Why Is My Cat Losing Weight?

Is your cat losing weight? Unintended weight loss is usually a sign of an underlying health problem. Many owners think that weight loss is normal for senior cats, but this is not the case. It's important to take action if you notice unexplained weight loss in your cat. Find out more about the underlying causes for weight loss, how a diagnosis is made, and how this condition may be treated.

Causes of Weight Loss in Cats

In many cases, cats lose weight when they are not eating enough. However, some diseases cause weight loss despite adequate food intake. Depending on the cause, weight loss may or may not accompany other signs of illness. Many health problems can cause weight loss in cats, some more serious than others.

Hyperthyroidism

Hyperthyroidism is a relatively common illness that most often affects older cats. Cats with hyperthyroidism produce too much thyroid hormone due to an enlargement of the thyroid gland. This enlargement is usually caused by a benign tumor that grows on the thyroid.

Common signs of hyperthyroidism include weight loss, increased appetite, and increased thirst and urination. Some cats also experience vomiting, diarrhea, and hyperactivity.1 Some will vocalize and act restless. Cats with hyperthyroidism may have coats that appear unkempt and greasy. Hyperthyroidism is treated with radioactive iodine or oral medications.

Chronic Kidney Disease

Chronic kidney disease is one of the most common illnesses seen in senior cats. The kidneys produce important hormones, filter out wastes from the blood, help regulate blood pressure, and facilitate the production of new red blood cells. When a cat's kidneys stop functioning properly, it leads to a variety of other issues.

Increased thirst and urination are among the first signs noticed when a cat has kidney issues, followed by loss of appetite, weight loss, and lethargy.2