Inherited progressive epilepsy of the dog with comparisons to Lafora's disease of man.

A familial progressive form of epilepsy in the beagle dog is clinically characterized by intermittent seizures, often of grand mal type. If not properly treated, the seizures may lead to status epilepticus. The seizures are often elicited by external stimuli, especially a change in noise or light in the surroundings. Histologically, intracytoplasmic inclusions, 2-10 mum in diameter, occur in glial and neuronal cells in the brain, especially the thalamus. The inclusions are strongly positive for carbohydrate stains, weakly metachromatic, and lipid negative. They are spherical with a dense core and an often radiating, less dense periphery. Histologic changes in other organs include basophilic myocardial degeneration, degeneration and variation in diameter size of skeletal muscle fibers, and deposition of periodic acid-Schiff positive material in the cytoplasm of reticuloendothelial cells of the liver, spleen, and lymph nodes. Based on clinical and morphologic manifestations, the beagle disorder resembles Lafora's disease of man. This disorder will provide a useful model for comparative studies with progressive myoclonic epilepsy (Lafora's disease) of man and for defining the pathomechanisms of other forms of epilepsy.