Dogs with Demodectic Mange Have Defective Immune Systems

It is common for dogs to have the Demodex canis mite living on their skin. The tiny cigar-shaped parasite burrows into the skin yet most healthy dogs show no signs of infection. However, in dogs with defective immune systems, the mites can multiply and cause a disease called demodectic mange or demodicosis.

Research suggests that certain breeds of dogs have a genetic predisposition to demodicosis. Transmission of the mite is from the mother to her puppies during nursing in the first 72 hours after birth. Demodicosis is not contagious to other dogs or to people.

There are many expressions of demodicosis and the prognosis for a permanent cure really depends on the type of demodicosis. For example, if your dog has localized demodicosis, it is a mild, self-limiting disease. This kind of demodicosis usually affects dogs 6 ot 9 months of age and clinical signs consist of nothing more than a patch or two of hairlessness with mild itchiness. Ninety per cent of these cases resolve on their own, regardless of whether they are treated or not. The prognosis for full recovery is excellent and recurrence is rare.

On the other hand, there is a generalized second form that results in large amounts of hair loss from all over the body. Dogs that have this form respond moderately well to treatment.

However, if there is a concurrent skin infection, the prognosis is more guarded. With this third type of mange, there is usually pain and itchiness associated with it and patients may exhibit depression, inactivity, appetite loss and irritability.

A fourth type of demodicosis (called pododermatitis) affects the paws only.

Treatment
The recommended treatment for generalized demodicosis is a topical treatment called Amitraz (Mitoban™). If used once weekly, it has been shown to be almost 80 per cent effective. There is also an antiparasitic medication called Ivermectin (Ivomec™)that has been shown to be safe and highly effective against the demodex mite. In order to use it, you must sign a release form authorizing its use on your pet. Since demodicosis is not so much the result of a mite problem as it is an immune-system defect, dogs that have been successfully treated for demodicosis will always be at risk of a relapse. However, there should be no Recurrence unless the patient becomes reinfected with demodex mites.

To note
If your pet scratches excessively or experiences patchy or generalized hair loss, you should consult your veterinarian so that he or she can rule out demodicosis as well as other skin disorders.