Anyway, this got me thinking about worms. Let's look at the subject of that article, the roundworm. Roundworms in horses, also known as ascarids, are relatively common, and are transmitted by swallowing eggs from contaminated hay or water. The eggs develop into larvae in the stomach of the horse, which then migrate to the liver, heart and lungs. They are then coughed up and swallowed - then develop into egg-laying adults, again in the stomach. This process takes about 3 months. They can cause coughing, pneumonia, liver damage, colic and diarrhoea. A heavy burden can cause intestinal blockage or rupture. Signs of worminess, from any species of parasite, include pot belly, rough coat, slow growth and general unthriftiness (among others).
I read just recently that these practices may actually contribute to resistance. We already have resistance to some of the current compounds by large roundworms, pin worms, small strongyles and small redworms. Without any new worming compounds expected on the market over the next few years, that is a problem that can't be ignored. And besides, why put chemicals into your horse if he/she doesn't need them anyway? You wouldn't do that to yourself, would you? Horse wormers also have side effects: putting extra strain on the liver, killing of good gut bacteria, can cause impaction colic if the horse has a heavy worm burden that suddenly dies, can have an adverse effect on earthworms and beetles etc, PLUS of course worms developing resistance.The "standard" worming practices we have known for decades really need to be challenged to keep resistance at bay.
How do we do this? Okay, it's gross, but Faecal Egg Counts. Yes, you guessed it, somebody looks at your horses' poo and tells you how many worm eggs are in it. Your vet should be able to do this, you can also get DIY kits if you don't mind playing with poop (You only need about a spoon full or something, it's not much). Some horses have a natural resistance, and will have a lower egg count than other horses on the same pasture with high counts, even if they were wormed on the same day. Adult horses with no heavy worm burden (and no health issues) should be wormed at longer intervals. Aged and very young horses still need to be targeted for intensive treatment but again, should be monitored for their actual worm burden. You can also monitor the effectiveness of your wormer - do a count before and shortly after worming. You'll soon see if your wormer is effective. Do another count at 6 or 8 weeks post worming and see if you need to worm again. I bet you probably don't. Continually de-worming just kills off the non-resistane worms, leaving ONLY the resistant ones to breed on, thus contributing to resistance.
Naturally, pasture management remains important - controlled stocking rates, regular harrowing, encouraging dung beetles, removing manure piles regularly, rotating pastures and grazing with cattle and/or sheep can all help reduce the reliance on chemical wormers. Frost and hot sun will kill worm eggs - so if your paddock needs a rest, the best time to do it is in the middle of summer, or the middle of winter if you're in a frost area. And don't forget to isolate and worm any new horses you introduce - preferably keep them separate for several days before putting out on your pasture. Oh, and get rid of those yucky botfly eggs you see on legs or belly. (see picture below)
There are also some natural wormers - garlic and fennel seed are two that are not highly toxic. Copper can also be added to the horse's diet to boost the immune system. Diatomaceous earth and crushed pumpkin seeds are two more examples, although less commonly used. I haven't had experience with these, but I do know people who swear by them.
Ultimately, it's up to individual horse owners to choose the worming program that suits them. But seriously, if we DON'T need to do it so often, why do we bother? Let's face it, it becomes a waste of time and money - and how many of us have horses who are easy to worm? (*puts hand up and grins*)
