hyperthyroidism in catsHave you ever wished you could eat whatever you want, whenever you want, and still lose weight? Some cats live this dream, but for them it is often more of a nightmare. Hyperthyroidism in cats is a real and a fairly commonly diagnosed condition, to boot. Fortunately, when properly diagnosed, Animal Internal Medicine and Specialty Services can often manage these sickly kitties quite effectively.

All About Hyperthyroidism in Cats

The thyroid gland is an important but often forgotten organ that plays a big role in day to day function, whether you are a human, cat, or mouse. The thyroid is part of the endocrine system, the body system responsible for secreting hormones. Be it insulin, growth hormone, or cortisol, hormones are an essential part of physiology.

The thyroid gland, in particular, secretes thyroid hormone, which plays a major role in metabolism. Hyperthyroidism in cats occurs when the thyroid gland produces too much hormone. This is usually due to a tumor in the gland itself. While the tumor is often not malignant, it does produce an excess of hormone, resulting in a hypermetabolic state responsible for the symptoms of hyperthyroidism:

  • Weight loss
  • Increased (often ravenous) appetite
  • Digestive problems like vomiting or diarrhea
  • Agitation/hyperexcitability
  • Vocalization
  • High heart rate
  • Increased blood pressure

Untreated, hyperthyroidism in cats can lead to serious consequences and even death. Cats who are exhibiting symptoms should be evaluated right away. Because several other health conditions can appear similarly, it is important for us to perform diagnostic tests in order to come to an accurate diagnosis.

Taming the Thyroid Gland

Thankfully, even though hyperthyroidism in cats is common, it is typically manageable. Treatment centers on stopping the thyroid gland from overproducing hormone, which can be accomplished in a few different ways:

Surgical removal of the thyroid gland – In some situations actual removal of the thyroid gland may be indicated. This option is typically effective, however removal of the thyroid gland involves removal of the parathyroid gland, which may result in trouble. Also, some cats who have the thyroid gland surgically removed may need to have thyroid hormone supplementation to prevent symptoms of hypothyroid function.

Iodine restriction – The thyroid gland requires iodine to synthesize thyroid hormone. Severely restricting iodine intake through the use of a prescription diet can be an effective option for some cats.

Inhibition of hormone production – Many cat owners choose to utilize daily medication that inhibits thyroid hormone production such as methimazole. This medication is typically administered in pill form, although it can be made into a liquid or transdermal lotion. This type of management does require frequent blood monitoring and dosages may have to increase or may even stop working after some time.

Radioactive iodine treatment (I-131) – A straight-forward way to deal with hyperthyroidism in cats is the use of radioactive iodine. With this type of treatment, the patient is given a one-time injection of I-131, which targets the thyroid gland and greatly decreasing thyroid hormone production. For most cats, this option results in a 95% or better cure rate.

Hyperthyroidism in cats is a serious but often well managed disease that we diagnose frequently. If your cat is exhibiting signs that he or she may be affected, don’t delay in calling. It is important for us to evaluate things as soon as possible so that we can head off the worst effects of the disease.