Hyperthyroidism is very common in middle aged to older cats. It occurs when the thyroid gland produces too much thyroid hormone. This seems to be diet related. Researchers have determined 2 things related to the diet of cats and hyperthyroidism. The first is that cats that consume large amounts of commercial fish-flavored cat food were more likely to develop the disease and the second was that limiting the amount of iodine in a cat’s diet often returned it to normal thyroid hormone levels.

Symptoms commonly seen are weight loss despite a great appetite, poor hair coat, increased drinking and urination, vomiting and or diarrhea, rapid heart rate, hyperactivity, increased yowling and irritability. This condition is diagnosed by a blood test.

Western treatments for this condition include:
Radioactive iodine. To receive this treatment your cat would have to go to a specialist center and be hospitalized for 3 to 7 days. The medication kills off the thyroid gland so the condition goes away. This is the most effective conventional treatment but it is costly.
Surgery–This is not done very frequently anymore with the availability of radioactive iodine but this was the standard treatment and is still done.
Medication –Tapazole is the most common medication used although there are others. This medication can cause problems with the cat’s blood, liver disease, decreased appetite, lethargy and vomiting. There is also a warning for humans giving this medication to wear gloves and not break the pills as there can be side effects in people.
Diet–Hills Prescription Diet Y/D is now available for cats with hyperthyroidism. This diet is iodine deficient and works by starving the thyroid gland of iodine. If the thyroid gland does not have a source of iodine, then it can not make thyroid hormone so the condition goes away. This can be recommended in cases where the cat’s can not take conventional medication. It should not be used along with any thyroid medication including herbal. The problem with this diet is we do not know the long term risks of iodine deficiency and in multiple cat households it would not be great for the normal cats to consume this diet. The dry form of this is almost vegetarian which is not ideal for carnivores like cats. The wet form at least has liver in it so is a bit better.

Holistic treatments for hyperthyroidism include :
Homemade diet with restricted iodine. High levels of iodine are found in fish as well as iodized salt, sea salt, aged cheeses, egg yolk, sea-products, including kelp, cured meats, bread and pasta, molasses, soy sauce, soy milk, meats injected with flavor enhancers,and fish oils – including cod liver oil. All of these need to be avoided.
Herbal supplements that support the thyroid and the liver. Two important supplements are Milk Thistle and Resthyro. These are safe and can be used even when the cat’s thyroid levels are high normal. When used in this manner, you may prevent the thyroid from becoming overactive. I have included the links for these products here: Milk Thistle and Resthyro