Demodex mites are microscopic normal inhabitants of dog skin. In a healthy animal, the mites are few in number and do not cause skin problems. In some cases, the mites are able to proliferate excessively, leading to a condition called demodicosis or "mange". Learn about the types of demodectic mange and various treatment options for this skin parasite.
Who Gets Demodicosis?
Demodicosis can be localized , affecting only small patches of skin, or generalized, involving large areas of the dog's face, feet and body. Generalized demodecosis also occurs when lesions begin spreading around the body or persist for at least six months.
Young dogs: Demodecosis is typically seen in puppies and young dogs less than two years old. This is thought to be due to an underlying genetic and/or immunologic disorder that contributes to the initial proliferation of mites. Risk factors for juvenile demodecosis are breed (American Staffordshire terriers, Staffordshire bull terriers, and Chinese shar peis), intestinal parasitism (coccidiosis, hookworms), and hair length.
Many young dog cases "outgrow" demodicosis without treatment within 1-2 months. This is because their immune system matures and keeps the Demodex mite population under control. Some puppies need medical treatment, including dogs where the disease becomes generalized.
Adult dogs: If an adult dog breaks out with demodicosis, your vet will want to look for reasons why their immune system may be weakened. Possible reasons include cancer, hormonal imbalances (thyroid, Cushing's disease), prolonged corticosteroid use, or other immune system changes that occur secondary to aging.
There is a hereditary component to demodicosis and affected dogs should not be bred.
What Does Demodicosis Look Like?
Hair loss is the most common sign. In more severe or generalized cases, the skin presents as bald, infected, odorous and scaly. Some dogs are itchy, while others are not. Secondary skin infections are common.
How Is Demodicosis Diagnosed?
The microscopic Demodex mite lives deep in hair follicles. Diagnosis is suggested by visualizing the skin lesions and confirmed with a skin scrape and observing Demodex mites within the sample.
The vet will gently squeeze an area of the skin and rub a scalpel blade over the ridge of skin to collect mites to look at under the microscope. This doesn't hurt the animal, even though this causes a small amount of bleeding.
Is Demodicosis Contagious?
Canine demodectic mange not contagious to humans. The mites are species-specific, meaning they stay on dogs. This mite is passed mother-to-pup and possibly dog-to-dog, but for animals with healthy immune systems, this doesn't cause disease.
How Is Demodicosis Treated?
Treatment options vary widely based on the severity of the case and the veterinarian's preferred protocols. In some cases, a medicated shampoo and "watch and wait" approach is the only treatment and for others multiple treatment options are required to bring the mite population and secondary skin infection under control.
Mild/localized cases: Shave affected area. Wash skin with a benzoyl peroxide shampoo to help "flush" out the hair follicles and keep secondary bacterial infections under control.
Generalized cases: Like the localized cases, shave affected areas and wash skin with a benzoyl peroxide shampoo to help "flush" out the hair follicles and keep secondary bacterial infections under control.
Additional veterinary treatment options for generalized demodicosis include, but are not limited to:
- Ivermectin - considered the best treatment option by many vets. This drug is used off-label for Demodex mites and not to be used in Collies or Collie-crosses.
- Amitraz (Mitaban) dips - approved by the FDA, but not to be used on small dogs or dogs younger than 4 months. Labor-intensive to apply, requiring multiple treatments spaced 2 weeks apart. Side effects can be mild and transient, but sometimes severe.
- Milbemycin oxime (Interceptor) - this heartworm preventative, when used on a daily basis, may be effective against generalized demodicosis. Cost may be a prohibiting factor, however.
- Promeris/Advantage Multi - have been used with mixed results for demodicosis. Please consult with your veterinarian.
Dogs affected with demodicosis should be checked for other parasites (skin, ears, intestinal) and treated accordingly. They should ingest a healthy and balanced diet and have any other health problems addressed for maximum effectiveness of the demodicosis treatment. Dogs being treated for demodicosis should not be given corticosteroids. Dogs with concurrent bacterial skin infections often need oral or injectable antibiotics.
Demodicosis is often a prolonged treatment protocol of weeks or months. Two negative skin scrapings, one month apart confirm successful treatment.