Allergic skin disease. Dogs, like people, can have allergies to house dust, ragweed and other things. If your dog rubs its eyes frequently, and bites and scratches its fur, especially on the paws, it could have an allergy. This can plague your cat. Ringworm actually isn't a worm at all but a fungus, a microscopic, single-celled plant.
Ringworm creates a dry, circular skin sore, which looks a bit like a mini-crater on the moon.
Veterinarians can treat these and other animal skin diseases.