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What You Need to Know about Hyperthyroidism in Cats

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If you're a cat parent, it's smart to educate yourself about common health problems that cats may have. Today, we're talking about the most common endocrine disorder in middle-aged and older cats. If your cat is more than 10 years old, she has a 1 in 10 chance of developing hyperthyroidism

Here's what you need to know about hyperthyroidism in cats.

What causes hyperthyroidism?

Hyperthyroidism happens when one or both of a cat's thyroid glands become enlarge and produce too much thyroid hormone. According to the University of California's Davis Vet School, more than 80% of cats suffering from hyperthyroidism have both thyroid glands enlarged. Another 15% of hyperthyroid cats have a benign tumour, which causes only one of their thyroid glands to be affected. 

Does it mean my cat has a cancerous tumour?

For most hyperthyroid cats, the answer is no. Only 2-3% of cats with hyperthyroidism have a cancerous tumour. It may affect one or both thyroid glands. For treatment options, consult your veterinarian.

What are the signs of hyperthyroidism?

According to Washington State University's School of Veterinary Medicine, "Thyroid hormone affects the function of most organs in the body, so the signs of hyperthyroidism are quite variable." The most common symptoms include:

  • weight loss
  • increased appetite and thirst
  • increased activity and restlessness
  • a matted, greasy, or unkempt coat
  • an increased heart rate

Cats suffering from hyperthyroidism may also suffer from diarrhea, vomiting, and vocalization. If your cat suffers from several of these symptoms, take him to the vet for a thorough examination. They may indicate hyperthyroidism or a different health condition altogether.

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How is hyperthyroidism in cats treated?

Cats with hyperthyroidism may be treated with 4 different options:

  • Medication: According to Cornell University's Vet College, "Anti-thyroid drugs act by reducing the production and release of thyroid hormone from the thyroid gland. These medications do not provide a cure for the disease, but they do allow either short-term or long-term control of hyperthyroidism. "
  • Surgery: Another effective treatment is surgical removal of the thyroid gland(s). However, surgery is not recommended for cats with prior health issues or advanced age. Although it does provide a permanent solution , most cat owners opt for a safer treatment option that carries less risk.
  • Radioactive iodine therapy: The most popular treatment option, this treatment involves injecting radioactive iodine directly into the bloodstream of the cat. Because the thyroid glands need iodine for the production of thyroid hormones, the radioactive iodine is quickly absorbed by the thyroid. Then, it emits radiation to the surrounding tissues, effectively destroying the abnormal tissue. According to Cornell University's Vet College, "The majority of cats treated with radioactive iodine have normal hormone levels within one to two weeks of treatment.
  • Dietary therapy: For a select few cats, the recommended treatment is restriction of iodine in the diet. For cats with other serious health conditions, this may be the safest option. The jury is still out on the possible side effects of long-term iodine restriction. Talk to your veterinarian to discuss the possible risks and benefits.

Is hyperthyroidism a life-threatening condition?

According to ICatCare.org, "Fortunately, the vast majority of cats that develop hyperthyroidism can be treated very successfully and most cats will make a complete recovery." An expert from Cornell University explains, "The prognosis for cats with hyperthyroidism is generally good with appropriate therapy. In some cases, complications involving other organs may worsen this prognosis."

Let's Chat:

Has your cat been diagnosed with hyperthyroidism? Or does she have any symptoms of hyperthyroidism? Share your experience in the comments!

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