Whipworms in Dogs

Dogs are much more likely to become infected with the intestinal parasite known as whipworms than cats are. Once an infection has occurred, symptoms range from none in very mild cases to bloody diarrhea, dehydration, and anemia in more aggressive cases. Fortunately, whipworms can be avoided with a monthly preventive, and they are treatable with deworming medication.


Whipworms are one of several internal parasites that commonly live in the large intestines of dogs — and only rarely in cats. This type of worm is named for the whip-like appearance of its body, which has a thicker head that tapers into a thinner tail.

Whipworms live in the dog’s large intestine, where they burrow their tails into the intestinal wall, leaving their mouths free to eat. Female whipworms produce eggs — as many as 2,000 or more a day! — which are passed in the dog’s feces. The eggs enter the soil, where they become infective in two to three weeks.

Dogs become infected by ingesting eggs from the environment, often during grooming. The eggs hatch in the small intestine, releasing larvae that eventually travel to the large intestine and become adults.

Symptoms and Identification

When the infection is limited to a small number of worms, dogs may show no signs whatsoever. Heavier infections may cause inflammation of the large intestine, resulting in diarrhea with mucus and fresh blood. Severe infections may cause bloody diarrhea, dehydration, weight loss, and anemia (low numbers of red blood cells). It’s important to note that people cannot get whipworm infections from their dogs.

A whipworm infection is almost always diagnosed by finding microscopic parasite eggs during a veterinary fecal examination. However, there are a number of reasons why parasite eggs may not be found on a fecal examination, even when the dog is infected with whipworms. First, female whipworms don’t lay eggs all the time, so multiple fecal exams may be required over several weeks before eggs are found. Second, from the time a dog ingests a parasite egg, it can take up to three months before the female whipworm lays eggs. As a result, dogs may show signs of infection long before eggs are released in the feces. Finally, even when eggs are in the feces, they may be difficult to find in the fecal exam.

Even if whipworm eggs aren’t found, veterinarians often treat for a whipworm infection anyway, if the dog shows signs of infection.

Affected Breeds

All breeds of dogs seem equally at risk.


Treating whipworm infections usually comes down to giving one of a number of drugs that kill the worms in the large intestine. It’s recommended that all dogs in a household are treated, even if they don’t all test positive for the presence of the parasite. At least two doses of drugs two to three weeks apart is a common protocol, but other approaches can be equally effective.


To prevent other dogs from being exposed to whipworm eggs if your dog is infected, you should make every effort to pick up and dispose of feces as soon as possible. However, whipworm eggs are very resistant to temperature extremes and radiation from sunlight, so they can contaminate the soil for months or even years. That’s why it’s a good idea for your dog to have periodic fecal exams and receive a monthly heartworm preventive that protects against whipworms.

This article has been reviewed by a Veterinarian.

Join the Conversation

Like this article? Have a point of view to share? Let us know!