Treatment of hyperthyroidism cats – The goal in treatment is to control the amount of thyroid hormone the thyroid gland excretes. There are three methods, the method chosen typically depends on the age and physical status of the cat, as well as the facilities available. Talk to your veterinarian about which method is best for your cat.
1. Drug Therapy – This is probably the most common treatment choice because it tends to be more economical. Medication (methimazole) can control the amount of thyroid hormone released by the thyroid gland. The drug is available in tablet form or transdermal. Transdermal medications are applied to the skin, in this case usually to the ears, where it is absorbed into the blood stream.The form of medication you choose generally depends on what your cat will tolerate. Some cats do not take pills easily and this is a daily medication, so you may not want to fight your cat everyday in order to give it a pill. If your cat is difficult to medicate the transdermal form may be the right chose for you but it tends to be more expensive.
2. Surgery – Surgical removal of the affected thyroid tissue generally provides a cure for hyperthyroidism. The enlarged glands are removed surgically, there are usually enough cells left behind to prevent the cat from becoming hypothyroid. Prior to surgery the cat will take hyperthyroid medication for a couple of months that way the thyroid levels in the body are normal at the time of surgery and the cat is more stable. Any kidney or heart problems that may surface should also be addressed before surgery.
Surgical complications include:
- Some cats will become hypothyroid (abnormally low thyroid levels) following surgery. These cats will need thyroid medications so that there body has enough thyroid hormone.
- Another complication is remaining hyperthyroid or becoming hyperthyroid again. These cats have ectopic thyroid tissue which means they have thyroid tissue in abnormal places. A special kind of scan should be performed at a specialty hospital to look for ectopic thyroid tissue prior to surgery. If this abnormal tissue is found then surgery may not be a good treatment option for your cat. Some cats will become hyperthyroid again if the tissue left behind at the time of surgery becomes diseased.
- The most serious complication is damage to the parathyroid glands. These glands are very close to the thyroid gland. If damage is done to the parathyroid gland the result could be low blood calcium which causes seizures. Cats are closely monitored following surgery for signs of low blood calcium, this can be treated with calcium or vitamin D.
- Occasionally there is damage done to the voice box which cause a change in the cats voice and nerve damage which might cause droopy eyelids or change in pupil size.
3. Radioactive Iodine Therapy – This is usually the treatment of choice. The diseased thyroid tissue will absorb more radioactive iodine then the healthy thyroid tissue, this will ultimately destroy the diseased tissue, stabilizing the thyroid hormone levels. This treatment will also destroy the ectopic thyroid tissue. The good news is cats rarely become hypothyroid as a result of this treatment. This treatment is performed by an IV infection and is only offered at specialty hospitals. The cat has to be hospitalized until their wastes (especially urine) is below hazardous radiation levels, this can take up to 3 weeks.
Additional Information:
- Surgery or radioactive iodine are the only cures for hyperthyroidism
- Drug therapy may cause side effects including lethargy, vomiting, and anorexia. These side effects should be reported to your veterinarian.
- Treatment may uncover renal disease. Kidney failure is common in older cats and hyperthyroidism can improve kidney function. Treatment for both problems should be closely monitored by your veterinarian.
- Before surgery can be performed any heart disease and kidney disease should be corrected.
- Hyperthyroid patients should continue to be monitored for high blood pressure, and thyroid function as well as other blood work that your veterinarian might recommend.
Symptoms and Diagnosing Hyperthyroidism in Cats
