Demodex Mange

Overview:

Demodex canis is a mite that is a normal parasite of dog’s skin. It can be found on virtually every dog. It coexists peacefully unless the pet becomes immunosuppressed for any reason. The mite can then multiply rapidly and cause skin disease. This happens in both young and old dogs.

Causes:

Many conditions can cause immune suppression. Puppies are in a state of lowered immunity as they grow, which makes them prone to this disease. Anesthesia procedures (during a spay or neuter) can allow Demodex to multiply. If an older dog is found to have Demodex mange, other conditions such as hypothyroidism or Cushing’s Disease are suspected.

Symptoms:

Demodex can either be in only one spot or all over the dog. Hair loss is patchy, and is generally around the eyes, face, trunk, or legs. The skin can be scaly with very little redness or inflammation. Demodex is not very itchy, but most animals will scratch periodically. If a skin infection has developed, the skin will become reddened, malodorous, and itchy.

Treatment:

For younger animals (< 1 year of age), treatment depends on whether there is one lesion or many lesions. If only one lesion is present and the patient is otherwise healthy, a topical ointment may be prescribed. However, many solitary lesions resolve on their own and treatment may not be necessary. As the patient becomes older, the lesions will disappear. If the patient has many lesions, more aggressive treatment is needed. Every other week (twice monthly) amitraz dips have been the main treatment for decades. There is a minimum of 3 dips needed-some patients need 5 or more. Due to side effects of amitraz dips (lethargy, vomiting, seizures, ataxia, increased itching), some doctors are prescribing daily oral Ivermectin. This does need to be given every day for a minimum of 3 months to completely eradicate the mite. Collies and sheepdogs should not take Ivermectin due to increased sensitivity. The monthly heartworm preventative Interceptor can also be used DAILY for several months to kill the mites. This becomes very expensive and is reserved only for the pets that can not tolerate either dips or Ivermectin.In older dogs, a primary condition is usually contributing to the disease. Once the condition is found and treated, the mite usually resolves. In some cases, the mange is severe enough to warrant treatment. Oral Ivermectin is usually the treatment of choice in older animals due to the side effects of amitraz dips.