Hyperthyroidism in Cats

 

BCR recently welcomed a new resident kitty, Gio, who arrived suffering from hyperthyroidism.  She weighed less than five pounds when she arrived because this condition had never been treated.  We're glad that she's here with us and that she's getting the treatment she needs.  Hyperthyroidism is something you need to be aware of and to watch for in your own cats.  Here is some information that will help you do just that.

Hyperthyroidism is a common disease usually found in middle-aged and older cats.
It's caused by an increase in the production of thyroid hormones (known as T3 and T4) from enlarged thyroid glands and is usually caused by a benign tumor on the thyroid gland called an adenoma. In rare cases, the tumor is a carcinoma, which is cancer.  In the US, 10% of cats over age 10 will develop hyperthyroidism, making it the most common endocrine disease in cats.

Why do so many cats develop this condition?  As is true with many diseases, there isn't one cause to point to that all vets agree on.  Some vets believe that there are steps cat owners can take to help avoid the things that cause hyperthyroidism, but, since they don't know exactly what the causes are, we're not sure this is true.  However, we'll share these steps anyway because it's good in general to be aware of them. 

* Feed a balanced, fresh food and species-appropriate diet that is respectful of a cat's natural iodine intake (much lower requirement than dogs!)  Food companies are unregulated as to how much iodine they put in their products.  Unless you're feeding your pet a raw diet, you have no idea what's in their food.

* Do not buy canned food that is not labeled BPA free.

* Avoid feeding your cat a fish-based diet or any food containing soy products. (That will be hard, fish oil seems to be in every single cat food out there and we're not sure how you would avoid it unless you are feeding your cat a raw diet.)

* Rid your cat's environment of flame retardant chemicals.   Here is the link to an interesting study regarding flame retardants and cats.  It might be hard to get rid of everything that has this element, from furniture to your own clothes.

* Provide your cat with an organic pet bed.   AmazonSmile has a very nice one.

* Purchase a high quality air purifier for your cat's environment.

Symptoms of Hyperthyroidism:
One of the most obvious symptoms is that cats start losing weight even though they're  eating like crazy.  Other symptoms may include:
                * High blood pressure
                * Frequent vomiting
                * Hyperactivity
                * Increased body temperature, heart and respiration rates
                * Howling at night
                * Increased thirst and urination

Testing and Diagnosing:
We say this a lot, but getting your cat regular check ups and blood tests throughout his life will help give your vet a good baseline health report to work from, which makes it easier for them to catch things like hyperthyroidism before it becomes a serious and life-threatening problem. 

Once your cat reaches seven years old, make sure their regular blood checks include a T4 test and a Free T4 test.  If your cat has chronic kidney problems, you may also ask for a Total T3, a Free T3 and TSH.  This will give your vet a good baseline to work from. 

Following this rule is how we discovered that Mack, Jewell, Yoshi, Serena, Jamie and Natasha were becoming hyperthyroid.  Their T4 test numbers were on the high end of normal but had been increasing over the years, so we added the Free T4 test and it showed they were all hyperthyroid. 

Treatment:
As with the cause of hyperthyroidism, vets don't all agree on the best and most effective treatments for the condition.  Some say if it's caught very year, natural therapies may work - things like homeopathic medicine, acupuncture and herbals. This path may have some benefit but it can also allow the condition to progress.  Your vet may also may suggest:

Thyroidectomy - Removing the thyroid gland may stop the condition, but the surgery can also cause complications and potentially leave active rogue thyroid tissues in the body that will continue cause problems.

Methimazole - This medication is inexpensive but has lots of nasty side effects, like diarrhea, appetite loss and vomiting.  Some cats are allergic to the drug and it can cause decreased platelets and increased liver enzymes.  Regulating the amount your cat needs to stop the damage is difficult and cats can develop toxic levels from the medication.

Radiation - Some vets view this as the gold standard treatment for hyperthyroidism.  It's commonly used on both people and pets.  It may be the more expensive treatment option, but it always provides a cure if a cat is in good enough condition to receive the treatment.  (BCR has had two resident kitties who first had methimazole instead of radiation because they had advanced kidney disease and wouldn't survive the treatment.  However, Natasha and Serena have successfully received radiation.)

Bottom line:
Vigilant cat parents will do this automatically every day and stay very aware of how their cats are acting.  If you notice anything about your cat that is not normal for him - from losing weight to vomiting or yowling - get to your vet right away and insist on the blood tests mentioned above.  If it's not treated, hyperthyroidism will cause very serious health problems for your cat and may even be fatal.  So, it's critical for you and your cat to work with your vet and stay alert to the signs.

CLICK HERE to read another BCR blog about hyperthyroidism.