by the VIN Dermatology Consultants
Demodicosis (red mange, demodectic 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 Demodex mites, but some dogs develop an overgrowth of these mites. In some cases, the tendency to develop demodectic mange runs in families.
Signs of demodicosis can include hair loss, reddened skin, scabbing, crusting and sometimes itching. Localized demodicosis involves only small areas of skin on a dog. Generalized demodicosis involves most of a dog’s body or paws. Skin infections from mite damage are common. Sometimes, these skin infections become life-threatening, and cause swelling and fever.
Many other skin conditions look just like demodicosis and skin tests need to be performed for diagnosis. In a skin scraping, a scalpel blade is used to gently but firmly scrape the skin layers to collect cells and mites. Samples from deep skin scrapings or hair plucks are examined under the microscope for the Demodex mite. Dogs with generalized disease also require further testing for underlying health problems.
Any skin infection needs to be treated with a topical medication or antibiotic. For localized demodicosis, most dogs resolve on their own and don’t need to be treated with an anti-mite medication. Instead, dogs with localized demodicosis are observed for spreading or worsening of mites. For dogs with generalized demodicosis, treatment requires an anti-mite medication such as one of the following below. Continue any anti-mite treatment until no mites are found on two consecutive skin scrapings.
Amitraz is available as a dip (Mitaban®). The Mitaban® is packaged in individual dosing vials of concentrate and diluted in water just prior to application. Side effects are more common in small dogs and can include the following: lethargy, decrease in body temperature, loss of appetite, vomiting, and diarrhea. Dips are usually applied either weekly or every two weeks according to the veterinarian's prescription. Dips are usually applied by grooming technicians in the veterinarian's hospital.
Occasionally, another form of amitraz (Taktic®) is chosen. Different dilution instructions are required for Taktic®.
Ivermectin is available as a liquid deworming agent (Ivomec® and generics) and as a monthly heartworm preventative pill. For canine demodicosis, the liquid form is given by mouth once a day. Side effects can include the following: lethargy, vomiting, diarrhea, and neurologic signs. Many veterinarians will gradually increase the dose of ivermectin to monitor for side effects. Side effects are more common in herding breed dogs (e.g. Collies, Border collies, and Old English sheepdogs). A genetic test is also available to determine if a dog may be sensitive to ivermectin.
Milbemycin is available as a monthly heartworm preventive pill (Interceptor®) for dogs. For canine demodicosis, the pill is given by mouth once a day. Side effects can include the following: lethargy, vomiting, diarrhea, and neurologic signs.
Moxidectin is available as a liquid deworming agent and as a monthly topical heartworm preventative (Advantage Multi®). For canine demodicosis, usually the topical form is applied to the skin once a week. Side effects can include the following: lethargy, vomiting, diarrhea, and neurologic signs.
The Isoxazoline Flea/Tick Products (Bravecto®, Nexgard®, and Simparica®)
These medications are available as oral flea and tick control pills for dogs. For canine demodicosis, the dose varies based on the specific product.
Many veterinarians will neuter dogs with generalized demodicosis as soon as the disease is under control. This is in the best interest of the dog since breeding and heat cycles can cause disease recurrence. Additionally, veterinarians recommend neutering dogs with juvenile-onset, generalized demodicosis because this disease likely has a genetic basis.
Animals with localized demodicosis have a good prognosis with proper care. As the severity of the disease increases, the prognosis worsens. Some dogs with generalized demodicosis must have regular treatment for the rest of their lives while others may be cured after a variable number of months of treatment. In all cases it is important to keep your pet as healthy and stress free as possible, including a good nutritional diet, regular checkups, routine deworming and heartworm prevention.
(Also see demodectic mange and demodectic mange in cats.)