I. The Demodex Mite

It is normal in most species to have microscopic organisms such as bacteria that inhabit the skin and other body surfaces. They perform important functions including protecting the body from other microscopic invaders that might cause disease. One of the normal inhabitants of dog skin is a microscopic cigar shaped mite called Demodex canis. This mite spends its entire life in the hair follicles of dogs. Under normal circumstances, it causes no diseases or problems. Puppies get demodex mites from their mother by direct contact sometime during their first few days of life, probably while they are nursing.

II. What is Demodectic Mange?

Demodectic mange is characterized by hair loss, with or without a skin infection, that happens secondary to overgrowth of the Demodex canis mite. Normally, the population of Demodex mites in a dog’s skin is kept under control by the dog’s immune system. When the dog’s immune system does not function correctly, the mite population gets larger and larger resulting in bald spots and other symptoms. There are two types of demodectic mange

• Localized Demodectic Mange


• Generalized Demodectic Mange

Both forms are more commonly seen in young dogs, particularly dogs younger than one year of age. The over-growth of the mite in both cases happens because the immune system is not working properly. This can be due to a genetic or inherited defect in the immune system, poor nutrition, or environmental stress. Demodectic mange is not contagious to other dogs or people.

If an adult dog develops demodecosis that is an indication that an underlying systemic disease is present. Some diseases that may be associated with adult onset demodecosis include hypothyroidism, hyperadrenocorticism (Cushing’s Disease), diabetes, and cancer. Drugs that suppress the immune system may also cause a dog to develop demodectic mange.

III. Symptoms – What to Look for at Home

• Localized Demodectic Mange – Localized demodectic mange is characterized by one hairless spot on the body. Occasionally there is more than one, but the spots are confined to one area of the body. The most common locations for the spots are on the head and face. There are no other symptoms associated with the hairless spots. The spots usually do not itch.


• Generalized Demodectic Mange – Generalized demodectic mange is characterized by widespread hair loss. There are also symptoms of a skin infection present including redness, bumps, scabs, crusts, and pustules or pimples. The dog may be itchy and the skin may feel thickened, greasy, and rough. Itching is not due to the mites but is because of the skin infection.

IV. The Veterinary Visit – How to Tell if a Dog has Demodex

For both types of demodectic mange, diagnosis is made with a skin scraping. The veterinarian will use a dull scalpel blade to scrape off the top layers of the skin in the affected areas. The material that is scraped off will be examined under a microscope. Even though the mites are a normal part of all dog skin, it is very rare to find a mite from a skin scraping in a normal dog. If any mites or mite eggs are seen in the skin scraping, then demodectic mange is present. If a dog also has pustules, scabs, crusts and other symptoms, then a skin infection (pyoderma) is present along with demodectic mange.

Adult and immature demodex mites in a skin scraping

V. Treating Demodectic Mange

• Localized Demodectic Mange – Localized demodectic mange does not need to be treated. There is usually not a skin infection associated with it, and the hairless spots will go away on their own in 4-6 weeks. It is important to follow-up with your veterinarian to make sure the problem is resolving. Rarely does a case of localized demodecitc mange become generalized.


• Generalized Demodectic Mange – Generalized demodectic mange is treated by treating the skin infection and killing the demodex mites. Treating the skin infection is accomplished using oral antibiotics and shampoos. Antibiotics are given for a minimum of three weeks and usually longer. They need to be given for two weeks after there is no evidence of a skin infection. Bathing weekly with a benzoyl peroxide shampoo is an important part of treating generalized demodecosis, also. Benzoyl peroxide shampoo helps treat the skin infection by killing bacteria and it helps to flush the demodex mites out of the hair follicles. Killing the demodex mites can be done in several ways. The only FDA approved treatment for demodecosis is a compound called amitraz. It is available as a dip that is applied weekly or every other week. The dip can have some side effects, and some demodex mites are resistant to it. Other oral and injectable treatments are available such as ivermectin and moxidectin. Your veterinarian will recommend the treatment that is most appropriate for your dog.

For dogs that are very itchy and have generalized demodectic mange, antihistamines can be used to help alleviate their discomfort. Corticosteroids should not be used to control itching because they can suppress the immune system. The effectiveness of treatment is monitored using skin scrapings every 2 weeks. Amitraz dips or other therapies are administered until two consecutive negative skin scrapings are attained. Fifty to seventy percent of dogs treated with amitraz dips will be free of infection after eight treatments.

Dogs that have had generalized demodectic mange should not be used for breeding since the tendency to develop this problem is thought to be inherited.

The information in this article is not intended to provide a diagnosis or treatment for your pet and is not a substitute for examination and appropriate treatment by your veterinarian