Hyperthyroidism in cats is the most common hormonal disorder that affects cats with an incidence of around 10% in cats over 10 years of age. It creates a wide range of signs resulting from the overproduction of thyroid hormone made by the thyroid glands, which are situated in the neck.
Cats have two thyroid glands, In the vast majority of cases, hyperthyroidism in cats is caused by a benign growth in one or possibly both thyroid glands. Rarely (in less than 1-2% of cases) hyperthyroidism is caused by a malignant tumor (thyroid adenocarcinoma).
What are the signs of hyperthyroidism in cats?
Hyperthyroidism in cats can occur in any breed of cat, male or female, but occurs almost exclusively in older animals, the youngest I’ve personally seen was 7 years old.
The ‘classic’ signs of hyperthyroidism are: Weight loss
Usually a good or increased appetite though occasionally you will see cats that aren’t eating very well Increased thirst.
Increased activity, restlessness or irritability A poor and unkempt hair coat.
Mild to moderate diarrhea and/or vomiting In some cases there may be a generalized weakness, lethargy, and loss of appetite An increased heart rate and heart failure.
Why should you care about the condition?
Well, hyperthyroidism in cats will kill your cat if left untreated and it is a condition which in general lends itself to treatment with most cases responding very well if treatment is begun early enough.
Unfortunately, some cases are presented at a late stage in extreme heart failure with their chest full of fluid squashing their lungs or sometimes they’ve suffered acute blindness due to high blood pressure leading to retinal detachment or occasionally they have a blood clot which is very sadly usually terminal.
How do we Diagnose hyperthyroidism in cats?
In most cases, it is possible to palpate an enlargement of the thyroid gland. Occasionally though there may not be a palpable goiter.
In all cases, the condition is usually confirmed by blood testing.
see also:The Smartest Dogs In The World
How do we treat hyperthyroidism?
Successfully treated cats, irrespective of what treatment is used, will usually have a complete reversal of all the signs of hyperthyroidism.
Further evaluation will usually be needed periodically to check the cells in the blood, assess kidney function and ensure long-term goals of thyroid hormone concentrations are being achieved.
There are four main options for treatment
Medical management (anti-thyroid drug therapy)
The most commonly used and effective anti-thyroid drugs belong to a group known as thioamides.
These drugs (available in tablet form ) reduce both the production and release of thyroid hormones from the thyroid gland. They do not provide a cure for, but they do allow either short-term or long-term control of hyperthyroidism.
However, to maintain control of the disease medication has to be given at least on a daily basis (usually twice daily is best).
The treatment dose is adjusted to effect and these drugs are usually both safe and effective.