Most mites are too tiny to be seen with the naked eye but the torment these parasites can inflict on dogs is out of proportion to their size. If your pet is scratching so fiercely that he draws blood but you see no evidence of fleas, mite-borne skin disease, called mange, is one possible reason. Treatments vary depending upon the dog, the type of mange and the severity of symptoms but in addition to killing mites on the dog's body, always include thorough decontamination of the indoor environment.
Ear Mites Can Migrate
Some mites burrow but those that make themselves at home in dogs' ears don't, staying on the surface of the skin inside the ear canal, feeding on wax and skin cells and causing scales and thick, reddish-brown crusts to form. Some dogs don't seem to notice; others may develop allergic reactions. The bugs can also migrate to other parts of the body, typically the neck, rump and tail. If severe infestations are left untreated, serious complications, including ruptured ear drums, may ensue. Ear mites are easily spread by contact so if one animal in a multi-pet household has them, all should be treated. Human infestations are possible but rare.
Sarcoptic Mites Penetrate Skin
Sarcoptic mange, also known as scabies, is caused by mites that tunnel into the skin and reproduce there. At best of times, this kind of infestation triggers intense itchiness; at worst, an allergic reaction compounds the problem. One of the most common skin diseases in dogs, the first signs of sarcoptic mange usually appear on the outer ears, elbows and abdomen but without treatment, can eventually cover the entire body. Dogs scratch so hard they may mutilate themselves, thereby inviting secondary skin infections. Together, the mites and the scratching cause patchy hair loss and formation of scabs on the skin. Sarcoptic mange is contagious among dogs and can also be passed to humans.
Demodex Mites: Longer Treatment Required
The three varieties of demodex or demodectic mites implicated in this type of mange, also known as demodicosis, spend their entire life cycle inside the hair follicles and sebaceous glands of their canine hosts. A modest population isn't harmful -- puppies contract them from their mothers and mild flare-ups in older dogs usually clear up without treatment. But according to "The Merck Veterinary Manual," when vets see adult dogs suffering from generalized democoidosis, they should test for underlying conditions such as immune system disorders. Cancer, diabetes and malnutrition are other possible culprits. This form of mange requires more aggressive treatment over a longer period of time to resolve, often a month or two after mites are no longer showing up in skin scrapes. Canine mange isn't contagious to people or non-canine animals.
"Walking Dandruff" Mites Move
If you spot what appears to be dandruff on the neck and back of your puppy, suspect a highly contagious type of mange colloquially called "walking dandruff." The reason for the name: As the cheyletiella mites underneath the "dandruff" walk around, the skin flakes move too. Look closer and you'll also see the red bumps of a rash. Since flea medications kill these particular mites, and most people protect their dogs from fleas, this form of mange is becoming less common, but it spreads easily among puppies in kennels and pet shops. Not all puppies find the rash itchy but all who have had contact with an infested animal, including fellow pets in homes, must be treated weekly for six to eight weeks. These mites can also produce an itchy red rash on human skin.