Internal parasites like pinworms and whipworms survive by eating the blood and muscle tissue of their host. The host becomes anemic and emaciated, and may have chronic diarrhea. While pinworm and whipworm symptoms and infestation methods are similar, major differences exist between pinworms and whipworms. Pinworms affect people; whipworms affect dogs.
Pinworms are small tubular white worms that range in size from 1 millimeter to 13 mm, or 0.03 inch to 0.5 inch. They infect the intestinal tract and can cause severe itching around the anus. Pinworms don't infect dogs, however; they limit themselves mainly to humans, rabbits and horses. They aren't passed between different animals, so a pinworm infestation in a human can pass only to other humans, and an infestation in a horse can pass only to other horses. Tapeworms are often misidentified as pinworms in dogs as sections of the tapeworm shed out in the feces or the dog drags his bottom on the floor due to irritation caused by the worms.
Whipworms are small parasites, about 1/4 inch long, with short, wormlike bodies and long, whiplike tails. They infect dogs, cats and other domestic animals but are very rare in humans. Whipworms attach themselves to a dog's large intestine and cause damage by slowly making small tears in the intestine. Most dogs don't show many outward signs of infestation, however, and the main symptom is chronic bloody diarrhea.
Both pinworms and whipworms enter their hosts through the mouth as eggs. In the case of a human infestation of pinworms, eggs are often transferred from the anal area to the mouth by unwashed hands, making it far more common in children than in adults. The eggs of whipworms are expelled in a dog's feces. They can live for up to five years outside a host. Typical infestation occurs when the eggs become attached to a dog's paws and he ingests them during regular grooming.
To identify a case of pinworms or whipworms a doctor or veterinarian will examine a fecal sample under a microscope to check for eggs. They are usually readily visible in the case of pinworms, but it may take several examinations to find whipworm eggs. This is because only a few eggs are shed at a time and they may not be present in every fecal sample, even if a dog has whipworms. Both humans and dogs are treated with worming medications to kill the worms. Several doses spread out over a period of days or weeks may be necessary to eliminate all of the worms. A dog may need regular preventive treatments for whipworms, since the eggs can survive for so long without a host.