9539 Liberty Road, Frederick, MD 21701
Phone: 301-898-4009 ~ Fax: 240-668-3664
clientcenter@frederickcatvet.com
Gentle, complete veterinary care for the felines in your family
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My Cat Has Thyroid Disease! What Does This Mean?

Thyroid disease is very common in both humans and cats. There is an important difference however between the disease processes in these species. Humans tend to have decreased thyroid levels (HYPOthyroidism) and cats tend to have increased thyroid levels (HYPERthyroidism). The thyroid gland is responsible for regulating metabolism. Hyperthyroid cats have increased metabolism (something most humans wish for). Therefore, common signs include weight loss despite increased appetite, increased thirst, nervousness, increased activity and sometimes intestinal disease. HYPOthyroid humans tend to be tired and have difficulty losing weight.

How do we diagnose hyperthyroidism?

There are a couple of common misconceptions which lead to a lack of diagnosis and treatment of a very manageable condition. These misconceptions include the belief that an active senior cat is a healthy senior cat and that weight loss is "normal" in senior cats. Yes, we all like to see our 17 year old cats play with string and run up the stairs but it is also very important that they be able to rest appropriately. Hyperthyroid cats are often hyperactive and can even be moody. An obvious behavioral change in a cat of this age may be a reason to look into hyperthyroidism. Another tip off is that your cat has struggled to lose weight for years and then suddenly, with minimal change in life style begins to lose weight. A sudden increase in metabolism secondary to hyperthyroidism may be the cause of this unexpected success. In the large majority of cases we can determine if your cat has hyperthyroidism with just a very simple blood test.

Why and how do we treat hyperthyroidism?

So, if your cat is playing and seems happy or has finally managed to 'tip the scale' in the right direction, why should you intervene? Doesn't everyone want to see a playful senior kitty?

Well, the consequences of lack of treatment can be very serious. The most significant consequences of an overactive thyroid are severe muscle wasting, high blood pressure, and heart disease. What are your choices for treatment? There are multiple great options:

Medication
Dietary treatment
Surgery
Radioactive iodine treatment

Typically we will recommend starting with medical management of the disease. Most commonly we will start with a medication called methimazole. This medication can be given as a pill or compounded into a transdermal cream which can easily be applied to the ear tip. It can't get easier than that!!! Right?? Once the medication is started, we will recommend initial monitoring of bloodwork, clinical signs, body condition, and sometimes blood pressure. It may take a bit of time to find the correct protocol for each individual kitty and dosages may change a few times in the beginning. It is important that we monitor kidney indicators and watch for any adverse effects during this initial period. Many of our senior or geriatric kitties have early concurrent kidney disease that only becomes apparent after we begin to treat their thyroid condition.

Another medical option which has just recently been developed is treating through feeding an iodine restricted diet called Hills y/d. This diet must be fed exclusively to our hyperthyroid patient. That means....no more Fancy Feast !! We have relatively limited experience with this method of treatment to date but studies and results of early use appear promising.

Surgery has fallen somewhat out of favor as a common treatment option because there is now a much safer long term treatment option. This treatment is called radioactive iodine. Radioactive iodine achieves a permanent cure to hyperthyroidism. A one-time injection, which targets hyperactive thyroid tissue, is administered at specialty treatment centers. There are many treatment centers around the country. Each center has an individual pre-treatment and post treatment plan. You can expect to visit your primary veterinarian for pre-treatment work up and then for post treatment evaluations to assure that the treatment has been effective.

In Summary

Feline hyperthyroidism is very prevalent in our senior kitty society. The good news is that with early detection, proper treatment and monitoring, your feline family member could live many happy years after diagnosis.

-Lisa Wolkind, DVM