Toxic myopathy in a dog associated with the presence of monensin in dry food.

This report describes a case of toxic myopathy in a two year old sheltie dog with clinical signs of profound weakness, myoglobinuria, and muscle enzyme elevations. The clinical signs were likely related to the accidental inclusion of monensin sodium in the dog's food. This food was prepared by a small feed milling company that also prepares cattle and chicken rations. A change of dog food resulted in remission of the clinical signs.