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

摘要

A 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 dosage 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.