Hyperthyroidism is the most common hormonal disorder in cats. It is usually caused by benign microscopic thyroid tumors or rarely thyroid cancer. The disease typically affects cats five years of age and older, with a peak incidence after 10 years of age. As such, I believe all cats five years of age and older should receive a physical examination and appropriate blood testing twice yearly.
Hyperthyroidism occurs when the cat's thyroid gland produces excessive amounts of thyroid hormone. This occurs due to enlargement of the gland, formation of benign thyroid tumors, or very rarely as the result of a malignant thyroid tumor. Unlike cats that develop hyperthyroidism, dogs develop the opposite problem (too little thyroid hormone, or hypothyroidism, due to immune destruction of the thyroid gland.) Clinical signs of hyperthyroidism include weight loss despite a ravenous appetite and hyperactivity. Rarely some cats develop the opposite signs (lethargy and lack of appetite.) Left untreated, hyperthyroidism can result in heart failure and death.
Diagnosis is confirmed by finding an elevated T4 value on a blood test. While natural therapies such as administration of herbs may help in mild cases, I usually recommend more definitive therapy for my more severe cases. Radioactive iodine sounds risky but is actually the safest therapy. It is also the only therapy that can cure the disease. The main drawback is cost (usually about $1000.) However, administration of medication (a drug called methimazole) actually costs more for most cats as blood must be drawn frequently (every 3-6 months) for the life of the cat to make sure the drug does not cause side effects (liver disease, bone marrow disease.) Some cats cannot be treated with radioactive iodine; most commonly these cats have kidney disease which may become worse with iodine therapy.
Surgery can be done to remove the affected thyroid gland but has fallen out of favor as iodine or methimazole is much easier on the pet. In addition to treatment with either iodine or methimazole, a general holistic protocol to ensure health of the pet is needed. This can include natural diet, supplements for the thyroid, heart, and liver (organs secondarily affected by excessive thyroid hormone levels,) and a health maintenance formula to support the immune and digestive systems.
Fortunately, hyperthyroidism is one of the few diseases of older cats that we can not only treat but actually cure. Regular veterinary visits can allow early diagnosis, treatment, and cure. The three most common conventional treatments for hyperthyroidism include surgical removal of the overactive thyroid gland, medication including tapazole, or radioactive iodine. Most veterinarians elect not to do surgery as it is challenging and requires anesthesia. Usually a veterinarian will recommend medication or radioactive iodine. While radioactive iodine sounds harsh, it is the only curative therapy for this condition as medication does not cure the cat would rather control clinical signs.
As long as your cat is in good health other than suffering from hyperthyroidism, radioactive iodine should be safe and effective. Cats with other medical issues such as kidney disease cannot be treated with radioactive iodine or their other medical issue will worsen.
In my practice, cats with mild hyperthyroidism may respond to treatment with homeopathics, herbs, or nutritional supplements. Cats with more severe hyperthyroidism usually require conventional treatment as well. I would suggest talking with your veterinarian to see if natural therapies might help your cat. If you elect to use radioactive iodine, there are natural therapies that can help support your pet during the conventional treatment. If your cat has secondary heart or liver disease, I would also use natural supplements such as hawthorn or milk thistle, respectively, to support your pet during the healing process.
