Hypothyroidism & Your Pet

What is Hypothyroidism?

Hypothyroidism results from inadequate production and release of thyroid hormone by the thyroid gland. A decreased level of the thyroid hormone can affect the body in many ways.

Hypothyroidism is quite frequent in dogs but rare in cats.

It can be acquired or is congenital (meaning present at birth). Congenital hypothyroidism has been reported in Fox-Terriers, Giant Schnauzers and Abyssinian cats.

Acquired hypothyroidism affects more commonly middle-age, larger breed dogs including Golden retriever, Doberman pinscher, Great Dane, and Irish setter.

Symptoms

The most commonly noted signs include abnormalities of the skin, weight gain, sluggishness (lethargy), and weakness. Most changes appear to be secondary to decreased metabolism due to decreased levels of thyroid hormones.

Skin changes are very common, but are not seen in every pet with hypothyroidism. The most common sign in the skin is hair loss, with usually symmetrical loss of hair on both sides of the trunk, in the lower part of the chest and neck, lower part of the abdomen, and on the tail. The hair loss is non-itchy unless in presence of secondary bacterial, yeast or parasitic infections which are common.

In rare cases of severe hypothyroidism, some neurologic signs can be present such as seizures; a wobbly, uncoordinated or “drunken” appearing gait or movement and even coma.

Other signs can be mistaken as allergies such as poor coat, frequent hot spots and slow healing wounds. Often these symptoms are written off as signs of ageing rather than having them investigated.

Very rarely, the disease can be associated with heart and eye abnormalities.

Diagnosis

Even though we can measure T4 levels at the clinic within 10 minutes, the full thyroid profile done by our external lab of choice gives us the full picture. You would need to bring your pet in the morning fasted, as the thyroid gland underlies circadian rhythm. 

These blood results usually come back within 3 to maximum 10 days of us sending them.

Treatment & Prevention

Hypothyroidism cannot be prevented.

Treatment consists in supplementation with a thyroid replacement hormone in the form of a daily tablet.

The thyroid hormone concentration in the blood should be checked after 3-6 weeks, and the treatment dosage can be adjusted.

Thyroid hormone supplementation in a life-long medication. Thyroid function should be monitored every 6–8 weeks for the first 6–8 months of thyroid hormone supplementation and then once to twice a year.