Does my cat have endocrine alopecia? Causes of hair loss in cats

Endocrine disorders in cats cause hormone imbalances that affect different parts of the body. Even though symptoms can include changes to the skin and coat, hair loss is not commonly associated with endocrine diseases in cats. If you are a cat owner, read on to learn more about:

• What causes cat alopecia?
• Can a hormonal disorder cause hair loss in cats?
• What is endocrine alopecia?
• How is alopecia in cats diagnosed and treated?

Hair loss in cats is most commonly caused by flea allergies, a food allergy, and bacterial or fungal infections. Veterinarians may use blood tests, skin biopsies, or a trial of flea medication to diagnose the underlying cause of your cat’s loss of hair.

Alopecia is the abnormal loss or thinning of hair in cats. This type of hair loss results in bald patches or areas where the skin is abnormally visible through the fur. It is different from normal shedding. Abnormal loss of hair in cats can occur due to a variety of different medical conditions. These conditions are divided into two categories: inflammatory and non-inflammatory causes. Inflammatory causes of feline alopecia include:

• Environmental or food allergies
• Bacterial or fungal infections
• External parasites

Inflammatory causes of feline hair loss are much more common than non-inflammatory alopecia, and itchiness is usually the main symptom.

Endocrine diseases are non-inflammatory and are an uncommon cause of hair loss in cats. Other causes of non-inflammatory hair loss in cats include:

• Psychological or psychogenic alopecia (such as overgrooming due to anxiety)
• Hair loss at an injection site
• Immune-mediated hair loss
• Hereditary skin conditions
• Hair loss on tumors or skin growths

There are a variety of endocrine disorders that cats can develop. Due to their resulting hormonal imbalances, endocrine diseases often have widespread effects on the body with a variety of symptoms, including changes to the skin and hair.

Hyperthyroidism

Hyperthyroidism, or the overactivity of the thyroid gland, is a common condition in senior cats. Due to too much thyroid hormone in the body, symptoms of hyperthyroidism include:

• Weight loss despite a good appetite
• Vomiting and diarrhea
• Urinating or defecating outside of the litter box
• Alopecia

Diagnosing hyperthyroidism involves evaluating the presenting symptoms and testing thyroid hormone levels in the blood. Alopecia is not a common symptom of hyperthyroidism, so cats are more likely to display other symptoms.

Cushing’s syndrome (hyperadrenocorticism)

Cushing’s syndrome, or Cushing’s disease, is rare in cats. Symptoms of Cushing’s disease in cats include:

• Excessive thirst and urination
• Thin skin
• Hyperpigmentation (discoloration of the skin)
• Unkempt hair or coat
• Alopecia

Other symptoms are far more common than alopecia in cats with Cushing’s syndrome. Cushing’s disease can be difficult to diagnose due to its rarity and need for special diagnostic blood tests.

Hypothyroidism

Hypothyroidism, or the lack of thyroid hormone in the body, is a rare condition in cats. Hypothyroidism usually occurs as a complication of treatment for hyperthyroidism. The condition can also be inherited or occur in kittens as a result of an iodine deficiency in the mother during pregnancy. Symptoms of hypothyroidism usually involve changes to the skin and coat, but the condition is not a common cause of alopecia in cats.

Hormonal changes during pregnancy

Altered hormone levels during pregnancy can produce symptoms similar to those that occur with endocrine diseases. Abnormal hair loss in cats can sometimes occur during pregnancy, but it usually resolves after the kittens are born.

“Feline endocrine alopecia” was used to describe symmetrical alopecia in cats, or hair loss on both sides of the body, that was assumed to be the result of some type of endocrine disease. However, it was later determined that these patterns of abnormal hair loss were primarily due to flea allergy dermatitis (FAD), the irritation of the skin due to an allergy to flea saliva. “A cat’s allergic response to flea saliva doesn’t involve the endocrine system at all,” explains Dr. Jo Myers, a veterinarian on the Vetster platform. “As a result, the name for the syndrome was changed to ‘feline acquired symmetric alopecia.’ This way all types of underlying causes are included.”

If there are no symptoms other than scratching and hair loss, a common first step is to treat your cat for fleas. Since flea allergy dermatitis is so common, this is done even if there is no other evidence of fleas. Other diagnostic tests that may be recommended include microscopic evaluation of skin scrapings and hair samples, and testing for fungal infections. In some cases, a skin biopsy may also be recommended. If your cat has other symptoms, such as changes in appetite, thirst, and litter box habits, your vet may suggest blood and urine diagnostic tests.

Treating alopecia caused by an endocrine disorder involves treating the underlying endocrine condition. Each type of endocrine disorder has its own specific treatment plan, so an accurate diagnosis is necessary before treatment can be given. Treatment may include:

• Adjustment to hyperthyroidism medication
• Oral medications
• Injectable medications
• Surgery
• Radioactive iodine therapy

Talk to a veterinarian any time you notice changes to your cat’s skin or coat. Many underlying health issues can contribute to cat hair loss or thinning. However, endocrine disorders are most likely not the culprit of your cat’s hair loss.

If you are concerned about your cat’s skin or coat health, you can talk to an online veterinary professional in an online virtual care appointment for advice.

Should I be concerned if my cat is losing hair?

The most common cause of alopecia in cats is flea allergy dermatitis, an allergic reaction to flea bites. Fungal and bacterial infections and other external parasites can also contribute to hair loss. Health conditions such as endocrine disorders are far more likely to show other symptoms than hair loss.

What does alopecia caused by an endocrine disorder look like in cats?

Alopecia in cats due to an endocrine disorder is typically non-itchy and has symmetrical hair loss on both sides of the body. Alopecia is a rare symptom of endocrine disorders in cats, and other symptoms are more likely to be seen. If a cat’s only presenting symptom is hair loss, it is likely due to a different health issue.