Myasthenia gravis is an autoimmune disease that targets the motor end plates, the connection between the nerves and the voluntary muscles. Affected dogs tire easily and may stumble for no apparent reason. They often also have megaesophagus. Vigorous exercise may bring on collapse and severe attacks can mimic toxic exposure. The disease can be acquired (in older dogs), but is more likely to be inherited.
The disease can be diagnosed with a blood test. MG dogs are treated with drugs that improve motor nerve cell communication. Prognosis in treated dogs is good though it is necessary to guard against aspiration pneumonia in dogs which have secondary megaesophagus.
MG is a type of autoimmune disease. Autoimmune diseases are genetically predisposed; if a dog has the disease, it has the genes. Dogs affected with MG should not be bred. Their near relatives should not be bred to mates with a family history of any autoimmune disease.