These microscopic members of the arachnid (spider) family cause itchy skin problems in dogs. Some mites are contagious to other animals, but in most cases they don't cause problems in humans. Four species of mites are known to infest dogs: Demodex canis, Sarcoptes scabei var. canis, Cheyletiella, and Otodectes cynotis. Skin diseases caused by demodex and sarcoptes mites are often referred to by the general term “mange.”

Demodicosis

Cigar-shaped demodex mites usually live harmlessly inside a dog's hair follicles, but every once in a while the demodex population runs amok, often in response to stress or illness. The result is canine demodicosis, also known as demodectic mange or red mange. Demodicosis can be localized — limited to the head and front legs, for instance — or generalized, covering the entire body. Demodicosis is most commonly seen in dogs three to twelve months of age (localized demodicosis) or younger than eighteen months of age (generalized demodicosis). Pugs are among the breeds known to have an increased incidence of juvenile-onset demodicosis.

Skin scrapings or a skin biopsy by the veterinarian can confirm the presence of demodex mites. Treatment requires a series of baths with medicated shampoo, topical medication, and antibiotics. Demodicosis isn't contagious, but it may be heritable. It's best to spay or neuter a puppy that develops it.

Scabies

Canine scabies, also known as sarcoptic mange, develops when the sarcoptes mite tunnels beneath a dog's skin, resulting in intense itching, crusty sores, hair loss, and wounds caused when the dog bites or scratches at the itchy areas. Sarcoptic mange can be confirmed with skin scrapings. Treatment requires a course of medicated baths over a six-week period. Short-term use of corticosteroids can help reduce itching. Scabies is highly contagious, so if your pug has it, any other pets in the household should also be treated, even if they don't show signs. Canine scabies can also cause temporary itching in humans (usually on the waist, chest, and forearms) and cats.

Cheyletiella

This mildly itchy skin disease is sometimes called “walking dandruff” because the mites that cause it are large enough to be seen with the naked eye. They look like small white specks marching along the dog's back. These mites can be spread to other animals and people, but they're not common in households with a good flea-control program. The usual treatment is a series of medicated baths and dips.

Ear Mites

These mites love warm, moist areas, such as your pug's ear canal. Suspect ear mites if your pug has dry, reddish-brown or black earwax and often shakes his head or paws at his ears. Unless you check the ears regularly, you might not notice an ear mite infestation until it's at the serious stage. Dogs with a bad case of ear mites have bald spots around the ears from scratching at them, often accompanied by bleeding sores. The mites can grow numerous enough to block the entire ear canal.

To treat ear mites, the veterinarian will clean the ear canal and prescribe eardrops to kill the mites. It will take at least a month of treatment before you can be sure all the mites are gone. Give your pug a bath to help speed them on their way.