Hyperthyroidism in Cats is a Common but Treatable Disorder

Hyperthyroidism, or an overactive thyroid gland, is the most common feline hormonal disorder. It usually affects senior cats at least ten years old. The condition may be caused by a toxic nodular goiter (swelling of the thyroid gland), a benign tumor or adenoma, and rarely, a cancerous tumor or adenocarcionoma. Usually the disease involves both thyroid lobes.

It is unclear why hyperthyroidism occurs so often in older cats. What is known is that it can lead to symptoms such as hyperactivity, irritability, and increased appetite and food consumption, vomiting and diarrhea. But about half the time these signs are absent and the cat may be lethargic, eat less, and appear depressed or weak. Or she may eat normally but lose weight and seem otherwise fine for months before hyperthyroidism is suspected. To add to the confusion, because of the variety of symptoms, hypothyroidism can mimic disorders like diabetes and kidney disease. These must be ruled out before hyperthyroidism is treated.

The presence of too much thyroid hormone in the blood can damage the heart muscle (cardiomyopathy), leading to congestive heart failure, as well as cause liver function problems, so it's a serious condition that requires veterinary intervention.

If the blood tests positive for hyperthyroidism, the cat can be treated with several conventional therapies:

· Surgical removal of the gland, which can be risky because the parathyroid gland nearby may be damaged, causing calcium imbalance, illness or death.

· Methimazole (Tapazole), an antithyroid drug, for life. Rarely, this causes side effects including suppression of appetite, vomiting, lethargy, facial skin lesions, liver disease, or low red blood cell counts.

· Radioactive iodine, which sounds dangerous but is probably the safest treatment. It rarely causes side effects and only requires one treatment. Use of radioactive iodine may lead to hypothyroidism (underactive thyroid), which will need to be treated accordingly. This treatment requires hospitalization for at least a week until tests show no radioactivity in the urine or feces.

· Percutaneous ethanol ablation, a newer treatment in which ethanol is injected into the thyroid using ultrasound. While this treatment looks promising, it can cause laryngeal paralysis and nerve inflammation if there is leakage.

Natural remedies may be useful if taken along with conventional modalities. These include:

· Glandular animal tissues or thyroid gland extracts

· Astralagus membranaceous, which strengthens the immune system

· Lemon balm, which decreases thyroid hormone output and may reduce blood pressure

· Homeopathic remedies

· Whole food supplements like raw broccoli, or a whole food broccoli supplement

· Bugleweed for mild cases

Hyperthyroidism is sometimes tricky to diagnose but relatively easy to treat. If you suspect that your cat is becoming hyperthyroid, take her to your veterinarian immediately for an evaluation and blood test and discuss all the treatment options.