Poo picking proven as powerful as giving a worming treatment to control parasites in horses

Resistance means we can no longer reach for a wormer and know it will work. But what if there was another way of reducing parasites that didn’t rely on chemicals? Westgate Labs shares how numerous studies have shown that poo picking can be just as effective as giving a treatment.

Parasite specialists Westgate Labs are calling for horse owners to get more serious about management as a way of tackling the increased threat of disease that wormer resistance poses and to reduce reliance on chemicals.

This focus on husbandry is incorporated into the easy three-step call to action they are promoting to manage parasite control effectively; Risk Assess, Test, Manage. Director Kristy Hodgson says: “We’re encouraging owners to go beyond the testing to tackle infection at source. Removing dung at least twice a week, before worm eggs hatch, prevents larvae from getting onto pasture and breaks the lifecycle mechanically without the need for chemicals. It’s hard work but if we can visualise the benefits to our horses and prevent them ingesting those larval worms, its motivation for us all to get out there!”

In one study by Corbet et al 2014, three herds of donkeys were monitored over a grazing season to assess how different dung removal strategies influenced parasite levels. The results were clear. Groups where dung was removed, whether manually or by mechanical means, had significantly lower worm egg counts than those grazing fields where dung was left in place.

A second study, Tzelos et al 2017, compared two groups of horses following treatment with the wormer moxidectin. One group grazed pasture where dung was removed regularly, while the other grazed fields where droppings were left. Horses on the poo picked paddocks had lower worm egg counts both before and after worming, showing that pasture hygiene supports and enhances the effectiveness of treatment.

In a third study, Osterman-Lind et al 2022 investigated the effect of faecal removal and harrowing as a way of reducing the number of parasite larvae in herbage. Research found that twice-weekly faecal removal significantly reduced larval yields, whereas harrowing on a single occasion under dry weather conditions in the summer did not. Results also found that resting of pastures for one year greatly reduced the parasite level, but two years of rest were required for larvae to die off on pasture completely.

These findings reinforce an important message in parasite control, chemicals alone are not the answer. Regular dung removal, combined with resting and rotating play a vital role alongside testing. By physically removing parasite eggs before they hatch and develop on pasture, poo picking can dramatically reduce infection pressure across the grazing season.

Anecdotal evidence in the lab highlights this in practice too. Westgate Labs reported higher than usual worm egg count results during the summer and autumn of 2025, resulting in an increase in the number of horses where treatment was indicated. Kristy commented:

“One yard with 12 horses, and who test with us regularly, typically have results that mean only two or three animals from the herd require treatment. But in the autumn of 2025, nine of the 12 tested needed worming. The fields were not poo picked, and warm temperatures combined with intermittent rain likely created ideal conditions for larvae to develop and survive on pasture. Testing revealed the problem, but management may have prevented it.

“It’s important to note that poo picking is a preventative, rather than an alternative to worming with a chemical. Where test results indicate, we would always recommend appropriate treatment as a first line of approach.”

With the recent heatwave we have experienced in the 2026 summer, we are expecting to see a similar pattern in horses grazing paddocks that aren’t poo picked. Regular worm egg counts remain the foundation of responsible parasite control, and research shows they work best when combined with good grazing management. Sometimes the most powerful tools are also the simplest, a wheelbarrow, a fork, and a commitment to keeping paddocks clean.

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References

Corbett, C.J.; Love, S.; Moore, A.; Burden, F.A.; Matthews, J.B.; Denwood, M.J. The effectiveness of faecal removal methods of pasture management to control the cyathostomin burden of donkeys. Parasit. Vectors 2014, 7, 48.

Tzelos T., Barbeito J.S., Nielsen M.K., Morgan E.R., Hodgkinson J.E., Matthews J.B. Strongyle egg reappearance period after moxidectin treatment and its relationship with management factors in UK equine populations. Vet. Parasitol. 2017;237:70–76. doi: 10.1016/j.vetpar.2017.02.018.

Osterman-Lind, E.; Hedberg Alm, Y.; Hassler, H.; Wilderoth, H.; Thorolfson, H.; Tydén, E. Evaluation of Strategies to Reduce Equine Strongyle Infective Larvae on Pasture and Study of Larval Migration and Overwintering in a Nordic Climate. Animals 2022, 12, 3093. https://doi.org/10.3390/ani12223093