What Is the Best Food for a Cat With Hyperthyroidism?

If your beloved kitty companion is diagnosed with a chronic thyroid-related condition, one of the first questions you may be confronted with is what is the best food for a cat with hyperthyroidism? In a nutshell, if your cat has hyperthyroidism, they should eat a high quality low carb diet rich in animal protien.

My top pick’s for best food for a cat with hyperthyroidism:

1.Instinct Grain Free Lamb Pâté Wet Cat Food

Instinct Grain Free Lamb Pate Wet Cat Food


  • Contains 95% meat and animal proteins
  • Highly digestible with high moisture content
  • High protein and low carb
  • No artificial flavors, preservatives, grains, corn, wheat, or soy
  • Made in the USA


  • Some cats don’t like pâté
  • Premium price
  • Contains fish oil

We earn a commission if you click this link and make a purchase at no additional cost to you.

Instinct Grain Free Lamb Pate wet cat food is ideal for hyperthyroid cats who have a sensitive stomach.

Along with lamb, there’s also turkey liver and eggs in this recipe, which brings the total meat and animal protein to a whopping 95%.

This easy-to-digest pate also includes a select few vegetable and fruit ingredients to bring additional vitamins and fiber to the recipe. Superfood pumpkin helps encourage healthy digestion and can combat diarrhea and constipation, which are common overactive thyroid side effects.

The high moisture content from turkey and lamb broth helps ensure your kitty stays hydrated, especially if they frequently urinate or have vomiting spells.

Without grains, corn, wheat, or soy, the carbohydrate content of this cat food is also lower than the average canned cat food.

2. Wellness Complete Health Pate Chicken Entreé

Wellness Complete Health Pate Chicken Entree


  • Contains multiple, easy to digest meat and animal proteins
  • High protein and low carb
  • No grains, corn, wheat, soy, potatoes, or artificial flavors or colors
  • Contains no fish
  • Packaged in BPA-free cans


  • Some cats don’t like pâté
  • Contains guar, cassia, and xanthan gums

We earn a commission if you click this link and make a purchase at no additional cost to you.

Every BPA-free can of Wellness Complete Health Chicken Pâté starts with wholesome meats like chicken, turkey, and chicken liver. Chicken broth brings an added boost of moisture and flavor to this easy-to-digest and highly palatable cat food.

The high protein content helps support lean muscle in your kitty. The two vegetables and one fruit in the recipe add immune system-friendly antioxidants and health-supporting vitamins and minerals like vitamin A which is crucial for bone growth and vision.

There are no grains, wheat, corn, or soy in this recipe, which helps make the carbohydrate content one of the lowest on the commercial cat food market. This is also one of the most budget-friendly non-prescription hyperthyroid cat foods you can find.

3. Nulo Freestyle Grain Free Turkey & Chicken Recipe Wet Cat Food

Nulo Freestyle Grain Free Turkey & Chicken Recipe Wet Cat Food


  • Contains multiple, easy to digest meat and animal proteins
  • High protein and low carb
  • No grains, corn, wheat, soy, potatoes, or artificial flavors or colors
  • No carrageenan, meat by-products, or preservatives
  • Limited vegetable ingredients


  • Contains tuna and fish oil
  • Contains guar gum
  • Premium price

We earn a commission if you click this link and make a purchase at no additional cost to you.

More veterinarians and feline health experts than ever before and saying that senior cats need as much protein as growing kittens. When you add hyperthyroidism to the equation, you need a high protein cat food that can give your kitty the fuel and energy they need to maintain their easily lost muscle mass and body fat.

Nulo Freestyle Grain Free Turkey & Chicken Recipe canned wet cat food is an ideal choice in part because it’s formulated for kittens and senior cats. This cat food is also energy-dense and features vitamin-rich organ meats like turkey liver, and whole chicken to provide easy-to-digest animal proteins.

There are just a few vegetable ingredients in this cat food and no grains, soy, corn, wheat, soy, or potatoes, making this another low carbohydrate option. The two vegetables in the recipe, tomatoes, and pumpkin are good sources of fiber and antioxidants for your kitty’s immune system.

What is feline hyperthyroidism?

This glandular disorder impacts your cat’s health and lifestyle and requires around-the-clock treatment. Beyond regular doses of veterinarian-prescribed medicines, your cat’s diet also plays a role in their thyroid health.

Thankfully, with modern medicine, radioactive iodine therapy, and high-quality over-the-counter and prescription diet cat food, hyperthyroidism is very treatable.

Here’s what you need to know about feline hyperthyroidism is and how to manage it, including:

  • The symptoms of hyperthyroidism
  • Treatments for hyperthyroidism
  • The best food for cats with hyperthyroidism
  • What should a cat with hyperthyroidism eat
  • The relationship between iodine and hyperthyroidism

Feline hyperthyroidism, also known as thyrotoxicosis, is the most common endocrine disease in cats. This condition occurs when the two thyroid glands in your cat’s neck begin to create an excessive amount of hormones.

In many instances, hyperthyroidism comes from an enlarged thyroid and non-cancerous tumors known as adenomas. (Less than 2% of all cases of feline hyperthyroidism come from a cancerous thyroid tumor.)

This glandular disorder causes your cat’s metabolism to skyrocket and directly impacts nearly every organ and bodily function. Thyroid hormones play a massive role in maintaining the health and functioning of your cat’s kidney, liver, digestive system, heart, and brain.

Veterinarians, researchers, and feline health experts have all had difficulty pinpointing just what exactly leads to the development of an abnormal or malfunctioning thyroid.

All of the below have been considered potential risk factors for feline hyperthyroidism.

  • Nutritional deficiencies
  • Thyroid-disrupting chemicals in pet food
  • Excessive minerals like iodine
  • Genetic predisposition
  • Environmental factors

what is the best food for a cat with hyperthyroidism risks

Secondary illnesses and conditions linked to hyperthyroidism

It’s common for cats who have hyperthyroidism to develop secondary illnesses and conditions like high blood pressure and heart disease. Here are a few other conditions hyperthyroid cats are at a risk for.

High blood pressure

High blood pressure, or hypertension, occurs in about 25% of cats who have hyperthyroidism. This is because an overactive thyroid directly impacts your kitty’s heart, and by extension, the way their heart pumps blood.

Hyperthyroidism often leads to an enlarged heart, also known as thyrotoxic cardiomyopathy. The oversized heart pumps blood increasingly harder and faster, causing your cat’s systolic blood pressure to spike above the normal rate of 160mm Hg.

Side effects from advanced hypertension include difficulty breathing, weight loss, seizures, and poor vision from retinal hemorrhaging.

Hypertension can be treated with medications like ACE inhibitors and calcium channel blockers.

Heart disease

Heart disease, specifically Hypertrophic Cardiomyopathy (HCM), is another secondary health problem from hyperthyroidism. This is when your cat’s heart muscle thickens to such an extent that it decreases the amount of blood in their heart’s chambers and increases their blood pressure.

Cats with HCM have hearts that have to work twice as hard to pump very small amounts of blood.

Severe cases of hypertrophic cardiomyopathy can end in the formation of blood clots in your cat’s heart, blood flow obstruction (thromboembolism), and heart failure.

HCM is not curable, but medications like beta-blockers and ACE inhibitors can help reduce symptoms.

Chronic kidney disease

Chronic Kidney Disease, or CKD, also frequently appears in hyperthyroid cats. CKD occurs in 30% of cats aged 10 and older, and is estimated to appear in 3% of the entire cat population.

CKD when your cat’s kidneys begin to fail. This is a big deal because your cat’s kidneys are vitally important for your cat’s bodily functions. Their kidneys keep their bloodstream cleared of toxins, maintain their electrolyte and fluid balance, produce hormones, and excrete waste products in their urine.

There’s no cure to CKD and the condition is not reversible, however medications, a specialized diet, and treatments can slow the progression and increase your kitty’s quality of life.

what should a cat with hyperthyroidism eat

How many cats have hyperthyroidism?

Unfortunately, hyperthyroidism is a common feline disease.

Middle-aged and senior cats, especially cats 12 years old and older, tend to be diagnosed most frequently. Only 5% of cats with this chronic condition are younger than ten years old.

There doesn’t appear to be a link between hyperthyroidism and any specific cat breeds nor sex.

Why are the symptoms of hyperthyroidism in cats?

There are many symptoms that indicate hyperthyroidism in cats. According to Cornell’s Feline Health Center, these symptoms often begin very subtly but can quickly escalate and intensify. This is especially the case with rapid weight loss despite your hyperthyroid cat’s increased appetite.

Other symptoms include:

  • Messy, greasy, or matted fur
  • Excessive thirst
  • Diarrhea and vomiting
  • Restlessness
  • Increased meowing and vocalization
  • Elevated heart rate and heart murmurs
  • Changes in personality like sudden aggression and nervousness
  • Frequent urination
  • High energy levels and hyperactivity
  • Weight loss despite increased appetite

Hyperthyroidism in cats | Dr. Justine Lee

How is hyperthyroidism in cats diagnosed?

The most effective way to diagnose hyperthyroidism is through a blood test.

This can reveal high levels of thyroid hormones or thyroxine (T4) in your cat’s bloodstream.

Technetium scans are another diagnostic tool. This specialized test uses radioactive technetium and a specialized gamma camera to take an image that can show enlarged thyroid glands. This procedure is not commonly done as it requires specialized equipment.

Treatment and diet for hyperthyroidism in cats

There are four treatment options for cats with hyperthyroidism: medication, surgery, iodine radiation, and dietary therapy. Here’s what you need to know about them.

Oral or gel medications

The first way to treat your cat’s overactive thyroid is to get them on a regular medication regimen. Medications like Felimazole which are FDA approved, and the generic methimazole, reduce the amount of thyroid hormones your cat’s abnormal thyroids create.

Often available in pill and gel form, these antithyroid medications are fast-acting and inexpensive. The downside with methimazole is that the pills are usually uncoated and reportedly taste bad.

Medication is often a lifelong treatment and needs to be administered two or three times a day. Other forms of antithyroid medication included specially compounded medicine.

There are some risk factors to antithyroid medications, like potential liver complications, bleeding disorders, low white blood cell counts, heart conditions, and kidney problems. Working closely with your veterinarian on hyperthyroid medication management is a must.

It’s essential that your cat gets frequent blood tests and wellness exams to check their thyroid levels and make sure they haven’t developed secondary health conditions.


Surgery is one of the only ways to cure feline hyperthyroidism, eliminating the need for medication, radiation, or a special diet.

The procedure, surgical thyroidectomy, involves removing your cat’s thyroid glands entirely.

Generally speaking, this isn’t a high-risk surgery and tends to be successful.

But thyroid surgery isn’t recommended for cats who are elderly or who have heart, liver, or kidney conditions.

One of the risks that come with thyroid surgery is that your cat’s parathyroid gland may be affected. A damaged parathyroid gland can cause unstable blood calcium levels and pose a host of new health problems.


Radioactive Iodine Therapy is another leading treatment for cats who have an overactive thyroid.

It works like this. Radioactive iodine is injected subcutaneously under your cat’s skin where it gets picked up by the bloodstream. That iodine directly targets your cat’s thyroid glands and attacks the abnormal thyroid tissue. This decreases the oversized thyroid and helps to reduce the excessive amount of thyroid hormones that are released.

This is one of the safest and most effective treatments as it doesn’t require any surgery or anesthetics. It also doesn’t impact any other parts of your cat’s body and has minimal side effects.

Radioactive iodine therapy can reduce the need for medication and can even cure your cat’s hyperthyroidism entirely.

Despite this treatment being costly upfront, it has a 95-98% cure rate with most cases being completely cured after one treatment. Because of the radioactive nature of the substances, it requires frequent multi-day hospitalizations for your cat after each round of treatment. It usually takes at least three months for significant changes or for your cat to be considered cured.

In very rare cases, your cat can develop underactive thyroid, or hypothyroidism, as a result of iodine therapy or as a result of surgery.

what is the best food for a cat with hyperthyroidism diet

Dietary therapy

Dietary therapy is one of the leading treatments for cats with hyperthyroidism. Foods specifically formulated for cats with hyperthyroidism are becoming easier to find and more affordable than ever with both prescription and over-the-counter options.

Prescription nutrition or dietary therapy effectively manages clinical symptoms, and in some cases, even lowering high concentrations of thyroid hormones in your kitty’s body.

These foods are not medicated. Instead, they’re formulated to have precise nutrient levels– especially iodine, which is often the lowest possible amount. Dietary therapy works best in combination with medication and/or radioactive iodine treatments.

But there is some concern about the long-term safety of iodine restriction diets.

Some veterinarians and feline health experts say that diets that restrict iodine to such low levels could cause feline hyperthyroidism symptoms to intensify and their condition to worsen.

It’s best to work with your veterinarian directly to figure out the best meal plan or dietary therapy for your kitty.

Frequent blood tests and urinalyses

Regular bloodwork and urinalyses are a must for hyperthyroid cats.

It’s crucial to stay on top of the thyroid levels in your cat’s bloodstream and to get frequent readings on their organs like their liver and kidneys through various blood chemistry panels and T4 tests.

Regular urinalyses can also ensure that your kitty’s kidneys, liver, and urinary tract are in good health, as some cats have both kidney disease and hyperthyroidism.

Heart exams

Checking the heart health of hyperthyroid cats is also essential.

Listening to their heart with a stethoscope can catch problems like irregular heart beats or heart murmurs. If anything else appears to be odd or out of the ordinary your vet may suggest an entire cardiac workup. This includes x-rays, cardiac ultrasounds with heart specialists, EKGs, and CBC (or, complete blood count) panels.

Wellness checks

General wellness checks are also crucial for cats who have hyperthyroidism.

Beyond bloodwood and urine tests, wellness checks, or general examinations, can also gauge where your kitty is in terms of their overall health.

Regular veterinary exams can especially keep tabs on your cat’s weight, body fat, and muscle mass. Weight loss, especially sudden, drastic weight loss, can be fatal in cats. It can also indicate that your cat’s muscle tissue is eating itself due to excessive thyroid hormones and a dangerously speedy metabolism.

Feline Hyperthyroidism

What should a cat with hyperthyroidism eat?

Beyond hotly contested low iodine levels, there are two other main things to look out for in the foods you feed your feline friend (and their overactive thyroid): protein and carbohydrates.

High animal protein content

Cats with overactive thyroids are still first and foremost obligate carnivores. Like their wild ancestors, cats with hyperthyroidism do best on diets high in meat and animal proteins. At least 50% of the calories from their food should be meat-based and easy to digest.

Cats with overactive thyroids require more protein than the average healthy cat for two main reasons:

  1. Their increased metabolism can cause them to lose their muscle tissue and their body to “eat” itself
  2. Many cats with hyperthyroidism are seniors, and because they naturally lose lean muscle mass, they also need high protein and highly digestible meat-based foods

However, if your hyperthyroid cat also has kidney disease their nutrition requirements are a little different. Read on below for more details about feeding a cat with both conditions.

Limited carbohydrate content

No more than 10% of the calories from your cat’s food should come from carbohydrates.

Hyperthyroidism raises your cat’s blood sugar, or blood glucose, levels. This can lead to issues with digesting sugars and starches and even insulin resistance or prediabetes.

It’s best to avoid the starchy, carb-heavy foods like corn, potatoes, pea protein, wheat, and grains that are often added to “bulk up” modern commercial cat foods and stick to meat-based cat food. For a list of high quality low carb cat food options check out our “Best Low Carb Cat Foods” roundup.

What if my hyperthyroid cat also has Kidney Disease?

If your kitty has both hyperthyroidism and chronic kidney disease (CKD) the best food for your cat gets a little more complicated. This is because cats with kidney disease may require a low protein diet.

Eating smaller amounts of protein slows the progression of CKD by putting less stress on your cat’s kidneys. However, if protein levels are too low, your cat runs the risk of losing muscle mass.

For these reasons if your cat has both CKD and hyperthyroidism the best food varies on a case by case basis. You’ll need to work with your veterinarian to come up with a meal plan tailored specifically to your cat.

what is the best food for a cat with hyperthyroidism symptoms

What to avoid when feeding a cat with hyperthyroidism

Fish-based food

Some studies have found that cats who eat a lot of canned fish cat foods may be at an increased risk of developing hyperthyroidism.

Fish often has higher rates of iodine than other meats. Some fish may also be contaminated with certain toxins or chemicals that are endocrine disruptors like Polychlorinated Biphenyls (PCBs). This means that diets high in certain fish can impact your cat’s thyroid hormone production.


Also known as Bisphenol A, BPA is another endocrine disruptor and can have a direct impact on your cat’s thyroid function and hormone levels. This chemical is notoriously known for coating the insides and lids of canned foods, where it can leach into the food contents. Unless otherwise noted on the can’s label, there’s a possibility that BPA can be lurking in your kitty’s cans of wet cat food.


In some studies, cats who eat diets high in soy products have been found to have higher levels of thyroid hormones, like thyroxine, or T4, in their bloodstream.

How much iodine does a cat with hyperthyroidism need?

AAFCO and the National Research Council (NRC) report the average 10 pound cat requires 0.22ppm of iodine. But when hyperthyroidism enters the picture, the question of appropriate amounts of iodine becomes more complicated.

Diets with high amounts of iodine may potentially lead to cats who are genetically predisposed to hyperthyroidism to develop the condition.

This has yet to be definitively proven. More studies need to be done to get a complete picture of environmental risk factors.

There’s a lot of uncertainty when it comes to how much iodine cats with hyperthyroidism need. Some experts suggest low iodine diets, while others believe that diets that are too low could make a hyperthyroid cats’ symptoms and condition worse.

If your cat has hyperthyroidism, work directly with your veterinarian to figure out exactly how much iodine your cat needs.

what should a cat with hyperthyroidism eat choices

What is the best food for a cat with hyperthyroidism?

While there are some prescription food options and prescription diets for hyperthyroid cats, more and more commercial cat food companies are coming out with affordable, accessible, and over-the-counter foods.

We’ve found the best food for hyperthyroid cats are canned cat foods because of their high water content (or moisture) and multiple sources of meat and animal protein that supports your cat’s muscle mass.


Key takeaways on feeding a cat with hyperthyroidism

One of the most effective ways to tackle feline hyperthyroidism is through a combination of medication and diet.

Our top picks for the best foods for cats with hyperthyroidism feature high protein, multiple and easy-to-digest meats, a high moisture content, and low carbohydrates to give your kitty the essential nutrition they need to keep their body going strong!

Before making any significant changes to your cat’s diet, be sure to consult your veterinarian. Meal plans and dietary therapy for cats with hyperthyroidism should be decided on a case by case basis, tailored to each individual cat. This article is not a substitution for professional veterinarian advice, treatment, or diagnosis.

Victoria Tomis