Inspiratory stridor secondary to palatolingual myokymia in a Maltese dog.

A nine-year-old male Maltese dog was presented with an eight-month history of inspiratory stridor leading to exertional dyspnoea and cyanosis. Myokymic contractions in the palatolingual muscles were noticed and confirmed by electromyography. Brain computer tomography-scan showed ventricular dilatation. Cerebrospinal fluid analysis revealed a slightly elevated protein level. Treatment with slow-release phenytoin was unsuccessful and symptoms gradually worsened over the next nine months. At post-mortem examination a small pituitary adenoma was found. Apart from a single canine report of facial myokymia, this is the only other description of spontaneous focal myokymia in animals. Palatolingual myokymia has only been reported in one human being. Although the co-occurrence with a pituitary adenoma might be incidental, a paraneoplastic pathogenetic mechanism is proposed. Its unique clinical presentation adds a new, albeit uncommon, syndrome to the differential diagnosis of upper airway complaints in dogs.