Hyperthyroidism in Cats

Hyperthyroidism in Cats
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vet verified PetCareRx Staff Veterinarian DVM

The thyroid is responsible for regulating hormones in the body. When hyperthyroidism develops, hormones can go haywire, with devastating effects on a cat's organs. Learn more about this condition here.

Hyperthyroidism in cats, also known as thyrotoxicosis, occurs when a catโ€™s thyroid produces too much of the T3 and T4 hormone, due most often to benign or sometimes malignant tumors on the thyroid. Hyperthyroidism is primarily found in middle-aged to older cats, typically 8-13 years and older, but not exclusively. Because thyroid health is an important aspect of overall good health, testing is important.

Causes of Hyperthyroidism in Cats

The thyroid is responsible for doling out the appropriate hormones the cat needs in order to maintain healthy organ function throughout the entire body. When there is a tumor on the thyroid, and the hormones are irregular, it results in serious organ function decline. Some of the tumors found to cause hyperthyroidism, are benign tumors called adenomas, while malignant tumors, which are far less common, are called adenocarcinomas. These tumors interfere with the thyroidโ€™s ability to determine the appropriate amount of hormone to excrete.

How to Prevent Hyperthyroidism in Cats

As there is no known way to effectively prevent hyperthyroidism in cats, it is crucial to perform diagnostic tests early enough to prevent further damage. As cats get older, more frequent visits to the veterinarian for blood tests may become necessary. Be diligent at notifying your veterinarian about any new behaviors or physical changes. This may help your vet in determining whether or not to test for hyperthyroidism.

Hyperthyroidism in Cats Tests Explained

To test for hyperthyroidism, your veterinarian will check the thickness of the catโ€™s neck, where the thyroid is located. If there is any additional tissue, such as a tumor or enlarged glands, the veterinarian will sometimes be able to feel the lump. If this is indicative of hyperthyroidism, a blood-chemistry test may be ordered. This test breaks down the blood chemistry into hormone levels. Usually hyperthyroidism is obvious, based on elevated levels of T4 hormone; however, T4 may be normal while hyperthyroidism exists. Additional testing of the heart and kidneys using urinalysis, can further determine the presents of hyperthyroidism.

Hyperthyroidism Symptoms

Because hyperthyroidism causes the body damage very slowly at first, the symptoms are often overlooked, and categorized as normal aging, such as a dull matted coat. However, a few symptoms may be more obvious, such as weight loss, increased appetite, thirst and urination. Symptoms may also include diarrhea, vomiting, and hyperactivity.

How to Treat Hyperthyroidism in Cats

Three options are available when considering treatment for hyperthyroidism in cats. They are medication (Methimazole tablets such as Tapazole is commonly prescribed for cats), surgery, or radioactive-iodine therapy. Consult with your veterinarian about the positives and negatives of each treatment, and which is best for the circumstances of your catโ€™s progress in the disease.

5 Facts on Hyperthyroidism in Cats

Cats between the ages of 8 and 13 are in the age range most commonly associated with the diagnosis of hyperthyroidism, which is the most common cause of hormone imbalance in cats. With that in mind, it is crucial to the future health of your cat, that you can identify the signs and take your cat in for testing before serious damage is done. These five facts may help you understand hyperthyroidism and how to proceed.

1. Can Hyperthyroidism in Cats be Cured?

Yes. If the thyroid is successfully removed, or the radioactive iodine therapy is successful, hyperthyroidism can be cured. Medication, however, does not cure, and requires lifelong treatment. When determining a course of action, it is important to keep in mind that there are risks to every option, and no guarantees.

2. Is Hyperthyroidism Preventable?

No. While some researchers believe that there are chemical causes which can be avoided, there is no real way to prevent hyperthyroidism. It is similar to trying to prevent cancer, just do the best you can in regards to keeping your cat healthy, by maintaining a balanced diet and frequent checkups to the vet, especially as they get older.

3. It Does Not Always Mean Cancer

Tumors on the thyroid, which cause hyperthyroidism, are rarely cancerous. Often when a cat has a visible mass on the thyroid, the immediate fear is cancer. And while cancer is a possibility in the cases of adenocarcinomas, the tumors are usually benign and do not spread.

4. Pay Attention to the Signs

Because hyperthyroidism can progressively do some serious damage to organ function, getting your cat tested is crucial. If you see any behavior that is unlike previous typical behavior, take note and make sure you tell your vet. The symptoms are what lead the veterinarian to perform tests, so accurately identifying them may speed up the process of figuring out what is wrong. If you notice a change such as hyperactivity, when previously the cat was consistently laid back, let your vet know.

5. The Thyroid Determines Metabolic Rate

Good thyroid health is important to the overall health of your cat, because it determines at what rate calories are metabolized into energy. This affects every cell in the body, and how they perform. While having a high metabolism may seem like a positive thing, especially to humans, hyperthyroidism is destructive to organ function.

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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