Traditional equine de-worming practices have been put under the microscope more and more in recent times, with the problems surrounding drug resistance and how it can effect equine welfare becoming more apparent. The ever-growing resistance to the anthelmintics (medication used to treat parasitic worms) available is making it difficult to create more sustainable and effective parasite control programmes

New research from leading equine parasitologist Dr Martin Nielsen, who is based at the University of Kentucky, shows that the traditional approach of frequent and routine de-worming at pre-determined intervals, without the use of diagnostic testing is unnecessary.

“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 said.

Health effects

Dr Nielsen’s study, consisting of 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 of less de-worming, more surveillance, worm egg counts and adopting a test-led approach.

Many horse owners are not comfortable with de-worming their horses less frequently, believing it will lead to poor health. However, no adverse health effects were seen during this study that could be related to less frequent de-worming.

What is suggested horse owners do instead? The researchers of this study are encouraging horse owners who have not already done so to change from their traditional habits of frequent de-worming, to a diagnostic test-led approach, or a more strategic approach with routine drug-resistance testing.

If you have not discussed a de-worming schedule with your vet in recent times, now is a good opportunity to discuss this with them and put a plan in place going forward into the spring.