Laryngeal Paralysis in a Cat with Malignant Thymoma

Abstract

A 10-year-old castrated male Domestic Shorthair cat visited a veteri- nary medical teaching hospital for emergency dyspnea. The cat was hypoxic and hypotensive, and stridorous respiration was remarkable. Visual inspection con- firmed laryngeal paralysis and a lack of mobility of the left larynx. Megaesoph- agus, aspiration pneumonia, cranial mediastinal mass, and positive Tensilon test results using neostigmine were observed, indicating acquired myasthenia gravis sec- ondary to thymic neoplasia. After 10 minutes of neostigmine 0.02 mg/kg IV admin- istration, laryngeal paralysis and dyspnea resolved. Histopathlogical examination for the cranial mediastinal mass after surgical resection confirmed malignant thymoma. Here, we report a case of acquired myasthenia gravis in a cat with a malignant thymoma that presented with life-threatening dyspnea due to laryn- geal paralysis. Feline laryngeal paralysis is uncommon, and myasthenia gravis, a cause of laryngeal paralysis in cats, has not yet been reported. Myasthenia gravis should be considered in cats with laryngeal paralysis.