The controversy with how to deworm, when to deworm and even IF you should deworm has been loud and heated. The solutions seem to either be overmedicate (and your horse develops a resistance to dewormers) or don’t deworm at all (and take a chance your horse becomes sick). But there IS a happy medium. The best place to start is with a fecal egg count (FEC) to determine if the horse is a high, medium or low “shedder”. Typically, 80% of horses are responsible for 20% of the parasites. This easy and relatively inexpensive test by your veterinarian helps you identify the horses that need the most aggressive treatment, and allows you to save money with risk of resistance on the others. Once identified, you and your veterinarian can map out the best plan for your horse from the different dewormers available.

Next it’s important to make sure and give the correct dose by weight. Use a weight tape to be sure that your horse is getting the proper amount. And be sure that your horse is swallowing all the medication. It’s a good idea to have another fecal egg count done 1-2 weeks after deworming to be sure that the medication is doing its job. If you still see a high egg count, it could mean that your horse is not getting the right dose of medication or that the worms are resistant to it.

Getting your horse on the right deworming program is only half the battle. Changes in pasture management are often also needed in order to lower the risks that worms will infect or reinfect your horse. Strongyle eggs are passed in manure. Larvae hatch in the field and are then picked up by grazing horses.

Ways to reduce this risk include picking up manure in paddocks, using hay/grain feeders instead of using the ground, keeping manure away from water sources, reducing the number of horses grazing in each pasture, rotating and resting pastures every few weeks to interrupt worm life cycles, and drag or harrow pastures in hot, dry weather to break up manure piles and kill eggs/larvae.

Parasites are a herd problem so a good plan covers all the horses on the property, whether that’s your backyard or a large boarding stable. The number and age of the horses, the amount of pasture they have and your geographic location are all factors. Frequent trips to shows and new horses coming onto the property can increase ­exposure risks. All new horses should have a fecal count done upon arrival.

By using this plan and cutting back on overuse of medications and underuse of pasture management you can help protect your horses from parasites.