Symptoms of Feline Thyroid Problems

There are two types of feline thyroid problems: hyperthyroidism and hypothyroidism. Though thyroid conditions are not as common as they are in dogs, they do occur, especially in older cats. Thyroid illnesses can be especially debilitating if left untreated because, as with humans, the thyroid gland controls hormones that regulate functions in many areas of the body, the most notable being metabolism.


Hypothyroidism is a gland disorder that slows down your cat's thyroid. While it isn't fatal, it can affect their quality of life. Cats can't inherit hypothyroidism like dogs. It is usually developed by injury to the thyroid gland, treatment for hyperthyroidism or a thyroid tumor if your cat's diet is low in iodine, which is rare since most cat foods contain sufficient levels of iodine.

A cat with hypothyroidism will have a sudden weight gain, a dull dry coat and lethargy or listlessness. It will appear as if your cat is depressed since his energy will be greatly reduced.

If you see these symptoms, ask your veterinarian for a complete T-4 blood panel. Hypothyroidism is easily treated with soloxine.


Hyperthyroidism is much more common in cats, occuring when the thyroid gland enlarges and produces excess amounts of thyroid hormones. This is usually caused by a tumor on the thyroid gland, which is usually benign but may be malignant.

Symptoms for hyperthyroidism include increased appetite, unexplained weight loss, irritability, nervousness, frequent vomiting, diarrhea, excessive thirst, weakness, lethargy and unhealthy coat appearance.

Hyperthyroidism can also lead to more serious problems, especially if left untreated. Excess thyroid hormones can cause, or worsen, kidney disease, heart disease, dental disease, sugar diabetes and hypertension, which can lead to blindness.

While a physical exam might reveal hyperthyroidism if a lump is discovered, a T-4 blood panel is often required. Since hyperthyroidism can mimic many other diseases, it can be difficult to diagnose.

Treatment of hyperthyroidism can be more invasive because surgery is sometimes required. It can also be treated with medication or radioiodine treatment.

Though young cats can be affected by thyroid problems, they are most common in older cats. If your cat is 8 years or older, he should be screened for thyroid problems each year during his annual exam.

While thyroid problems are usually easy to treat, they can affect your cat's quality of life if left untreated and, in the case of hyperthyroidism, lead to much serious problems. If you have noticed extreme weight changes associated with other healthy problems and an unhealthy appearance in your cat, ask your veterinarian for a blood panel.