It is critical that horse and yard owners and vets work together to delay further resistance to wormers, as research finds “vital clues” to aid the fight.
Two surveys were organised by Project WORMS (Working to Overcome Resistance and Make for a Sustainable future). The aim was to investigate parasite control in UK horses, identify areas where management practices could be improved and look at whether vets can better target their advice.
H&H has reported extensively on the issue; resistance to all available worming drugs is present and increasing and no new products are being developed. A spokesman for WORMS, a collaboration between VetPartners, CVS Group, IVC Evidensia and Equine Reproductive Services, supported by the British Equine Veterinary Association (BEVA), said: “The horse world could be left without effective anthelmintics in the near future, putting horses at an increased risk of parasite damage-related illnesses such as severe diarrhoea, weight loss and colic, which are currently preventable.”
The horse owner survey, completed by 4,233 people, found that 84% carry out regular faecal worm egg counts (FWEC), 40% routinely test for tapeworm, 73% poo-pick grazing and 22% graze with or alternate grazing with ruminants. Of those who do FWECs, 37% routinely worm horses at least once a year, regardless of results.
In the second survey, focusing on the breeding industry, 36% of stud managers said they have experienced parasite-related illness within the last year, most often weight loss, diarrhoea and colic. Over 20% were aware of wormer resistance on their premises.
Of those who said veterinary advice was “very important” when deciding whether to worm, nearly half used moxidectin and praziquantel as their first-line anthelmintic.
Julia Shrubb, deputy chair of VetPartners’ equine clinical board and a vet at Ashbrook Equine Hospital, said it is critical that horse owners, stud farms and veterinary surgeons work together to delay the onset of further resistance.
She said: “The information from the surveys is vital to give us a further understanding of how and why anthelmintics are given to horses. The surveys have identified areas where management practices can be improved and this will allow veterinary surgeons and SQP [suitably qualified person] professionals to give more appropriate and targeted advice and encourage responsible anthelmintic use.
“It is very encouraging that high levels of testing were reported, which underpins responsible anthelmintic use.”
Graham Hunter, IVC Evidensia equine group veterinary advisor, said a “huge educational piece” is needed on a targeted approach to wormer use.
Tim Mair, CVS equine director, added: “Resistance among horse parasites to the currently available wormers is widespread and increasing. We desperately need to reduce the overuse of these drugs, not only to stem the tide of resistance, but also to reduce the toxic effects that these drugs have on the environment.”
Key actions
CANTER (Controlling Antiparasitic Resistance in Equines Responsibly), a group set up to tackle wormer resistance, recommends owners risk assess each horse’s likelihood of suffering as a result of parasites, and work with vets to ensure appropriate control programmes.
Camilla Scott of Rossdales Veterinary Surgeons, added: “With the survey results showing that stud farms are seeing anthelmintic resistance and parasite-related disease in horses, ensuring faeces are removed from paddocks regularly, FWECs are carried out and targeted treatment is performed rather than interval dosing are key. In light of new evidence of macrolytic lactone resistance on UK stud farms, it is also critical that the indiscriminate use of moxidectin as a first-line wormer is stopped.”
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