Feline Hyperthyroidism: When There’s Too Much of a Good Thing

Maybe one of your older cats has seemed to have a “new lease of life.” He or she may be more active – even acting like a kitten – eating well, “chattier” than normal and perhaps losing some of that extra weight. Chances are that your kitty hasn’t found the feline “Fountain of Youth.” You may be living with a cat who has hyperthyroidism, the most common endocrine (glandular) disease of cats over seven years of age in the United States. The thyroid gland is shaped like a bow tie and lies on the trachea (windpipe). Thyroid hormone (thyroxine) helps to regulate many bodily functions, including, the metabolic rate, fat metabolism, the excitability of the heart, gastrointestinal tract motility and muscle function. When thyroxine is in excess, several things can occur: Fat stores decline (and the patient becomes thin), the heart rate increases, the appetite increases and the motility of the gastrointestinal tract speeds up. Without treatment, the typical hyperthyroid cat is a very active, thin kitty with an excellent appetite, a very fast heart rate and often diarrhea or vomiting. Many cat guardians mistakenly think that cats with these signs aren’t ill (in fact, many are thrilled that their once-sedate older friend is now acting like a youngster) and don’t take them to the veterinarian for an examination and labwork. That’s a mistake, as uncontrolled hyperthyroidism can have serious consequences, including high blood pressure, stroke and heart failure.