Whipworms

Advocate^®: Effective Against Whipworms

Whipworms are parasites of the caecum, and in heavy infections the colon, of many mammalian species. The canine whipworm, Trichuris vulpis, is found worldwide and may be of considerable clinical significance. There is no evidence that T. vulpis is capable of infecting cats.

The Parasite

Fig. 1: Trichuris vulpis

T. vulpis is a blood-feeding nematode and is found with its anterior end embedded in the mucosa of the caecum. T. vulpis measures 45 – 75 mm in length and the male worms possess a very long speculum at the rear end. As for all whipworms, the T. vulpis body has the typical name-giving feature of a long and thin, hair-like anterior part and a short and thick posterior body part.

Life Cycle

The whipworm has a direct life cycle. Inside the excreted egg, the infective larval stage (L2) develops within 3 to 4 weeks. Under optimal conditions, this may occur in even less than 2 weeks. However this development can also be prolonged for as long as several months. Infective eggs may survive in soil for several years and be a source of re-infection for dogs exposed to a contaminated environment.

After ingestion, the larvae hatch and penetrate the mucosa of the gastrointestinal tract. Here, development occurs and migration to the mucous glands of the caecum, where the adult stages can be found. The pre-patent period of T. vulpis is reported to be 70 – 100 days, and adults live for up to 16 months. There is no age restriction for whipworm infections.

The eggs are in lemon-shaped with distinct plugs on both pole sides. As mentioned previously, the eggs can survive for long periods in the soil, however they are affected by desiccation.

To watch or download the animation of the Canine Whipworm's life cycle please visit our download area.

Pathogenesis and Clinical Appearance

T. vulpis is a blood feeding nematode, with the anterior end of the body embedded in the mucosa of the caecum. In heavy infections, the mucosa may show thickening, edema, and petechial bleeding.

Clinical signs of massive infections are hemorrhagic enteritis, with mucus and blood in the faeces and often foul smelling. Concurrent anaemia may also be present. The slow development time of T. vulpis, together with mainly sub-clinical signs, may be the reason for the general belief that whipworm infections in dogs may be less pathogenic. However, infections may cause reduced growth in young dogs and wasting.

Zoonotic significance

On rare occasions, the common whipworm of dogs has been reported in man. However, in comparison to hook and roundworms, T. vulpis does not play a zoonotic role of importance in transmission to humans.

Diagnosis

Fig. 2: Trichuris vulpis egg

The lemon-shaped eggs with plugs on both ends are clearly distinguishable (Fig.2). The egg size is 70-85 µm in length and 35-40 µm in width.

Efficacy of Advocate^® against adult hookworms

In several of the studies that were carried out in dogs to determine the efficacy of Advocate against other gastrointestinal nematodes, it was possible to investigate efficacy against Trichuris vulpis. Out of five such studies, a total of 814 worms were recovered from 18 control dogs, whilst only 2 worms were identified in one Advocate-treated dog. All the other dogs treated with Advocate were free of whipworms. The efficacy of Advocate against T. vulpis based on these five studies was 96-100%.

This corresponded well with a specific study conducted in dogs naturally infected with whipworms.¹ Twenty-two whipworm-positive dogs were randomly allocated to either a placebo-treated control group or an Advocate-treated group. On day 0 of the study, Advocate was applied using one of the four pipette sizes according to the respective bodyweight of each dog. All dogs were examined 10 days post-treatment. The efficacy of Advocate against a patent whipworm infection was found to be 97% (Table 1).

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References

1. Bayer Study No. 23300