Demodectic mange is a noncontagious, nonitchy skin disorder caused by mites that results in hair loss and occasional skin infections in dogs.
As repugnant as it sounds, harmless mites live in our dogs' skin (and our skin too for that matter). Female dogs spread the microscopic Demodex canis mites to their nursing pups.
These cigar-shaped mites normally live quietly in your dog's hair follicles throughout his life. But some dogs with underdeveloped or compromised immune systems can't contain them. The result: patchy hair loss.
The good news: Your dog can't spread his demodectic mange to your family or other dogs. The bad news is that demodectic mange is a lifelong struggle for some furry friends.
Risk factors and detection
Demodectic mange can be localized or generalized. Localized demodicosis usually affects puppies and appears as patchy hair loss around the eyes and mouth or front legs and feet. About 10 percent of cases progress into the generalized form, causing larger areas of hair loss over the entire body and occasional secondary bacterial infections of the skin and feet.
Some adults develop localized demodectic mange, but most suffer from the generalized form.
Generalized demodectic mange affects dogs of any age, but it usually affects puppies with immature immune systems or older dogs suffering from underlying illnesses that weaken their immune systems. Veterinarians believe heredity plays a role too, because demodectic mange appears more frequently in certain dog breeds, including Shar-Peis, West Highland white terriers, Scottish terriers, and English bulldogs.
Your veterinarian will examine your dog to rule out other conditions, such as allergies, ringworm, bacterial infections, and endocrine diseases, including hypothyroidism and Cushing's syndrome. He or she also will perform multiple skin scrapings and possibly biopsies to find the mites. Older dogs suffering from the generalized form require blood tests and X-rays to rule out other underlying disorders.
Prevention and treatment
Good breeding practices may lessen—but not prevent—your dog's chance of developing demodectic mange. Because dogs may be able to pass on the immune system defect that leads to demodectic mange, breeders should spay or neuter affected dogs.
Twice-monthly baths and medicated dips provide relief and often a cure for dogs suffering from generalized mange, but treatment may take several months. Trimming hair away from affected areas helps the topical treatment penetrate hair follicles and makes your job easier.
Veterinarians often recommend benzoyl peroxide shampoos to open up and flush the follicles. This prepares the skin for the leave-on medicated rinse.
Amitraz is the FDA-approved topical treatment for demodectic mange. Side effects include sleepiness and lethargy, and about 30 percent of dogs also lose their appetite. Your veterinarian can fully explain the treatment protocol and possible complications.
When using amitraz, wear gloves and work in a well-ventilated area to avoid inhaling the fumes. Contact with amitraz can cause skin inflammation, severe headaches, and asthma-like attacks in people. Also keep the solution out of your dog's eyes and mouth.
Your dog will need two or three more topical treatments after the veterinarian diagnoses your dog mite-free. Sometimes you can only control, not cure, the disease, especially in older dogs with concurrent illnesses or those dealing with a troublesome case of foot demodectic mange.
Your veterinarian may prescribe ivermectin or milbemycin, which you administer orally once a day until your dog tests negative for mites and for 60 days afterward. Ivermectin can cause rare but serious side effects, especially in such herding breeds as collies, Shetland sheepdogs, Australian shepherds, Old English sheepdogs, and their crossbreeds.
Milbemycin appears safe for ivermectin-sensitive breeds. Make sure your dog tests negative for heartworms before using either of these medications.
Some dogs also may need antibiotic therapy to treat accompanying bacterial infections. Talk with your veterinarian about treatment options.
When treating localized demodectic mange, your options are few but simple: Do nothing. It often goes away on its own within a few weeks, although your doctor might recommend oral vitamin E supplements to boost your dog's immune system. Such topical ointments as rotenone or benzoyl peroxide gel can help, but occasionally these treatments make the symptoms appear worse before improving. And you must take precautions to keep these products out of your dog's eyes.
Your veterinarian will recommend the best treatment options based on your dog's breed and age, his overall physical condition, and results from the physical examination and blood tests.
