The particularly warm and dry 2025 summer is thought to be linked to a “notable rise” in worm egg count results in UK horses – even among those horses who have historically had low or clear results.
Provisional Met Office statistics, shared on 1 September, confirm that summer 2025 was officially the warmest summer on record for the UK. Westgate Labs, which specialises in parasite control for horses and offers postal worm egg count testing, noticed the pattern through this autumn’s test results in UK horses – and believes the two are linked.
Experts are urging owners to test regularly and poo pick frequently as the “first line of defence” against worm infestations.
“What we’re likely seeing is the impact of a warm summer allowing the larval development phase to speed up, meaning horses can become more readily infected as they graze,” said Professor Jacqui Matthews, recognised specialist in parasitology and director of veterinary science at Austin Davis Biologics.
“There’s also been less forage available, so horses have been cropping the grass closer to the soil and dung piles and there’s been less opportunity to rest and rotate grazing, further increasing infection potential.
“What this means for horse owners is that they need to be regularly testing all horses as even those with historically good results may be more at risk of worm infection than in previous years and prioritising poo picking.”
Westgate Labs highlighted that many owners carrying out their routine autumn tests were surprised to see higher counts than expected – horses who had previously shown low or clear results are now presenting with medium or high readings, despite no change in management.
Horse & Hound Newsletter
Never miss out on the latest happenings in the equestrian world
Westgate Labs’ director, Kristy Hodgson added: “Alongside worm egg counts every eight to 12 weeks, poo picking is our first line of defence in helping to combat parasite infection, physically breaking the life cycle by removing the eggs from the pasture.
“I chat to tens of horse owners every day and it’s consistently our customers who aren’t able to clear dung who have seen the biggest rise in the number of horses requiring treatment this autumn.
“The data reinforces the importance of pasture hygiene over harrowing, which in warm, damp conditions may spread larvae rather than destroy them.”
Westgate Labs recommends testing all horses every 12 weeks, plus twice-yearly tapeworm tests, to ensure targeted treatment and avoid unnecessary worming, which contributes to drug resistance.
Westgate Labs and Austin Davies Biologics are presenting a free webinar with a focus on redworm infection at 7pm on 14 January. Find out more at: fb.me/e/4rPYI7SHH
Stay in touch with all the news in the run-up to and throughout the major shows and events during 2026 and beyond with a Horse & Hound subscription. Subscribe today for all you need to know ahead of these major events, plus online reports on the action as it happens from our expert team of reporters and in-depth analysis in our special commemorative magazines. Have a subscription already? Set up your unlimited website access now
Lucy is an experienced news journalist, reporter and presenter. Since joining the Horse & Hound team in 2015, Lucy has reported from major global sporting events including the Tokyo Paralympic Games and multiple European Championships, as well as Badminton, Burghley and London, to name a few. She has covered current affairs and sports news across the full spectrum of equestrian disciplines and racing, as well as human and equine welfare, industry news and court cases.
