when your dog scratches he/she might have MITES if i were u I'd take it to a vet pronto or it could get worse. Its kind of like a skin infection and your pet could then get really bad wounds if not treated so take it to the vet!!!!!!!!!!! your cat is probably just cleaning himself its nothing to worry about
A lot of times it is allergies. I had a dog that scratched constantly with no fleas or mites. The vet gives them an allergy shot and it goes away.