Demodectic Mange in shar-pei dogs, Demodex

Sharpei

Demodectic Mange
(Demodex)

There are two common types of mange that affect pets: Demodectic Mange and Sarcoptic Mange are both types of mange are caused by microscopic mites that burrow under the skin of your pet...

Demodectic Mange is more serious due to its ability to spread quickly and because it is much harder to treat. This mite burrows into the skin of your pet, attacking the hair follicle which can result in major hair loss. Your pet's immune system tries to fight off the invading mite, which results in major inflammation with "pustules", bloody lesions and scabs. While quite nasty for your pet, this type of mange can't be passed on to the pet owner. As you can see these mites, Demodex canis & cati are tiny (less than a hair width) and can only be seen under a microscope.

Beware of the well meaning, but unknowledgeable novice who suggests everything from yoghourt to dancing in the early morning dew to cure Demodectic mange.....Early Veterinary treatment for Demodectic mange is critical as it can require a long and difficult treatment program...

Demodex Mite...Skin Section

Sarcoptic Mange is the less serious, but more highly transmittable type of mange. Sarcoptic mange, otherwise known as "Scabies," has zoo tonic potential, meaning that in addition to other sources, you can get it from your pet! (in the unlikely event that you get it, a solution from a pharmacy, applied a couple of times after a bath/shower gets rid of it) The mite's motion while burrowing into and moving on top of the skin causes extreme itching followed by flaky or scabby dandruff and loss of hair. Sarcoptic mange is much easier to cure than Demodectic mange because the Sarcoptic mite doesn't burrow deep into the skin of your pet! ...

Demodecosis is an inflammatory parasitic disease of dogs,..., characterized by the presence of a high number of mites in the hair follicles, which often leads to inflammation and infection. The mite, Demodex, is part of the normal make up of the skin and is normally present in small number. The mite resides in hair follicles and glands surrounding the follicles (sebaceous glands). Due to changes in either the genetic or immune system of the animal, the mite begins to proliferate and causes the clinical signs of the disease.

CANINE DEMODEX

Most cases in dogs occur at a young age. There are no sex or breed predilections. Transmission occurs by direct contact from the bitch to nursing neonates during the first two or three days of neonatal life. Puppies delivered by caesarean section and raised away from the infected carriers mother do not develop the disease. Adult onset Demodex may be due to a decreased resistance to the mite as a result of a compromise of the immune system. It is speculated that some internal disease may cause immuno-suppression. The feeling is that there is a subnormal percentage of interlukin-2 receptors on certain blood cells called lymphocytes. In adult onset mange, owners should be aware of the possibility of a major internal illness or a malignant cancer.

CLINICAL SIGNS

Localized Demodex

Signs are usually mild and one to several patches of hair loss and inflammation are noted. The most common sites are the face and fore legs. Most cases heal with less then 10% progressing to generalized Demodecosis.

Generalized Demodecosis

There are many lesions. These are reddened patches and may be itchy.
Secondary bacterial infections occur as the numbers of mites proliferate.

Differential diagnosis includes primary bacterial infection, fungal infections, contact dermatitis,
and immune mediated skin diseases.

TREATMENT

Localized Demodex

If mild, the disease usually heals spontaneously. Topical treatment a diluted amitraz (3ml to 30 ml of mineral oil), or rotenone may be used. After four weeks of treatment the numbers of mites should be greatly reduced. If more mites are observed then the condition should be treated as a generalized form.

Generalized Demodex

Adult onset forms may become a management problem due to an underlying cause. Many of these animals may be medically controlled rather than cured. The prognosis is dependent upon the genetic, immunologic, and underlying disease.

Juvenile forms are treated by the following medications.
(Great care should be taken when bathing as described below and we
recommend that it is only carried out by an experienced person or vet!)

Amitraz (Mitaban-Upjohn) is the first line in the treatment. Dosage and regimen: use weekly to every other week. Apply a protective ophthalmic ointment to the eye. Wash the entire dog with an antibacterial shampoo, and gently towel dry the pet. Then apply the amitraz. Use either weekly or every other week.
Mix ½ vial per gallon of water. Apply to the entire body. Wear protective gloves when applying.
This medication may cause transitory sedation for 12-24 hours. We recommend keeping your pet confined during the day of treatment. Do not towel dry, but let your pet air-dry...

An antibiotic should also be used to control secondary skin infections.

Continue treatment until two successive bi-weekly skin scrapings are negative for the mite.

Animals which have recovered should be excluded from breeding!

Other treatments include Ivermectin and Interceptor.(not licenced to use on dogs in the UK)
In the UK a new product - Selamectin - has just been licensed for this and other uses.

It is contra-indicated to use corticosteroids in patients with Demodecosis. Steroids are immunosuppressive.

Demodex

Therapeutic Plan

Topical keratolytic agents

Antibacterials

Topical drugs to kill the mite

Demodex is part of the normal skin fauna and is usually present in small numbers in healthy animals

The entire life cycle is spent on the host in the hair follicles or sebaceous glands

Adult Demodex Mite

Dietary Plan

A diet suitable for tissue repair

A diet based on individual patient evaluation, including body condition and other organ system involvement in the disease

Diagnostic Plan
History
Physical Examination
Skin Scrape
Skin Biopsy
Skin Culture