Feline myasthenia gravis: a review

Myasthenia gravis is an immune mediated disorder of neuromuscular transmission. Both an acquired and a congenital form have been reported in cats. Generalised weakness is considered a hallmark of myasthenia gravis, but in cats, due to their sedentary nature, this may not be as evident as in dogs. Feline acquired myasthenia gravis is associated with a significant incidence of cranial mediastinal masses, and a lower percentage of associated megaoesophagus than myasthenia gravis in dogs. The diagnosis of acquired myasthenia gravis remains challenging for the clinician, and there are currently no evidence-based treatment protocols. Reports describing outcomes in acquired feline myasthenia gravis are conflicting, with survival rates ranging from 42–85%. Data concerning the rate of spontaneous remission in feline acquired myasthenia gravis is limited, however the reported incidence appears low (9.2%). Recently, a mutation affecting the COLQ gene has been identified in the Sphynx and Devon Rex breeds, demonstrating a genetic basis to feline congenital myasthenia gravis.