[HYPP--hyperkalemic periodic paralysis in horses]

A literature review of the clinical syndrome HYPP (Hyperkalemic periodic paralysis) affecting Quarter Horses is given. HYPP is characterized by sporadic attacks of muscle tremors, weakness and/or collapse, lasting for variable periods of time. Diagnosis is based on physical findings in association with hyperkalemia. In horses with HYPP, the regulation of ion transport through the sodium channels in the muscle cells occasionally fails, causing uncontrollable muscle twitching. Further investigations into molecular genetics reveals a mutation in the gene responsible for sodium and potassium regulation. The identification of this gene mutation is the basis for the blood test used to diagnose HYPP. HYPP is inherited as an autosomal dominant trait. Treatment of HYPP attacks by intravenous application of calcium gluconate, bicarbonate and glucose results in rapid recovery. Consequent dietary management and daily administration of acetazolamide effectively controls the disease.