Understanding Canine Whipworm

Whipworm is the smallest of the four most common types of internal parasite that affect canines, which also includes roundworm, tapeworm and hookworm. Its name is derived from the shape of the worm, which has a skinny head and wider tail, resembling a whip. Though it often goes undiagnosed, whipworm was present in 20% of stool samples in the Southeast, 16% in the Midwest and 15% in the Northeast during a United States fecal parasite survey of shelter dogs. Whipworm cannot be passed to humans.

Whipworm lives in the large intestine, where a canine absorbs all his nutrients. The worms embed their heads in the tissue and suck blood. Eggs are laid in the large intestine and then passed into the stool, where they absorb in the soil and form embryos in two to four weeks. Thus, the infections come from the ground, not fresh stool. The eggs, which are even resistent to freezing, can live in the soil for years as long as the conditions are relatively moist. The eggs are usually ingested through grooming after the dog contracts them from the soil.

Whipworm Symptoms

There are few whipworm symptoms since a small amount of worms will cause no harm at all. Large amounts cause bloody, gooey diarrhea, which can become chronic and hard to control. Other symptoms include dull coat, anemia and sudden weight loss. A more rare symptom mimics Addison's disease, which prevents the dog's body from conserving salt and can result in severe dehydration requiring hospitalization.

In severe cases, whipworm may penetrate through the intestinal wall, resulting in an inflammation that causes the intestine to stick to the body. You may be alerted to this condition if your dog frequently licks his right flank area.

Detecting the Dog Worms

Dogs do not begin to shed the whipworm in their stool until about three months after being infected, so it is difficult to detect whipworm with a typical fecal test once the symptoms begin. Adult worms are 4.5-7.5 cm long, recognized by their distinct whip shape. Eggs are yellowish-brown and shaped like a barrel with a smooth shell, and a female can lay up to 2,000 eggs in a day.

Whipworm Treatment

Not all deworming products work on whipworm, so whipworm treatment presents few options, the most common being fenbendazole (Panacur) or febantel (Drontal Plus). Because of the worm's long maturation cycle (they can live for years in the intestines), a second deworming is required after about 75 days, which can be easy to forget.

Preventing Whipworms in Dogs

Some types of heartworm prevention are now designed to prevent against whipworm, including Sentinel and Interceptor. Ivermectin is effective at higher doses.

Though this is a common canine parasite, it can be very difficult to identify and treat. If you suspect whipworm in your yard, it may take years for the parasites to die, so put your dog on a dewormer and consider keeping him out of the yard on dry gravel and cement, where he cannot contract it.