What Is Hyperthyroidism In Cats And Can It Be Cured?

what is hyperthyroidism in cats

As a pet parent you may want to know what is hyperthyroidism in cats, and if it can be cured. Hyperthyroidism is a fairly common disease, mostly found in older animals. Many will get it at some point in their lives, but regular checkups can help spot signs in the early stages.

What is hypothyroidism in cats?

In this post you’ll learn all about hyperthyroidism in cats, including causes, what to look for, and available treatments. Fortunately, this disease is easily treated and managed, providing it’s caught in the early stages. If your cat is middle age or older, she should be examined by a vet at least once a year. It pays to keep up with medical checks and vaccinations, saving you expensive bills further down the line.

Common signs of hyperthyroidism in cats-what you should be on the lookout for

signs of hyperthyroidism in cats

Hyperthyroidism basically means an over active thyroid. This vital gland helps control your cat’s metabolic rate. An imbalance of chemicals can create havoc with your kitty’s bodily functions. This applies to both cats and humans. Excessive production of a hormone known as as T4 can cause your cat’s thyroid to become over active. This can lead to symptoms such as increased appetite.

One of the commonest signs your cat may have hyperthyroidism is weight loss. She may be eating plenty of food, yet losing weight. An increase in appetite is common, so if your cat keeps pestering you for more kibbles, or treats, it’s possible she may be developing thyroid problems.

Your kitty may also have an unkempt coat, with matted fur. Other symptoms include vomiting and diarrhea. All cats vomit at one time or another, especially when they bring up hairballs. However, if it becomes very frequent you need to get advice, especially if your cat is in her senior years.

What causes hyperthyroidism in cats?

Most cases of hyperthyroidism in cats are caused by enlarged thyroid glands. Almost all of which are the result of a benign tumour. Only around 2% are cancerous, so your cat has a high chance of recovery.

No one really knows what triggers excessive amounts of T4. However, research has suggested a link between exposure to flame retardants and hyperthyroidism in cats. It was also found those worst affected were indoor cats. There’s no definite proof, but we’re all becoming more aware of the dangers of toxic chemicals.

Fourty years ago, hyperthyroidism in cats was relatively rare, and nowadays it’s becoming far more common. Outdoor cats are less likely to develop the disease, though many still do. Research has also suggested cats fed on tinned food are more likely to develop hyperthyroidism. However, it’s all speculation and there are other factors at play.

Hyperthyroidism in older cats

It’s rare for hyperthyroidism to develop in younger cats, and most cases are found in those aged over 10. Just as in humans, seniors are more prone to health problems. Older cats often lose weight, especially in their final years. The problem with this is it can be overlooked.

This is why regular checkups are so important. Your vet will know your cat’s medical history, and take routine blood and urine tests during a visit.

How hyperthyroidism is diagnosed.

The vet will weigh your cat to check for any significant loss of weight. A cat with hyperthyroidism will be losing rapid amounts of weight. He or she will also listen to your cat’s heartbeat, and possibly check blood pressure. Rapid heart rate and high blood pressure can be a sign of an over active thyroid. However, it can also be a sign of kidney disease as well. Blood tests can confirm elevated levels of T4, and urine tests rule out other conditions.

Is hyperthyroidism fatal in cats?

is hyperthyroidism in cats fatal

Hyperthyroidism is rarely fatal unless untreated. As most cats suffering from the disease are elderly, they may have already reached a good age. It’s much more likelier a cat will die from kidney disease in old age than hyperthyroidism. In fact many cats continue to enjoy a long and happy life with treatment.

Treatment for hyperthyroidism in cats

The most effective treatment is surgery to remove the thyroid glands. However, there’s always the risk of a general anaesthetic with older cats. A thyroidectomy is in most cases a complete cure. Your cat will still need regular checks to keep an eye on kidney function and other possible conditions.

Radioactive iodine injection

Radioactive iodine can be highly successful in treating hyperthyroidism. It’s administered as an injection, and your cat’s T4 levels may return to normal in a few weeks. The main drawback with this treatment is cats have to remain in hospital until their radioactive levels are safe for humans and other animals to come into contact with them.

Also veterinary staff have to use protective measures when handling radioactive iodine. Not all practices are equipped for this, so you may need to travel some distance.

Is medication the best treatment?

Medication is probably the most common treatment for hyperthyroidism in cats. The drug used is methimazole, and highly effective. It’s fairly inexpensive so won’t create a mountain of debt! The downside is you’ll need to give your cat a pill each day for the rest of her life. Some owners find this tricky especially if their cat isn’t used to taking pills.

Fortunately many vets offer the option of a cream applied to the ear making it easier. However, if you’ve only been given the option of tablets, read my post to discover how to get your cat to take a pill.

Can diet help control hypothyroidism in cats?

Diets are available that help control levels of iodine in the body. This chemical is used to make thyroid hormones. Feeding your cat high levels of protein can help control weight loss, but you need to discuss this with your vet first. Any diet prescribed for your cat has to be adhered to. You won’t be able to feed her anything else.

The only supplement I can recommend is NHV Hyperthyroidism Gold Support Kit for Cats, Dogs & Small Pets. It’s absolutely not a replacement for medication and you must ask your vet’s advice before using it. However, it’s advertised as being vet formulated and approved.

nhv hyperthyroidism gold

NHV Hyperthyroidism Gold contains a mix of herbs that helps control thyroid hormones. Includes turmeric, a powerful antioxidant that helps relieve pain and inflammation.

It’s recommended to give your cat one drop twice a day, depending on body weight. It mustn’t be given to pregnant cats or those on blood thinning drugs.

Looking after your cat in her older years

It’s important to monitor your kitty’s health as she enters her golden years. Any unusual symptoms including weight loss must be reported to your vet. Most elderly cat health problems can be managed successfully, including diabetes and kidney failure. Getting your cat examined yearly can reveal any problems in their early stages.

Hyperthyroidism in cats is best treated using conventional medicine. Unfortunately, there are no natural treatments. The best option in my opinion is probably the iodine injection. Even though you won’t see your cat for several weeks it’s usually very effective. There are rarely any side effects, and only one treatment is needed in most cases.

In this post you’ve learnt all about hyperthyroidism in cats, including signs to look for and diagnosis. We’ve also looked at treatments your vet may recommend. If you’ve enjoyed reading this post and found it useful please share:) If you have any questions or want to share your experiences, please leave your comments in the box below.

Wishing you a purrfect day:)



  1. Thank you for this very informative article. I was worried about my two little kitties, but as you say, it would be very rare in younger cats. They have been vomiting and yet were very hungry any way. Playing around a lot and eating tons of food. Yet they don’t seem to grow. Well, one of them. So I was worried. The vet sad, that it was completely normal, but I wanted to see for myself with some online research.
    Your article has been very reassuring, so thank you for that. I guess I will trust the vet and just get another check up very soon, if they do not get better.
    Thank you so much for sharing!

    1. Thank you Jan:) You did the right thing getting them checked out, as it’s not completely ruled out in younger cats. So glad you found this post reassuring, and hope they put on weight:)

  2. Interesting post. I have a siamese cat and he is a indoor cat and totally healthy on his dried food and mineral water diet. I see they blame tinned cat food for this condition but I reckon it could be the fact that a lot of people still give their cat milk even when their adults. Adult animals are not supposed to have milk. Might be some truth in that. Thanks.

    1. Thank you Adrian:) You’re so right that milk is bad for adult cats. They’re actually lactose intolerant, and no one one knows the harmful long term effects of giving a cat milk.

  3. I’m so glad I ran across your article Kathy. After reading this I going to make an appointment with the vet for my cat, Chloe. She has been losing weight and throwing up, so I’m thinking it may be hyperthyroidism. Thanks to you, I know what to tell the doctor.

    1. So glad my post helped you. IF Chloe is an older cat then hyperthyroidism could well be the cause. Don’t worry though, I had a cat with that condition and she survived for years on medication. She eventually passed away in her early twenties! That’s over 100 in human years!

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