Feline acquired thymoma‐associated myasthenia gravis managed with surgery and therapeutic plasma exchange

Abstract

AbstractA 3‐year‐old cat with thymoma‐associated myasthenia gravis underwent thymectomy. Skeletal muscle weakness deteriorated after surgery, and the cat became non‐ambulatory tetraparetic. A higher dose of pyridostigmine failed to improve the weakness. Therapeutic plasma exchange was performed twice, 4 and 8 weeks after surgery, with continued pyridostigmine treatment. Improvement in clinical signs was noted after each therapeutic plasma exchange. Improvement was short‐lasting after the first and long‐lasting after the second session. The dose of pyridostigmine was reduced 4 and 21 months after thymectomy without relapse. Thirty‐two months after thymectomy, the cat remained in clinical remission with continued pyridostigmine treatment, but serum anti‐acetylcholine receptor antibody titre remained elevated (2.0 nmol/L). This is the first report of therapeutic plasma exchange in a cat with acquired thymoma‐associated myasthenia gravis. Therapeutic plasma exchange may be considered an additional immune‐modulating option to medical treatment in cats with acquired myasthenia gravis.