Written by Dr Marion Welch

Troublesome Thyroids

The thyroids are a little pair of glands in the neck that have a big role in controlling the metabolism. They produce thyroid hormone and when the production of this goes wrong the whole animal is affected.

Strangely enough dogs and cats generally have opposite problems with thyroid hormone production…..too much in cats …..too little in dogs!

Dogs that have low levels of thyroid hormone become sluggish and slow. Their heart rate slows down, they feel the cold, they tend to get fat and often lose their hair. Their bodies don’t fight infection well and chronic skin infections are common. They often have a “tragic” facial expression.

Diagnosis of this problem is by blood test; measuring the level of thyroid hormone in the blood, although sometimes interpreting the result can be tricky as other diseases can lower the thyroid hormone level as well.

Luckily treatment is easy; supplementing the dog with thyroid hormone tablets can dramatically resolve the symptoms.

Cats always like to be different and although low thyroid hormone levels do occasionally occur, high levels of the hormone are far more common. The high thyroid production can be due to an overactive nodule in the gland or sometimes a thyroid cancer.

These cats are usually older cats, most commonly over 10 years and their metabolism goes on overdrive. They lose weight despite eating you out of house and home. Their coat often looks unkempt, their heart rate rises and their temperament may deteriorate……even tempered cats may become cranky. They can seem like people that have had 10 cups of coffee!!

Diagnosis is again is by blood test but treatment is a bit more complicated than treating low levels in dogs.

The most common treatment is using a twice daily medication that stops the produced thyroid hormone from becoming biologically active. This drug is usually a tablet but it is also available in a transdermal form, that is, a skin absorbing cream, for those cats that are difficult to tablet. This type of treatment does not give a cure but manages the problem, as long as the cat stays on the medication.

Treatment can also be by radiation of the thyroid gland to destroy enough of it to reduce production. This is generally a cure but does require an amount of health testing beforehand and a trip to a special facility to get it done.

Sometimes only one thyroid gland is affected and can be surgically removed- the cat can manage very well with the remaining one thyroid gland.

So like many hormones in the body the thyroid hormone works best when the level is kept not too high and not too low…….in fact just right!