LARYNGOSPASM, DYSPHAGIA, AND EMACIATION ASSOCIATED WITH HYPERKALEMIC PERIODIC PARALYSIS IN A HORSE

Hyperkalemic periodic paralysis (HPP) is a dominant heritable muscle d isease of horses. Clinical signs associated with HPP are muscle fascic ulations, spasm, weakness, sweating, involuntary recumbency, prolapse of the third eyelid, and respiratory strider. Serum potassium is usual ly, but not always, high during clinical episodes. Abnormal electrical activity of musculature may be observed using electromyography. Endos copic evaluation of HPP-affected horses with respiratory signs may rev eal pharyngospasms and laryngospasms, and abnormalities of the nasopha ryngeal openings of the auditory tube diverticuli. Regardless of age a nd serum potassium concentration, HPP should be considered as a differ ential diagnosis for pharyngeal and laryngeal dysfunction and dysphagi a in any horse with Quarter Horse breeding.