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AskHQ: Worms in the paddock

Q: How do you manage pastures to reduce the incidence of worms?

Answered by Jassy MacKenzie

A: In the vast open spaces of their natural environment, wild horses would not graze near their droppings, but very few owners are fortunate enough to have this kind of space. In limited space, or where grass is short or scarce, horses graze contaminated areas and risk picking up high worm-burdens. Dr Maitland-Stuart emphasises, “Responsible horse management means not relying solely on wormers to control the problem.”

If the paddock is badly contaminated, worming the horses will have only a temporary benefit, as they will immediately start picking up worms again, and now some will be resistant to the wormer. This is why removing manure from paddocks is as important as removing them from stables.

According to Andrew Peregrine, associate professor at the University of Guelph’s Ontario Veterinary College, removing droppings from paddocks twice or more per week can be as effective in controlling worms as the most rigorous worming programmes.

In hot, dry weather, harrowing paddocks to spread the droppings will kill strongyle eggs and larvae, as they will dry out and desiccate. After this, paddocks should be rested for two weeks before they are grazed again. Grazing cattle or sheep either in rotation or along with horses is a good way of helping break the worm cycle. Chickens can also assist in scratching and drying out piles of manure.

Properly composted manure creates a lot of heat, and temperatures of over 40°C for a few days will kill off any worm eggs. Composted manure can thus be spread on paddocks to fertilise them. However, un-composted manure should never be spread on the paddocks, as it may be full of viable worm eggs.

Answered by Jassy MacKenzie