Parasite Resistance Live Q&A on

Have questions about parasite resistance and how to manage it on your farm?

On Tuesday, July 14, at 8 p.m. EDT, hosted a live question and answer session with Martin Nielsen, DVM, PhD, from the Faculty of Life Sciences, University of Copenhagen, and Craig Reinemeyer, DVM, PhD of East Tennessee Clinical Research. This live question and answer session was sponsored by Intervet/Schering-Plough Animal Health. The archived Q&A session is below.

Who Should Attend: Veterinarians, researchers, vet students, and vet techs.

Anthelmintic resistance is recognized as a serious challenge for the control of equine gastrointestinal nematodes, particularly small strongyles (cyathostomins). Some of the world's leading researchers presented a series of nine talks at the University of Kentucky's Gluck Equine Research Center this spring. and sponsor Intervet/Schering-Plough Animal Health offer videos of eight presentations that can be found on Presenters addressed the current state of anthelmintic resistance in equine parasites, with emphasis on mechanisms of development and methods to diagnose dewormer resistance. Development of sustainable methods for control of equine parasites was also discussed.

Topics Covered Include:

  • Anthelmintic Resistance, A Status Report
  • Multidrug Resistant Farms--How to Design a Treatment Schedule
  • Restriction of Drug Usage--Lessons from European Experience
  • Mechanisms of Anthelmintic Resistance and Methods For Detection
  • Shorter ERPs in Cyathostomins--Interpretation and Implications
  • Anthelmintic Resistance in Non-Strongyle Nematodes
  • Immunity to Cyathostomins and its Impact on Control Program
  • Equine Tapeworms--Do They Cause Disease?

Presenters and their topics that are now available at on video are:

Ray Kaplan, DVM, PhD, Dipl. EVPC, from the University of Georgia College of Veterinary Medicine, reviewed the prevalence of cyathostomin (small strongyle) resistance to commonly used dewormers and discussed standard parasite control practices that contribute to the spread of resistance.

Tom Craig, DVM, MS, PhD, from Texas A & M's College of Veterinary Medicine, discussed the practical difficulties of effectively managing parasites at typical horse farms where various age cohorts of horses have different needs, multiple owners all want to implement their own programs, and evidence-based recommendations must compete with blind tradition and economic limitations. 

Nielsen reviewed the recent, unique experiences in Denmark, where over-the-counter sales of equine anthelmintics were banned and veterinarians are only allowed to use dewormers therapeutically after a diagnosis of clinical parasitism. Reducing the frequency of deworming has resulted in the reappearance of some parasitic pathogens that have been all but eradicated at most North American horse farms. 

Kaplan also discussed the genetic basis of anthelmintic resistance in cyathostomins (small strongyles) and demonstrated the impact of certain control strategies on the genetic composition of worm populations. The limitations of current laboratory methods for detecting anthelmintic resistance were reviewed. 

Gene Lyons, PhD, of the Gluck Equine Research Center, reported on research conducted in the Lexington, Ky., area during 2008 that demonstrated ivermectin is no longer as effective against cyathostomin (small strongyle) populations as it had been historically. Lyons also discussed his experiences with anthelmintic-resistant ascarids at major Thoroughbred breeding operations near Lexington. 

Reinemeyer reviewed evolving anthelmintic resistance in ascarids, which are important pathogens of foals and yearlings. Practices that select for ascarid resistance were identified, and recommendations for managing resistance and preventing its introduction into a herd were discussed. 

Tom Klei, PhD, of the Louisiana State University School of Veterinary Medicine, reviewed the current state of knowledge regarding acquired immunity to equine parasites. As the options for effective chemical control become more limited, exploitation of horses' inherent and acquired immunity to parasites will be an increasingly valuable adjunct. 

Nielsen reviewed the controversial topic of whether or not tapeworms can be considered serious pathogens of the horse. His conclusions might impact your anthelmintic selection choices and control programs. 

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.