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'An itchy dog feels miserable': an infestation of parasitic mites can cause hair loss, dandruff and infected sores, and also be contagious.

Dogs with mange look scruffy, with missing patches of hair or oozing sores where they've scratched or bitten themselves trying to tame the itch. But mange is more than unsightly. "An itchy dog feels miserable," says William H. Miller, VMD, Medical Director of the Cornell University Hospital for Animals. What's more, the disease can cause skin conditions ranging from dandruff to hair loss to infected sores.

The types of mites that cause problems in dogs are Demodex, Sarcoptic (scabies), Cheyletiella and Otodectes (ear mites). The type a dog contracts depends on genetics, immune health, environment, preventive treatment and contact with infected animals.

For instance, the cigar-shaped Demodex mites, which can't be seen by the naked eye, live normally in hair follicles. They cause problems only when they multiply because the immune system is weak or abnormal. A genetic basis for deodectic mange exists in many dogs.

Spread By Contact. Scabies, ear mites and Cheyletiella are contagious. They spread through contact with an infected animal or environment. "Most mites die off in the environment within 24 hours, but they could last longer in dens and bedding," Dr. Miller says.

Dogs can spread scabies to each other, people and other animals such as cats, although this is uncommon. Scabies is common in areas with foxes and coyotes. Domestic dogs don't play with their wild cousins, but if they find the den of an infested fox or the body of a fox or coyote that has died of the disease, they can pick up the mites through contact.

Some mites move between species. Otodectes are most common in cats (especially kittens), but they're spread by contact and can take up residence in a dog's ears. Cheyletiella can also be transmitted between species. Products that kill fleas and tickets keep this mite under control, so the frequency of the disease has decreased. Dogs on a sound flea-preventive program with a product that kills both fleas and ticks should not have problems with Cheyletiella.

A New Species. Demodex injae, a new species of hair follicle mite, causes skin to be itchy and greasy on the face, feet and body. It's sometimes mistaken for an allergy. Demodex canis causes itching, hair loss and pustules. Signs may be limited to the head, neck and ears, known as localized demodicosis. "True localized demodicosis typically is a self-curing disease that isn't too much of a big deal," Dr. Miller says.

Generalized demodicosis is a bigger concern. It has two forms. The adult form is usually triggered by a serious underlying metabolic or neoplastic (abnormal mass) disease. Dogs with the juvenile-onset form may have a genetic predisposition. "It tends to occur in certain purebred dogs more often than mixed breeds," Dr. Miller says. "The breed predisposition can vary depending on the part of the country you're in, but the Bulldog, Pit Bull and various terrier breeds are seen across the country."

Dogs with juvenile-onset demodicosis shouldn't be bred to prevent passing the tendency to puppies.

Tormenting Itch. Signs of scabies are severe itching on the head, neck or front feet, hair loss, and red, raw or crusty skin. Affected dogs will scratch, lick or bite until the fur comes off in patches. They may have difficulty sleeping through the night because they're tormented by the itch.

Suspect Cheyletiella if your dog itches or has dandruff along his spine, where mites tend to feed. He may have a dark-brown discharge that fills the ear canal. We think of Otodectes as an ear disease, but the mites can live and feed outside the ear, in rare cases causing signs elsewhere on the body.

In severe cases of any infestation, itching is so intense dogs can't get any relief. They may lose weight from constant scratching or biting at the skin, or develop painful, crusty sores from the self-inflicted wounds. Bacterial infections of the sores can be a complicating factor.

When treating generalized demodectic mange, medicated shampoos and dips can help but take up to a year to be effective. The coat may need to be shaved or clipped to ensure the medication reaches the skin effectively.

Treatment for most other mites is easy and quick, Dr. Miller says. Dips, drops or topical treatments kill the mites. After taking a skin scraping and examining it microscopically to identify the type of mite, the veterinarian will choose the treatment based on the mite's species, your dog's age, and any other health issues he may have. In most cases, the problem resolves within a month.
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Title Annotation:HEALTH
Publication:Dog Watch
Date:May 1, 2013
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