Parasitemia in a neonatal bison calf

Abstract

A 3-day old female bison calf (Bison bison) was presented in lateral recumbency to the Université de Montréal Veterinary Teaching Hospital. The animal was severely depressed and dehydrated (10%) and died a few hours after admission. Prior to death, blood samples were obtained for CBC, clinical chemistry, and serology tests. Abnormal CBC findings included thrombocytopenia, lymphocytosis, mild monocytosis, and a toxic left shift. Abnormal serum clinical chemistry findings included marked azotemia, hyperphosphatemia, hypernatremia, hyperalbuminemia, hypoglobulinemia, and low gamma-glutamyltransferase activity. Serologic test results for bovine leukosis virus and bovine viral diarrhea virus were negative. Blood smear examination revealed numerous elongated organisms that were tapered at both ends and characterized by an undulating membrane and a long flagellum. The organisms ranged in length from 35 to 40 micro meter, excluding the flagellum, and were identified as Trypanosoma theileri. Postmortem examination revealed that the animal suffered from concurrent mycotic abomasitis and colisepticemia.