Clara Mason, DVM

44 Cloverleaf Street
Winfield, WV 25213


Tapeworms and Fecal Egg Counts


We are all trained to deworm our horses. But, should we deworm without knowing exactly which and how many worms our horses have inside of them? In the last few years, our parasitacides or dewormers are becoming ineffective.  Simply stated, the worms are resistant to our dewormers.  So what do we do now?  First, we need to be diligent about removing our manure from the barn and surrounding areas. This alone will decrease re-infestation of worms in our horses. Secondly, do not mix a new horse in with the herd until he/she is dewormed.  Our goal with deworming is to keep our pastures "clean" or free from burdens of parasites that will attack our horses intestines. Thirdly, and most importantly, submit a fresh fecal sample to your veterinarian for analysis of parasite loads and identification. Standard measurement of parasite eggs is the number of eggs per gram of feces. 

Not all dewormers will kill all parasites. We need to choose the appropriate dewormer for the parasite load that your horse is carrying.  Our fecal analysis is submitted to an equine laboratory in Lexington, KY for the most accurate identification.  Cost for this service is $25.  Once the parasite load is identified, we will guide you in choosing the appropriate dewormer and the correct schedule to deworm your horse.


Anoplocephala perfoliata - That is the proper name for one of (and most common) tapeworms that occurs in horses. It is a big name for a very small worm that creates an enormous amount of damage in the horse. Since the 1980's, much of the research in equine medicine has shown that the tapeworm in horses is linked to significant amounts of intestinal rupture, impaction, intussusception or "telescoping intestines", large intestinal obstruction, colic, volvulus or "twisted-gut" and finally death. Often if the horse survives, the walls of the intestine are damaged and actually become thicker and the nerves supplying the intestine can become injured and not function properly. 

The life cycle of the tapeworm is very complicated and requires intermediate hosts between the egg and the horse. Anoplocephala perfoliata requires an Orbatid mite or "grain mite" to complete the life cycle. The horse passes tapeworm eggs in the feces. The egg is either in a casing called a "proglottid" or just in a stage called a "free egg".  The orbited mite which is located in the pasture, eats the tapeworm eggs. The egg then becomes a "cyst" inside of the mite's body.  This is an intermediate stage of the life cycle and these cysts are called cysticercoids. The horse then incidentally eats and digests the mite while grazing the pasture or eating hay. The mite then releases immature tapeworms from the cysticercoids.  These immature tapeworms then migrate through the gut to the ileocecal junction where they attach themselves to the intestine and begin their damage to the intestinal wall. These tapeworms will mature to adults over the course of 1-2 months and then begin laying eggs which will start another life cycle and consequential contamination to your pasture.

In the Ohio Valley area of the United States, we recommend that you deworm your horse in early spring and late fall with a dewormer that contains Praziquantel. This dewormer will eliminate tapeworms before they create damage in your horse. Please contact us if you having questions concerning deworming in your horse.