Juvenile onset acquired myasthenia gravis in a Shih-tzu dog

A 7-month-old female Shih-tzu dog was presented with intermittent trembling, dyspnea, generalized muscle weakness, and unconsciousness after exercise. No remarkable findings were shown in the complete blood counts and the radiographic examination. On serum biochemical profiles, alkaline phosphatase and creatine phosphokinase were mildly elevated. Based on history takings, physical examination, and neurological findings, presumptive diagnosis was made as a myasthenia gravis (MG). Clinical signs of this patient were dramatically improved after administration of neostigmine. The result of acetylcholine receptor antibody test in serum was 0.89 nmol/L and the histopathology of muscle were normal. Clinical sign of the patient evaluated in this study is stabilized with long-term administration of pyridostigmine at this time. This case report here describes clinical and clinicopathological findings of a juvenile onset acquired MG in a Shih-tzu dog.