Understanding Feline Hyperthyroidism


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Presence of excess thyroid hormone can lead to a number of undesirable effects on the body of your cat. Some of the most common symptoms that are seen in cats with excess thyroid hormone include:

  • Increased appetite
  • Increased thirst
  • Weight loss
  • Increased urination
  • Diarrhea
  • Vomiting
  • Hyperactivity/restlessness

Besides these common symptoms, there are a number of other complications in cats that suffer from hyperthyroidism. The toxic effect of ll the circulating thyroid hormones can lead to heart disease. Hypertension is also another common complication. Some of the cats who are diagnosed with hyperthyroidism also develop kidney disease. If you cat has a kidney ailment due to excess thyroid, he will need treatment for both and kidney disease can affect the prognosis of his thyroid condition. There are a number of treatment options for cats suffering from hyperthyroidism:

  1. I131 or Radio-iodine treatment uses radioactive iodine to remove all the diseased tissue in the thyroid gland. Most of the cats that undergo the treatment are cured of the condition. However, they must be closely monitored for recurring signs of hyperthyroidism after the treatment is over.
  2. The doctor might also recommend surgically removing the diseased tissue in the thyroid gland. Just like the I131 treatment, it is curative, and the cat must be monitored for recurring signs afterward.
  3. Another common treatment option is treating the cat with methimazole. It can be formulated into a transdermal (through the skin) gel that is applied to the ear of your cat or can also be administered through the mouth. It has been shown to be effective in controlling the symptoms of hyperthyroidism. However, it doesnโ€™t cure the disease and if you decide to go this route, your cat will have to be on medication for the rest of his life.

Cats that undergo curative treatments like I131 or surgical treatments have much longer survival times than the cats that undergo dietary or medical therapy alone. This is particularly significant for cats that are diagnosed with hyperthyroidism at a very young age. Compensatory hyperthyroidism is also more common in cats that have undergone treatment than was believed previously. Correcting such cases can improve the function of the kidneys and help resolve the cases of kidney disease, prolonging the life of the cats and also giving them a higher quality of life while they are alive.There have been some cases where sarcomas, a particularly aggressive form of cancer, has been responsible for feline hyperthyroidism. Although it needs further study and validation, it cannot be ignored completely. A sarcoma in the thyroid gland of your cat can be much more difficult to treat. It also poses a serious threat to the survival rates for cats that have this type of cancer. If you have any doubts about your catโ€™s physical condition, consult with the vet immediately.

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