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Page 46
Sarcoptic mange, also known as canine scabies, in dogs, is caused by the parasite Sarcoptes scabiei. These microscopic mites can invade the skin of healthy dogs or puppies and create a variety of skin problems, the most common of which is hair loss and severe itching. While they will infect other animals and even humans, sarcoptic mites prefer to live their short lives on dogs. Fortunately, there are several good treatments for this mange and the disease can be easily controlled. Who gets canine scabies? Canine scabies can infect all ages and breeds of dogs. While it prefers to live on dogs, this particular mite will also infect cats, ferrets, humans, and fox. Cats, fox, and humans all have their own particular species of mite within the Sarcoptes family. Each species of mite prefers one specific kind of host (e.g.; dog), but may also infect others. What is the life cycle of Sarcoptes scabiei? The mites usually spend their entire life on a dog. The female mite burrows into the skin and lays eggs several times as she continues burrowing. These tunnels can actually reach the length of several centimeters. After she deposits the eggs, the female mite dies. In 3-8 days, the eggs hatch into larvae which have 6 legs. The larvae mature into nymphs which have 8 legs. The nymph then molts into an adult while it is still in the burrow. The adults mate, and the process continues. The entire life cycle requires 2-3 weeks. The mites prefer to live on the dog, but will live for several days off of the host in the environment. In cool moist environments, they can live for up to 22 days. At normal room temperature in a home, they will live from 2 to 6 days. Because of the mite's ability to survive off the host, dogs can become infected with-
out ever coming into direct contact with an infected animal. What are the symptoms of canine scabies? The symptoms of canine scabies are varied, but usually include hair loss and severe itching especially on the elbows, ears, armpits, hocks, chest, and ventral abdomen (belly). The mites prefer to live on areas of the skin that have less hair. As the infection worsens it can spread over the entire body. Small red pustules often develop along with yellow crusts on the skin. Because of the severe itching and resultant scratching, the skin soon becomes traumatized and a variety of sores and infections can develop as a result. The itching seems to be much worse in warm conditions such as indoors or near a stove or heat vent. If the infection goes untreated or is mistakenly treated as an allergy, the skin may darken due to the constant irritation, and the surrounding lymph nodes may become enlarged. Sarcoptic mange is a somewhat common infection and many cases have often been misdiagnosed as severe atopy (inhalant allergy). Any time we see a dog who does not have a prior history of allergies and develops severe itching, or if the itching is not seasonal but year-round, we have to suspect canine scabies. The intense itching caused by the sarcoptic mite is actually thought to be caused from a severe allergic reaction to the mite. When dogs are initially infected with Sarcoptes they do not develop itching for several weeks. If the animals are treated and then reinfected at a later time, severe itching starts almost immediately, which indicates the itching may be due to an allergic reaction. However, the standard treatments for allergies generally will not decrease the symptoms of scabies, and will do nothing to cure the disease.