Equine Parasite Research Update

Researchers continue to study internal parasites with a focus on preventing resistance to deworming drugs. Read more in this article from The Horse‘s 2023 Research Roundup issue.

No account yet? Register


Researchers continue to study internal parasites and their evolution, with a focus on preventing resistance to deworming drugs

deworming horse
If you deworm without testing fecal egg counts first, you’re not only wasting time and money but also making anthelmintic resistance worse by giving unneeded treatments. | iStock

Mark Twain probably wasn’t talking about equine parasites when he said, “It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.”

Still, few sentiments ring truer when it comes to the rapidly changing world of parasite control in horses.

It wasn’t long ago we knew regular rotational deworming as the best way keep internal worms at bay. While that was true to the best of our knowledge at the time, it was what we didn’t know—and what researchers sought to find out—that’s led to our current understanding of parasites and how to manage them.

But even that is ever-evolving.

“It’s important to keep researching parasites because all horses are constantly exposed to them, they can cause significant disease, and, as living biological organisms, they keep evolving and changing,” says Martin K. Nielsen, DVM, DVSc, PhD, Dipl. EVPC, ACVM, the Schlaikjer Professor of Equine Infectious Disease at the University of Kentucky Gluck Equine Research Center, in Lexington.

So, he and other researchers carry out new studies to advance their knowledge about equine parasites, the drugs that help manage them, ways to control them sans medications, and more. Here’s what some of that recent research has shown us.

Key Focus: Anthelmintic ­Resistance

One of the main topics scientists are focusing on is anthelmintic resistance (AR), which occurs when parasites survive deworming treatment and then pass that resistance on to subsequent generations. And, says Ray Kaplan, DVM, PhD, Dipl. ACVM, EVPC, it’s a problem all horse owners should understand.

A bit of background: While dewormers are likely some of the most common treatments owners administer to horses, parasites typically don’t cause serious disease in adult horses

This story requires a subscription to The Horse magazine.

Current magazine subscribers can click here to and continue reading.

Subscribe now and gain unlimited access to premium content.

Subscribe Now

We at The Horse work to provide you with the latest and most reliable news and information on equine health, care, management, and welfare through our magazine and TheHorse.com. Our explanatory journalism provides an understandable resource on important and sometimes complex health issues. Your subscription will help The Horse continue to offer this vital resource to horse owners of all breeds, disciplines, and experience levels.


Written by:

Erica Larson, former news editor for The Horse, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

Related Articles

Stay on top of the most recent Horse Health news with

FREE weekly newsletters from TheHorse.com

Sponsored Content

Weekly Poll

sponsored by:

When do you begin to prepare/stock up on products/purchase products for these skin issues?
3 votes · 3 answers

Readers’ Most Popular

Sign In

Don’t have an account? Register for a FREE account here.

Need to update your account?

You need to be logged in to fill out this form

Create a free account with TheHorse.com!