Hypothyroidism in Cats

December 09, 2007 :: Posted by - kittyluver :: Category - Diseases

Hypothyroidism is the most common hormone imbalance of cats. It seems like it would be a straight forward problem: the body does not produce enough thyroid hormone, problems result, a test shows thyroid hormone level is low, the hormone replaced given in pill form, problem solved. Unfortunately, it is not quite so straight-forward in real life. This article attempts to review the issues relevant to this condition and the pitfalls that keep it from being a simple problem.

In short, hypothyroidism is the natural deficiency of thyroid hormone. This deficiency is produced by immune-mediated destruction of the thyroid gland, by natural atrophy of the gland, by dietary iodine deficiency, or as a congenital problem. In the cat, the first two causes listed account for almost all cases.

Clinical Signs of Hypothyroidism

Hypothyroidism is a classical disease with a classical collection of clinical signs.

Skin abnormality, hair loss, brittle or dry coat, obese and anemic are the signs of hypothyroidism.

Thickeneing of some tissues, especially of the head and face is being noticed in the cats suffering from hypothyroidism.


The diagnosis of this disease is not so simple as we think. It requires at least a week to study the level of the thyroxine in blood to give confirmative diagnosis.


At least treatment of hypothyroidism is relatively straight-forward. Hypothyroidism is treated with oral administration of thyroid hormone (T4). Even hypothyroid cats are perfectly capable of converting T4 to T3. Pills are given usually twice daily to start but may be dropped to once a day after good thyroid control has been achieved.

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