Osteogenic sarcoma and myasthenia gravis in a dog.

A 7-year-old Saint Bernard developed muscular weakness 1 year after right forelimb amputation and adjuvant cisplatin chemotherapy for osteogenic sarcoma. Clinical and laboratory findings supported a diagnosis of myasthenia gravis, and the dog had clinical improvement in response to prednisone treatment. Two additional dogs with myasthenia gravis and osteogenic sarcoma were identified by review of the medical records of the University of California Veterinary Medical Teaching Hospital. Findings indicated that myasthenia gravis or other neuromuscular transmission disorders may be associated with muscular weakness in dogs with osteogenic sarcoma.