Hyperthyroidism occurs when the thyroid gland produces too many thyroid hormones. In cats, it typically results from a benign tumor of the thyroid gland. Symptoms can include weight loss, increased appetite, vomiting, and diarrhea.
People may also refer to hyperthyroidism in cats as feline hyperthyroidism.
If you think your cat may be experiencing this condition, it is important to speak with a veterinary professional as untreated feline hyperthyroidism can cause a range of complications and may be fatal.
In this article, we outline the causes, symptoms, diagnosis, and treatment of hyperthyroidism in cats.
Similar to humans, hyperthyroidism in cats results from the thyroid gland producing too many thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3). The thyroid gland is shaped like a butterfly and is located in the neck.
If the thyroid gland produces too many hormones, it leads to a high metabolic rate, which negatively affects nearly all of the cat’s organs.
The Food and Drug Administration (FDA) notes that, in
Rarely, a form of cancer called thyroid carcinoma may cause feline hyperthyroidism.
The
Other symptoms to look out for include:
- diarrhea
- vomiting
- drinking and urinating more than usual
- hyperactivity
- an unkempt coat
- increased vocalization
- increased heart rate
It is important to note that symptoms come on gradually, so they can be difficult to notice at first.
Complications
Hyperthyroidism in cats can lead to heart disease and high blood pressure.
Heart disease develops because the cat’s heart has to pump faster and more forcefully to meet their body’s increased metabolic rate. This results in thickening of the heart muscles, which, in turn, causes the heart to enlarge and eventually fail.
High blood pressure results from the cat’s heart pumping at an increased pressure. Sometimes, high blood pressure can lead to retinal detachment, causing sudden blindness.
If left untreated, feline hyperthyroidism is fatal.
To start the diagnostic process, a veterinary practitioner will ask you about your cat’s symptoms and examine your cat’s neck to see if they have an enlarged thyroid gland. They may then conduct blood tests and urinalysis.
If the veterinarian suspects any complications, they may also conduct imaging tests, like X-rays, CT scans, or ultrasound scans, to view the thyroid gland and a biopsy to assess any tumors that are present.
The FDA highlights that feline hyperthyroidism is the
Two oral medications (Felimazole and Felanorm) that contain an active ingredient called methimazole are
Your vet will explain how to give your cat the medication at home, but it’s important to remember to wear gloves when handling it or giving it to your cat. You should also wash your hands after giving your cat the medication.
A vet will regularly monitor your cat with blood and urine tests to help prevent severe side effects of methimazole, which include liver disease and immune-mediated anemia. If they suspect your cat is at risk of severe side effects, they may recommend stopping methimazole treatment.
If you notice your cat is experiencing any of the following side effects while taking methimazole, you should contact a veterinarian:
- decreased appetite
- vomiting
- diarrhea or loose stool
- weight loss
- decreased activity level
- skin reactions, such as a rash or itchy skin (especially on the face, head, and neck), and hair loss
- behavioral changes, such as vocalizing or hiding
Another possible option for managing feline hyperthyroidism is feeding your cat an iodine-restricted diet. Your cat’s body uses iodine in food to synthesize the thyroid hormone. By putting them exclusively on a diet that is restricted in iodine, it prevents their body from making too much thyroid hormone, inhibiting the disease.
However, this option is not always suitable because many cats can be picky about their food.
In some instances, a veterinary professional may recommend surgery to remove thyroid tumors. If the tumor cannot be removed surgically or if the vet cannot remove all of it, they may recommend radiation therapy, radioactive iodine therapy, or chemotherapy.
Hyperthyroidism in cats results from the thyroid gland producing too many thyroid hormones. It typically occurs due to the presence of a benign thyroid tumor.
Symptoms appear gradually, but the
It is important to speak with a veterinarian if you notice any signs of feline hyperthyroidism, as it can lead to heart disease, high blood pressure, and even death if left untreated. A veterinary professional can accurately diagnose the condition and recommend appropriate treatment.