In spite of our best efforts, parasite resistance to dewormers is becoming a problem, particularly on high-density farms. With this in mind, our pratices need to change from blanket deworming of all animals on a property, to finding who needs to be dewormed by performing routine fecal egg counts.
Fecal egg counts involves submitting a fecal sample from the horse and having it read by one of our doctors. Depending on the number of parasite eggs found, horses are divided into one of three catagories: Low Shedders, Moderate Shedders or High Shedders. By determining the statuses, we can decrease the frequency of deworming in some cases, and avoid medicating horses that may not need it. More importantly, we determine who the “high shedders” in the herd are. It is thought that somewhere between 20-30% are high to moderate shedders and are possibly responsible for 75% of the worms. These horses have a natural susceptibility to worms and will have this problem usually for life. These shedders are the horses that we need to find, and then devise a deworming program to get rid of parasites.
Be sure to talk to one of our doctors during your spring check-up to deterimine if this would be of benefit for your farm!
(Drawing by Dr. Kathy Lamb)