Fecal Egg Counts

Fecal egg counts can be performed on any species, but they are especially important for horses.  Parasite resistance to dewormers is starting to be a problem in horses.  You can learn how to do the process yourself at most Extension Offices. 

Most people use fecal egg counts to figure out if their dewormer is still working on their farm.  They will perform a count, deworm the animals that need it, and then two weeks later, do another count.  If the worm egg load has not decreased by 90%, then the dewormer you are using is starting to lose its effectiveness.  You have severe resistance issues when your egg counts show less than a 60% reduction.  There are three classes of dewormers and in this case, you would have to switch.  You cannot just switch to another brand name of dewormer because it could be in the same class, you must look at the active ingredient when switching dewomer classes.

When counting, you are checking for strongyles in horses, because they are the parasite that causes most of the problems.  However, there have been a few cases when other parasites are the real culprit such as liver flukes or coccidia.  They require different treatments, so it’s important to first figure out what you are dealing with.  You may have some animals on your farm that have problems, but when you check the fecal eggs in the microscope, they may not have a heavy worm load.  This is important to find out as you are trouble shooting, because you can eliminate parasite pressure as being a possibility.  The animals may have a disease that you will need to treat.

When checking fecal egg counts, you may discover a few animals in your herd that always have high worm loads.  This is why keeping good records is really important.  At that point, you may decide to cull those high worm load animals off your farm.  Parasite resistance is moderately heritable, so it’s a good idea to sell those animals instead of breeding them since they can pass on the problem to their foals.

Several farmers have gotten serious about fecal egg counting after getting trained and have bought their own microscope and supplies to do their own counts on the farm.  If an animal is doing poorly, that is often the first step they take towards troubleshooting the problem.  Some farmers chose to only run samples every once in awhile and in that case will bring their samples to the Extension office to run them.  Some farmers will bring their samples to a local Veterinarian to analyze.  Which ever way you decide to go, fecal egg counts can be very beneficial to your farming management plan.

You can work with your Veterinarian on threshold limits, so that you know when deworming is needed.  Just a few worm eggs in every sample is normal.  Parasites like warm, wet weather, so you may need to do fecal egg counts more frequently during this time, but you can check them all year.  Some supplies that you will need are a microscope that is able to magnetize 100 times, a measuring vial or scale, a McMaster slide (preferably with green lines for more visibility, cups, fecasol, a strainer, popsicle sticks, a timer, gloves, and an eye dropper.

If you need help with deworming information or would like to learn how to do your own fecal egg counts, please call your local Extension Office.