Mary Allen
The thyroid gland is located on the left and right of the cat’s neck and produces thyroid hormones that influence cell function and thus the cat’s metabolism. The overproduction of thyroid hormones is called hyperthyroidism.
General Description
Most cats (about 70%) with hyperthyroidism have benign changes in both lobes of the thyroid that produce too much thyroid hormone. About 30% of cats have a single benign tumor in one of the two lobes, and only a very small proportion (about 2%) have a malignant tumor.
The overproduction of thyroid hormones leads to an acceleration of cell metabolism, which can lead to various symptoms. The most common are weight loss, increased appetite, uneven shedding or a shaggy coat, increased water intake, increased urination, and increased activity. Vomiting and diarrhea or increased aggressiveness are also possible. Rarely is a decreased appetite, lethargy, panting, and going to cool places.
Diagnosis
Diagnosing thyroid disease is relatively easy and inexpensive by measuring the level of thyroid hormone (T4) in the blood. If the symptoms match but the T4 remains unchanged, it is advisable to repeat the test after a few weeks. Since the symptoms mentioned can also occur with other diseases and the increased concentration of thyroid hormone can have a harmful effect on other organ systems, we always recommend carrying out a complete blood count and, depending on the findings, X-rays of the chest and abdomen.
Therapy & Prognosis
Therapy for hyperthyroidism always begins with the administration of tablets containing the active ingredients thiamazole and carbimazole. These are optimally administered twice a day and prevent the production of thyroid hormones, the higher the dose, the lower the production. Since the overproduction of thyroid hormone leads to better blood flow to the kidneys, the kidney values must be checked during therapy for hyperthyroidism in order to prevent the kidneys from being damaged by the reduced blood flow. Therefore, the dose should be started carefully and increased slowly. If the kidney values increase, the effect is completely reversible by stopping the drug. If you have problems entering the tablet, it may be possible to have the active ingredient processed by a pharmacist into an ointment that can be massaged into the ears twice a day with gloves on for 30-120 seconds.
Some cats may initially eat a little worse or vomit after starting therapy. If you notice these or other symptoms in your animal, bring your animal to us as soon as possible. If your cat is well controlled with thiamazole and the kidney values do not increase, it is possible to carry out radioiodine therapy. Iodine is one of the most important components of the thyroid hormone; through the administration of radioactive iodine, this is absorbed into the thyroid gland and destroys the surrounding cells, so that an overactive thyroid gland can be permanently corrected. Radioiodine therapy must be performed in specialized facilities and your cat will need to be hospitalized for a period of time. The advantages of radioiodine therapy are that it works quickly and can be carried out without anesthesia, you don’t have to administer any more tablets afterward. Disadvantages are the high price and the long hospital stay (several days to weeks) to carry out the therapy.
Another option is the surgical removal of the altered thyroid, especially if only one side is affected. The healthy side is then able to take over the work of the missing half.
Cats that are only kept indoors can be fed food that does not contain iodine. This is only available from the vet, cats without an overactive thyroid should not eat this food. It must be ensured that the cat only eats this food, so this therapy option is not suitable for outdoor cats.