Sarcoptic mange is the name for the skin disease caused by infection with the microscopic Sarcoptes scabei mite. Mites are not insects; instead they are more closely related to spiders. Adult Sarcoptes scabei mites live 3-4 weeks in the Host’s skin. After mating, the female burrows into the skin depositing 3-4 eggs in the tunnel behind her. The eggs hatch in 3-10 days which molts into intermediate stages and finally becomes an adult. The adults move on the surface of the skin where they mate and the cycle begins again with the female burrowing and laying eggs.
Appearance of the Disease in Pets
Mites prefer hairless skin, which leads to the majority of lesions appearing on the ear flaps, elbows and abdomen. The presence of the crawling mites causes extreme itchiness and an allergic reaction, which causes even more itchiness. The pet scratches the area and develops red, scaley, thickened patches of skin. With time, most of the dog’s body will be involved.
Diagnosis of Scabies by Our Veterinarians
Diagnosis of Scabies can be difficult because the mites are often killed by the pet’s scratching. Our veterinary team attempt to find the mites by scraping the skin and looking at the debris under the microscope. If we find the mites, the diagnosis is clear. If our veterinarians do not find them, we still must consider that mites are the cause of the itchiness. Since negative test results do not rule out mite infection, a “Maybe Mange” test is frequently performed. This consists simply of treating for sarcoptic mange and observing for resolution of the signs within 2-4 weeks.
Treatment of Scabies by Our Veterinarians
While sarcoptic mange is difficult to diagnose definitively, it is fairly easy to treat and a number of choices are available. The choices include injectable drugs (Ivermectin), medicated dips (Lym Dip) and some topical spot-on drugs. Frequently our veterinary team may select more than one drug to help relieve the problem. Typically, we treat for 4-6 weeks to eradicate the infestation. Because this is a highly contagious disease, we need to treat all the dogs and cats in the home. All bedding should be washed and pets should not be allowed on the furniture until the treatment is completed. Some pets may require medicated shampoos, antibiotics and steroid drugs to help relieve the itchiness and correct any secondary infections caused by the mites.
How the Infestation is Spread
Sarcoptic mange mites are usually spread by direct contact from host to host. Mites are only infective for about 36 hours after falling off the host. Therefore, environmental decontamination is generally not necessary. The dog is the natural host for Sarcoptes scabei. Howeve, the mites can infect humans and cats although they tend not to persist on these hosts. When people (including some veterinarians) refer to “sarcoptic mange” or “scabies” in the cat, they are usually referring to infection by Notoedres cati, a mite closely related to Sarcoptes scabei..
Mite infections on humans are self-limiting (ie they go away on their own) as the mite is not able to complete its life cycle on the “wrong” host. The condition is extremely itchy, though, while it lasts. The mites are most active where skin is warm (in bed and where clothing is snug such as the beltline, bra straps etc). Lesions on people generally start out as small red bumps that are extremely itchy. Although the infection will subside in time, infected people should consult with their doctors for therapy. Topical lotions can be administered to help kill off the mites.
Prevention of Scabies
Prevention of Scabies is difficult because you cannot see the mites and frequently pets may have only minor symptoms. Since Scabies is transmitted from pet to pet, the best defense is to isolate all new pets in the house for 2 weeks before exposing other pets to them. If they are itchy during this period, bring them to the veterinarian for evaluation.