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July 23, 2003
Mange (Demodicosis)

Demodectic mange (also called red mange, follicular mange, and Demodex) is a common skin disease of dogs caused by a tiny mite that cannot be seen without the aid of a microscope. This mite is normally found in the hair follicles of all dogs. Mites are transmitted from nursing mothers to their puppies within the first few days of life. The reasons that dogs develop mange are not fully understood, but genetics and immune suppression both play a role. Signs of disease appear only when mites reproduce unchecked. In puppies, this may occur due to an immature immune system; and in older dogs, mange usually occurs secondary to drug therapy or a disease such as cancer or hypothyroidism that suppresses the immune response. In mild cases, signs of demodectic mange include itching and scratching, reddened or scaly skin, blackheads, and patchy hair loss. More severe cases are accompanied by widespread hair loss, pustules, a crusty appearance, and bacterial skin infections. The head and feet are most commonly involved.

Demodicosis can only be definitively diagnosed by a veterinarian with a skin scraping. Milbemycin, which is normally marketed as a monthly heartworm preventive, may be effective against generalized demodicosis when it is used on a daily basis; however, the downside to this oral treatment is expense, as the medication may have to be given daily for up to 3 months to achieve cure. Therefore, treatment of generalized mange frequently involves regular dipping using the parasiticide amitraz. Initially, the dog’s hair may be clipped so that the dip can better reach the skin, and the dog should be bathed with shampoo which helps to clear up skin infections and opens the hair follicles so the dip can penetrate to the mites. Many dogs will relapse if not treated every eight weeks or so, even after an apparent cure.

Amitraz dips should be used only under the supervision of a veterinarian, and with caution and dosage adjustment in very small dogs. Many animals treated with amitraz experience side effects, most notably sedation. Development of more severe side effects may require an antidote. Amitraz is a drug of the monoamine oxidase inhibitor class, and any pet or person who is taking antidepressants known as selected serotonin reuptake inhibitors (such as Prozac®) could have a bad reaction if exposed to amitraz. Amitraz can cause a significant rise in blood glucose levels, so the dip should be used with caution on diabetic dogs, and humans with diabetes should avoid exposure. It is very important to keep amitraz out of the reach of children and pets, as severe toxicity has been reported following oral ingestion. The solution is flammable until diluted. Federal law restricts amitraz to use by or on the order of a licensed veterinarian.

Amitraz has been commercially unavailable, but can be compounded upon a prescription order from a licensed veterinarian. Please contact our compounding pharmacy for more information.

Copyright 2003, Storey Marketing - Veterinary Website Updates. Reproduction prohibited without subscription from Storey Marketing. Questions regarding this article should be directed to the compounding professionals at Martin Avenue Pharmacy, Inc. by calling 630-355-6400.