Trichuris vulpis

Adults of the nematode Trichuris vulpis live in the large intestine of dogs and rarely cats. The life cycle is direct and the infective stage is a larvated egg.


Summary

Adults of the nematode Trichuris vulpis live in the large intestine of dogs and rarely cats.  The life cycle is direct and the infective stage is a larvated egg.  Dogs and cats infected with T. vulpis may show minimal or no clinical signs, but in some cases there can be recurrent mucoid diarrhea and dysentery.  Trichuris vulpis is usually not considered to be a zoonosis.

Taxonomy

Phylum: Nematoda
Class: Enoplea
Subclass: Dorylamia
Order: Trichurida
Family Trichurida

Trichurs vulpis, the whipworm of dogs, and the other species of Trichuris infecting domestic and free-ranging mammals, is one of a few parasites of veterinary importance in the Class Enoplea (most are in Orders in the Class Rhabditea). Others within the Order Trichurida are species within the genera Trichinella and Capillaria, which infect a variety of mammals and birds.

All species of Trichuris have a similar structure and life cycle.

Note: Our understanding of the taxonomy of helminth, arthropod, and particularly protozoan parasites is constantly evolving. The taxonomy described in wcvmlearnaboutparasites is based on that in the seventh edition of Foundations of Parasitology by Larry S Roberts and John Janovy Jr., McGraw Hill Higher Education, Boston, 2005.
 

Morphology

Adult T. vulpis are up to approximately 75 mm in length and have a characteristic “whip” shape, slender anteriorly and broader posteriorly.

Eggs of T. vulpis measure approximately 70 to 90 µm by 30 to 40 µm and, because of the polar plug at each end, are commonly described as “lemon” shaped.

Host range and geographic distribution

Trichuris vulpis occurs in dogs throughout the world, including in Canada. There is uncertainty as to whether T. vulpis occurs in cats or whether the very rare reports of whipworms in this host are a different species – possibly Trichuris serrata.

Life cycle - direct

Adult T. vulpis live in the caecum, with their anterior ends “threaded” into the mucosa. Eggs are passed in the feces and larvate in environment in 10 days. Infection follows ingestion of the larvated eggs which hatch in the intestinal lumen, releasing larvae that undergo a mucosal migration. The pre-patent period is realtively long, approximately three months.

Life Cycle: Trichuris vulpis

Pathology and clinical signs

Clinical signs of whipworm infection in dogs are associated primarily with the adult parasites and their invasion of the mucosa of the large intestine. Typical signs include diarrhea, often with blood and mucus, which may appear for a few days and then apparently resolve only to recur later. In dogs, infection with T. vulpis is more common than is disease.

Diagnosis

Typical lemon-shaped T. vulpis eggs can be detected in feces. They can easily be differentiated from eggs of intestinal Capillaria species, which is a rare infection in dogs, at least in Canada.  The eggs of Capillaria species are more parallel-sided than those of Trichuris.

Epidemiology

Probably the key element in the successful transmission of T. vulpis is the eggs, which take only a few days to become infective, and which are very resistant to adverse environmental conditions. Thus an environment contaminated by an infected dog becomes a source of infection very quickly and remains so for a very long period.

Treatment and control

Several products available in Canada are effective against the stages of Trichuris vulpis in the GI lumen of dogs. Trichuris vulpis is not susceptible to some of the more traditional anti-parasitics used for ascarids and hookworms, but most of the newer products are very effective.  There are no products approved in Canada for Trichuris infection in cats, which either does not occur or is very rare.

Drug(s) Product(s)
Fenbendazole PANACUR
Mibemycin INTERCEPTOR
Mibemycin with Lufenuron SENTINEL
Milbemycin with Spinosad TRIFEXIS
Moxidectin with Imidacloprid ADVANTAGE MULTI
Oxantel pamoatewith
Pyrantel pamoateand
Praziquantel		 DOLPAC
FOR DOGS
Pyrantel pamoate  with Febantel and Praziquantal DRONTAL PLUS

Additional information on the products mentioned is available from the Compendium of Veterinary Products (Twelfth Edition, 2011), or from the manufacturers.

Control of T. vulpis in individual dogs can usually be achieved by appropriate anti-parasitic treatment. In groups of dogs in kennels, however, control may be more difficult, primarily because the eggs of T. vulpis are extremely resistant to adverse environmental conditions and to cleaning agents. Some sources suggest using a flame thrower to optimize egg destruction!

Public health significance

People have their own species of whipworm – Trichuris trichuria, which is a major cause of human morbidity in several areas of the world. Trichuris vulpis is not known to be zoonotic.
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