This worm is a common intestinal parasite. The whipworm of the dog is substantially smaller than the other worms (about two inches maximum in length) and is rarely seen as it lives in the large intestine. The “head” (or more accurately the digestive end of the worm) is skinny versus its stout tail (or reproductive end) which gives the worm a whip shape, hence the name.
The large intestine is the home of the whipworm. The adult worms bite the tissue of the intestine, actually embedding their “heads” inside, and suck blood there.
Eggs are laid inside the large intestine and pass with the stool. Once in the outside world, the eggs require about 2-4 weeks to form embryos and become capable of infecting a new host. (This means that contaminated soil is the source of infection, not fresh feces).
The new host is infected by consuming the egg (usually during grooming). A few whipworms generally do not pose a problem for the host but if large numbers of worms are present embedding themselves in the large intestine tissue, tremendous inflammation can result leading to a bloody, gooey diarrhea. Usually there is not enough blood loss to be dangerous but the diarrhea readily becomes chronic and hard to control.
Clinical signs include: straining, mucous diarrhea with occasional blood and an urge to defecate small volumes frequently.
Because female whipworms only periodically lay eggs, a fecal sample tested may easily be negative for eggs. This makes the confirmation of a whipworm infection a challenge. It may require several fecal samples to demonstrate the egg in a microscopic exam.
It is common to deworm for whipworms if the symptoms are suggestive of the whipworm presence even if the fecal test is negative. Most common deworming agents do not work on whipworms so particular medications must be selected. Treatment for whipworms requires several treatments with for 3-5 days and repeated in 3 weeks. Because of the long maturation cycle of young worms, a second deworming some 75 days or so after the first deworming is needed to fully clear the infection. Often another deworming in between these doses is recommended to further control the whipworm numbers. Severe cases of whipworms are not common but, can require surgical intervention.
Prophylaxis includes careful removal of feces and bleaching dog runs regularly. More recently, regular heartworm prevention products have been developed to remove and control whipworms.
Soil contaminated by whipworm eggs is contaminated for years. It is virutally impossible to remove the eggs from the soil or kill them. The egg is capable of surviving in the environment for months. Happily, however, this is one pet intestinal parasite that is not readily transmissible to humans.