Hyperthyroidism is a disease that can negatively impact both humans and animals. Unfortunately, it is quite common among cats and can impact them enough to lessen their quality of life. This disease most frequently affects middle-aged and older cats causing all kinds of negative symptoms, like weight loss and vomiting.

The primary cause of hyperthyroidism in cats, or thyrotoxicosis, is an increase in the T3 and T4 hormones produced and released from the thyroid glands. Once your cat is diagnosed with hyperthyroidism, you will need to start managing their diet and medication to ensure you have good control over their condition

In recent years, studies have shown that a cat’s diet can either help manage hyperthyroidism or make it worse. You want to feed your cat a diet with severely restricted iodine levels. This helps normalize the levels of T4 produced by the thyroid. It isn’t the only thing that you can do, but it is another option for the medical management of the disease.

Many standard cat foods, particularly those created for senior cats, are suitable to continue feeding a hyperthyroid cat, but to make sure you are giving them the best possible diet, talk to your vet. If your vet recommends changing to a more suitable food, it is best to switch them to cat food for hyperthyroidism right away. To help you make the change smoothly, we have reviews for the top six best cat foods for hyperthyroidism, so you can make an efficient and well-informed decision.

The ideal diet for the hyperthyroid cat is one that is high in protein, low in carbohydrates, and lower in iodine (but not too low). According to the Feline Hyperthyroid Treatment Center, we should look for the following:

*values are based on dry matter. Wet food is usually around 75-80% moisture, so to get an approximation of these values, multiply them by 4 or 5. For example, wet food with 10.5% protein and 75% moisture has the rough equivalent of 42% protein. A food with 8% protein and 80% moisture will have approximately 40% protein.

Cats that are also experiencing kidney problems will have different protein requirements, so it is important to discuss the ideal food with your vet.

Disclaimer: The foods reviewed here were chosen because they have certain characteristics that might help with some of the causes or consequences of this medical condition. However, they are not a medical treatment or a substitute for medical treatment. Keep in mind that each medical case is different and what works for some pets may not work for others. Your veterinarian is the right person to advise you on the best diet for your pet’s individual case.

A Quick Comparison of Our Favorites in 2024

The 6 Best Cat Foods for Hyperthyroidism

1. Wellness Complete Health Grain-Free Canned Cat Food – Best Overall

This food is a wet canned food in the form of pâté, and is a healthy, grain-free option for your furry feline. It is filled with high-quality protein that comes from chicken. It also has ingredients like carrots, flaxseed, and cranberries. These ingredients help support your cat’s immunity via antioxidants and urinary health and help them grow a healthy coat and maintain healthy skin through omega fatty acids.

Although this food was ultimately crafted for whole-body health, it functions as a positive balancing agent for cats with hyperthyroidism because it has low iodine levels. It avoids ingredients that often bring in high levels of iodine, such as eggs, dairy, and seafood.

This thyroid food is completely free from corn, wheat, soy, and any other grain. It is meant to support your cat’s urinary and digestive health, which helps mitigate some of the symptoms associated with hyperthyroidism. It is also made in the U.S.A., with internationally sourced ingredients, and it has a texture that most cats love.

All in all, we think this is the best cat food for hyperthyroidism.

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2. Solid Gold Indigo Moon Dry Cat Food – Best Value

This food from Solid Gold comes in 3-pound, 6-pound, and 12-pound bags, making it a practical choice if you want to try it out or commit to it for longer. It is entirely grain- and gluten-free, making it healthier for the average cat and easier for a cat with hyperthyroidism to digest.

The protein level in this food is 42%, which is relatively high. This protein is suitable for a cat that needs to rebuild their muscles after the loss of muscle mass that comes with an overactive thyroid. If your cat is beginning to experience kidney failure, though, this is not the best option for them.

The protein comes from chicken and eggs and is made specifically to encourage gut health in cats by including probiotic supplements. We would prefer higher fat levels for a hyperthyroid cat, but it is still a healthy food and the best cat food for hyperthyroidism for the money.

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3. Hill’s Prescription Diet Thyroid Care Dry Cat Food – Premium Choice

Hill’s Prescription Diet Thyroid Care Dry Cat Food is arguably one of the best choices out there when it comes to prescription food and dealing with thyroid problems. It is third on our list because, as a prescription food, it must only be fed to cats that have hyperthyroidism, and must also be the only food that cat eats, which can be tricky if you have more than one cat. It is, however, a great option if medicating your cat will prove very difficult. It comes in 4- and 8.5-pound bags.

Due to the outstanding balance of ingredients in this food, it has been clinically proven to restore thyroid health in as little as 3 weeks. It does this by decreasing T4 hormone production while supporting the health of the kidney, urinary tract, and heart. Although the food does specifically help balance the thyroid and does it well, it contains ingredients which are not ideal for cats, particularly those with hyperthyroidism, such as corn gluten meal and soybean mill run.

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4. Hill’s Prescription Diet Thyroid Care Canned Cat Food

The Hill’s Prescription Diet Thyroid Care Canned Cat Food comes in a case of 24 which is great in terms of supply, but could be problematic if your cat doesn’t like eating it. You may be able to obtain 1 or 2 cans from stores if you want to give it a try.

This canned food’s texture is pâté, making it palatable for even the pickiest of cats. It also helps them stay hydrated even as they experience more challenging symptoms associated with hyperthyroidism. When this thyroid cat food is the sole source of nutrition, it is proven to restore thyroid health within 3 weeks. This may be used in preparation for alternative treatments, or as a lifelong management.

Other than helping restore the health of your cat’s thyroid, the food also supports kidney health by keeping the phosphorus and sodium levels low. It also contains omega fatty acids. These encourage healthy skin and coat, to keep your cat looking healthy as they begin to feel better again.

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5. Nulo Freestyle Grain-Free Canned Cat & Kitten Food

This food from Nulo in their Freestyle line helps keep your cat feeling healthy, even with a thyroid issue. It comes in cases of 24 and 12, with respective sizes of 5.5 and 12.5 ounces. It is cheaper than Hill’s Prescription Diet but won’t actually treat your cat’s thyroid problems; medication (or other treatments) will still be needed.

The Nulo Freestyle Turkey and Chicken recipe is made with real turkey as the first ingredient and then chicken and turkey liver. Unfortunately, the food does contain tuna, which increases the iodine levels slightly, but not significantly.

The positive aspects of this thyroid cat food are that it is entirely grain-free, it has no corn, soy, or gluten, and it is low glycemic and pea-free. Also, it is high in healthy protein. As long as your cat isn’t suffering from kidney failure, they will benefit from the protein level of at least 11% in this food. The texture and broth base is also palatable to a wide variety of cats.

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6. Feline Natural Grain-Free Canned Cat Food

Feline Natural is the most expensive food on this list, but it is because of the priority that this New Zealand-based company puts on its ingredients and recipes. This canned food is full of feline-specific ingredients. That is why it comprises 98% fresh meat, organs, and ground bone.

The rest of the food is water for processing canned food, nutrients like taurine to promote heart health, and Vitamin D3 supplements. Although it is not usually an issue for cat food, this recipe does include New Zealand green mussel and dried kelp. While these are highly nutritious for cats, they do increase the iodine level present in the food. These ingredients collectively only make up 1% of the total recipe, though.

Every ingredient that the company includes in this grain and gluten-free high-protein diet is high-quality. The chicken and venison are only sourced from the best throughout New Zealand and are free-range and grass-fed. There are no artificial ingredients or preservatives. It is a nutritionally appropriate diet meant for all breeds.

Buyer’s Guide: Picking the Best Cat Food for Hyperthyroidism

Feeding a cat with hyperthyroidism can be tricky. There are different kinds of foods that they should get depending on their age, stage of the disease, and whether they have any other health issues. What might not be suitable for them at some points might end up being necessary at others.

If you are struggling to figure out how to feed your cat, here is a brief buyer’s guide to help point you in the right direction. Each cat and each case is different, so be sure to discuss your food and treatment options with your vet before stocking up on a new food.

Iodine Levels

Iodine levels are the most crucial consideration when you are dealing with a cat with hyperthyroidism. High levels of iodine can fuel the already overactive thyroid gland, but levels that are too low can actually trigger the body’s feedback system to increase thyroid activity even more, so we need our foods to contain some iodine.

Research has shown that, historically, the iodine concentration in standard cat food has varied significantly between brands and locations, with some foods containing excessive amounts. This was likely due to problematic wording in recommendations for iodine levels, where a ‘minimum of 0.3ppm’ was advised, without an upper limit being set. As mentioned above, high iodine levels can lead to hyperthyroidism, but too little iodine can also lead to its development by forcing the body to increase thyroid activity to compensate. Standard cat food should contain a minimum of 0.06ppm, and no more than 1.1ppm.

For cats with hyperthyroidism, you want to look for cat food that contains approximately 0.2ppm iodine. Unfortunately, most cat food ingredients and nutrition lists won’t show this, so you will have to do deep research or read reviews to find low-iodine healthy cat food.

These iodine requirements may alter with the form of treatment your cat is on, so always discuss this with your vet.

Protein Levels

Although not necessarily the nutrient of most importance when getting control of this condition, high protein levels are essential to help cats regain any muscle mass lost during the onset of the disease. While normal feline protein requirements are usually around 25-30%, we aim to give hyperthyroid cats food containing around 40% protein.

The only other thing to keep in mind when it comes to high-protein foods is their effect on your cat’s kidneys. Higher levels of protein can put extra stress on failing kidneys. Talk to your veterinarian if your cat is struggling with kidney health before deciding to switch to a high-protein food.

Canned or Dry?

There is debate about whether canned or dry food is better to feed a cat struggling with hyperthyroidism. It is ultimately up to both you and your cat. What does your cat prefer, and what are they more likely to eat? They need to eat plenty of food while they struggle with their thyroid, or they could lose dangerous amounts of weight.

There is the argument that canned cat food is better for them than dry food, which often contains more carbohydrates than necessary and more protein from plants, which can be more challenging for cats to digest. But dry food is typically cheaper than wet food and is easier to find, store, and distribute. Wet foods can also sometimes cause stomach issues in some cats. The best thing to do is ask your vet what kind of food your cat needs at this time.

Our Cat Foods for Hyperthyroidism Selection Process

Catster’s dedicated team of writers and editors collaborate with expert veterinarians, considering a wide range of factors when selecting the best cat foods for cats. These parameters include customer reviews, brand reputation, veterinary experience, and in some cases, hands-on testing. Of course, our cats have a say in the process, too! We strive to select and review the highest-quality products available, to help you choose the best possible product and make the most informed decision for your and your cat’s needs.

Why Trust Catster?

Catster has been a trusted online brand since 2001, so we know a thing or two about cat foods. We’re a team of cat-loving writers, editors, and veterinarians dedicated to helping you make the most informed decision for your feline. We deeply believe in providing the best information for cat owners to help their cats live their best life possible. We look at reviews from the most trusted sources available, and this, combined with our veterinary team’s experience and expertise, helps us gather the best options on the market. Our team is invested in the welfare and health of cats around the world, and believe that expert knowledge is one of the best ways to achieve this.

Conclusion

It can take a while for your cat to land on their feet again after getting diagnosed with hyperthyroidism. However, with medical management and dietary restrictions, your cat can find their way back to stability.

If you want the best overall cat food, Wellness Complete Health Grain-Free Canned Cat Food is low in iodine and supports your cat’s overall health. Also, many healthier cat foods are expensive, but the Solid Gold Indigo Moon Dry Cat Food gives you a health-conscious and budget-friendly option. Do you need something incredibly effective? Visit your vet about Hill’s Prescription Diet for Thyroid Care.

Finding the right food is hard enough, but it can be even more of a challenge when your cat struggles with health issues. We hope that our reviews have helped you find the right food so your cat can regain their health and balance.

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