You have asked…
Do I need to treat whipworm infection before starting a monthly heartworm preventive that is also labeled for whipworm?
The expert says…
Whipworm (Trichuris vulpis) is a parasite of the cecum and colon of dogs.1-3 Although dogs may present no clinical signs, heavy infections can cause bouts of diarrhea (with mucus and frank blood) that alternate with periods of passing normal stools. In light infections, the worms are restricted to the cecum, but as the parasite burden increases, worms are found more distally into the colon. In very heavy infections, worms can cover almost the entire wall of the large bowel, from cecum to rectum.
Related Article: Canine Diarrhea
Clinical signs appear to be due mainly to the number and physical presence of worms that have their anterior ends threaded through the colonic mucosa. Whipworms, both males and females, live with their anterior thin, whip-like stichosome esophageal portion of the body threaded within the surface epithelium of the large bowel wall (Figures 1 & 2). The host reacts with inflammatory cells, including eosinophils, and blood is lost into the bowel lumen. The posterior of the worm’s body is free within the lumen of the large bowel. The vulva of the female worm is located where the body leaves the mucosa. The male has a tail that ends with several spirals and looks like a coiled spring (Figure 3). Mating probably occurs regularly, with the male wrapping its spring-like body around the female. A single spicule has a sheath covered with spines. It takes approximately 74 to 90 days for adult females to begin passing eggs into the host's feces. The eggs, which are football or lemon shaped (Figure 4), are not infectious when passed but require several weeks in soil to develop into infective larvae within their eggshell. The life cycle is direct, with infection by ingestion of eggs in soil or soil-contaminated objects. Once whipworms reach adulthood, they probably do not change their location within the intestine.