All horses are prone to having internal parasites, aka worms.
This is why people have used deworming remedies for their horses for centuries and why chemical products were developed in more recent decades. However, with any type of deworming protocol, the goal should not be to eradicate all worms from your horse (nor is this possible). Instead, we should strive to maintain a healthy parasite load.
One worrisome issue that has developed due to the overuse of chemical dewormers is that of anthelmintic resistance, in which some parasites have adapted to deworming chemicals, making the products ineffective. Because of this issue, it is no longer recommended that horses be dewormed blindly. Instead, owners should find out if their horse needs a dewormer in the first place, and, if so, what type. This is where fecal egg counts can help.
What is a Fecal Egg Count?
A fecal egg count is exactly what it sounds like: it’s when a count of parasite eggs is taken from a sample of your horse’s manure. The sample can help identify which types of parasites your horse has in order to
devise a more targeted deworming approach. While not completely foolproof, FECs are useful for two main reasons:
1.) They can determine which horses need to be dewormed by identifying the type of parasites as well as the approximate parasitic load.
2.) They can determine if the product you already used to deworm your horse was effective.
When using FECs to determine a product’s effectiveness, it will need to be done twice: before the product is given and then 14 days afterward. If the egg count has not significantly decreased (by at least 90%) in the retest, then another type dewormer is likely needed. If using FECs to see if deworming is needed for your horse, it’s generally recommended that they be performed at least twice per year: in early spring and late fall. However, doing them more frequently can be helpful too. In large herds where individual FECs may be impractical, an alternative is to take random samples within a group of horses housed together and then evaluate and treat the group as a whole. Keep in mind that FECs cannot identify every type of parasite. Two that will not show up in an FEC are tapeworm and pinworm eggs. Therefore, you’ll need to ask your veterinarian about deworming for these parasites.
