This technical information is used by permission from The Companion Animal Parasite Council. For questions and more information specific to your pet(s), please contact your personal veterinarian or write us at info@ahsvet.com.
Whipworm
Adult Whipworms
Adult Whipworms
Species
Canine
Trichuris vulpis occurs in the dog, fox, and coyote.
Feline
Although feline whipworms occur in tropical areas, they appear to be rare in domestic cats in North America; putative whipworm eggs in feline fecal samples are more likely to be a capillarid other than Trichuris sp. Additional information about feline whipworm infections can be obtained by consulting Bowman et al., Feline Clinical Parasitology, Iowa State University Press, Ames, Iowa, 2002:348–350.
Overview of Life Cycle
- Trichuris vulpis has a direct life cycle.
- Eggs are unembryonated when passed in feces and are highly resistant to desiccation, extremes in temperature, and ultraviolet radiation. Eggs embryonate in 9 to 21 days (or longer) depending on the temperature and moisture content of the soil. Infective whipworm eggs can remain viable for many years. Hosts are infected by ingesting embryonated eggs from the soil or other substrates in which eggs are found.
- Larvae hatch from eggs (generally in the small intestine) and penetrate the mucosa. They develop for 2 to 10 days in the mucosa, move to the cecum (occasionally the terminal small intestine or colon), and mature to adult worms.
- The prepatent period of T. vulpis is 74 to 90 days.
Stages (see images below)
- Whipworms are named for their characteristic whip-shaped body. The body is composed of a thin, filamentous, anterior end (the “lash” of the whip) and a thick posterior end (the “handle” of the whip). Adult worms are 4.5- to 7.5-cm long. Approximately 75% of their length is composed of the anterior (lash) portion of the whipworm (see image on right).
- Eggs are barrel-shaped and yellow-brown, with prominent bipolar end plugs and a smooth shell.
- Eggs are approximately 79 by 38 μm (link to image). They must be distinguished from eggs of Eucoleus spp. and Pearsonema spp., which are smaller and have a rough surface (Lungworms and Urinary Nematodes).
- Larvae hatch from ingested embryonated eggs and enter the mucosa of the small intestine (occasionally the large intestine). Larvae reenter the lumen and move to the cecum where they mature to adult worms (see image on right).
- Adult worms begin producing eggs between 74 and 90 days after infection. Each female T. vulpis can produce more than 2,000 eggs per day.
Whipworm Eggs
Adult whipworms in a dog's cecum.
Disease
- Many canine whipworm infections are either asymptomatic or subclinical.
- Some infections result in typhilitis or colitis characterized by diarrhea that is often streaked with mucus and fresh blood.
- Severe infections result in bloody diarrhea, weight loss, dehydration, anemia, and in the most extreme cases, death.
Prevalence
- Prevalence surveys confirm that T. vulpis occurs in dogs worldwide.
- Whipworms were reported in 14.3% of shelter dogs sampled in a U.S. national fecal parasite survey (Blagburn et al., 1996).
- In a retrospective study of fecal exams, whipworms were found in 10% of dogs presented to a veterinary teaching hospital in Pennsylvania (Nolan and Smith, 1995).
Host Associations and Transmission Between Hosts
- Dogs acquire T. vulpis infections only by ingesting eggs containing infective larvae from the environment.
- Indirect transmission between animals via paratenic hosts and transplacental or transmammary transmission from the dam to her offspring does not occur.
Prepatent Period and Environmental Factors
- The period from ingestion of embryonated eggs until eggs appear in feces is 74 to 90 days.
- Infective whipworm eggs may persist in the environment for several years.
Site of Infection and Pathogenesis
- Developing larvae of T. vulpis live in the mucosa of the small intestine (rarely the large intestine).
- Development of larvae in the mucosa does not appear to result in demonstrable disease.
- Trichuris vulpis adults live primarily in the cecum. Occasionally adult worms are recovered from the posterior small intestine or the anterior large intestine.
- Adult worms “thread” their anterior ends through the superficial mucosa. The larger posterior end extends into the cecal lumen.
- Adult whipworms consume blood, tissue fluids, and mucosal epithelium.
- Feeding habits of the worms can result in bloody diarrhea, weight loss, dehydration, anemia, and in severe cases, death.
Diagnosis
- Trichuris vulpis infections are usually diagnosed by detecting characteristic eggs in feces.
- Even when eggs are not present, disease caused by T. vulpis may be identified on the basis of history, clinical signs, and response to therapy.
- Three issues may complicate diagnosis:
- Because of the long prepatent period, infected animals may show clinical signs before eggs are shed in the feces.
- Eggs may be shed intermittently.
- Eggs are quite dense (average specific gravity = 1.15); proper technique (centrifugation) must be used to recover them on fecal flotation. Some data indicate that the use of sugar solution can increase the sensitivity of whipworm egg detection (Dryden et al., 2005).
Treatment
- The following anthelmintics are approved for treatment of T. vulpis infections in dogs:
- Drontal Plus® (febantel [25 mg/kg], pyrantel pamoate [5 mg/kg], and praziquantel [5 mg/kg]), single administration)
- Panacur® (fenbendazole [50 mg/kg]) for 3 consecutive days
- To achieve control, treatment can be administered once a month for 3 months.
- The following anthelmintics are approved for treatment and the continued monthly treatment of T. vulpis infections in dogs:
- Interceptor® (milbemycin oxime [0.5 mg/kg])
- Sentinel (milbemycin oxime [0.5 mg/kg] and lufenuron [10 mg/kg])
- Advantage Multi (moxidectin [2.5 mg/kg] and imidacloprid [10 mg/kg])
Control and Prevention
- Prevention of T. vulpis infections requires reducing exposure of dogs to embryonated eggs in the environment. This is best achieved by promptly removing feces from yards and other environments where dogs defecate.
- Perform periodic fecal examinations and treat infected dogs immediately with one of the products offered by your veterinarian.
- Control of T. vulpis can be achieved by use of monthly broad-spectrum heartworm prevention products that also control whipworms.
Public Health Considerations
- Although there are reports in the medical literature of human infections with T. vulpis, these reports lack sufficient validation to consider T. vulpis a zoonotic parasite at this time.
This information was made available by The Companion Animal Parasite Council. (CAPC)
ABOUT CAPC
The Companion Animal Parasite Council (CAPC) is an independent council of veterinarians and other animal health care professionals established to create guidelines for the optimal control of internal and external parasites that threaten the health of pets and people. It brings together broad expertise in parasitology, internal medicine, public health, veterinary law, private practice, and association leadership.
Initially convened in 2002, CAPC was formed with the express purpose of changing the way veterinary professionals and pet owners approach parasite management. The CAPC advocates best practices for protecting pets from parasitic infections and reducing the risk of zoonotic parasite transmission. The council has four major objectives:
- adoption of practices and procedures to protect pets from infections by parasites;
- adoption of practices and procedures to reduce the risk of transmission of zoonotic (transmittable from animals to humans) parasites from pets to people;
- collaboration among pet owners, veterinarians, and physicians to control infections by parasites; and
- collaboration with other groups that share the common interests of parasite control and animal and human health.
