Internal parasites affect all horses, but the key is to maintain a healthy level of them. Unfortunately, after years of overuse of chemical dewormers, many parasites have become resistant to the very chemicals that were developed to combat them.
This has led to new deworming strategies along with the popularity of fecal egg counts, which can help identify the approximate number of parasites, as well as the type of parasites affecting your horse.
Anthelmintic Resistance
The traditional approach to deworming involved rotating through the different classes chemical dewormers every few months. The problem is that this practice was developed over 40 years ago when the main threat to horses was the large strongyle bloodworm (Strongylus vulgaris).
While rotational deworming was effective in controlling large stronglyles, two new worms have since taken over as the largest threat to our horses: small strongyles (cyathostomins) in adult horses and ascarids (parascaris equorum) in horses under the age of three.
Fecal Egg Counts (FECs)
Fecal egg counts involve taking a count of parasite eggs from a sample of your horse’s manure. While not completely foolproof, FECs are a useful tool in determining if your horse needs to be dewormed.
It’s generally recommended that FECs be performed at least twice per year in the early spring and late fall, but 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.
FECs can also be used after a dewormer is given or if your horse is on a long-term natural dewormer in order to monitor the product’s effectiveness. In this case, they are known as Fecal Egg Count Reduction Tests (FECRT). If the egg count has not significantly decreased (by at least 90%) after fourteen days, then another type dewormer is likely needed.
McMasters Test
Most veterinarians offer fecal egg counts tests if you bring either your horse or the sample in to them. However, we recommend using Idexx Laboratories McMasters fecal test. This is a quantitative test which can assess the eggs per gram (EPG), making it easier to monitor your horse’s parasite load over time. An EPG of less than 100 is considered low. A count between 100-500 is moderate, and anything above 500 is considered high. We consider 200 EPG or less to be acceptable.
FECs can help guide your parasite control program, but it’s also important to keep in mind that no horse is or will ever be 100% parasite-free. Taking environmental measures, such as picking up manure from pastures, harrowing (in dry, sunny climates), and implementing pasture rotation can also go a long ways in preventing further infection.
Natural Parasite Control
Along with using FECs, we recommend using one of our all-natural dewormers such as:
These products work mechanically to kill parasites and, unlike with chemical dewormers, parasites cannot become resistant to them. They are safe and effective, as many of our customers have verified by using FECs.