Sending out a fecal test at your annual vet visit is highly recommended.
Nematodes (roundworms) are free-living in the intestines. They can be transmitted from dog to dog via eggs shed in the feces.
Puppies who have a large amount of roundworms have a 'pot bellied' appearance
If a growing puppy is infected with a large number of roundworms, the worms can stunt the puppy's growth, cause serious digestive upsets and result in excessive gas formation.
Hookworms, particularly Ancylostoma, are one of the most pathogenic intestinal parasites of the dog.
The hookworm is approximately ½ to 1" (1-2 cm) long and attaches to the lining of the small intestines, where they feed on blood. As a result of blood sucking, hookworms can cause severe anemia.
The infective larvae can enter the host either by mouth or through the skin, particularly the feet.
Eczema and secondary bacterial infection can result due to irritation as they burrow through the skin.
Whipworms are small worms, usually only ¼" (6 mm) long, that live in the large intestine, where they cause irritation and inflammation.
Symptoms of whipworm infection include chronic watery diarrhea, bloody diarrhea, and weight loss.
In order to get tapeworms, an intermediate host (such as a flea or certain species of rodent) is required. In other words, your dog cannot get tapeworms directly from another dog or a cat.
Dipylidium caninum, the most common tapeworm of the dog, causes few problems in the adult host but can result in digestive upsets and stunting of growth in puppies. The intermediate host of Dipylidium is the flea.
Taenia species of tapeworms usually infect adult dogs and cause few problems. Puppies are occasionally infected and, depending on the type of worm involved, the large number of worms can cause intestinal blockage. The intermediate host for Taenia species is small mammals such as rodents or rabbits.
Echinococcus, another type of tapeworm, is important because it is zoonotic- meaning humans can be infected. The adult tapeworm is tiny, only about ¼" (5-6 mm) long. Sheep and sometimes people can act as the intermediate hosts in which the immature forms of Echinococcus develop inside hyadatic cysts in various organs. In people, these cysts can involve the lungs or brain.