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What are the signs of hyperthyroidism in cats

The signs of hyperthyroidism in cats are many, but the most obvious are:

Rapid heartbeat or heart palpitations

Excessive sweating

Increased appetite

Weight loss

Excessive thirst

Lethargy (Listlessness)

Skin problems (excessive shedding of hair, hair matting)

What are the treatment options?

The treatment options are dependent on the cause and extent of the disease. The treatment options include:

Drug therapy – these include:

Thyroid hormone therapy



Radio therapy


Drug therapy can be very effective in both hyperthyroidism and hypothyroidism. It is important to monitor the patient, and their body temperature, heart rate, weight, appetite, and hydration, as these can all be affected by the medication and can be signs of thyroid deterioration.

Radiation therapy can be very effective in treating hyperthyroidism, but long term side effects can include cataracts, hair loss, and loss of fertility.

Thyroidectomy is a surgical procedure in which the thyroid is removed. Depending on the extent of the disease, it can be an effective treatment, but the long term side effects are unknown.

What are the prognosis and complications of hyperthyroidism?

The prognosis for cats who have hyperthyroidism is dependent on the cause, the severity of the disease, and the treatment.

Cats with hyperthyroidism caused by thyroid hormone can have a rapid improvement in their condition, and if treated early, they can be almost fully cured.

Cats who have hyperthyroidism caused by a tumor or inflammation of the thyroid gland will have a better outcome, but the prognosis is not clear. Cats with severe hyperthyroidism can experience rapid deterioration.

Some cats with hyperthyroidism experience a recurrence of the disease after treatment. Symptoms include rapid heartbeat, palpitations, and excessive weight loss.

If you suspect your cat has hyperthyroidism, seek veterinary attention immediately.

If you're interested in reading more about hyperthyroidism, please see:

Thyroid disease in cats

Hyperthyroidism in cats

Cat skin problems

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Copyright © 2006-2019 Dr. Jennifer Coates, DVM and Dr.

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Hyperthyroidism can be treated medically, surgically, or with radio iodine. Medical treatment consists of administration of methimazole (Tapazole) one to three times per day. Methimazole treatment will usually control hyperthyroidism but is not a cure (i.e., the drug will block thyroid hormone secretion but will not remove the thyroid tumor), and the drug must be given for the rest of the cat’s life. Surgery will cure the hyperthyroid condition and consists of the removal of part or all of the thyroid gland (the feline thyroid gland consists of two separate lobes). Read more

Hyperthyroidism can cause fertility issues in men and women, however it would be a mistake to assume that because a man is hyperthyroid that he cannot father a child.Re: HypothyroidismYes!!! It is one of the most common known causes of Erectile Dysfunction, or "E D"... Read more

Unfortunately, with hyperthyroidism comes a host of concurrent diseases such as thyrotoxic heart disease, high blood pressure, chronic kidney disease, medically-induced hypothyroidism, and urinary tract infections. Cat owners need to be aware of these side effects, but Dr. Putter points out that overall, "the long-term prognosis is usually very good depending on the treatment chosen, the type of underlying hyperthyroidism (tumor-forming... Read more

Your cat may also be unusually cranky or aggressive.[7] X Trustworthy Source Washington State University College of Veterinary Medicine Leading veterinary medicine training institution and biomedical research center Go to source. Remember that hyperthyroidism’s clinical signs often resemble those of "older cat" diseases, like diabetes and chronic kidney disease.[8] X Research source Your veterinarian will be able to be able to perform specific diagnostic tests to confirm hyperthyroidism. Read more

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