Ask the Vet Live FREE Q&A on Horse Parasite Basics/Deworming

Do you have questions about how best to deworm your horses? You're not the only one! Join us for the extended Ask the Vet LIVE Q&A chat event on Parasite Basics and Deworming April 27, from 2-3 p.m. EST. Our veterinary experts have graciously offered to extend the session from 30 minutes to a full hour because we've received quite a few deworming questions from owners interested in learning how to manage their horses' parasite loads.

Deworming a horse This live chat event was brought to you free by Intervet Schering-Plough Animal Health.

Following are just a few of the questions we've received so far that will be discussed during this event:

  • How does harrowing a pasture affect the spread of parasites?
  • How should you approach deworming a colicky horse (timing, dewormer type, etc.)? I have concerns of impaction due to the dying worms.
  • I am using a holistic approach ... is it good to kill tapeworms?
  • Does each region of the United States call for its own deworming schedule?
  • How often and when should I do fecal tests?
  • If fecal egg count shows that a horse is a low shedder ... is twice yearly deworming adequate, and what products should be used?
  • Is it possible to "over-worm" your horse?
  • When is it best to start deworming a foal and with what product? What is the best deworming schedule for pregnant mares?
  • The new protocol is extremely expensive for owners of farms with multiple horses. How can this owner decrease these expenses?
  • What are the pros and cons of daily deworming vs. rotational every 2 months in very crowded fields?

Our on-call veterinarians for this event will include:

Martin Krarup Nielsen, DVM, PhD, who has been an assistant professor in equine clinical parasitology at the University of Copenhagen, Denmark since 2007. He teaches at the University Large Animal Hospital and conducts research that mainly focuses on diagnosis and control of equine helminths (worm parasites). He has spent sabbaticals at the University of Georgia and the University of Kentucky in the United States, and he is collaborating widely with colleagues in North America. He has received several research awards, including the Outstanding Graduate Student Award given by the American Association for Veterinary Parasitology in 2007 and the Danish national Young Elite Scientist Award given by the Danish Ministry of Sciences in 2009. For more information, visit

Wendy E. Vaala, VMD, Dipl. ACVIM, Sr. Equine Technical Services Specialist at Intervet/Schering-Plough Animal Health. She specializes in internal medicine and equine neonatology and perinatology. Prior to joining Intervet/Schering-Plough Animal Health in 2004, Dr. Vaala served on the staff of BW Furlong and Associates in New Jersey, where she started both a new foal intensive care unit and a foaling program for mares with high-risk pregnancies and a general medicine referral service. She also established a neonatal intensive care facility and medicine referral service while on staff at Mid-Atlantic Equine Medical Center. She has been an invited lecturer at seminars and symposiums for horse owners and breeders in the United States, Canada, Australia, South America and Europe. She also has authored articles for the Journal of American Veterinary Medical Association, Equine Veterinary Journal and Compendium.

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