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Thursday, February 19, 2009

Zoonosis Week: Scabies

Zoonosis: An infectious disease in animals that can be transmitted to people. The natural reservoir for the infectious agent is a animal.

From rabies to scabies! You'd think I planned my alliteration.

Today I saw a pair of dogs, one with scaly patches on her ears and the other with extremely itchy skin. One of the main things I considered in this case was scabies, also called sarcoptic mange. The name comes from the microscopic mite that causes the disease, Sarcoptes scabiei. This mite burrows under the skin and will usually cause a localized allergic reaction and intense itching. As the mites grow and spread, the itching can be severe enough for the pet (or person) to cause sores because of self-trauma, as well as reddened or scaly skin due to the mites' effects.

Skin mites such as scabies can affect many types of animals, though each species of mite is usually specific for a single or a small group of species. Even though a host such as a human or a dog might not be its preferred environment, mites aren't always picky and will invade whatever is close that may be used as a meal. The mites are mostly transmitted through close contact with an infected animal or person, as they do not live long off their host.

Diagnosis is normally made by performing a superficial scraping of the skin in several locations, and then looking under the microscope to identify the mites or their eggs. Because the mites can cause such an intense reaction, it is possible (and not uncommon) for the vet to not be able to find them even if they are present. Sometimes we do a "therapeutic trial" in cases that are highly suspicious, giving treatment and see if it helps.

There are several accepted treatments. One of the easiest and most common is a series of 2-3 injections of an antiparasitic medication called ivermectin. Special medicated dips can also be used. There are also a few topical flea and tick medications that have been used for treating this mite. Your vet can recommend the treatment that he or she feels is best.

So the next time you bring an itchy pet to your vet and they want to scrape the skin for mites, don't ignore the recommendation and refuse the service. If it is scabies, it can affect not only your pet, but the whole household.