Actually, your dog could have mange. There are two common types of mange seen in dogs. A thin, sneaky looking cur with patchy hair, scabby, crusty skin, and itching like mad while he is hanging around the city dump. That is sarcoptic mange. The dog's constant scratching produces hair loss, scabbing lesions, and often secondary bacterial skin infections.
Sarcoptic mange occurs in dogs of all ages, and is transmitted via contact with an infected dog.
Common locations for skin lesions to develop include the ear margins, the elbows, and the abdomen. Some skin diseases of dogs are zoonotic, meaning they can be transmitted to people, and sarcoptic mange is one of these diseases. In people, it usually produces an itchy rash, and is often self-limiting. A diagnosis of sarcoptic mange is based on finding the parasitic mites on a skin scraping done by the veterinarian. Because the mites burrow through the skin, they can be difficult to find on skin scrapings.