Q. What are the symptoms, causes and treatments for hyperthyroidism in cats?
A. Hyperthyroidism is a disease of an overactive thyroid gland, either from a growth on the thyroid gland (located in the neck) or from benign increased function.
The reason for a dramatic increase in the diagnosis of this disease since the 1970s is not known, but environmental contaminants and diet have long been suspected (but not proven).
The thyroid gland functions as a thermostat to the body, regulating a lot of the body’s functions.
When this thermostat is set higher, these functions tend to become overactive. For example, the blood pressure increases, the cats tend to lose weight, they eat more (and vomit more) and are generally more active.
This comes at a price, however. In particular, the increased blood pressure leads to kidney issues, potential heart issues, some damage to the liver and even blindness from hypertension.
The gold standard is to treat the patient with radioactive iodine.
This is selectively taken up in the thyroid gland, decreasing the production and leading to normal levels of thyroid hormone.
A good second choice is medication which decreases the production of thyroid hormone.
Surgery and iodine restrictive diets are also options, depending on the level of the disease.
It is a slowly-building disease which is quite common, and regular lab work in older cats can catch it early in their lives.
Fortunately, it is very treatable, although it requires close monitoring to maintain stability and limit side effects.
If managed well, it can allow our patients to lead long and happy (no one expects a cat to be productive!) lives.
Grass Valley Veterinary Hospital’s Mace Dekker, DVM, will answer questions regarding pets each month in the Vet Tips. Have a question? Submit it to firstname.lastname@example.org, attention Dr. Dekker.