Systemic glycoproteinosis resembling Lafora's disease in a cow.

A 6-year-old, Hereford/Angus crossbred cow which died acutely was submitted for necropsy and diagnostic evaluation. A toxicity was suspected by the owner who had noticed incoordination of one week's duration. The animal was last observed 24 hours prior to death. Toxicology screens for alkaloids, heavy metals, pesticides and nitrates were negative. The significant histologic abnormalities were confined to the thalamic nuclei, periventricular neurons and the liver. Neurons and hepatocytes contained 1 to 2 intracytoplasmic inclusions which stained faintly eosinophilic to slightly basophilic with H&E. The inclusions frequently had dense central cores and a fibrillar to homogeneous periphery. Based on a battery of histochemical stains for carbohydrates, and other mucosubstances and the morphology and location of the inclusions, a diagnosis of systemic glycoproteinosis consistent with Lafora's disease was made. This case represents the first report of lesions consistent with Lafora's disease in the bovine species.