Mites on dogs are small wingless eight-legged insects that occur very commonly throughout the animal and plant kingdoms. Dogs suffer very severely from at least three types of mange.
The Demodex canis type leads to a gradual loss of hair over the body and thickening of the skin while the Sarcoptes scabiei type is more localized but more irritant and severe in its effects. Thirdly, there is a form that is restricted to the ears.
Sarcoptes scabiei mites
The most common canine infection caused by itch mites is sarcoptic mange.
Veterinarians in urban practice have seen less of sarcoptic mange in recent years, but it is quite common in rural areas where dogs have contact with foxes or native animals.
Usually, the disease is noticeable first on the dog’s muzzle and ears. Later the legs and the trunk may be affected. Small pustular skin eruptions emerge and the hair covering takes on a mottled appearance.
The dog usually is intensely itchy and may rub large areas of skin raw. Puppies often develop a very dry skin with large scales and loss of hair in tufts.
The Sarcoptes scabiei mites burrow into the outer layer of the skin to lay their eggs. Fortunately, because it does not burrow very deeply, it is easily treated.
Insecticidal washes or medicated shampoos are usually prescribed as these are safe. Long-coated dogs should be clipped before treatment. Washes are repeated weekly until all signs of irritation have disappeared and the hair grows again.
Sarcoptic mange causes an irritating skin rash on parts of the human body that have been in contact with the infected dog.
Demodex canis mites
The second form of canine mange is caused by the Demodex canis mite which burrows into the deep layers of the skin.
Demodex canis mite is most commonly found in short-haired dogs less than a year old. The first signs are usually small hairless areas on the face and the outside of the legs.
The dog does not seem to be greatly irritated unless a secondary skin infection occurs. Staphylococcal infection results in pustules and small abscess formation which causes intense itching and matting of the hair with a thick scab.
Fortunately, demodectic mange is far less common than sarcoptic mange as it is far more difficult to treat. The parasite is less accessible to insecticides and special formulations have to be used to treat severe cases.
The uncomplicated disease in puppies is usually self-limiting and demodectic mange is not infectious to humans. Soaps and creams containing sulfur have been used as the standard home treatment for mites.
Otodectes cynotis mites
The other form of mite infestation, otodectes cynotis, inhabits the ear canal of both puppies and cats. The infected dog tends to shake its head frequently and scratch vigorously at its ear.
Ear mange is caused by the otodectes cynotis mite that does not burrow into the skin but continually punctures it, causing great irritation to the ear which may become inflamed and subject to secondary infections.
A commonly accepted cure is the use of a 25 percent benzyl benzoate emulsion. Four ounces are required to dress a dog the size of a Fox Terrier. Repeat treatment after 7 days.