Laryngeal Paralysis in a Cat with Malignant Thymoma

Abstract

A 10-year-old castrated male Domestic Shorthair cat visited a veterinary medical teaching hospital for emergency dyspnea. The cat was hypoxic and hypotensive, and stridorous respiration was remarkable. Visual inspection confirmed laryngeal paralysis and a lack of mobility of the left larynx. Megaesophagus, aspiration pneumonia, cranial mediastinal mass, and positive Tensilon test results using neostigmine were observed, indicating acquired myasthenia gravis secondary to thymic neoplasia. After 10 minutes of neostigmine 0.02 mg/kg IV administration, 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 laryngeal 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.