Hyperthyroidism in Cats: Symptoms, Treatment, and What to Feed a Cat with Hyperthyroidism

hyperthyroidism in cats

Hyperthyroidism is one of the most common problems that felines can suffer. 95% of the cases in which cats suffer from hyperthyroidism happen when the age of the cat is over 13 years. Now, it is essential to know what hyperthyroidism is and how you should approach when your cat is suffering from hyperthyroidism. Figuring out hyperthyroidism in cats and taking actions according to the guidance of a veterinarian should be the right way to go. 

Another important factor in controlling hyperthyroidism in your cat will be the diet. You have to understand the right diet for your cat with hyperthyroidism. Otherwise, controlling it will be a difficult thing. As you can see, there are lots of things to learn about hyperthyroidism in cats. So, without further ado, let’s see learn about it. 

What is Hyperthyroidism in Cats?

Before you know hyperthyroidism, you would have to find out about what is thyroid and its role in your cat’s body. Now, the thyroid is a hormone. Two thyroid glands are located at the neck of your cat. These thyroid glands produce thyroid hormone that regulates the metabolic rate of your cat’s body. Hyperthyroidism happens when one or both the glands become enlarged and overproduce thyroid hormone. When the T-4 hormone gets over-circulated in the bloodstream of your cat, that condition is known as hyperthyroidism. 

Symptoms of Cats with Hyperthyroidism

It is crucial to know the signs and symptoms of your cat suffering from hyperthyroidism. Otherwise, it will be difficult for you to take prompt action by seeking medical help. Here are some common symptoms of a cat having hyperthyroidism;



Weight Loss

A cat with hyperthyroidism will lose its weight rapidly which is a thing of concern for the owner of the pet. You have to take control of the situation with the proper diet for your cat as per the guidance of the veterinarian.

Increased Appetite

A cat with hyperthyroidism not eating is a rarity because of the cats that have an increased level of thyroid hormone production will have an increased appetite and thus, the cat will want to eat more.

More Active

When you see a cat having hyperthyroidism, one of the common things you will notice is the cat is more active. It happens because of the high level of thyroid circulation in the bloodstream of the cat.

Increased Aggression

You normally see that a cat is a cute and meek animal. Aggression is something that is not associated with cats. However, due to hyperthyroidism, you will see a cat getting aggressive often.

Improper Hair Coat

If you see that the hair coat of your cat is getting worse or the skin of your cat becoming flaky, then you should know that it is one of the signs that your cat could be having hyperthyroidism.

Quicker Heart Rate

When you take your cat to a veterinarian for a check-up, you tend to monitor the heart rate of your cat as well. If your cat has hyperthyroidism, you will see that his or her heart rate is becoming faster.

Increased Thirst

A very good and clear indication that you can get about your cat suffering from hyperthyroidism is that the cat will want to drink lots of water due to the increased level of thirst.

More Urination

As you can already know that the cat will be drinking plenty of water due to increased thirst, you will also see that your cat is urinating frequently and that is also a symptom of hyperthyroidism.

Regular Throwing Up

A cat with hyperthyroidism throwing up is something that you will see regularly. Vomiting is a clear symptom that your cat is having hyperthyroidism and you need to take medical help.


A cat with hyperthyroidism will suffer from diarrhea more often than not. Also, you will see your cat is having an increased amount of stool when he or she is suffering from hyperthyroidism.

Trouble in Breathing

When your cat is having an increased amount of thyroid production and circulation in the bloodstream, you will see that your cat is having problems with breathing occasionally. It is also a major symptom of hyperthyroidism.

Becoming Weak

Hyperthyroidism is a condition in which your cat will become more active. But, this hyperactivity of your cat will lead to his or her weakness occasionally as well and this is also a good sign of hyperthyroidism in a cat.

Feeling Depressed

You associate cat as a jovial animal. Depression and sadness are some of the things that a cat will not have unless there is something wrong. Hyperthyroidism is one case where your cat can become depressed.

Diagnosis of a Cat with Hyperthyroidism

If your veterinarian suspects that your cat has hyperthyroidism, then the doctor will have a physical examination of your cat and touch the part of the body where thyroid glands are located. Apart from that, the doctor will also check the blood pressure and the heart rate of your cat. After that, the veterinarian will order you to have a blood test of your cat to check the increased level of thyroid circulation in the bloodstream. Under the normal circumstances of hyperthyroidism, a cat will have a higher level of T-4 concentration in the bloodstream.

However, at times, a cat will have hyperthyroidism without any elevated level of T-4. So, in such conditions, the veterinarian will have for further tests to figure out whether your cat is suffering from hyperthyroidism or not. Now, it is essential to understand that hyperthyroidism will lead to many other conditions related to heart and kidney for your cat. So, you should also check the general health of your cat periodically if your cat has hyperthyroidism. 

Treatment of Hyperthyroidism in Cats

When it comes to the treatment of your cat’s hyperthyroidism, there are four major options. Now, each of these four treatment measures will have its advantages and disadvantages. Now, the treatment your cat will get from the doctor will depend on his or her health condition primarily. Therefore, let’s have a look at these four treatment measures.


In the market, you will find multiple anti-thyroid medications that can reduce the production of the thyroid hormone from your cat’s thyroid glands. You should know that these medications are not effective if you are looking for a long-term solution for your cat. But, you can get these medications easily from your local market, and you will also not have to spend a huge amount of money for that. However, these medications are not devoid of side-effects for your cat. 

The side-effects will include anemia, vomiting, lethargy, and many others. The dosage of an anti-thyroid medication will be two times in a day. Also, the anti-thyroid gel is available, which you can apply on the skin of your cat, and it will effectively lower the thyroid production of your cat. No matter what anti-thyroid medication you give to your cat, you have to go for regular health checkups of your cat and keep an eye on the side-effects and the functioning of the kidney of your cat. 

Radioactive Iodine Therapy

If you can have the radioactive iodine therapy, it will arguably be one of the most effective treatment processes for a cat with hyperthyroidism. The radioactive iodine will be injected in the cat and will get absorbed in the cat’s bloodstream quite quickly. After that, the thyroid gland will absorb the iodine because it needs iodine to produce T3 and T4 hormones. However, the radiation that is deployed along with the iodine will destroy the excess and abnormal thyroid tissues that are the primary reason for the excess production of T4. Most of them take one or two weeks to have their thyroid level back to normal after this therapy. 

The major advantage of using radioactive iodine therapy for hyperthyroidism is its effectiveness along with no producing any side-effective and not having to use anesthesia. But, it has the involvement of radioactive substances that are to be injected in the body of the cat. So, you have to check whether the facility from where you will have the therapy is certified to provide such treatment or not. Because of the use of radioactive substances, the cat needs to be hospitalized for 3 to 5 days after the therapy. It will take around three months of therapy to cure hyperthyroidism.


Surgical thyroidectomy or the removal of thyroid glands through surgical measures is a treatment for hyperthyroidism that has produced great results. The biggest advantages of this treatment are that it will be a permanent or long-term cure for hyperthyroidism for the cat, and you don’t have to do for the medications. One major concern for this treatment is the use of anesthesia. It means if the cat is older or has heart or kidney problems, it could face complications during the treatment. Another major risk is the damage to the cat’s parathyroid glands, which is responsible for the maintenance of the calcium level in the cat’s blood. Furthermore, surgical thyroidectomy is an expensive treatment process. So, the owners of the cats rarely choose this treatment measure for hyperthyroidism.

Dietary Therapy

The dietary therapy for treating hyperthyroidism in cats is about limiting the amount of iodine your cat intakes in his or her diet. This therapy could be useful in cats that cannot undergo other treatment measures. However, limiting the iodine consumption for a longer amount of time could lead to other health problems, which make this therapy a bit controversial. The research on this therapy is still going on, and you should consult with your veterinarian before choosing this therapy. 

What is the Best Food to Feed a Cat with Hyperthyroidism?

Now, you will be wondering what can a hyperthyroid cat eat? Well, you have to smart while designing the treatment plan. You can talk to your veterinarian, who will be an expert in suggesting the right food for your cat. Moreover, there are certain things you have to keep in mind before giving your cat any food. The food should be:

  • Higher content of calorie
  • Low level of carbohydrates
  • Dry kibble food
  • Avoid grains, fruits, and soya

Recommended Kibble Food

Whiskas 1 Cat Complete Dry With Chicken


Provide a good amount of nutrients, high in calorie, 


There is no such negative point for this product as it is a wonderful raw food diet for cats with hyperthyroidism.

Hyperthyroidism in Cats Life Expectancy

If your cat is diagnosed with hyperthyroidism, then you can expect your cat to survive for 3 to 5 more years. However, for that, you need to take proper medical care of your cat. Otherwise, it will be impossible for your cat to survive that long, and your cat could succumb to the heart or kidney problems. However, with proper medical treatment of hyperthyroidism, the late stage hyperthyroidism in cats could be of good life quality. 

The Bottom Line

Hyperthyroidism in cats is curable with proper treatment measures. There are many treatment options available for hyperthyroidism. You should consult with your veterinarian and choose the one that will suit your cat according to the age of the cat and your finances. Also, regular checkups of the kidney and heart of your cat will ensure that the cat is staying healthy and living a quality life.