosis Analysis. MAFF, Tolworth, UK. Ayling R.D., Nicholas R.A.J. and Johansson K.E. (1997). Application of the PCR for the routine identification of Mycoplasma bovis. Veterinary Record 141: 307-398. Ayling R.D., Baker S.E., Peek M.L., Simon A. J., and Nicholas R.A.J. (2000) Comparison of in-vitro activity of danofloxacin, florfenicol, oxytetracycline, spectinomycin and tilmicosin against recent field isolates of Mycoplasma bovis. Veterinary Record in press Esslemont R.J., Kossaibati M.A. and Reeve-Johnson L. (1998) The costs of respiratory disease in dairy heifer calves. In Proceedings of XX World Buiatrics Congress, Sydney 6-10 July 1998 pp685-690 Laak E.A. ter (1993) Isolation of Mycoplasma canis from pneumonic cattle. Veterinary Microbiology 34: 175-181. Nicholas R.A.J., Hannam D.A.R., Baker S.E.., Weaver C.R. and Laak E.A. ter, (1995). Mycoplasma canis in a British calf. Veterinary Record. 139: 443-444. Nicholas R.A.J. (1997). The other M.bovis, Mycoplasma bovis. VOL 8 PART 2 Table 3. Susceptibility of M.bovis, MIC and MMC results for five antimicrobial agents. M bovis Ranges, MIC90, MIC50, MMC90, MMC50 in μg ml-1 Minimum Inhibitory Concentrations (MIC) Minimum Mycoplasmacidal Concentrations (MMC) Range MIC50 MIC90 Range MMC50 MMC90 Danofloxacin 0.125 - 2 0.5 0.5 0.25 - 8 0.5 1 Florfenicol 1 - 64 4 16 4 - 128 16 32 Oxytetracycline 1 - 128 32 64 2 - >128 64 128 Spectinomycin 1 - >128 4 >128 2 - >128 16 >128 Tilmicosin 4 - >128 >128 >128 16 - >128 >128 >128 The range shows the spread of MIC and MMC values determined from the 62 cultures examined. The values for 50% and 90% of inhibition of the cultures (MIC and MMC) for all antimicrobial agents is also shown. Antibiotics with MIC values < 2 are considered to be effective.