Veterinary Care for Animals Planning Overseas Journeys

Veterinary Care for Animals Planning Overseas Journeys

Hyperthyroidism In Cats - Signs, Diagnosis and Treatment

by Sophie Knight

As your cat gets older, you may notice some behavioural changes.  Most of these changes are perfectly normal and are to be expected in an older pet, for example, sleeping more or a waning interest in playtime.  However, there are other signs that could be indicative of hyperthyroidism, a common condition in older cats.

Could your cat be developing hyperthyroidism?  Read on for more information.

What is feline hyperthyroidism?

Hyperthyroidism is a glandular disorder that most commonly affects older cats.  The condition is caused by the over-production of the thyroid hormone, thyroxin (t4), which is responsible for the regulation of the cat's metabolic rate.

Your vet will be able to diagnose hyperthyroidism in your cat by taking a history of your pet's symptoms and carrying out blood tests.  An examination of your pet might reveal swelling of the thyroid glands in the cat's neck – a common indicator of hyperthyroidism.

What are the symptoms of hyperthyroidism?

The following are all symptoms that your cat might display that could indicate the onset of hyperthyroidism:

  • increased appetite, but losing weight
  • increased and excessive thirst and urination
  • hyperactivity
  • not grooming and increased shedding of the coat
  • panting
  • diarrhoea

How can your vet treat feline hyperthyroidism?

There are several ways in which your vet could treat your cat's hyperthyroidism.


The condition is often caused by a benign tumour in one or both of the cat's thyroid glands.  It is possible to surgically remove these tumours, but this won't cure the condition completely.  Anaesthesia can also be challenging in older cats.  Surgery is expensive and not without risk, so your vet will probably recommend an alternative treatment.

Radioactive iodine therapy

This is a very effective and safe treatment.  The vet administers radioactive iodine by injection.  The substance enters the thyroid gland where its concentration is such that it destroys the faulty tissue.  Only one treatment is usually necessary to elicit a cure. 

The major disadvantage of iodine therapy is that it is very expensive, although your pet insurance company should cover the costs, once the excess on your policy has been paid.  Your cat will have to be hospitalised for a couple of weeks, until all the radioactive iodine has been excreted from his system via his urine.

Drug therapy

There are a number of drugs that your vet could prescribe to treat your cat's hyperthyroidism.  Drug therapy is a long term option for treatment, so can prove expensive if your cat is relatively young.  Some cats are also difficult to dose with tablets, but your vet will show you how to administer your pet's medication if necessary.

Whilst on hyperthyroid medication, your cat will have to attend the vet's for annual blood tests to make sure that the level of medication is controlling the condition satisfactorily.

In conclusion

Hyperthyroidism is a common illness in older cats.  If your cat shows any of the above symptoms, seek veterinary advice immediately.  The condition is easily treatable, and your cat should still be able to enjoy a long and happy life.


About Me

Veterinary Care for Animals Planning Overseas Journeys

When you have a dog or a cat, they become a treasured part of the family, and you don't want to leave them at any cost. This is true even if you move or travel abroad. Hi, my name is Katie, and I traveled with my dog for nearly 10 years before his passing one year ago. I loved every moment we had together, but I also learned a lot of important things about the type of veterinary care travelling animals need. If you want to learn about veterinary care or tips for travelling animals or just in general, I invite you to explore my blog.