Identify the sequence.
Did your pet start scratching before a rash developed? Or did a rash appear first, then the scratching? Knowing the order of actions can help a vet narrow down the possible causes. Scabies, a contagious form of skin parasite that can infest pets and people, usually begins with a rash, then an itch. "When pets have skin problems, people need to be aware that it may be contagious," says Dr. Ackerman. Atopic dermatitis (hypersensitivity to pollens, dust mites, or mold spores), however, usually starts with an itch and then develops into a rash.