The best place to start is with a fecal egg count (FEC) to determine the high, medium and low “shedder” – those horses that seem most prone to worms. Typically, 80% of horses are responsible for 20% of the parasites. This easy and inexpensive test by your veterinarian on your horse’s manure helps you identify the horses that need the most aggressive treatment, and allows you to save money and the risk of resistance on the others. Once identified, you and your veterinarian can help map out the best plan for your horse from the different drug classes of dewormers available.
Next it’s important to give the correct dose by weight. Use a weight tape of necessary to be sure that your horse is getting the right 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.
But getting your horse the right deworming program is only half the battle. Changes in pasture management are often also needed management to cut the risks that worms will infect or reinfect your horse. Strongyle eggs are passed in manure. Larvae hatch in the field and are picked up by grazing horses.
Ways to reduce this risk include picking up manure in paddocks, putting hay/grain in feeders instead of 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 to kill eggs and 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.
Using this plan can help protect your horses from parasites now by cutting back on overuse of medications and underuse of pasture management.
<span style="color:#000000;">Photo Credit: Practical Horsemen</span>