Newsdate: Friday June 29, 2018, 9:00 am
Location: MIDDLE STOBSWORTH MORPETH, Northumberland

From October 2018 the wormer brand, Equitape®, commonly used to treat tapeworm infection will be discontinued from sale in the UK. This wormer is the only licenced product for horses containing praziquantel as a single active ingredient. Going forward, it will only be available in ‘combination wormers’ also containing either ivermectin or moxidectin, the drugs most commonly used to treat small and large redworm (strongyles).

Research tapeworm specimen

Horse health professionals rally to determine best practice as 'Equitape' horse wormer to be discontinued October 2018.
© 2012 by Lorren Alumasa

Equitape’s removal from the portfolio of veterinary medicines available to target specific worm infection presents a challenge to prescribers and horse owners alike.

Two leading laboratories; Westgate Labs, postal worm count specialists, and Austin Davis Biologics, manufacturers of the innovative EquiSal Tapeworm test, are responding to this news to stress the increasing importance of evidence-based control in managing worm burdens in horses. In partnership with Professor Jacqui Matthews FRCVS, Moredun Research Institute, they have set out to develop best practice advice to minimise the impact on sustainable worm control.

Professor Matthews commented: “I think it’s an issue that limits prescribers’ options for worm species-targeted treatments. Wormer resistance is a growing problem and has the potential to become a major horse welfare threat. Losing the option of a praziquantel-only product means that any treatment option for tapeworm infection will now also impact redworms, whether required or not. Frequent drug exposure speeds the development of resistance and, over time, has potential to significantly decrease the effectiveness of the few chemicals that we have to treat life-threatening worm burdens in horses.

“To guard against this, we must become more strategic with parasite control. This means seeking tailor-made solutions for worm control based on knowledge of management, infection risk, drug sensitivity and, importantly, robust diagnostic tests.”

Evidence based control

Regular testing should form the centre of any programme to determine whether or not a worming treatment is required to keep drug exposure to a minimum. Worm egg counts should be conducted every two-three months (with frequency depending on risk) and tapeworm tests performed every six months to monitor infection levels in healthy adult horses.

Lester & Matthews (2013) identified that: “Faecal egg counts can be used to identify the likely 15-20% of horses that need worming to reduce worm egg shedding and can reduce wormer use by up to 82%”. EquiSal Tapeworm test data shows that fewer than 27% of horses tested require treatment for tapeworm (Austin Davis Biologics) and Lightbody et al (2017) demonstrated that using EquiSal Tapeworm in a targeted worm control programme reduced the use of tapeworm wormers by 86%.

The exception to evidence-based control is treatment with moxidectin late autumn/winter dose to target encysted redworm and large redworm larvae, which can’t be detected using worm egg count methods.

Consultant vet to Westgate Labs, Carolyn Cummins MVB PhD MRCVS commented: “With reduced specificity of treatment options, we are concerned that the temptation could be to treat more and test less. However with resistance rising, the only way of identifying problems is by testing routinely, together with resistance testing, to build up a picture of what’s going on. Giving a wormer without understanding the worm burden present or without being aware of the efficacy of the wormer you’re using is a false economy for your horse’s health.”

What does this mean in practice?

Testing for tapeworm prior to the annual treatment for encysted redworm in late autumn/winter is an easy win. This will help to decide whether a moxidectin only (or where there is no resistance known, a 5-day fenbendazole) treatment is required, or if a moxidectin + praziquantel combination wormer is advised to include treatment for tapeworm at the same time.

At other times of year where it has been confirmed that treatment for tapeworm is needed, a worm egg count should be conducted. If treatment for redworm is indicated at the same time, then an ivermectin + praziquantel combination wormer should be the first choice.

Alternatively, a double dose of pyrantel can be recommended for administration if;

• the treatment is for tapeworm only
  or
• ascarids are also present (more likely in foals or yearlings)
  or
• the redworm population in question is known to not be resistant to pyrantel.

*seek advice from prescriber on efficacy testing

**seek advice from a veterinary surgeon or Suitably Qualified Person on the use of moxidectin outwith autumn/winter

N/A – not applicable

Reducing reliance on chemicals

Professor Matthews commented, “Wherever possible, we must look to reduce infection risk and break the lifecycle of the worms without overly relying on wormers. Best practice control should include the following; strategic treatments, targeted (diagnostic test led) treatments, annual tests for wormer resistance, good pasture hygiene such as poo picking and implementing appropriate quarantine procedures for new horses.”

For more information please visit www.westgatelabs.co.uk or www.equisal.co.uk or www.moredun.org.uk/research/diseases/parasitic-roundworms-equine.

Westgate Labs and Austin Davis Biologics are independent laboratories and do not sell wormers, they are diagnostic service providers and provide expert evidence-based control advice.

References

Lester, H., Matthews, J.(2013) Equine Vet. J. 46, 139e145.

Lightbody, K. L. et al (2017) Equine Vet J, 50: 213-219.

High resolution image available to download at https://www.westgatelabs.co.uk/media/1255/westgate-worming-consultation.jpg please credit Jon Stroud
Horse Worm Treatment Prescribing Options table download as a .png https://www.westgatelabs.co.uk/media/1286/tapeworm-treatment-options-v2-white.png
Horse Worm Treatment Prescribing Options table download as a .pdf https://www.westgatelabs.co.uk/media/1284/tapeworm-treatment-options-v2.pdf

For relevance to the horse owner we have referred to parasites by their common names in the above text. For the avoidance of doubt these are:

Tapeworm; Anoplocephala perfoliata, Anoplocephala magna and Anoplocephaloides mamillana.
Small redworm; also known as small strongyles or Cyathastomin (spp)
Large redworm; also known as large stronyles or Strongylus vulgaris
Roundworm; also known as ascarids or Parascaris equorum

Bayer Animal Health is responsible for the production of Equitape and are the designated Marketing Authorisation Holder. The product is distributed by Zoetis.

As there are sometimes several brand names associated with the same active ingredient in wormers we have chosen to use the chemical name of the drug in the description above in order to avoid confusion.

There are only five main types of wormer available to treat horses in the UK, namely:

About Westgate Labs

For the past 19 years Westgate Laboratories has been leading the field in helping horse owners to manage the parasite control of their horses and other grazing animals. The laboratory offers a trusted postal worm count and testing service including friendly veterinary approved advice, enabling carers and keepers to target the wormers given to horses and keep them as healthy as possible.

About Austin Davis Biologics

Austin Davis Biologics Ltd (ADB) is a science and technology company focussed on biosciences. As well as inventing the EquiSal Tapeworm test, used to diagnose tapeworm burdens in horses their additional parasitology research includes diagnostic tests for other equine helminth species, as well as diagnostic tests for various farm and domestic animal parasites. The team pursue collaborative research with a number of universities and partner companies, currently involved in projects with the Royal Veterinary College, Moredun Research Institute and University of Kentucky.

About Professor Matthews

Jacqui Matthews, a qualified veterinarian, has worked in livestock and equine parasite research and education for more than 25 years. Her group studies roundworms, focussing on vaccine development, anthelmintic resistance and parasite epidemiology. One of her highlight research outputs is the development of a diagnostic test for small redworm infection in horses. As well as publishing prolific numbers of peer-reviewed research papers, reviews and book chapters she dedicates much of her time to the transfer of knowledge on sustainable parasite control to industry, stakeholder and scientific audiences and shares this information on Twitter: @ProfJBMatthews.