Worms are a huge problem in horses. If present long enough, worms can damage a horse’s internal organs and intestinal lining, result in a dull coat and poor nutrition, and cause weight loss and muscle wasting in addition to many other symptoms. There are a number of ways to combat worms, but take some time to learn about all of them to determine what’s right for your horse.
Daily deworming consists of adding a product such as Strongid to your horse’s daily grain. The daily dewormer continuously kills any worms in your horse’s system, so theoretically the worms are never present long enough to do damage to your horse’s internal organs. With daily dewormers you will still need to deworm your horse with a paste product twice a year to kill species of worms that daily dewormers do not affect.
Rotational deworming refers to the use of paste dewormers at certain intervals throughout the year. You rotate the products with each dose to make sure that you target all varieties of worms. Each paste dewormer is only effective during the dosing – in other words, if you deworm a horse in January, he could potentially contract worms and carry those worms until he’s next dewormed again, typically 30 to 90 days later. When you deworm rotationally it’s important to make sure that all horses are dewormed within the same day or two of each other, so that they can’t continuously re-infect each other with worms.
The Case for Strategic Deworming
Parasite resistance to dewormers is a growing concern in the horse industry. In each type of parasites, a small percentage of the population is resistant to the dewormer chemicals and survives the deworming. Because the rest of the population of worms is killed by the dewormer, the dewormer-resistant parasites live on to reproduce, creating more parasites with the ability to survive the next round of dewormer. Using deworming products when they’re not actually needed contributes to the parasite resistance, and could cause a major problem for horses down the line as our current deworming products are rendered ineffective.
Testing for the presence of eggs in your horse’s manure (getting a fecal egg count, or FEC), can allow you to deworm your horse only when absolutely necessary. According to Kentucky Equine Research’s Dr. Bryan Waldridge, fecal eggs per gram (EPG) counts are “the best source of information to tailor a deworming program that is best for your farm.”
In conducting an EPG count, your horse’s manure is weighed, floated in a solution, and worm eggs are then counted under a microscope. The test can determine what types, if any, of parasite eggs are present, indicating what type of dewormer your horse would need to be treated with. When a fecal egg count results in less than 200 EPG, a horse is considered to be a low level worm shedder, meaning that he passes relatively few worm eggs through his manure, and a pasture mate would face a low risk of worm infestation by being exposed to that horse’s manure. On the other hand, if a horse’s test reveals a count above 200 EPG, then he’s considered to be a high shedder. A high shedding horse has high volumes of worm eggs in his manure and infestation for pasture mates is a definite risk.
If your horse is a low level shedder, then he probably only needs to be dewormed twice a year, greatly reducing the amount of chemicals to which you will need to expose him. High level shedders need more frequent deworming.
The benefit of having a fecal egg count conducted on your horse is that it may reveal that you can do much less deworming than you were doing before, saving you in both money and trouble. According to Dr. Waldridge, a study from Denmark revealed that horses “tend to be consistent in the amount of worm eggs shed in their manure,” meaning that if your horse is a low shedder, he will likely continue to be a low shedder, and vice-versa.
If you’ve never had a FEC done on your horse, talk to your veterinarian. Your vet can help you decide what’s best for your horse and can help to tailor an appropriate deworming program to your situation. Factors such as pasture maintenance, climate, exposure to other horses, and general barn up keep all affect your horse’s exposure risk, so have a discussion with your vet about the best and most effective deworming strategy for your horse.
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