Hypokalemia is a common serum electrolyte abnormality affecting both young and old cats. Causes include dietary deficiency, chronic renal insufficiency, diabetes mellitus, and just about any condition involving metabolic alkalosis. Rare causes include aldosteronoma or other reasons for hyperaldosteronism.

The most common clinical signs, as shown in the accompanying large photograph, are diffuse skeletal muscle weakness and ventral cervical flexion. These signs result from hyperpolarized muscle cell membranes (which eventually become hypopolarized). Diagnosis is based on history, physical examination findings, and serum chemistry documentation of hypokalemia (serum creatine kinase is also increased). Treatment consists of oral or parenteral administration of potassium salts and correction of the underlying problem. The prognosis is generally favorable-the kitten depicted was experiencing dietary deficiency and recovered after overnight treatment with intravenous fluids containing potassium chloride.