deworming gray horse
Photo: Elizabeth Moyer

For decades, horse owners followed routine rotational deworming schedules. That approach fueled drug resistance in equine parasites, leaving fewer effective options today. Smarter management now relies on testing, timing, and targeted treatment.

In this episode of Equine Innovators Dr. Martin Nielsen, professor of equine clinical sciences at Aarhus University, in Denmark, shares insights from decades of research that shaped modern parasite control. He explains why elimination of equine internal parasites is not possible, what mistakes owners still make, and how veterinarians and farm managers can adapt their programs.

From tapeworms in adult horses to ascarids in foals, Nielsen outlines today’s biggest concerns and the evidence-based strategies that help preserve drug efficacy for the future. He also previews emerging diagnostic tools that could transform parasite management in the years ahead.

Tune in to learn how science-driven parasite control protects horses’ health and keeps deworming drugs effective for the next generation.

The Equine Innovators podcast series is brought to you by Zoetis. You can find the Equine Innovators podcast on TheHorse.com, Apple Podcasts, Spotify, and many other podcast apps. Don’t miss a single episode! Sign up now to receive email reminders from The Horse.

Additional Reading:

 

About the Researcher: 

Dr. Martin Nielsen

Martin Nielsen, DVM, PhD, DVSc, Dipl. ACVM, Dipl. EVPC, was the Schlaikjer Professor in Equine Infectious Disease at the M.H. Gluck Equine Research Center at the University of Kentucky until 2024. In late 2024 he started working as professor of equine clinical sciences at Aarhus University, in Denmark.

Promotional references: 

  • American Association of Equine Practitioners. 2024 Revised AAEP internal parasite control guidelines.  https://aaep.org/post/aaep-publishes-updated-internal-parasite-control-guidelines/. Accessed August 8, 2025. 
  • Lawson, A., Malalana, F., Mair, T. Larval cyathostominosis: Clinicopathological data and treatment outcomes of 38 hospitalised horses (2009-2020). Equine Veterinary Education Vol 35, Issue 8.
  • Corning, S. Equine cyathostomins: a review of biology, clinical significance and therapy. Parasites Vectors 2 (Suppl 2), S1 (2009).
  • Proudman, CJ, et al., Equine Vet J, 1998.