Deworming protocols have changed radically over the past decade, thanks to research into how to best manage parasite control within herds and individual horses. One of the pioneers of this research is Martin Nielsen, DVM, PhD, Dipl. EVPC, Dipl. ACVM, professor at the University of Kentucky’s Gluck Equine Research Center. He described current parasite control recommendations and emerging technologies in this field during a presentation at the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah.

For a parasite control strategy to be effective, the owner and practitioner must balance treatment and surveillance. “Monitoring of dewormer efficacy is required for herd health,” Nielsen began. “Egg counts are here to stay!”

He first listed individual worm types and described some significant points about each for horse owners and veterinarians to consider:

  • Ascarids (roundworms) This year’s foals are infecting next year’s foals, said Nielsen, because ascarid eggs are environmentally resistant (i.e., capable of withstanding fairly warm summer temperatures and cold extremes in winter). Of the deworming drugs used, ivermectin and moxidectin are ineffective for controlling these worms; pyrantel salts might or might not work; and benzimidazoles are still doing a pretty good job, he said.
  • Small strongyles (cyathostomins) There are 50 different small strongyle species, the larvae of which encyst in the walls of horses’ large intestines. Ivermectin and moxidectin do not control these worms as effectively as they did in the past, and Nielsen sa