Changing the Game: Fecal Egg Counts and Deworming

For decades horse owners have heard, “Deworm every 2 months” or, “Rotate dewormers.”

Now you are hearing, “Have your veterinarian perform Fecal Egg Counts.”

What is with the change?! No person in their right mind wants to take a fresh sample of your horses poop, mix it with solution and look at it under a microscope for fun! It would be much easier to just stick dewormer in a horse’s mouth…even if they put up a fight! Fecal Egg Counts are a change from previous deworming strategies, but they are an improvement and are very important to sustaining horse health. Internal parasites are silent killers. They can cause extensive internal damage, and you may not even realize your horses are heavily infected. At the very least, parasites can lower resistance, rob the horse of valuable nutrients and cause gastrointestinal irritation and unthriftiness. At their worst, they can lead to colic, intestinal ruptures and death. The best news- parasites ARE preventable!

Fecal egg counts have been around for a while now, yet they are not main-stream among horse owners. It is still more convenient to pick up tubes of dewormer while at the feed store than to have your veterinarian perform a fecal egg count. But efficacy and sustainability beat convenience any day.

Deworming strategies that are currently main-stream for parasite control in horses are mainly based on information and recommendations that are >40 YEARS OLD! It should come as no surprise that A LOT has changed over the last 40 years regarding equine parasites and the best deworming strategies. Decades of changes in equine parasite prevalence, resistance, and technology available leaves us with better ways to take care of our horses.

Parasite control involving rotational deworming at regular intervals is an older technique that was developed due to the prevalence of the Large Strongyle (Strongylus vulgaris). If you have ever been given the advice, “deworm your horse every 2 months.” Yep, that advice originated circa 1960s because the Large Strongyle was the most important equine parasite at the time. Luckily, interval deworming defeated the Large Strongyle; disease due to this worm is now rare in horses. So why are we still using this deworming strategy? We are creatures of habit. We don’t like change.

These days, major equine parasites include the Small Strongyle (Cyathostomins), Roundworms (Parascaris equorum), and Tapeworms (Anoplocephala perfoliata) are major equine parasites that cause disease in horses. The life cycles of these parasites differ from the Large Strongyle, therefore the rotational/interval deworming strategies are not appropriate. In fact, decades of frequent dewormer administration has led to high levels of dewormer resistance in Small Strongyles and Roundworms. Once parasite resistance to a drug is present, repeated deworming with the same drug allows the resistance parasites to survive over others and increase in numbers.

To sustain equine parasite control, we MUST transition to effective deworming strategies.

The goals of equine parasite control are:

1. Minimize risk of disease due to parasites
2. To control parasite egg shedding
3. To maintain effective drugs
4. Avoid further development of parasite resistance to dewormers

To achieve these goals, Fecal Egg Counts are our best strategy.

Along with Fecal Egg Counts and using effective dewormers, good management is important for controlling equine parasites. The main method of transmission for equine parasites is through manure- so good manure management is key!
To get rid of parasites before they attack your horse, follow these suggestions from the American Association of Equine Practitioners (AAEP):
1. Pick up and dispose of manure droppings in the pasture at least twice weekly.
2. Mow and harrow pastures regularly to break up manure piles and expose parasite eggs and larvae to the elements.
3. Rotate pastures by allowing other livestock, such as sheep or cattle, to graze them, thereby interrupting the life cycles of parasites.
4. Group horses by age to reduce exposure to certain parasites and maximize the deworming program geared to that group.
 5. Keep the number of horses per acre to a minimum to prevent overgrazing and reduce the fecal contamination per acre.
6. Use a feeder for hay and grain rather than feeding on the ground.
 7. Remove bot eggs quickly and regularly from the horse’s hair coat to prevent ingestion.
8. Consult your veterinarian to set up an effective and regular deworming schedule. With the many safe, convenient products available today, establishing an effective deworming program is easy. Discuss a plan with your veterinarian and implement it without delay. A good parasite control program will go a long way toward maximizing your horse’s appearance, performance and comfort. The net result will be an animal that is as healthy on the inside as it appears on the outside.