Does Your Cat Have Hyperthyroidism? Here’s a Brief Review

Cats with hyperthyroidism can live a long and quality life if the condition is managed with treatment. But without treatment, they can suffer from weight loss, heart diseases, and death.

Here’s a quick glance at the most important facts about hyperthyroidism you should know.

What Is Hyperthyroidism?

Hyperthyroidism is when the thyroid gland produces too much thyroid hormone called thyroxine. Cats typically have two thyroid glands on each side of their neck.

Since the thyroid gland produces too much thyroxine, this leads to an increase in the cat’s metabolism. This, in turn, can cause a variety of clinical signs, including weight loss, increased appetite, hyperactivity, increased thirst and urination, vomiting, and diarrhea.

In general, the cause of hyperthyroidism is an enlargement of the thyroid gland or goiter. In fact, almost 99% of feline hyperthyroidism cases are caused by a benign thyroid gland tumor. This type of tumor is called an adenoma. While the cause of hyperthyroidism is most often benign, in rare cases, it can result from a cancerous thyroid gland tumor. This type of tumor is called carcinoma.

Cats with hyperthyroidism often suffer from other health problems as well. The most common complications associated with feline hyperthyroidism are heart and kidney disease. 

Signs and Symptoms of Hyperthyroidism in Cats

The most common signs and symptoms of hyperthyroidism are:

  • Weight loss
  • Increased appetite
  • Hyperactivity
  • Increased thirst and urination
  • Vomiting
  • Diarrhea
  • Fast heart rate
  • High blood pressure

If your cat shows any of these signs, you should take them to the vet for a check-up. Early diagnosis and treatment of hyperthyroidism are important to improve the chances of a successful outcome.

How Is Hyperthyroidism Diagnosed?

The first step in diagnosing feline hyperthyroidism is to take a complete history and perform a physical examination on the cat. A thorough physical examination will help rule out other potential causes of the clinical signs.

For example, weight loss can be caused by many different things such as parasites, poor nutrition, or another underlying disease. So, it’s important to exclude these other potential causes before diagnosing hyperthyroidism.

The next step in diagnosing hyperthyroidism is to perform some routine blood tests. The most important blood test for diagnosing hyperthyroidism is the thyroid hormone level. This test measures the amount of thyroxine in the blood.

In a cat with hyperthyroidism, the thyroid hormone level will be high. Other blood tests that may be performed include a complete blood count (CBC) and a biochemical profile. These tests help rule out other potential causes of the clinical signs and evaluate the cat’s overall health.

In some cases, additional testing may be necessary to confirm the diagnosis of hyperthyroidism. For example, if the thyroid hormone level is borderline high, a second test may be performed to confirm the diagnosis.

Other tests include an ultrasound examination of the thyroid gland and a nuclear medicine scan. These tests are used to evaluate the size and function of the thyroid gland. In some instances, cat scans may be necessary to see thyroid nodules (see cat scans in Bonita Springs).

Treatment Options for Hyperthyroidism in Cats

1. Radioactive Iodine Therapy

The most common treatment for feline hyperthyroidism is radioactive iodine therapy. This therapy involves giving the cat a small amount of radioactive iodine, which destroys the overactive thyroid cells while leaving the healthy thyroid cells unharmed.

It is the most effective treatment for feline hyperthyroidism and has the lowest risk of side effects. After treatment, most cats will become euthyroid, meaning they will have normal thyroid hormone levels. Follow this link for more info.

2. Surgery

Surgery is another option for treating feline hyperthyroidism but is not as common as radioactive iodine therapy. The surgery involves the removal of the diseased part of the thyroid gland. This can be tricky since the thyroid glands are located close to vital blood vessels in the neck.

Like with any surgery, there is always a risk of complications such as bleeding or infection. In addition, 10-20% of cats will develop hypothyroidism after surgery, which means they will need to take thyroid hormone supplements for the rest of their life.

3. Medical Treatment

Medical treatment for feline hyperthyroidism is often used as a temporary measure to control the clinical signs until the cat can be treated with radioactive iodine therapy or surgery. The most common medication used to treat feline hyperthyroidism is methimazole.

Methimazole is given orally (by mouth) and works by blocking thyroid hormone production. It is usually given twice a day and takes 1-2 weeks to start working. The most common side effects of methimazole are vomiting and loss of appetite.

Prevention Is Better Than Cure

There is no way to prevent feline hyperthyroidism. However, you can help to keep your cat healthy with the following measures:

  • Feed them a balanced diet. For example, avoid giving them table scraps or feeding them raw fish.
  • Provide them with fresh water at all times.
  • Take them to the vet for regular check-ups. This is especially important if they are over the age of eight.
  • Have them vaccinated against feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV). These viruses can weaken the immune system and make cats more susceptible to disease.

The Bottom Line

Feline hyperthyroidism is a common disease in older cats. It is caused by an overactive thyroid gland and can lead to various clinical signs, including weight loss, increased appetite and thirst, and urination. Regular vet visits are essential to keep your cat healthy and catch any problems early.

Ultimately, choose a vet clinic or hospital with complete services, facilities, specialists, and diagnostic tests, including cat and dog x rays, ultrasounds, etc., so your pet receives the best possible care.