Acquired myasthenia gravis in a domestic shorthair cat with cranial mediastinal mass

A 7-year-old castrated male domestic short-hair cat presented with anorexia, constipation, depression, and voice alteration. Physical and neurological examinations revealed hyperthermia (40.5C), ventroflexion of the neck, reduced responses to external stimuli, generalized muscle weakness, and exercise intolerance. Thoracic radiographs revealed the presence of a cranial mediastinal mass. The history, clinical signs, and other examination results were compatible with acquired myasthenia gravis (MG). Acetylcholine receptor (AChR) antibody titers were determined to confirm MG and the serum AChR antibody concentration was 1.24 nmol/L (reference interval, < 0.3 nmol/L). This is the first diagnosis of acquired MG in a cat in Korea.