FELINE HYPERTHYROIDISM

This is a disease that affects older cats, where an excess of thyroid hormone is being released from the thyroid gland. Most of the time, this is due to a benign growth on the thyroid gland. This condition severely accelerates the cat’s metabolic rate, putting stress on all the organs, especially the heart. If left untreated, this disease could be fatal. In rare cases (less than 1% of all hyperthyroid cats) the growth on the thyroid gland is cancerous, or malignant.

Cat’s, like humans, have a double lobed thyroid gland located in the neck, this gland produces thyroid hormone which is essential in regulating metabolism.

Feline Hyperthyroidism is a condition in which excessive thyroid hormone is released into the cats’ blood stream from the thyroid gland. Ninety six percent of the time this is caused by a benign tumor growth.  This disease process increases metabolism, which leads to physiological manifestation including weight loss, increased appetite, rapid heartbeat and/or arrhythmia, vomiting, diarrhea, and increased water consumption. Behavioral changes such as hyperactivity or nervousness may also be noted. While many of these signs can mimic other diseases in the cat population, i.e. diabetes mellitus, kidney failure, hyperthyroidism can be easily diagnosed.

Hyperthyroidism can be easily diagnosed with a single blood test that measures thyroid levels.

At Valley Central we can easily and completely cure this disease, eradicate the thyroid tumor and return your cat’s thyroid function back to a normal state.

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What are the treatment options?

There are three: medicine, surgery and radioactive iodine therapy.

 Medical therapy does not cure hyperthyroidism; it only suppresses the excessive release of thyroid hormone, requiring lifelong oral medication to be administered to the cat, usually several times a day. This medication can result in gastrointestinal upset, liver toxicity, skin irritation, or more severe reactions such as bone marrow failure.

Surgery may result in a cure; however the risk of anesthesia is a concern. Virtually all hyperthyroid cats have some alterations in their heart muscle due to the disease. There is also a risk of removal of too much, or not enough tissue, resulting in complications or treatment failure. Most cats treated surgically need to have thyroid supplementation for the rest of their life.

 Radioactive iodine therapy is a form of radiation therapy that does not have the above mentioned disadvantages. After one injection more than 96% of  cats with hyperthyroidism are cured. There is no anesthesia required, and there are no oral medications to give. There are virtually no side effects.

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Frequently Asked Questions

What is Nuclear Medicine?

Nuclear Medicine is an area of medicine that uses radioactive isotopes to safely diagnose and treat many diseases. Here at VCVRC, we use I131 (Radioactive Iodine).

What is Feline Hyperthyroidism?

This is a disease that affects older cats, where an excess of thyroid hormone is being released from the thyroid gland. Most of the time, this is due to a benign growth on the thyroid gland. This condition severely accelerates the cat’s metabolic rate, putting stress on all the organs, especially the heart. If left untreated, this disease could be fatal. In rare cases (less than 1% of all hyperthyroid cats) the growth on the thyroid gland is cancerous, or malignant.
Signs of the disease include weight loss, increased appetite, vomiting, diarrhea, excessive thirst and urination; high blood pressure and heart disease that can lead to heart failure and fatal arrhythmias. 

Physical examination findings that raise suspicion for hyperthyroidism include  weight loss or poor body condition, hair loss and or an unkempt appearance. Many times an enlagred thyroid gland or heart murmur are detected by your veterinarian. You may also observe aggressive behavior at home.

What is Radioactive Iodine?

 Radioactive Iodine is a radioactive form of the mineral iodine. Dietary iodine that is ingested and concentrated into the thyroid gland to make thyroid hormone, an essential hormone for normal body function. Because of this we are able to administer radioactive iodine, and we know that the drug will be concentrated only in thyroid tissue. There it will destroy the abnormal cells that are overproducing thyroid hormone, sparing normal cells in the throid gland as well as the rest of the normal cells in the body. This is why the treatment works so well.

How is Radioactive Iodine given?  

I131 is prepared by the nuclear pharmacy in liquid form and given intravenous or subcutaneously. The cat will receive one injection and will board with us until the radiation has been metabolized and we can release your cat to you safely.

When can my cat come home?

The Nuclear Regulatory Commission regulations are such that the length of boarding usually varies from 96 hours-14 days. You will be contacted every weekday with an update on your cat.

Once your cat is released you will receive complete discharge instructions and your veterinarian will be contacted by fax. A case summary will also be sent to your referring veterinarian. Blood tests to check the thyroid level and general metabolism are required at three weeks and three months post therapy.

 How do I make an appointment?

You can make an appointment for consultation by calling the Nuclear Medicine Department at (610) 435-1553.

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