When we say that a pet has worms, what we are actually talking about one of a number of different intestinal worms. There are four types of worms that commonly affect dogs and cats, namely hookworm, roundworm, tapeworm and whipworm. These worms all have different ways of infecting a host, cause different health issues, and require different treatment. As a pet owner the best thing you can do is to educate yourself on the risks and find the best protection for your furry friend.