Hyperthyroidism In Cats: An Endocrine Disease All you need to know about hyperthyroidism in cats.

Hyperthyroidism In Cats: An Endocrine Disease

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Hyperthyroidism is the medical term for when the thyroid gland generates excessive amounts of the hormone T4, responsible for producing the hormones that control metabolism and energy levels.

Hyperthyroidism is the most common endocrine disease in cats. It affects the thyroid gland, which produces hormones that control metabolism, including heart rate and body temperature. When this organ becomes overactive, it produces excessive amounts of thyroxine hormone that causes symptoms such as weight loss and hyperactivity.

What Is Hyperthyroidism?

You may not know this, but your cat may have hyperthyroidism. It's a common endocrine disease that affects many cats and can be managed with pet medication.

You might have heard of hyperthyroidism before, but you're not sure what it is or how to spot it in your pet. So let's break it down. Hyperthyroidism is an overactive thyroid gland, the organ that produces hormones responsible for regulating metabolism and energy levels. When the thyroid gland produces too much hormone (called T4), we call that hyperthyroidism.

Who Gets Hyperthyroidism?

You should be aware that older cats, as well as female cats, are at a higher risk of developing hyperthyroidism. Cats with a history of thyroid disease are also more likely to develop it again in the future. Certain breeds of cats, like Siamese and Himalayan breeds, have a slightly higher chance of developing hyperthyroidism than others. In general, if you have one pet or several pets with this condition, it's possible that there was some genetic influence on their conditions (especially if they were related).

How Is Hyperthyroidism Diagnosed?

Thyroid hormone levels are measured in the blood. Thyroid function tests can help to diagnose hyperthyroidism and rule out other causes of your cat’s symptoms, such as a thyroid tumor. If the results of these tests are abnormal, further testing may be necessary. If you think your cat has hyperthyroidism, it is important to consult with a veterinarian and get the right pet meds, who can order further testing such as blood pressure and heart rate monitoring.

You should also have your veterinarian perform an examination of your cat’s neck area (which includes feeling for enlarged lymph nodes) and perform abdominal palpation (feeling for enlarged organs). Finally, radiographs (x-rays) may be needed to rule out other conditions that cause signs similar to those displayed by hyperthyroid cats.

How Is Hyperthyroidism Treated?

A treatment called methimazole for cats is the main option, and it has been shown to be effective in controlling hyperthyroidism. Methimazole for cats is an antithyroid drug that reduces thyroid hormone production by blocking the activity of an enzyme called thyroid peroxidase (TPO), which is involved in synthesizing T4.

Methimazole doesn’t actually cure your cat’s hyperthyroidism, but it does help control symptoms by reducing thyroid hormone levels. As such, it can also help prevent some of the long-term complications associated with this disease: heart disease and kidney failure.

The typical pet medication for cats is 10–15 mg/kg twice daily; however, your vet may recommend a different dosage based on how well your cat tolerates it. It is easily available at any pet pharmacy. Opting for a thyroid-friendly diet specially designed like Hills prescription diet can help in maintaining the right thyroid hormone levels. 

A Common Endocrine Disease

Hyperthyroidism is a common endocrine disease in cats. It's estimated that 25% of all cats older than 10 years suffer from hyperthyroidism. The thyroid gland (located at the base of your cat's neck) releases hormones into your pet's bloodstream, which help regulate other organs and bodily functions such as metabolism. When this is not functioning properly, it causes an overabundance of these hormones to be released into the body, causing health problems like weight loss but also anxiety, and heart disease.

Hyperthyroidism can be treated with pet meds if caught early enough; however, veterinarians recommend regular checkups for any cat you suspect may have hyperthyroidism so that treatment can start sooner rather than later if needed.


When a cat is found to have hyperthyroidism, it can be treated with pet medicines. The prognosis for cats with this disease is excellent, and most cats can live out a normal lifespan if treatment begins as soon as possible. It's important for owners of hyperthyroid cats to be aware of the symptoms so they know when their pet should be examined by a veterinarian.

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