Oleander (Nerium oleander) intoxication in a bison

Clinical History: Two 18-month-old female bison and a heifer died suddenly in the same ranch. The three animals were submitted for postmortem examination and diagnostic workup. The changes of one of the bison are presented here. Necropsy Findings: The carcass was in fair nutritional condition, with small amount of fat reserves, but still well fleshed, and in mild state of post-mortem decomposition. There was a small amount of clotted dark-red blood in the nostrils and anus. The heart presented extensive sub-endocardial hemorrhages in all four chambers. These lesions were most pronounced in both ventricles where they extended deep into the underlying myocardium (Figs. 1 and 2). The mucosa of the abomasum was diffusely and mildly congested, and the mucosa of the small and large intestine was diffusely and severely congested (Fig. 3). There was a moderate amount of red fluid in the lumen of the small intestine, cecum, and colon. Both lungs had a few, small, welldelineated, deep, firm, multifocal dark-red areas in all pulmonary lobes, but lung tissue samples floated when placed into formalin.