A study by Janssen Animal Health has, according to the company, demonstrated that a leading herbal wormer had no demonstrable efficacy against common poultry worms¹.

The trial, done to Good Clinical Practice (GCP) Standards, involved 48 chickens that had become naturally infected with three different poultry worms - Capillaria (Hairworm) species, Heterakis gallinarum (Caecal worm) and Ascaridia galii (Large roundworm). The birds were randomly assigned to one of three groups:

A. Flubenvet treated group
B. Herbal wormer treated group
C. Control (untreated) group.

The herbal treatment was administered for 3 days in-feed, as required by the 'on-pack' instructions and Flubenvet was given for 7 days as required on the product data sheet. Droppings were collected from individual birds and group pens at intervals for 2 weeks and examined for the presence of worm eggs

Table 1: Worm Count Summaries

The results showed that very few worm eggs were present after one 7-day treatment with Flubenvet. In contrast, those that had no treatment or the herbal treatment still had hundreds of worm eggs in their droppings, suggesting that there were still many adult egg-laying worms present inside the chickens.

Janssen says poultry keepers who rely on preparations like this particular natural wormer may well be building up problems, as the additional numbers of worm eggs in the environment add to the infection pressure and can result in greater worm burdens for their birds. Birds with high worm burdens are more likely to become ill.

• H. gallinarum - causes mild illness but also acts as a carrier for the microscopic protozoan parasite Histomonas meleagridis (Blackhead) in turkeys. The eggs of the worm can live for years in soil so this parasite can be difficult to eradicate and re-infection is common unless regular and effective worming is carried out.
• Capillaria - causes malnutrition, emaciation and anaemia in chickens and death in other poultry species.
• Ascaridia gali - causes emaciation, drop in egg production, ill thrift, anaemia, intestinal blockage and death. Occasionally the parasitic worms may be found in chicken eggs. Earthworms are a common intermediate host, particularly likely to result in parasitic infection of free-range poultry when they eat earthworms.

According to the Veterinary Medicines Regulations 2009 any product making veterinary medicinal claims needs to be licensed by the Veterinary Medicines Directorate. A licensed product has to show proven efficacy and safety for the animal species involved. Licensed veterinary medicines can be identified by their Vm number, which is shown on-pack. Products termed 'nutritional supplements', that are not licensed do not require the manufacturer to produce any proof of efficacy or safety. It is often easy to buy such products 'off the shelf' because they are not subject to any controls. Any poultry keeper who cares about the health and welfare of the birds is advised to think carefully about their choice of wormer and to seek advice from a vet pharmacist or Suitably Qualified Person (SQP).

¹ Evaluation of the efficacy of flubendazole in comparison with a herbal wormer in the treatment of naturally acquired infections of Ascaridia galli, Heterakis gallinarum, and intestinal Capillaria spp in Chickens, Janssen Animal Health

PS: Whilst you're here, take a moment to see our latest job opportunities for vets.