Acquired immune‐mediated myasthenia gravis in a cat associated with a cystic thymus

O'Dair, H. A.; Holt, P. E.; Pearson, G. R.; Gruffydd‐Jones, T. J.

Acquired myasthenia gravis was diagnosed in a five‐year‐old domestic shorthair, neutered, female cat with generalised muscle weakness, tremors, dysphagia and alterations in voice. Radiographs indicated the presence of a mass in the anterior thorax. A response to edrophonium chloride, and raised levels of anti‐acetylcholine receptor antibodies in the serum, confirmed the diagnosis and indicated an immune‐mediated aetiology. Clinical remission occurred following thymectomy and the use of immunosuppressive corticosteroids. This is the first fully‐documented case of acquired feline myasthenia gravis associated with the presence of a thymic abnormality in the United Kingdom. The clinical features, laboratory findings and response to treatment are compared with those reported previously in cats and other species.