Feline hyperthyroidism is the most frequently diagnosed endocrine disorder in cats – especially those over the age of eight.
Your kitty's thyroid is a butterfly-shaped gland at the base of the throat. When this little gland overproduces thyroid hormone, the disorder known as hyperthyroidism is the result.
The disease 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.
Symptoms of Hyperthyroidism
About half the kitties that develop hyperthyroidism have an increased appetite. And about 90 percent with the disease ultimately lose weight because one of the side effects of too much circulating thyroid hormone is an increase in metabolism rates.
Other symptoms of hyperthyroidism include:
- High blood pressure
- Frequent vomiting
- Increased body temp, heart and respiration rates (due to the up regulation of metabolic processes)
Another notable symptom is hyperactivity.
I have clients call my practice regularly to report that their 13, 14 or 15 year-old cat has suddenly acquired the energy level of a kitten. These cats are running around, in constant motion – even to the point of keeping their owners awake at night.
So the combination of increased appetite, weight loss and sudden, unexpected bursts of energy in an older cat is a definite sign you might have a kitty with hyperthyroidism.
Make an appointment with your cat's veterinarian as soon as possible. The disorder can be diagnosed with a simple blood test.
There are three traditional treatments that are typically recommended to manage hyperthyroidism.
- The medical management option
"Medical management" means putting your cat on medication. For hyperthyroidism, the drug is called methimazole, which is often sold under the name Tapazole. Methimazole inhibits thyroid hormone production, so the amount of the circulating hormone in your cat's body is reduced.
The dosage is twice daily, and the vast majority (87 percent) of cats on this therapy will have normalized thyroid levels within a couple weeks of starting the drug. Only 54 percent of cats normalize on a once a day dosing, so at my clinic we recommend the twice a day program for clients who opt for medical management of their pet's hyperthyroidism.
Side effects of methimazole can include GI upsets which cause kitties to vomit. I've had some success avoiding GI problems by using a compounded transdermal methimazole ointment applied inside the cat's ear.
Occasionally, we'll see a patient with an almost immediate allergic response to the drug in the form of an intense facial itch that comes on after the first pill is administered. This reaction means the drug cannot be continued and another treatment option is needed.
Other very rare side effects include decreased platelets and increased liver enzymes.
The drawbacks to medical management of your kitty's condition is that she'll need to be on methimazole for the rest of her life, and her blood levels must be routinely monitored to keep her stable.
Hyperthyroidism is known to mask kidney problems in cats, so it will be important for your veterinarian to monitor not only thyroid hormone levels but also kidney function while your cat is taking methimazole. Elevated kidney enzymes can become a secondary problem pretty quickly once your kitty is stabilized, his blood pressure returns to normal and there's less blood flow to the kidneys. In my practice, we routinely start holistic kidney support via herbal and nutritional supplementation when the diagnosis of hyperthyroidism is made.
This is a more aggressive approach involving a thyroidectomy, which is the surgical removal of the benign tumor from your cat's thyroid gland.
This operation should only be performed by a very skilled soft tissue surgeon who has done many of these procedures. This surgery is actually my first treatment of choice because it cures the problem, but there can be surgical complications – including accidental removal of the parathyroid glands which sit on the thyroid glands – which can cause a whole host of other problems.
But successfully done, this surgery cures your cat of the problem, which is the ultimate positive outcome.
- Radioactive iodine treatment
A third traditional treatment for hyperthyroidism involves the use of radioactive iodine.
You take your kitty to a specialized, radioactive-approved facility for a single injection of I-131, a radioactive form of iodine that attacks the diseased portion of your cat's thyroid gland.
Your cat must stay at the facility for seven to ten days until the level of radioactivity in her body drops to a safe enough level that she can be taken home.
As spooky as it might sound to inject a radioactive substance into your kitty, this therapy is used very commonly – not only on cats, but also on people.
But there are a few downsides:
- Your beloved pet is made temporarily radioactive (scary)
- The treatment is very expensive
- The process can be quite stressful for both you and your cat, primarily due to the seven to ten day separation during which your kitty must remain at the radioactive-approved facility
If this procedure sounds nothing but disturbing to you, I agree. However, cat owners have had great success with it. But as with any form of invasive therapy, I encourage you to investigate all the risks and benefits, positives and negatives of the procedure.
How About Alternative or Integrative Therapies for Hyperthyroidism?
Since I successfully practice integrative medicine protocols involving both traditional and non-traditional treatments at my clinic every day, I encourage you to investigate alternative therapies as well for your kitty's hyperthyroidism.
There are many natural remedies that can be provided to manage your pet's condition if it's caught early.
One very small study documented a few years ago demonstrated that eight of 13 cats had clinical resolution of hyperthyroid symptoms with the use of homeopathic remedies.
In additional to homeopathic remedies, alternative therapies include:
- Herbal remedies (Eastern, Western and Ayurvedic)
I recommend you consider checking your cat's thyroid levels annually after the age of 10.
If it's early enough in the development of your cat's hyperthyroidism, my recommendation is to start with homeopathy and/or other natural therapies that avoid many of the risks and side effects associated with more traditional approaches.