Whipworms are an intestinal parasite of dogs and rarely, cats. Human whipworm infection is not caused by the species of worm that infects our pets, so zoonosis is unlikely in healthy people. Female whipworms lay eggs intermittently and in low numbers, making them easy to miss during a fecal exam. The adult worms reach a length of about 2 inches, so they can be seen by the unaided eye. However, they are seldom passed in stool, so rarely are they observed. Heavy whipworm burdens cause significant inflammation in the gut and lead to bloody diarrhea. Undiagnosed whipworm infections can cause waxing and waning symptoms that can mimic other diseases.
Whipworms are blood suckers, but they usually do not cause anemia by themselves. They pass eggs in the stool which incubate in the environment for 2 to 4 weeks before becoming infective. A microscopic larva forms inside the egg which will hatch in the digestive tract when a new host inadvertently ingests it. This typically occurs when an animal grooms itself. The larva will mature into an adult whipworm as it makes its way into the cecum, the area where the small and large intestines connect. About 80 days pass after ingestion of an egg before adult worms are mature enough to mate.
Whipworm infection may be diagnosed when a veterinarian performs a fecal flotation. Eggs are floated in a salt solution and observed under a microscope. Because there are typically so few eggs present, a negative test is not a rule out for suspected whipworm infection. The veterinarian may choose to prophylactically de-worm your pet if intermittent lethargy and diarrhea persists. De-worming is repeated three times at monthly intervals because of the long lifecycle of the whipworms.
Viable, infective whipworm eggs can persist in contaminated soil for years, so stools should be removed from the pet’s environment.