Q: We took Jake, our 10-week-old pit bull, to the veterinarian because he has very little hair and scratches almost constantly, even though we see no fleas. The vet said Jake has Demodex mites and prescribed a monthly chewable pill that kills them as well as fleas and ticks. Where could Jake have caught the mites? Can he pass them to us or our other dog?
A: Demodex mites are normally present in small numbers on dogs' skin, so you don't need to worry about Jake passing them to other dogs. And since these mites are species-specific, they won't spread to humans, cats or other pets.
In some puppies, an inherited immune system abnormality causes the mites to proliferate. Fortunately, treatment is effective, and the condition rarely returns. The disease also can develop in an adult dog whose immune system is suppressed.
Demodex mites are microscopic, cigar-shaped creatures that live in hair follicles. If they proliferate, they cause demodectic mange, also called demodicosis (pronounced "de mo di CO sis"), that can be localized or generalized. Clinical signs include hair loss, crusting, redness, scabs and thickened skin. Scratching occurs in dogs with secondary skin infections.
The diagnosis is confirmed by seeing Demodex mites with the microscope. Affected dogs should be sterilized so they don't pass on the genetic predisposition to demodicosis and because recurrences are common during a female's heat cycles.
Treatment options include medication to kill the mites, a shampoo or gel that flushes the mites from the hair follicles, and an antibiotic if the skin is infected.
Lee Pickett, V.M.D. practices companion animal medicine in North Carolina. Contact her at email@example.com.