The Horse Trust calls on horse owners to 'stop over-worming'

The Horse Trust is launching a campaign to ask horse owners to take a more informed and strategic approach when worming their horses to tackle the growing problem of drug-resistant worms.

"With the start of the grazing season, owners will be thinking about worming their horses. We are asking owners to stop over-worming their horse and to work with their vet in developing a tailored management programme for each horse," says Paul Jepson, Chief Executive and Veterinary Director of The Horse Trust.  "This will not just reduce the risk of the worms in their horses becoming resistant to worming drugs, but could save them money on expensive worming drugs,"

"Many owners simply buy drugs from veterinary supply stores and give their horse the drug at regular intervals. As many horses have a natural resistance to small redworms, they may not need to be treated for this type of roundworm, so owners could save money by getting their vet to test their horse first," added Paul.

Small redworms (cyathostomins) are the most important parasite affecting horses. A severe infection of small redworms can lead to weight loss, colic, diarrhoea and death.

But overuse of worming drugs has led to the development of drug-resistant worms. Researchers have found evidence of small redworm resistance to each of the three drug types, and the first incidence of multi-drug resistance was recently discovered in Brazil².

"If we don't take action now, there is a risk that we may see multi-drug resistant small redworms in the UK within a couple of decades," said Paul. "This would have a devastating effect on horses and their owners, with many horses suffering the horrific effects of severe small redworm infections."

A current research project being funded by The Horse Trust has found that UK stud farm managers and other horse owners are worming their horses unnecessarily and too frequently.

The research project, led by Professor Jacqui Matthews¹ group at the Moredun Research Institute in Scotland, aims to develop a test that can quickly screen for horses infected with drug-resistant small redworms. Her group is also investigating how the worms adapt to drugs at the level of their DNA.

The first stage of Professor Matthews' research was a background survey of stud farms around the UK. She found that the majority of the people who responded to the survey were worming the horses in their care too frequently - few stable managers were performing faecal egg counts before treatment for small redworms (this would help assess which horses were contaminating pasture most and therefore requiring treatment) and in some cases horses were being given medication more often than recommended³.

The Horse Trust plans to run a marketing campaign over the coming months to raise awareness among horse owners and stable managers about the risks of over-worming and the need to take a more responsible approach when treating horses for small redworms. It also hopes to raise money to fund further research into drug-resistance in small redworms.

For more information, or to donate money to the campaign, please visit www.horsetrust.org.uk/small-redworm-campaign/