Granulomatous encephalitis in a neurologically impaired ...

416 Brief Communications

J Vet Diagn Invest 13:416–419 (2001)

Granulomatous encephalitis in a neurologically impaired goat kid associated with
degeneration of Neospora caninum tissue cysts

Lu´sı Gustavo Corbellini, Edson Moleta Colodel, David Driemeier

Abstract. Congenital Neospora caninum infection was diagnosed in a Saanen goat from a farm in southern
Brazil. The kid was unable to nurse and had difficulty rising, ataxia, and opistothotonos. The neurologic signs
became more severe 3 days after birth, when it was euthanized. No gross lesions were observed at necropsy.
Multifocal infiltrates primarily of mononuclear cells, nodular microgliosis, and perivascular cuffs of lympho-
cytes, plasma cells, and few neutrophils were observed in the brain, mostly in the cortex and adjacent to
ventricles. Rare multinucleate giant cells were observed adjacent to inflammatory foci. Several tissue cysts with
a thick wall that reacted strongly with polyclonal antiserum to N. caninum were in the cerebral cortex and
medulla oblongata. Lesions were also present in heart, lungs, and liver, but N. caninum tachyzoites were not
found. Distinguishing features in this goat kid included neurologic impairment resulting from congenital infec-
tion with N. caninum and the presence of granulomatous inflammation with rare giant cells associated with
degeneration of tissue cysts.

Neospora caninum is a protozoan parasite of animals first ically, lesions were found in the central nervous system,
recognized in dogs with neurologic disease.7 This parasite is heart, lungs, and liver. In the brain, the lesions were char-
a cyst-forming coccidium in the phylum Apicomplexa and acterized by multifocal infiltrates, often locally extensive
is closely related to Toxoplasma gondii.7 Dogs were recently and composed primarily of mononuclear cells and glial
confirmed to be a definitive host of N. caninum.16 Neospo- cells, with slight to moderate perivascular cuffs of lympho-
rosis has been described in cattle,5 sheep,10 goats,1,6,11 deer,19 cytes, plasma cells, and a few neutrophils and marked con-
and horses.15 Recently, serologic evidence of human expo- gestion. Small foci of necrosis surrounded by nonsuppu-
sure to N. caninum was found.18 Neosporosis is an important rative inflammation were sometimes observed. These le-
cause of fetal loss in dairy cattle throughout the world.5 In sions were predominantly in the cortex and areas adjacent
Brazil, N. caninum has been described in aborted bovine to white matter and ventricles and in the gray matter of the
fetuses.3,12 This report contains a describes a?? description medulla oblongata. Rare multinucleate giant cells were ob-
of a congenital N. caninum infection in a Saanen goat from served in the proximity of inflammatory foci (Fig. 1). Nu-
a farm in Rio Grande do Sul state, southern Brazil. merous protozoal tissue cysts could be seen in the brain,
sometimes in association with the inflammatory lesions;
Prior to the present investigation, abortions and birth of most cysts were located in the cytoplasm of neurons (Fig.
underweight kids had occurred in 3 other does during the 2) and glial cells. Degenerating tissue cysts were surround-
previous 4-month period. A 1-day-old female Saanen kid ed by nodular gliosis and mononuclear cells, and these le-
was presented in November 1997 to the Department of Vet- sions were characterized by a granulomatous appearance
erinary Pathology at Universidade Federal do Rio Grande do and the presence of epithelioid cells (Fig. 3). The smallest
Sul, Brazil. The kid had been weak at birth, was unable to tissue cyst was 14.0 ϫ 12.4 ␮m, and the largest was 35.1
nurse, and had difficulty rising, ataxia, and opistothotonos. ϫ 32.2 ␮m. Cyst walls were 1.1–3.0 ␮m thick. The cysts
Neurologic signs became more severe 3 days after birth, and contained slender bradyzoites that stained strongly with
the kid was euthanized. Specimens of several organs, in- PAS and anti-N. caninum antiserum. The tissue cyst walls
cluding central nervous system, were collected, fixed in 10% reacted weakly when exposed to the anti-T. gondii serum.
neutral buffered formalin, and processed routinely for his- Nonsuppurative myocarditis was characterized by mild
tologic examination. Sections from paraffin-embedded tissue lymphocytic infiltrates in the myocardium, and there was a
blocks were cut at 3 ␮m and stained with hematoxylin and mild interstitial pneumonia. Proteinaceous fluid, fibrin, and
eosin (HE) or with immunohistochemical techniques to de- neutrophils were observed in alveolar spaces. Infiltrates of
tect N. caninum. Sections of brain also were stained with mononuclear cells and a few neutrophils were scattered in
periodic acid–Schiff (PAS). The immunohistochemical pro- portal regions of the liver. Tachyzoites were not observed,
cedures were previously described.3 An avidin–biotin–per- even by means of immunohistochemical staining.
oxidase complex kita was employed as the immunohisto-
chemistry detection system. The primary antibodies used The histopathologic changes observed were consistent
were anti-N. caninumb at 1:3,000 dilution and anti-T. gondiib with a protozoal infection. Sarcocystis, T. gondii, and N.
at 1:2,000 dilution. caninum can all cause abortion and stillbirth in goats and
other ruminants.4,11,13,14 The thick cyst walls and immunore-
At necropsy, gross lesions were not observed. Histolog- activity are consistent with previous descriptions of neos-
porosis in goats.1,6 The tissue cyst walls of T. gondii are
From the Department of Pathology, Veterinary Faculty, Univer- thinner than those observed in this goat.2 Cross-reactivity
sidade Federal do Rio Grande do Sul, RS, Brazil.

Received for publication September 19, 2000.

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Brief Communications 417

Figure 1. Goat brain with multinucleate giant cell (arrow) adjacent to focal inflammatory infiltrate. HE. Bar ϭ 20 ␮m.

Figure 2. Neospora caninum tissue cysts in the cerebrum of goat. A large thick-walled cyst is in the cytoplasm of a neuron (arrowhead).
HE. Bar ϭ 20 ␮m.

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418 Brief Communications

Figure 3. Goat brain showing degenerating tissue cyst of Neospora caninum (arrow) within a focus of granulomatous inflammation.
HE. Bar ϭ 25 ␮m.

between N. caninum and T. gondii has been documented in Sources and manufacturers
goat fetuses and in a calf with encephalomyelitis.1,2 In the
present study, the organisms differed from those of Sarco- a. Dako LSABϩ kit, Peroxidase, Dako Corp., Carpinteria, CA.
cystis species by lack of septa within tissue cysts.8,14 Fur- b. VMRD, Pullman, WA.
thermore, endothelial tropism, typical of Sarcocystis schiz-
onts, was not seen.13 Mononuclear inflammatory cells ob- References
served around some degenerating tissue cysts were sugges-
tive of a rupture of these tissue cysts and subsequent host 1. Barr BC, Anderson ML, Woods LW, et al.: 1992, Neospora-like
reaction.9 Nodular gliosis around a degenerating tissue cyst protozoal infections associated with abortions in goats. J Vet
was previously reported in a aborted fetus from a Saanen Diagn Invest 4:365–367.
doe.11 Histopathologic examination revealed multinucleate
giant cells adjacent to inflammatory foci, which has not been 2. Barr BC, Conrad PA, Dubey JP, Anderson ML: 1991, Neospora-
reported in infections caused by N. caninum. The finding of like encephalomyelitis in a calf: pathology, ultrastructure, and
only tissue cysts and not tachyzoites suggests that the infec- immunoreactivity. J Vet Diagn Invest 3:39–46.
tion was chronic.6 The presence of large tissue cysts of N.
caninum resulting in chronic congenital disease has also 3. Corbellini LG, Driemeier D, Cruz CEF, Marona M: 2000, Abor-
been reported in a calf.2 The cellular response composed to bovino por Neospora caninum no Rio Grande do Sul. Cieˆnc
primarily of mononuclear cells and the presence of focal Rural 30:863–868.
gliosis and several tissue cysts are all consistent with chronic
infection.17 Abortion and stillbirth resulting from natural N. 4. Dubey JP: 1981, Epizootic toxoplasmosis associated with abor-
caninum infections have been reported in goats from the tion in dairy goats in Montana. J Am Vet Med Assoc 178:661–
USA.1,6 Neospora caninum infection was also reported in an 670.
aborted fetus from a farm in Costa Rica that had experienced
abortions and the birth of a kid with hind limb paralysis.11 5. Dubey JP: 1999, Recent advances in Neospora and neosporosis.
Unique features of this goat kid from Brazil with congenital Vet Parasitol 84:349–367.
N. caninum infection included neurologic impairment and
the presence of granulomatous inflammation with rare giant 6. Dubey JP, Acland HM, Hamir NA: 1992, Neospora caninum
cells that was associated with degeneration of tissue cysts. (Apicomplexa) in a stillborn goat. J Parasitol 78:532–534.

Acknowledgement. We are grateful to Dr. Jose´ Felipe 7. Dubey JP, Carpenter JL, Speer CA, et al.: 1988, Newly recog-
Amato for photographic assistance. nized fatal protozoan disease of dogs. J Am Vet Med Assoc
192:1269–1285.

8. Dubey JP, Leathers CW, Lindsay DS: 1989, Neospora caninum-
like protozoan associated with fatal myelitis in newborn calves.
J Parasitol 75:146–148.

9. Dubey JP, Lindsay DS: 1993, Neosporosis. Parasitol Today 9:
452–458.

10. Dubey JP, Lindsay DS: 1996, A review of Neospora caninum
and neosporosis. Vet Parasitol 67:1–59.

11. Dubey JP, Morales JA, Villalobos P, et al.: 1996, Neosporosis-

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Brief Communications 419

associated abortion in a dairy goat. J Am Vet Med Assoc 208: 16. McAllister MM, Dubey JP, Lindsay DS, et al.: Dogs are de-
263–265. finitive hosts of Neospora caninum. Int J Parasitol 28:1473–
12. Gondim LFP, Sartor IF, Monteiro LA, Haritani M: 1999, Neos- 1478.
pora caninum infection in an aborted foetus in Brazil. NZ Vet
J 47:35. 17. Summers BA, Cummings JF, de Lahunta A: 1995, Inflammatory
13. Hong CB, Giles JR, Newman LE, Fayer R: 1982, Sacocystosis disease of the central nervous system. In: Veterinary neuropa-
in an aborted bovine fetus. J Am Vet Med Assoc 181:585–588. thology, pp. 95–188. Mosby, St. Louis, MD.
14. Jones TC, Hunt RD, King NW: 1996, Diseases due to protozoa.
In: Veterinary pathology, 6th ed., pp. 549–600. Willians & Wil- 18. Tranas J, Heinzein RA, Weiss LM, McAllister MM: 1999, Se-
kins, Baltimore, MD. rological evidence of human infection with the protozoan Neos-
15. Marsh AE, Barr BC, Madigan J, et al.: 1996, Neosporosis as a pora caninum. Clin Diagn Lab Immunol 6:765–767.
cause of equine protozoal myeloencephalitis. J Am Vet Med
Assoc 209:1907–1913. 19. Woods LW, Anderson ML, Swift PK, Sverlow KW: 1994, Sys-
temic neosporosis in a California black-tailed deer. (Odocoileus
hemionus columbianus). J Vet Diagn Invest 6:508–510.

J Vet Diagn Invest 13:419–421 (2001)

Haemophilus somnus bronchopneumonia in American bison (Bison bison)

N. W. Dyer

Abstract. Immunoperoxidase assays were performed on 21 archived formalin-fixed, paraffin-embedded
tissues from from American bison (Bison bison) with bronchopneumonia. Seven of the 21 bison had positive
staining for Haemophilus somnus in alveolar exudate, visceral pleura, lung parenchyma, and chronic necrotic
lesions, and H. somnus was isolated from tissues from 1 of these 7 animals. Results suggest that H. somnus is
a respiratory pathogen in bison.

Haemophilus somnus is a well-documented cause of bron- volvement (Fig. 1). Faint staining was noted in more chron-
chopneumonia in cattle worldwide.6,7,9,10 Gross lesions in- ic, necrotic lesions. One bison had less intense staining that
clude fibrinous pleuritis and variable amounts of craniov- was widely distributed in lung parenchyma.
entral pulmonary consolidation. Microscopic changes asso-
ciated with H. somnus infection include fibrinopurulent to Because H. somnus is optimally recovered under specific
necrotizing bronchiolitis and bronchopneumonia with fibri- medium (chocolate agar) and atmospheric (5% CO2) condi-
nous pleuritis, vasculitis, thrombosis, and dilation and tions,8,11 the original cases were examined to assess the mi-
thrombosis of septal lymphatics.1,2,4 Recent research with crobiologic techniques used. Haemophilus somnus isolation
American bison (Bison bison) indicates that H. somnus is was requested by the diagnostician of record in all cases.
sometimes recovered from the tonsils of clinically normal The organism was recovered from only 1 of the 7 animals
animals.12,13 Although Mannheimia haemolytica has been as- with positive staining. Referring histories indicated that an-
sociated with bronchopneumonia in bison,3 respiratory dis- tibiotics were administered to 2 of these 7 bison prior to
ease associated with H. somnus infection has not been doc- submission of tissues, possibly inhibiting recovery of the
umented in this species. This study was initiated to identify, organism. Incomplete information was available on the other
by culture and immunoperoxidase assay, H. somnus in bison 4 bison. No antibiotics were given to the animal from which
with bronchopneumonia. H. somnus was actually isolated.

Twenty-one archived cases of bison bronchopneumonia The culture-positive animal was a 182-kg bull calf sub-
that occurred from 1995 to 2000 and for which there were mitted in December 1995. A single animal from a contem-
formalin-fixed, paraffin-embedded tissues available were ex- porary group of 50 bison died. The producer typically pur-
amined for evidence of H. somnus infection. Replicate sec- chased bull calves from several sources and commingled
tions from the original blocks were cut and processed with them for finishing and slaughter. Upon arrival at the feedlot
an avidin–biotin complex immunoperoxidase assay.5 Tissues 6 weeks earlier, the animal received levamisole and a 7-way
were stained using a rabbit polyclonal antisera against H. Clostridium vaccine. Nutrition consisted of pelleted feed and
somnus outer membrane proteins.5 Positive staining was ob- hay. Gross lesions described by the referring veterinarian
served in 7 of the 21 bison. Positive staining was primarily included severe lung consolidation and tracheal hemorrhage.
in alveolar regions of the lung with occasional pleural in- Fluorescent antibody analysis of frozen sections of lung,
spleen, and kidney were negative for infectious bovine rhi-
From the Department of Veterinary and Microbiological Sciences, notracheitis virus, bovine viral diarrhea virus, bovine respi-
Van Es Hall, Veterinary Diagnostic Laboratory, Fargo, ND 58105. ratory syncytial virus, and parainfluenza 3 virus. Culture of
lung tissue yielded moderate numbers of H. somnus and low
Received for publication September 19, 2000. numbers of mixed contaminants. Neither M. haemolytica nor

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