Targeted worm control to take care of the environment
There’s another alarming side to using these chemicals and that’s the effect they have in our environment when we use them in our horses without taking steps to mitigate their impact. A burgeoning area of research is revealing the devastating effects they can wreak on our ecosystems.
We were shocked to discover that 80-98% of an oral dose of ivermectin passes straight through the horse and is excreted in the dung, totally unmetabolised by the body. Once in the environment the chemicals have the same impact on flora and fauna as they do on the intestinal worms. Soil ecosystems, dung beetles, plants and invertebrates receive toxic doses of paralysing wormer as the chemical is leached into the surrounding soil and watercourses.
You only have to turn on a nature programme to hear the devastating decline of our much loved species in the environment. Overuse of chemicals – over a million wormers a year in horses, many more in agriculture animals, have a big part to play in this.
The good news is there are simple steps we can take to reduce chemical contamination in the environment AND our reliance on treatments.
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Start by making sure the parasite control programme is working.
A regular testing programme based on worm egg counts will identify any problems in the herd and allow any wormy individuals to be treated accordingly. Avoid blanket treatments to slow resistance and maintain some non-toxic dung available to dung beetles.
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Research suggests that poo picking twice a week is sufficient to significantly reduce infective larvae on the pasture.
Dung beetles prefer fresher animal poo up to 48hrs old. Begin to leave the newest piles on the pasture and clear them after 3-4 days.
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If owners can only stable for a short time, advice is to keep horses in off this pasture for 24-48 hrs following worming.
Most chemicals reach their highest concentration in faeces 24-35 hours after being administered but they can shed toxic metabolites for up to 10 days. Minimising the horse’s time on the pasture and poo picking at least daily during this time is advantageous. It may also help to restrict treated horses to a smaller paddock to aid dung collection. The more eco-toxic the chemical, the more diligent carers should be. Of our five licenced wormers for horses, ivermectin is the most toxic to dung beetles, moxidectin moderately toxic while pyrantel, fenbendazole and praziquantel are significantly less poisonous.
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Where possible, worm when dung beetles are less active.
This is between November and February.
Managing contaminated dung
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Dung that’s been collected from treated horses can be placed in a carefully situated manure pile and allowed to rot down.
Research has shown thermophilic composting (where the centre of the pile reaches a min 60 °C) will cause even ivermectin, one of the most resilient worming compounds, to break down almost entirely after a few weeks.
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The siting of muckheaps should be carefully considered.
The main environmental risk comes from the impact of residues in rainwater run-off leaching into soils and watercourses. They should be positioned at least 3m outside of fields to prevent hatching larvae re-contaminating grazing land, away from areas where there is a lot of surface groundwater, field drains and not within 10 metres of a watercourse. In an ideal world cover your muck heap with a roof/tarp to reduce the risk of run-off.
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Manure should not be spread back on the land for at least 6 months (ideally longer).
By then concentrations of parasiticides should be low and worm eggs will be much reduced to minimise reinfection.
A little bit of strategic thinking will pay huge dividends to our horse’s health and the environment in the long run. An investment worth making for all our sakes and yet another reason to move to targeted parasite control as the best, most sustainable option.
Read our previous blog about the risks of parasite infection, or find out more at www.westgatelabs.co.uk
About the Author
Westgate Labs leads the way in helping owners to manage the parasite control of their horses and other grazing animals. With tests and advice you can trust the laboratory offers a quick, easy to use, great value postal worm count service that enables carers and keepers to target the wormers given to their animals and keep them as healthy as possible.
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