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What is Feline Hyperthyroidism?

A Manageable Disease!

The thyroid is a butterfly shaped gland located on either side of a cat's windpipe. The thyroid produces hormones that regulate metabolism and organ function. With hyperthyroidism, the thyroid becomes overactive, and produces an excess of thyroid hormone.

How do cats get Hyperthyroidism?

The main way cats develop hyperthyroidism is due to development of a benign tumor, known as an adenoma, in their thyroid gland. The tumor secretes excess thyroid hormone, creating the condition of hyperthyroidism.

How common is hyperthyroidism in cats?

Hyperthyroidism is one of the most common endocrine conditions affecting cats, in particular, older cats over the age of 10. The median age for acquiring hyperthyroidism is approximately 13 years of age, and very few cats develop the condition before the age of 10. Some veterinarians estimate that about 2% of cats over 10 will develop hyperthyroidism, and, due to factors that may include environmental exposures, that number is on the rise.

Is hyperthyroidism dangerous?

Untreated, hyperthyroidism in cats can lead to heart failure or kidney failure or even develop into thyroid cancer.

What are the symptoms of Feline Hyperthyroidism?

Weight loss (typical, but not always) Drinking more water
Increased appetite without weight gain More frequent urination
Vomiting and Diarrhea Decreased appetite (less common)
Increased energy and friskiness Decreased activity (less common)
More vocalization Weakness (less common)
Demanding food more frequently Labored breathing and panting (less common)

How is hyperthyroidism in cats diagnosed?

Primarily, diagnosis is made by blood test, measuring the level of thyroxine (T4) in the blood. High T4 levels are considered indicative of hyperthyroidism. Occasionally, if results are not conclusive, a more definitive -- and costly -- test known as Free T-4 may be run. And, some veterinarian will use other tests including T3 levels, T3 suppression test, thyrotropin-releasing hormone stimulation test, and thyroid radionuclide uptake and imaging ("thyroid scans"), to verify a hyperthyroidism diagnosis.

What are the treatment options for hyperthyroidism?

The three conventional treatment options are antithyroid drugs, surgical removal of the thyroid, and radioactive iodine treatment to disable the thyroid gland. Some practitioners also work with alternative therapies for milder forms of hyperthyroidism.

What is involved in anti-thyroid therapy?

Antithyroid therapy was formerly the treatment of choice for many practitioners and cat owners, because it's non-invasive, and inexpensive. Anti-thyroid drug therapy involves putting the cat on the drug methimazole -- brand name Tapazole -- a human anti-thyroid drug. Downsides are that in some cats, it does not resolve the hyperthyroidism, and giving the cat a pill daily for life may be difficult. Some cats do not tolerate the drug and may develop several gastro-intestinal upset.  When this happens, the drug is made into a cream by a compounding pharmacy which is usually rubbed inside the cat's ear.  This still may not resolve the gastrointestinal issues and it is hard to deliver an accurate dose.  Typical cost of anti-thyroid drug therapy is $25 a month for life; this is higher when the ear cream is used..

What is involved in surgery for hyperthyroidism?

Surgery -- known as thyroidectomy -- removes the affected part of the thyroid gland. Surgery can be an effective cure, and many veterinarians are capable of performing this surgery. Only a few days of hospitalization is required. Drawbacks, however, include the risk of anesthesia, particularly in an older cat, and the risk of removing the parathyroid glands, which can cause hypoparathyroidism. In some cases, there is also a risk of Hyperthyroidism if both lobes of the thyroid are removed. The typical cost of a thyroid surgery is approximately $900.

What is involved in radioactive iodine treatment for cats?

This is currently the "Gold Standard" treatment with most veterinarians.  With radioactive iodine therapy, the cat receives a one-time injection of iodine I-131, which concentrates in the thyroid and irradiates and destroys the malfunctioning part of the gland. Healthy thyroid tissue is not damaged, and the risk of hypothyroidism (low thyroid) is low. Almost all cats receiving radioactive iodine will return to normal thyroid function within a month or so of treatment. This procedure used to be quite expensive running well over $1,000 for the treatment alone.  In recent years, the treatment cost has been running $400-$800 plus the cost of preliminary x-rays and blood work.

Many veterinarians are not set up to do this sort of treatment, as it requires about a week's isolation for the cat while the radioactive material clears their system and the cat and their waste products are again safe for human exposure. 

A national network, Radiocat, runs specialty radioactive iodine clinics for cats at 16 locations (2014) around the country.

Currently, when the kitty returns home he can be free to mingle with other cats, roam the house but not spend much time lap sitting or cuddling with his/her human for 2 weeks. Also, during that time, he/she must use flushable kitty litter - Radiocat recommends "Swheat Scoop". The reason as explained by Radiocat vets is that the kitty's urine will be radioactive for a couple of weeks. If you use non-flushable litter, it will go into your trash which is supposedly run by a geiger counter on its way into the landfill. If something radioactive sets it off, workers will pull the truck aside and root through the trash until they find the source of the radiation. If your trash happens to include your name and address in it....oops! But isn't radioactive poo and urine a bad thing to flush down the toilet, you say? Again, the vets explain that this same procedure is used on humans and that's where our unmentionables end up. Apparently the sewage treatment system is prepared to deal with all sorts of toxic wastes coming down the line.

What alternative/complementary approaches may be pursued?

Some practitioners use alternative therapies for cats with mild hyperthyroidism. Because of the potential seriousness of hyperthyroidism, it's recommended that you work with a good holistic veterinarian or naturopath who specializes in pets to determine an effective treatment regimen for your cat.

Some of the alternative medicine approaches that have been effective include:

All info is from internet sources and is for general informational purposes only. It is not intended as medical advice. C.A.R.E. is not a veterinary facility. Consult a licensed veterinarian if your pet exhibits any unusual symptoms or behavior.

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