The FEC: Do you know your horse’s count?

FEC? Say what? For the uninitiated, FEC stands for fecal egg count. Egg of what, you may ask? Well, worms. Worms that can have negative health consequences for your horse. For the why/when/how of equine FEC’s (fecal egg counts), I recommend the following sources of information:

What is Your Horse’s Fecal Egg Count Telling You?

Smart Equine Parasite Control: Fecal Egg Count Cheat Sheet

The Fecal Egg Count for Horses

When I bought my first horse, rotational deworming (deworming your horse with a different class of chemical dewormer every other month) was the norm. In the last ten years or so, many veterinarians have switched to recommending deworming based on an individual horse’s fecal-egg-count as a way to combat worm resistance to currently available deworming drugs.

On this topic of FEC’s, my horse, Bear, has a confession to make. Drum roll . . . He is what is known as a “high shedder” and tends to have FEC’s in the 1000 eggs-per-gram range. He used to be a medium shedder, but now that he is a senior horse with PPID(Cushing’s Disease), his FEC’s have gone even higher. Age and PPID tend to reduce immunity.

In case you are wondering if I might already have a case of dewormer resistance on my property, the FEC reduction test we had done last year showed that the deworming chemical Moxidectin still works well to temporarily reduce his egg burden. But the egg numbers build back up in between dewormings.

Bear’s FEC for this Spring was 1050. Shiloh’s FEC was 75. Two horses sharing the same home environment. Two horses cared for pretty much the same way. Yet two horses showing very individual FEC results. My veterinarian recommended that I deworm Bear this month but not Shiloh. Both horses were recommended for retesting in the Fall.

Last week, I took both these photos of Bear shown here in this post. Yes, he is a retired, senior horse (turning 26 next week!) with Cushing’s disease. He no longer has the muscle of a horse in work. He is still in the process of shedding his now dull, end of Winter coat. Even so, I wouldn’t suspect that Bear’s FEC was so high just from his outward appearance.

To me, that is a big benefit of fecal egg counts. It helps identify an internal issue that doesn’t necessarily show externally. Having said that, it should be noted that a horse who is a high shedder does not necessarily have a heavy parasite load.

“Egg counts can never indicate any role of parasites in disease or even predict the risk of disease . . . Many people still believe that egg counts correlate with worm burdens, and I am correcting that misconception on a weekly basis.” – From Frustrated By Fecal Egg Counts? by Stacy Oke, DVM, MSC, an article that appeared in the May 2022 issue of The Horse: Your Guide To Equine Health Care magazine.

How about your horse(s)? Have you had a FEC performed? Has a FEC result ever surprised you?

***As with anything horse-health related that you read on the internet, please remember to consult your veterinarian for guidelines about how you should treat your particular horse(s). What my veterinarian recommends for my own horses may not be appropriate for yours. ***

This post was originally published in April 2021 and was last updated May 2022.