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More evidence shows traditional frequent worming is unnecessary

A persistent growing resistance to anthelmintics is challenging vets to find more sustainable and yet effective parasite control programmes

18 January 2021, at 9:00am

New research, from leading equine parasitologist Dr Martin Nielsen, has provided more evidence to show that reducing worming (or more correctly, de-worming) intensity, does not have any adverse health risks to horses. The work confirms that the traditional approach of frequent routine de-worming at pre-determined intervals, without the use of diagnostic testing is unnecessary.

To help share the results of this significant study Dr Nielsen has produced two short explanatory videos, one for vets and one for horse owners .

The videos are being shared by BEVA to spread the word to members and to give practices an easy and engaging way to share the information with their clients on social media platforms.

“Internal parasites, predominantly strongyles and ascarids, are omnipresent at equine yards,” said Dr Nielsen. “But a persistent growing resistance to the anthelmintics we have available is challenging us to find more sustainable and yet effective parasite control programmes.”

“De-worming every six to eight weeks and rotating between products is still very common around the world but this sort of carpet bombing is completely unnecessary and drug rotation does not prevent drug resistance,” Dr Nielsen continued. “Many people are not comfortable with de-worming less frequently, thinking it will compromise horse health, but our study shows that this is not the case; no adverse health effects were seen that could be ascribed to scaling down de-worming intensity.”

The study, involving 99 mares and 93 foals at four stud farms in New Zealand, evaluated the worm egg count levels, bodyweight and equine health of groups of mares and foals under different parasite control protocols. These included traditional approaches with frequent de-worming and drug rotation, as well as the currently recommended protocols involving less de-worming and more surveillance and worm egg counts.

David Rendle, Chair of BEVA’s Health and Medicines Committee said: “This study provides further evidence to show that there is no justification for the traditional approach of calendar-based routine treatment and gives further reassurance that the frequency of treatment can be reduced without detriment to equine health or development of youngstock.

“Spreading this information will hopefully encourage any horse owners who have not done so already to change from their old-fashioned habits of frequent de-worming, to a diagnostic test-led, or at least a more strategic approach with routine drug-resistance testing. In so doing we can help avert the potential equine welfare crisis that all are agreed will inevitably ensue if the equine industry continues with the indiscriminate use of anthelmintics. I would urge anyone who has not discussed worming with their vets recently to do so before the Spring.”