Modern strategic deworming for horses

Modern strategic deworming for horses

For years, horse owners have dewormed horses using a rotational deworming program. This usually meant deworming every horse every couple of months and using a different product every time. Nowadays, we recognize that rotational deworming doesn’t control internal parasites effectively. Parasite resistance has become a significant problem due to constant deworming, so some of the deworming products we have relied on in the past don’t work well anymore.

Nowadays, veterinarians recommend running fecal egg counts a few times a year to determine whether the horse needs to be dewormed – a process called Strategic Deworming. It’s simple – your vet will just need a small sample of fresh manure. The number of parasite eggs per gram of manure is counted to determine if the horse is a heavy egg shedder or if parasites have become resistant to the dewormer product being used. Your horse is then only treated with a dewormer if he has a heavy parasite load. Each horse is treated as an individual and not according to a routine that delivers unnecessary medication. This usually results in horses being dewormed less often so it is more economical in the long run, and certainly better for your horse.

The chart below is an example of how your veterinarian will use the results of the fecal egg count to make a deworming recommendation. This chart only applies to adult horses – foals, weanlings, and yearlings require special attention as they are more susceptible to parasite infection, and are more at risk for developing disease.


It’s time to leave the old method of rotational deworming behind for the benefit of our horses. Work with your local veterinarian to make a strategic deworming plan.



Elizabeth Yorke, DVM, DACVS

Associate Professor of Equine Surgery

Tuskegee University College of Veterinary Medicine


To contact Dr. Yorke with questions, email her at or call the Tuskegee University Large Animal Hospital at 334-727-8436