• Whipworms are small parasites that can live in the large intestines of dogs and, rarely, in cats.
• Dogs become infected by eating the whipworm eggs in the soil, usually during grooming.
• Not all dogs show signs of a whipworm infection, but those that do may have diarrhea with blood and mucus, dehydration, and weight loss.
• Whipworm infections are diagnosed by finding parasite eggs during a veterinary fecal exam.
• Infections are treated with medications given once a month for a few months or with monthly heartworm preventives that protect against whipworms.

What Are Whipworms?

Whipworms are one of several internal parasites that can live in the large intestines of dogs and, 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 2000 or more a day, which are passed in the dog’s feces. The eggs enter the soil, where they become infective in about 2 to 3 weeks.

How Do Dogs Become Infected With Whipworms?

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

What Are the Signs of a Whipworm Infection?

When the infection is limited to a small number of worms, the dog may show no signs at all. Larger 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). People cannot get whipworm infections from their dogs.

How Are Whipworm Infections Diagnosed?

A whipworm infection is 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 3 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 if the dog shows signs associated with an infection.

How Is an Infection Treated?

Whipworm infections are generally treated with medications given once a month for a few months. Some monthly heartworm preventives also contain medications that are designed to eliminate whipworm infections. Talk with your veterinarian about giving your pet preventive medication against whipworms.

How Can I Protect My Dog From Whipworm Infections?

To prevent your dog from being exposed to whipworm eggs, 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 monthly heartworm preventives that protect against whipworms.