Feline myasthenia gravis: a review

Abstract

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.

Laryngeal Paralysis in a Cat with Malignant Thymoma

“…Although the incidence rate of seronegative MG in both dogs and cats is now known, it has been classified as a subgroup of acquired MG in recent review papers because there are often case reports of dogs (15). However, to date, there have been no reports of cats (5,14). Given the unclear history of prior medication, steroid administration could not be completely excluded in this cat.…”