Detection of Sarcocystis neurona in the brain of a Grant's zebra (Equus burchelli bohmi)

An 8-yr-old intact male Grant's zebra. (Equus burchelli bohmi) was referred to the Veterinary Medical leaching Hospital of the University of Californi a-Davis after being found in the owner's pasture obtunded and in lateral re cumbency. The animal was hypothermic, weak, and unwilling to rise. There wa s no evidence of trauma, and the zebra had seemed normal the preceding even ing. There was no extensor rigidity, and cranial nerve reflexes were normal . Flexor and extensor reflexes were weak upon Initial examination. A comple te blood count and serum biochemistry analysts revealed a mild leukocytosis , hyperfibrinogenemia, hypoglycemia, hyponatremia, hypochloremia, hypocalce mia. and hypoalbuminemia. Urinalysis was normal, and a urine toxicology scr een for alkaloids was negative. No toxic substance was found in the hay or pasture grasses although the owner reported the presence of yellow star thi stle and mushrooms in the pasture. The cerebrospinal fluid cytologic and bi ochemical analyses were normal, but antibodies to Sarcocystis neurona detec ted. The zebra died despite aggressive supportive therapy over a 4-day peri od. The necropsy demonstrated severe gastrointestinal nematodiasis that cou ld account for hypoalbuminemia and electrolyte abnormalities. Histopatholog ic examination of the nervous system revealed focal areas of perivascular c uff Ino In the brainstem that were comprised mainly of lymphocytes, monocyt es. and plasma cells. Immunohistochemical staining identified the presence of S. neurona merozoites associated with the lesions. This zebra probably d ied from severe endoparasitism that resulted in malabsorption, weakness, an d recumbency rather than from encephalitis associated with S. neurona meroz oites. Equine protozoal myeloencephalitis has not been reported previously in nondomestic equids.