Use Equine Fecal Egg Count to Improve Your Horses Worm Control Program


Nikki Alvin-Smith


Give yourself a pat on the back if you’ve already taken the positive step of collecting a manure sample from your horse and sending it in for a FECT (fecal egg count test).

Your report will give you an indication of whether your horse has a negative egg worm count, or is a high, low or medium shedder of strongyle worm eggs. What do you do with this information?


A report that is negative for a strongyle egg worm count is great news. Dr. Byrd explained “A negative egg count means no worm eggs were found on the counting chamber.  Our lab uses the McMasters test  to do equine fecal egg counts and this method is accurate down to 25 eggs/gm”. While this may indicate that you don’t need to administer any dewormer at this time, it does not necessarily mean your horse does not host any worms. It could indicate he has just been dewormed, but he could still harbor encysted strongyle larva that are waiting to excyst and become adults and start laying eggs, or other common parasites whose eggs are not regularly found in the horse’s manure (tapeworms, bots and pinworms”. When should you retest your horse? How often should you retest a horse based on this report? In the world of equine parasitology the answers to these questions change based on the latest scientific knowledge. Are you up to date on that information? Perhaps not.


If the F.E.C.T. came back positive with a shedding worm egg count, then should you deworm your horse and if so with what? How long after treatment should you retest and why? Is it possible your horse is infected with a dewormer resistant worm population? So many questions!


Every horse is an individual and while a standard protocol for deworming may be to treat a horse with a positive shedding egg worm count result with a dewormer, it is important that you retest to ascertain if the treatment has worked. It is also important to schedule these tests appropriately, as mentioned above even a negative test may not mean that the horse does not have encysted strongyles present in his system waiting to excyst and become adult strongyles and start laying eggs which will appear in the horse’s manure.


Worm egg reappearance periods (ERPs) are extensively used in equine parasitology and while ERP was originally used primarily for designing suppressive treatments it has evolved to become a tool for detecting increasing dewormer resistance. The time interval for retesting has subsequently also become more complicated, as scientists continue to discover correlations between particular herds of horses and decreasing efficacy of certain dewormers. When you are reading your horse’s history based on FECT reports, you may not have the detailed knowledge that is important to determine if you need to switch to a different type of dewormer or the optimal time schedule for repeat testing.


In order to make a smart decision for the go forward on how to manage your targeted worm control program, any counsel you take from a vet that reads the FECT reports and provides advice should be based on several factors. There is a triangle of factors that affect parasitism: the host, the organism and the environment. For this reason an inquisition into your particular horse keeping methods, horses, horse traffic, and equine and pasture management programs is in order is somewhat helpful but not definitive. The classic Who, What, Where, Why and How conversation, is just the starting point for understanding the best program for your herd and it is important that the vet take the time to understand all aspects of the triangle as it pertains to your horses reports.


Equine Worm Testing Kits for Sale

Round worm egg and strongyle egg

As you may be aware, strongyle worms are only one of several different types of internal parasites that may infect your horse. So you should also think about bots, tapeworms, ascarids, pinworms and a myriad of other parasites in your worm control program.


The equine parasitology topic is more complex than it might at first appear. However, with a little guidance you can successfully navigate it and you can construct an appropriate schedule for testing, retesting and dewormer administration for your entire herd. Your efforts will not only be rewarded with peace of mind that you are engaging in a sustainable method of equine internal parasite management, but also you won’t be throwing unnecessary chemicals into your horse’s system or tossing dollar bills out the window.


As you may already know, leading online resource for equine worm egg testing Horsemen’s Laboratory, has tested over 75,000 FECTs and offers a full service, one stop shop for all my needs when it comes to targeted horse worm control. Their office will send me reminders to keep me on schedule of when to test, ship me sample kits throughout the year automatically on my account and generally ensure the testing process is very easy. They’ll even keep reports for all my horses on record and remind me by individual horse name which horse needs testing when based on their previous testing results.


But by far the greatest benefit of utilizing their services is the help that is on hand from Dr. John Byrd. When reports come in and I need advice as to what to do about the results, what products are the most effective to use and what risks may be involved for special circumstances, such as for a horse that demonstrates a high shed count and is in compromised health for any reason, I am confident that Dr. Byrd’s advice will keep me on the right track. It allows me to make any prudent adjustments to my evidence based equine parasite control program in a timely manner.


While regular field vets offer FECT services, they are not necessarily up to date on the detailed knowledge that is presently available for effective equine parasite control and management protocols. Vets are always busy! Like any other area of equine medical care, targeted worm control is a specialist subject.


There is always more to learn about our beloved horses and how to best care for their needs in a responsible and sustainable manner. Like the field vets, I am too busy to have time to get too in-depth about every possible topic. I do realize that I can’t just read one good book and then believe that I know as much about the topic as the author(s). An expert with a wealth of hands-on experience working with the results of the samples, different case histories, and someone that has successfully navigated the equine parasitology topic, and keenly keeps up to date on new developments is a valuable resource.