Symptoms of Thyroid Disease in Cats

The most common thyroid diseases in cats are hypothyroidism or hyperthyroidism. Even though these diseases designate conditions that are very different (thyroid hormones in excess and deficiency of thyroid hormones), they often have similar symptoms and tests are required to distinguish between them.

Appetite Changes

A thyroid disease can influence the appetite of the cat. If the cat is affected by hyperthyroidism, he will eat more and may even double his food intake. This is due to the increased metabolic rate. If the cat has an impaired thyroid gland function, he will be lethargic and may often refuse to eat.

Weight Loss

Weight loss may be present both in the case of hypothyroidism and hyperthyroidism. This is due to the fact that the thyroid gland is hyperactive and will speed up the metabolism, so the cat will lose weight even if he eats more than usual. If the cat has hypothyroidism, the condition will cause lack of appetite, so he will lose weight.

Increased Frequency of Drinking and Urination

Hyperthyroidism can cause increased thirst, so the cat will tend to drink more water and will urinate more as a consequence of that. Monitor the water bowl and if you notice it empties faster, you should take your pet for tests. This can be a sign of thyroid disease, but may also be an indicator of diabetes or a kidney problem.

Skin Problems

Skin problems may occur as a consequence of a thyroid disease. This can be due to:

  • Excessive dryness of the skin, caused by hypothyroidism, which makes the skin more prone to infections.
  • Excessive oil on the skin, caused by the hyperactivity of the hormones and the production of sebum in excess.

Coat Changes

The fur may suffer from changes if the cat has a thyroid disease:

  • It will be greasy and matted, due to the excess of sebum produced by the skin.
  • It will be coarse and lack the normal shine, due to the dryness of the skin.

These changes will be more visible if the cat's fur is longer. You may also notice changes in the color of the coat, and some cats may lose hair.

Agitation and Activity

A cat affected by hyperthyroidism can be extremely agitated and active. On the other hand, a cat with low thyroid gland function can be less active than usual, but may still be restless.


If the cat starts being particularly vocal, this may be due to the mating season, but it can also be caused by a thyroid disease.

Hyperthyroidism in felines is more common than hypothyroidism; however, if you notice any symptoms of thyroid disease, you need to get veterinary help. If left untreated, a thyroid disease in your pet can lead to heart and kidney disease. Thyroid diseases can be controlled with medication, radiation therapy or surgery.