There are a large number of different types of intestinal worms, but dogs are most commonly affected by tapeworms, roundworms, hookworms, and whipworms.
"Pet Wormers" is a name which is used to describe medications used to treat internal parasitic infections, usually of the digestive tract. Each wormer kills different species of worms, so it is necessary to know which parasites an animal has before selecting the wormer.