Mange is a term that is often used incorrectly - "mangy-looking" is a description often applied to any dog that has a skin problem involving some degree of hair loss. Strictly speaking however, the word mange only refers to skin disease caused by mites, small insect-like parasites which live on the surface of the skin, or burrow into it.
There are several types of mites that affect our pets. Demodex probably causes the most severe problems. It is a mite that lives deep within the hair follicles, mainly of dogs. Many dogs carry the mite with no apparent disease, but if the dog’s immune system is not working at 100%, the mites can cause problems such as hair loss, scaling and inflammation, sometimes with secondary infection by bacteria.
The hair loss usually starts on the face and forelimbs, and typically, there is no itchiness. The immune system can become suppressed for a number of reasons - the dog may have inherited a weakness for instance, or it may be fighting of another infection. But stress is also a factor in immune suppression, and we see cases of demodectic mange most commonly in pups that have been raised in less than ideal conditions. Poor nutrition, lack of worming and general lack of hygiene can stress the puppies to the point where they have no resistance against the mites, resulting in extensive hair loss and skin disease.
Because the mites live deep within the hair follicles, they are not visible and a skin scraping is necessary to confirm the diagnosis. They can also be difficult to kill. Treatment will obviously depend on the severity of the infection, but usually involves clipping of the hair, cleansing of the skin plus repeated application of a solution that is poisonous to the mites - severe cases may take several months to clear up completely. If infection with bacteria has occurred, antibiotics will be needed as well.
Demodectic are not usually passed from one dog to another except from a bitch to her pups in the first few weeks of life.
Another mite that causes problems mainly in dogs is Sarcoptes. Unlike demodectic mange, sarcoptic mites cause intense itching as they burrow through the upper layers of the skin. Crusty lesions are usually noticed at the edges of the ears, later spreading over the face and head. Sarcoptics mites can be passed to humans, causing the condition known as scabies, and are easily transmitted from one animal to another, especially in crowded conditions, so infected dogs should be kept isolated.
The Notoedres mite causes a similar type of problem in cats - again very irritating, with dry crusty lesion on the ears, face and neck.
Once again, these mites need to be identified from a skin scraping to confirm the diagnosis. Treatment involves softening and removal of the crusts before applying skin preparations. Injections of substances that pass to the skin through the bloodstream are also effective.
A mite that lives mainly in the hair and fur is cheyletiella, found in cats, dogs and rabbits, which causes excessive scurf or dandruff. It is easily passed on to other animals and humans, but is relatively mild and easy to clear up, because the mites don’t penetrate the skin.
One of the mites we see most commonly, and one which is easy to see through an auroscope, is the so-called "ear mite" - Otodectes. This lives in the ear canal of cats and dogs, causing intense irritation - animals scratch at their ears and shake their heads, sometimes causing hair loss, and occasionally causing the rupture of a blood vessel in the ear flap so that a large blood clot forms. Early in the infection, there is often a dark brown discharge from the ear - later, if bacterial infection occurs, the discharge may become thick and yellow.
The ear mite is readily passed from one animal to another, so all animals within a household should be checked if infection is found in one. Treatment involves cleansing of the ear canal, plus the use of drops and systemic injections.
- Virginia Williams & Bert Westera