A worm egg count specialist has warned of a spike in worm egg count results among the UK equine population following this year’s warm, dry summer. Those involved in horse care are urged to ensure they clear their horses’ paddocks of droppings to help mitigate the risks.
Westgate Labs reported the “notable” rise in this autumn’s test results. Many owners carrying out their routine tests were surprised to see higher counts than expected, with horses who had previously shown low or clear results now presenting with medium or even high readings despite no change in management.
It is thought that the relatively high temperatures in summer combined with intermittent rain may have provided ideal conditions for larvae to develop and survive on pasture, leading to infection and, subsequently, higher levels of egg shedding.
Professor Jacqui Matthews, Recognised Specialist in Parasitology and Director of Veterinary Science at Austin Davis Biologics, said poo picking should be prioritised, as well as regular worm testing.
“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,” she said. “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’s findings
Monthly summary of equine worm egg count results for 2025 shows a higher proportion of horses shedding more strongyle eggs compared with previous years.
In September, 13.34% and 19.42% of worm egg count results were above 200 eggs per gram (epg.) in 2023 and 2024 respectively, rising to 24.12% in 2025. A similar pattern was seen in October, with 13.44% of tests above 200 epg. in 2023, 19.18% in 2024, and 25.04% in 2025. Egg shedding stayed high November 2025 with 25.29% above the threshold, compared to 20.46% in 2023 and 20.56% in 2024.
The threshold of 200 epg. is important, as it marks the level at which treatment is indicated for most healthy adult horses within a targeted parasite control programme.
Westgate Labs’ director, Kristy Hodgson, echoed Jacqui’s advice, stressing the importance of clearing pastures of droppings.
“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,” she said.
“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.”
Mitigating the risks
Westgate recommends regular worm egg counts every season. Testing all horses every 12 weeks, alongside twice-yearly tapeworm testing, ensures targeted treatment and helps avoid unnecessary worming that contributes to drug resistance.
Owners are recommended to risk assess their horses for parasite infection, using either the CANTER or What’s Your Worm Risk profiling tools and speak to their prescribers to decide on their approach to encysted stages of small redworm this autumn and winter.
Those interested in finding out more about redworm infection can tune into a free webinar by Westgate Labs and Austin Davies Biologics.
The webinar take place on Wednesday 14 January at 7pm, to sign up click ‘going’ on the Facebook event page.
