| DERMATOLOGY By Carol S. Foil, DVM, MS, Diplomate A.C.V.D. Board-certified specialist through the American College of Veterinary Dermatology |
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Demodicosis (Red Mange)
Demodicosis (red mange) is a skin disease caused by a small mite not visible to the naked eye. This mite lives down in the root of the hair. All normal dogs have a small population of mites, but only certain animals will get a disease from mite overgrowth. In some cases, the tendency to develop demodectic mange runs in families.
The disease is seen in TWO FORMS in dogs. There is a localized form where only small areas of the skin are affected, and a generalized form where the majority of the body and/or the feet are involved. Symptoms include loss of hair and reddening of the skin. Affected areas may be scabby, crusty and sometimes itchy. Skin infections due to damage by the mite are common. Skin infections can become so severe that they threaten a dog’s life, with ulcers, swelling and fever. Juvenile-onset generalized demodicosis is a familial disease and affected dogs and their parents should not be bred. Diagnosis of demodectic mange is made by examining debris from deep skin scrapings under the microscope. Dogs with generalized disease also require further testing for underlying health problems.
Treatment of demodectic mange depends on the patient’s age and the severity of the disease. In the localized form, the dog may heal on its own. Many times a cream or gel will be used to aid in healing. It is important that dogs with the localized form be observed for a worsening of the condition or spread to other areas. Dogs that are intended for breeding should be observed without treatment to be sure the generalized form does not develop. Infrequently the topical medication may cause the affected areas to look worse before the areas begin to heal. If a skin infection is present, antibiotics will be needed.
Dogs with generalized demodicosis may require intensive treatment with amitraz (Mitaban®) dips or oral medications. If a skin infection is present, antibiotics will be needed.
Mitaban dip is the only FDA-approved drug for this disease. WHOLE BODY CLIPPING is required throughout treatment so that the dip solution can reach the mite down in the hair follicle. Dips are usually preceded by a medicated shampoo to fight infection. The Mitaban is packaged in individual dosing vials of concentrate which is diluted in water just prior to applying to the patient. Side affects of Mitaban can be encountered, especially in small dogs, including sedation, decrease in body temperature, loss of appetite, vomiting and diarrhea. Treatment with an antidote, yohimbine, can be used to decrease the severity of some side effects. Dips are usually applied either weekly or every two weeks according to the veterinarian’s prescription. We generally recommend that dips be applied by grooming technicians in the veterinarian’s hospital.
If no severe side affects are seen, treatment will be continued until repeated skin scrapes reveal no mange mites (typically 6 to 9 treatments) and for one more month after that. Scrapings will be performed every 2 to 4 weeks to evaluate response to treatment. Occasionally, another form of amitraz (Taktic®) is chosen because of lack of availability of Mitaban (but it is not an approved formulation). Different dilution instructions are required for Taktic.
Ivermectin or Milbemycin Treatment: Some dogs are very sensitive to amitraz and others do not respond even after many months of therapy. For these dogs, veterinary dermatologists often turn to extra-label use of oral parasiticides that can be used for generalized demodicosis. Ivermectin is available as a cattle worming agent (Ivomec® and generics) and milbemycin is available as a heartworm preventive pill (Interceptor®) for dogs. At very high daily dosages, these can be used to treat generalized demodicosis successfully in a majority of cases.
