At the cats-only boarding facility, I see a lot of guests who are taking a medication called methimazole — enough that I looked up the medication to see what it treats! Hyperthyroidism is relatively common in older cats, and owners have a variety of treatment options available.
The thyroid is a gland in the neck that helps regulate the body’s metabolism. When the thyroid overproduces hormones, the entire body can be affected. The heart may beat (and pump blood) faster, eventually causing high blood pressure and other problems. The cat may have an insatiable appetite, yet still lose weight. Digestive issues may arise. The coat can become dull and unkempt. The thyroid itself becomes enlarged.
Veterinarians don’t exactly know what causes hyperthyroidism in cats. One possible cause under investigation is the role of iodine in the diet. The average age of an affected cat is twelve — middle-aged and older cats seem to develop thyroid problems more often than young cats.
Diagnosing hyperthyroid disease can be relatively easy. Often, one or both lobes of the thyroid can be felt during a physical examination. If one or both lobes are swollen, the veterinarian may be able to feel it — and may suspect hyperthyroidism. Next, a blood test will look at the levels of a thyroid hormone called thyroxine (also known as T4). High T4 levels will confirm a diagnosis.
In some cats with symptoms of thyroid disease, the T4 levels are within normal ranges. Your veterinarian may perform other blood tests or suggest a thyroid scan to help confirm a diagnosis.
As with many diseases, the earlier you catch hyperthyroidism, the better your cat will do in the following years. Experts suggest that middle-aged and senior cats should have a full physical exam annually; a thyroid check is usually part of this exam.
The good news: less than two percent of hyperthyroid problems involve a malignant growth. Chances are very good that if your cat has hyperthyroidism, it is benign and your cat can live a long and healthy life with proper treatment.