What Should I Feed a Hyperthyroid Cat?

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Hyperthyroid Cat

Hyperthyroidism, also known as thyrotoxicosis, is a serious condition that affects older cats. It’s more common than feline lovers think, plaguing approximately 10 percent of cats over the age of 10.

Marked by an increase in thyroid hormone production, a cat’s entire well-being rests on the diet you provide.

This disease impacts your cat’s metabolism while also making them susceptible to a host of health complications. Many felines become emaciated and unkempt if you do not change their diet to follow their body’s needs.

So, how should you feed a hyperthyroid cat?

About Hyperthyroidism

Before we get into the dietary information, it’s important to understand hyperthyroidism and how it affects the body.

Essentially, this disease occurs when the thyroid gland begins to produce more hormones than it needs.The most problematic hormone is Thyroxine, which is commonly referred to as T4.

Too much T4 in the bloodstream increases the metabolism to unhealthy levels. Cats become hyperactive. In the meantime, they experience a range of harmful symptoms.

Many adopt insatiable thirst, increased hunger levels, and frequent urination. Those symptoms, however, don’t hold a candle to the physical effects of hyperthyroidism.

Increased Metabolism and Weight Loss

The increased metabolism causes the body to waste away. To fuel the chronically high metabolism, the body starts to break down muscle proteins.

As a result, most felines lose weight quickly. All the while, they become weaker from the decreased muscle mass.

It’s a scary sight to see. The longer the condition goes undiagnosed, the worse the effects can get.

Cats can develop hyperthyroidism for many reasons. However, most cases are caused by a non-cancerous tumor called an adenoma. The adenoma makes the thyroid gland enlarge, resulting in hormone overproduction.

What to Feed a Hyperthyroid Cat

The best way to manage hyperthyroid is to provide a premium diet that counteracts the effects of the disease. The goal is to help your cat recover from weight and muscle loss while also supporting the overactive thyroid.

Here are a few things to consider when creating your cat’s diet.

Wet Canned Food

When planning a diet for a hyperthyroid cat, stick with canned food. Usually, kibble is the better choice because of its teeth-cleaning texture and low moisture content.

However, dry kibble can cause more complications when a cat suffers from hyperthyroidism.

Dry foods contain more ingredients and unnecessary fillers. Canned foods, however, are much more straightforward.

Sure, they might have more moisture. But, the ingredients list is shorter and to the point. Plus, the extra hydration is always good. The best choice is a high-protein pate with no gravy or extras.

High Protein Content

Provide a food product that’s at least 40 percent protein. This higher content will help your feline friend recover some of the muscle mass they lost. It encourages them to pack on the pounds while regaining their strength.

Make sure to choose highly digestible protein sources. Older cats can’t digest complex proteins like younger cats.

Choose pure meat, meat meals, or meal byproducts. They’re easier for your cat to process and absorb.

Do not provide plant-based proteins like legumes and peas. This is one of the reasons why you should avoid dry kibble. Canned foods usually pair plant-based proteins with animal proteins.

That’s not something you usually have to worry about in canned food.

Reduced Carbs

Your cat’s meals should be comprised of less than 15 percent carbohydrates.

Carbs directly impact blood glucose levels. Excess carbohydrates can cause glucose levels to spike and drop off. Cat with hyperthyroidism is already at an increased risk of diabetes. Providing too many carbohydrates will only exacerbate the problem.

The goal is to stabilize glucose levels as much as possible and prevent energy levels from spiking.

Look for complex carbohydrates when possible. They absorb into the body slowly to avoid unwanted energy spikes.

Low in Phosphates

High phosphorous content can spell trouble for hyperthyroid cats, too. This disease makes felines more susceptible to kidney disease, so you want to put as little stress on the organs as possible.

Low-phosphorous diets reduce the kidney workload.

Generous Fat

A higher percentage of fat is good for hyperthyroid cats shortly after diagnosis. The fat will help your kitty gain weight quickly as you attempt to stabilize their health.

That said, make sure to adjust as your cat’s conditions approve. Too much fat in the long term will only lead to unnecessary weight gain.

Specialty Diets

Specialty diets do exist for hyperthyroid cats. Not only do they contain fewer carbs and more protein, but they have less iodine.

Typically, iodine is an essential nutrient that cats need to produce the T4 hormone. But since hyperthyroidism causes an excess of T4, specialty diets restrict this nutrient.

They can help maintain ordinary hormone production and might be a worthy alternative to radioactive iodine therapy.


Hyperthyroidism doesn’t have to be a fatal condition. It’s perfectly manageable with the proper diet and care. Consult with your vet to go over your options.

There are many ways to treat hyperthyroidism, and the right food is just part of the equation. It takes commitment, but a healthy diet can make all the difference in fighting this disease.

Also Read: My Cat Smells Like Poop: 6 Causes & Solutions

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