Roundworms

Several of these parasites affect dogs but the most important are the ones that belong to the Ascarid family, and live in the small intestine. Other roundworms infest the large intestine, blood vessels and respiratory tract.
Ascarids feed on digesting food in the dog's gut, and are particularly harmful to puppies. They penetrate a puppies gut wall and pass via the blood to the liver and then to the lungs. From there they crawl up the trachea to be coughed up and swallowed, again ending up in the gut. Infected puppies may develop :-

Hepatitis, pneumonia, fits, and obstruction to the gut, so regular treatment is vital.

As the puppy gets older most of the worms travel to the muscles, where they form cysts. These lie dormant until the puppy bitch becomes pregnant. They then migrate to the puppies lungs, and this is why virtually every puppy is born with roundworm, and must be wormed regularly.

How Roundworms Affect Humans

These worms can infect humans, and in a very low number of cases, cause disease. Good hygiene and common sense concerning children and puppies should control the problem.

Tapeworms

The tapeworm tickle the dog's anus and make the dog drag it's rear end along the floor. If you see any worm segments in your dog's faeces, treat it as soon as possible.

As a dog lover myself, I treat my own pets at least twice a year. Worming tablets can be bought cheaply at your local supermarket or petshop, so there's no excuse for not treating your own pet on a regular basis.