Moderate to severe ulcerative colitis of the right dorsal colon was diagnosed by necropsy or by exploratory celiotomy and biopsy in 13 horses with a primary clinical complaint of either colic, diarrhea, or weight loss. Clinical signs varied from acute fulminating diarrhea (possibly with fever), colic, dehydration, endotoxic shock and death, to a chronic condition manifested by mild intermittent colic up to several months in duration, and weight loss with or without mild diarrhea. In a large percentage of the horses, those affected had been hypovolemic and received nonsteroidal anti-inflammatory drugs (NSAID) or had received inappropriately high doses of phenylbutazone before the onset of illness.Experimental treatment of two horses with high doses of a phenylbutazone oral paste preparation (6 gm once daily for 5 days) and limitation of their water intake to approximately one half of maintenance requirement (for 5 days) resulted in reproduction of ulcerative colitis involving only the right dorsal colon, which was apparent a t necropsy examination 11 and 15 days after initiation of drug use. It was concluded that localized ulcerative lesions in the right dorsal colon may be a previously unreported manifestation of toxicity due to the administration of NSAID. (Journal of Veterinary Internal Medicine 1990; 4:247-253)

Thrombocytopenia was observed in 15 of 146 cases of clinically acute bovine viral diarrhea virus (BVDV) infection in adult cattle. Platelet counts ranged from 2,000 to 33,000/~1. Clinically, a bleeding tendency was manifested by bloody diarrhea, petechial and ecchymotic hemorrhage, epistaxis, and abnormal bleeding from injection sites. Coagulation testing (six cases) gave no evidence of disseminated intravascular coagulation. Bone marrow aspirates were suggestive of active marrow necrosis (two cases) or recent repopulation (three cases). Treatment, when given, was supportive and empirical in nature. Six animals experienced complete clinical recoveries; the others died or were euthanatized. Although the pathogenesis of the thrombocytopenia was not definitively determined, thrombocytopenia associated with acute BVDV infection should be considered in the differential diagnosis for cattle with bleeding disorders. (Journal of Veterinary Internal Medicine 1989; 3:42-46)

and Texas up to 1988. The highest rate of infection was found in young Thoroughbred, Standardbred, and quarter horses. Differences in geographic location, sex, and month (season) of infection were not discernible. This report, the first comprehensive survey of EPM in North America, is intended to serve as a basis for evaluating future changes in prevalence and spread of EPM. (Journal of Veterinary Internal Medicine 1990; 454-57) SEVERAL equine diseases designated as focal myelitisencephalitis, segmented myelitis-encephalitis, equine spinal ataxia, and equine protozoal myelitis have similar