External parasites in dogs, like fleas, mites, ticks, and lice, can cause itching, irritation, and diseases. This simple guide shows how to identify, treat, and prevent them.

Roundworms: These parasites are common in dogs, especially puppies, and are 3- to 6-inches long, smooth, and round-bodied. You might not know your dog has roundworms, particularly if they have ...