What to know about canine whipworm infection

Whipworm egg.

Photo: Saiful52/Adobe Stock

Canine whipworm infection occurs after a dog has eaten an egg left in the soil or other contaminated environments. Although some infected canines may not show signs, diarrhea or soft stool with blood or mucus, as well as lethargy, weight loss, and dehydration, may be seen in other infected dogs.¹

Susan E. Little, DVM, PhD, DACVM, the Krull-Ewing professor of parasitology at the Center for Veterinary Health Sciences at Oklahoma State University in Stillwater, identified parasites that commonly infect canines and expressed a need for comprehensive control strategies to address them, during an educational session at the 2025 Veterinary Meeting & Expo, hosted by the North American Veterinary Community, in Orlando, Florida. The session included discussion on the prevalence, diagnosing, and concerns related to canine whipworm.²

“They can survive freezing. They can survive in the dirt for years, though they last 6-7 years or longer, still remain effective,” said Little.

Prevalence

In 2024, 0.4% of more than 13.7 million dogs—or 1 in [250]—tested positive for whipworm in the United States. A Companion Animal Parasite Council (CAPC) map shows incidence of infection is higher in the US southeast with Kentucky and West Virginia having the highest prevalence.^2,3

According to Little, older literature has shown that whipworm larvae require warmer temperatures and high humidity environmental conditions to develop. “It sort of explains, a little bit, some of the whipworm patterns that we've seen over the years.”

Citing a study she coauthored in 2020, Little said 300 dog parks across the US were used to collect fecal samples that were tested for whipworm. Like the CAPC map, prevalence was shown to be higher in dog parks in the southeastern US with 2% to 3% of tested canines reported positive for infection.⁴

Diagnostics

“Whipworms are tricky to diagnose compared to hookworms and roundworms. They're way easier to diagnose than tape worms," said Little.

Little said that whipworms in dogs can cause blood loss, fluid loss, and damage to the gastrointestinal tract. Because they’re internal, they are seen by humans as eggs and in wood form.

“[Whipworm] eggs are one of the veterinary students’ favorite eggs to identify, because they're so clear and standard and readily recognized. We can find them in practice, but we also overlook a lot of them, and it depends on how you're doing fecal flotation and what solution is being used that influences sensitivity of detection,” said Little.

Passive fecal flotation is “very insensitive,” Little said. She recommends active centrifugal fecal flotation, ideally with a higher-gravity solution, such as a sugar solution.

“Now we have antigen tests as well, and that's why we're learning more that lower prevalence in the western US is real. The lower prevalence in pet dogs is real because they're also coming up antigen negative,” said Little.

PCR testing is also available for canine whipworms. However, Little said, the sensitivity of these tests compared to other diagnostic methods is unknown.

Concerns

Whipworms are hardy, and persist in the environment once contamination has occurred.^1,2 “[Once] you get whipworms in your backyard, you got whipworms, and so that's the reason we focus so hard on trying to make sure dogs don't have whipworms, because of that persistent contamination,” Little said.

Whipworm eggs must be in an environment for 9-12 days after an infected dog passes them to become larvae and infective to another dog. After being consumed by a dog, whipworm larvae can take up to 90 days to mature to egg-producing adulthood.¹

Lifestyle plays a role in a dog’s risk of whipworm infection. “Did they go to the dog park? Were they a shelter dog, a rescue dog, a street dog, rehomed, she asked. “With whipworms, we're moving toward the recommendation on risk assessment, where we look at age. Younger dogs are more likely to be infected with parasites, in general.”

Takeaway

Canine whipworm can cause gastrointestinal damage, according to Little, but infection is preventable and treatable, and there is little resistance to drug therapies.² Monthly parasite preventives are recommended as well as immediate removal of canine feces to prevent environmental contamination. Pet owners should also use caution when visiting dog parks and other locations where canines frequent.¹

Additionally, this parasite is not considered zoonotic. “There's not as much concern about having constant, recurrent infection,” said Little.

However, vigilance is key to preventing canine whipworm infection and recurrence. “Once they're in the backyard, you can get rid of them. You just have to keep up the antigenic pressure. It's going to be a lot of work,” she said.

References

1. Cohen A. Whipworms in dogs. Cornell Richard P Riney Canine Health Center. August 2024. Accessed January 26, 2025. https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information/whipworms-dogs
2. Little SE. The early vet catches the worms. Presented at: Veterinary Meeting & Expo; Orlando, FL. January 25-29, 2025.
3. Parasite prevalence maps. Companion Animal Parasite Council. Accessed January 26, 2025. https://capcvet.org/maps/#/2024/all-year/whipworm/dog/united-states
4. Stafford K, Kollasch TM, Duncan KT, et al. Detection of gastrointestinal parasitism at recreational canine sites in the USA: the DOGPARCS study. Parasites & Vectors. 2020;13:275. doi:10.1186/s13071-020-04147-6