Deworming Horses: Dealing With Differing Opinions

A reader trying to adhere to current deworming recommendations wonders how to manage her horse who is boarded at a farm that still practices rotational deworming. An equine parasitologist weighs in.

deworming horses
Keeping pastures and paddocks free of manure can help reduce the number of anthelmintic treatments horses require. | Photo: Alexandra Beckstett/The Horse

Q. My senior gelding is out for a lease trial. At home he lives in a drylot, and his fecal egg counts always show him to be a 0 shedder, so I treat him twice a year with a product that includes praziquantel for tapeworms. The barn he is moving to is impeccably clean and has excellent manure management. There, he will get turnout time in shared grass paddocks. However, this farm does not do fecal egg counts and still uses an eight-week rotational program on all the horses. I tried to explain the current recommendations for parasite control to the owner but to no avail.

Our agreement is that I will manage my horse’s parasite program separate from the farm’s. But I’m concerned that he is at risk because of the barn’s practices, although I’m happy there is never manure left on the paddocks. Should I be concerned, and what’s the best way to protect him from internal parasites while he lives there?

Ashley, via

Create a free account with to view this content. is home to thousands of free articles about horse health care. In order to access some of our exclusive free content, you must be signed into

Start your free account today!

Already have an account?
and continue reading.


Written by:

Martin Krarup Nielsen, DVM, PhD, Dipl. ACVM, is an associate professor of parasitology and the Schlaikjer professor in equine infectious disease at the University of Kentucky’s Maxwell H. Gluck Equine Research Center, in Lexington. His research focus includes parasite diagnostic measures and drug resistance. Known as a foremost expert in the field of equine parasites, Nielsen chaired the American Association of Equine Practitioners’ (AAEP) parasite control task force, which produced the “AAEP Parasite Control Guidelines.”

Related Articles

Stay on top of the most recent Horse Health news with

FREE weekly newsletters from

Sponsored Content

Weekly Poll

sponsored by:

How often do you buy blankets for your horse?
129 votes · 129 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!