Cats with overactive thyroid glands may appear “nervous”. The disease (hyperthyroidism) most commonly affects older cats. Other symptoms include a healthy appetite (initially) with weight loss and increased activity. Owners can be fooled into thinking their older cat is doing great because he or she is more active and has lost weight when actually they are seeing early symptoms of hyperthyroidism. The nervousness, increased appetite and activity are due to the revved up metabolism that occurs from elevated thyroid hormones. Another health problem that may cause “nervousness” in cats is hypertension. Cats are well known for their ability to hide illnesses until the disease is well advanced. Watching for behavioral changes can be one of the best early indicators of disease in cats.