Hyperthyroid Cat Symptoms

Some of the most common cat symptoms can be attributed to an overactive thyroid gland in cats. The condition is called hyperthyroidism and results when the thyroid gland produces too much of one or both hormones this gland is responsible for. It’s important to understand the physical affects of the disease as well as to know what symptoms to look for. Several treatments can help once the diagnosis is made.

The Function of Glands in the Endocrine System

The endocrine system includes the thyroid gland and the pituitary gland which work in tandem with each other. The thyroid gland is comprised of two small lobes. The lobes sit one on each side of the cat’s neck next to the windpipe. The thyroid produces two hormones called T3 and T4. The pituitary gland works with the thyroid gland by producing a hormone that stimulates the latter. This thyroid stimulating hormone is called TSH. All of these hormones work together to regulate metabolism. They affect many systems and functions including heart rate, eating and elimination.

Hyperthyroidism and Changes in the Body

In cats with hyperthyroidism, the thyroid gland produces too much of one or both of the thyroid hormones. The gland is usually enlarged in addition to being overactive. Sometimes the problem is due to an excess of abnormal cells in the thyroid gland. Sometimes, the abnormal cells form small nodules on one or both lobes of the gland.


Each cat develops different symptoms when the thyroid gland is malfunctioning. Most cats develop a rapid heart rate and lose weight even though they are eating more. In around 50% of hyperthyroid cases, increased water consumption and vomiting develop. The speedier heart rate can lead to a variety of behavior changes including nervousness and increased motor activity. Approximately 33% of cats with hyperthyroidism stop caring for their fur. They thus may have matted or foul smelling fur and skin. In a few of afflicted cats, diarrhea, weakness, and tremors also develop.

Diagnosis Confirmation

A vet can confirm a diagnosis of hyperthyroidism in several ways. Through a medical exam, the vet can feel the enlarged gland with a bare hand. Blood and urine tests can determine the exact level of T3 and T4. It is more common for T4 to show up in higher levels than T3.

Treatment For Hyperthyroidism

There are several options to help a cat with this disease. There are various medicines that can help control the over-production of the hormones. Acupuncture and other natural remedies can help with the symptoms, particularly over activity and rapid heart rate. The cat may also develop other diseases as a result of the endocrine imbalance which can be treated accordingly.