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Hyperthyroidism in Cats Treatment Plan: Steps and What to Expect

Cat at veterinarian
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Hyperthyroidism is a common condition in middle-aged and older cats that is characterized by an enlarged and overactive thyroid gland. With this condition, high levels of thyroid hormones are released, which can cause various effects on a cat’s body, including an increased heart rate, excessive appetite, and weight loss.  

When hyperthyroidism is suspected, appropriate testing is done to confirm the diagnosis so that a treatment plan can be made. Treating hyperthyroidism in cats may seem overwhelming, but with the help of a veterinarian, pet parents can better understand what to expect and feel more prepared after this diagnosis. 

Hyperthyroidism in Cats Treatment Plan: What to Expect

After a cat has been diagnosed with hyperthyroidism, treatment begins immediately to help them feel better and minimize secondary complications. Treatment may consist of medication, a diet change, radioactive iodine therapy, or surgery. 

The specific type of treatment will depend on the age of the cat and any underlying health issues, the severity of the condition, and the preference of the pet parent. Some cats may not respond well to one form of treatment but do very well with another option. Pet parents can work with their veterinarians to determine the best option for their unique cat. 

Hyperthyroidism in Cats Treatment Cost

Cats who have hyperthyroidism need to see the veterinarian frequently after first receiving the diagnosis. These initial visits are generally done to ensure the cat is tolerating the treatment plan well and that their condition is well-managed. Frequency of visits will depend on what treatment option is chosen. For example, if medication is used to treat hyperthyroidism, a cat may initially need to be seen every month to assess their response and determine whether any dosing adjustments should be made. The veterinarian will guide the pet parent through the initial diagnosis and start of treatment to determine a visit frequency that is appropriate for each individual cat. 

Veterinary visits will become less frequent after the cat’s condition is managed well. However, pet parents can still expect to visit the veterinarian every six to 12 months for the remainder of the cat’s life. Initially, pet parents can expect to spend around $100 a month for veterinary visits, a special diet, blood work, and medications. Of course, radioactive iodine therapy and surgery would have greater costs overall. 

Cat Hyperthyroidism Medication and Treatment Options

Veterinarian gives a pill to a cat

Methimazole is the most common medication prescribed to cats with hyperthyroidism. It is an anti-thyroid medication that decreases the number of hormones that the thyroid gland produces and releases into the bloodstream. This drug is affordable for pet parents but it must be used for the life of the cat in order to manage their condition. It is usually given twice daily orally, but since some pet parents may find difficulty in giving medication to their cats. It is also available in a gel and cream that can be applied to the cat’s skin. Side effects may include lethargy, vomiting, and decreased appetite [1]. 

Radioactive iodine therapy is used for some cats with hyperthyroidism. The radioactive iodine is administered into the cat’s vein and then travels through the bloodstream to the thyroid gland, where it works by destroying this tissue through radiation exposure. It is typically effective within the first two weeks following treatment, and it has been shown to cure this condition within three months in approximately 95 percent of hyperthyroid cats. However, a major disadvantage is that cats are considered radioactive for a short period of time following treatment and must remain hospitalized until their radioactivity decreases [1]. 

While surgery is an option for treating cat hyperthyroidism, it is not commonly performed due to the other more favorable options available. It also requires general anesthesia, which may be unsuitable for some cats [1]. 

Hyperthyroidism in Cats Natural Treatment

Research is very limited on the use of homeopathic medicines for cat hyperthyroidism treatment. Homeopathic remedies, acupuncture, and herbal medicines are a few treatment options available. While a couple studies have demonstrated a favorable outcome using these alternative therapies, more research is needed to compare this holistic approach to conventional medicine [2, 3].  

Hyperthyroidism Cat Diet: What to Feed

Cat approaches their food bowl

A special diet can be prescribed by a veterinarian for hyperthyroid cats. Because iodine plays a role in the production of thyroid hormones, these diets are specially formulated with less iodine content. A special diet alone may not be enough to fully manage hyperthyroidism, but it can be helpful in combination with medication therapy or in pet parents who prefer this option. Cats on a low-iodine diet must not receive any other food or treats apart from this special diet in order for it to be most effective. 

Homemade food is not recommended for cats with hyperthyroidism because it is difficult to restrict the amount of iodine content if it is not commercially formulated. Ingredients may be inadvertently added, which could actually worsen the cat’s condition as well. 

Hyperthyroidism in Cats Treatment: Tips and Advice 

Once a cat with hyperthyroidism is on a treatment plan, pet parents should see an improvement in symptoms relatively soon. These may include a return to a normal appetite, less hyperactivity, and an improved hair coat. Additional signs of improvement include reduced thirst and urination and some weight gain. If the cat initially experienced vomiting or diarrhea as a result of increased thyroid hormone levels, these symptoms should disappear as these levels decrease as well. 

During treatment, pet parents should watch for extreme lethargy, low appetite, and vomiting, as this would indicate that the cat needs to be evaluated by a veterinarian. 

While there are many negative consequences to cat hyperthyroidism, such as high blood pressure and heart disease, starting treatment early can reduce the risk of these adverse effects. Cats that have been diagnosed with hyperthyroidism can live long, happy lives with the proper treatment plan and the guidance of a veterinarian. 


  1. Chapman S. F. (2011). Homeopathic and integrative treatment for feline hyperthyroidism–four cases (2006-2010). Homeopathy : the journal of the Faculty of Homeopathy100(4), 270–274. https://doi.org/10.1016/j.homp.2011.05.004
  2. Dobias, P. (2006). Homeopathic treatment of feline hyperthyroidism . Veterinary Information Network, Inc. Retrieved December 12, 2022, from https://www.vin.com/apputil/content/defaultadv1.aspx?pId=11223&meta=generic&catId=31450&id=3858944&ind=45&objTypeID=17
  3. Hyperthyroidism in cats. Cornell University College of Veterinary Medicine. (2017, January). Retrieved December 10, 2022, from https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/hyperthyroidism-cats