Potassium is an important electrolyte (salt) that affects the function of nerves, muscles, and the heart. A high level of potassium in the blood is known as hyperkalemia, whereas a low level is called hypokalemia.
Hypokalemia can occur when there is inadequate potassium in a cat's diet or when a cat receives a large amount of intravenous fluids. Severely low blood levels of potassium result in muscle weakness, an inability to raise the head, and arrhythmias (abnormal heart rhythms). If left untreated, muscle disorder that is hard to treat can develop. All breeds of cat can develop feline hypokalemic polymyopathy, which is a muscle disorder that causes generalized weakness, and Burmese cats can inherit a genetic muscle disorder due to low potassium levels.
Potassium is normally excreted through the urine. When an animal cannot eliminate urine properly, the level of potassium in the blood can rise to dangerous levels. An obstruction of the urinary tract is the most common cause of hyperkalemia in cats. It can also occur in cats with a ruptured urinary bladder. Severe hyperkalemia is associated with widespread muscle weakness, depression, and life-threatening arrhythmias. Seek immediate veterinary care if your cat appears unable to urinate properly, because urinary tract obstructions and hyperkalemia are serious medical conditions that can result in death if left untreated.
Also see professional content regarding disorders of potassium metabolism.