Quick Links

Putting a Prairie Spin to Deworming Programs By Lynne Gunville

posted by Horse Owner Today    |   October 6, 2010 07:27


It was a conversation over coffee one morning that prompted a Western College of Veterinary Medicine research team to investigate the intestinal parasite load of horses living on the Prairies.

As Drs. Chris Clark and Steve Manning were discussing how often horses in the region should be dewormed, they realized that there was no solid scientific evidence to support their typical recommendations. “We’re borrowing recommendations from other parts of the world that may not be appropriate,” explains Clark. “The western Prairies need a western Prairie deworming program.”

 Shortly after that conversation, Dr. Ela Misuno began her residency in large animal medicine at the College. Having worked in Denmark where dewormers are sold by prescription only, she was well aware of the growing problems resulting from parasites becoming resistant to deworming products.

Clark says that the timing was ideal: “Dr. Misuno joined us and had this interest and experience, so it was a perfect fit as her residency project.” Misuno, who has been instrumental in designing the project, will collect and test fecal samples for parasite load while Clark and Manning will co-ordinate the project.

The research team, which is funded by WCVM’s Equine Health Research Fund, also includes Dr. Lyall Petrie who has done extensive research looking at parasite burdens in sheep and cattle, including a study of how worm burdens in sheep change throughout the year. Dr. Emily Jenkins, a veterinary parasitologist from WCVM’s Department of Veterinary Microbiology, will make her laboratory available to Misuno and help interpret the data to determine whether or not the Prairie environment should influence deworming practices.

The researchers will identify approximately 20 mare-foal pairs from three local breeding farms and will follow them over a 12-month period. Clark explains that they included the foals in order to investigate parasites known to affect foals more than mares. They also want to determine whether foals are exposed to a high worm burden from their mothers — a condition known to occur in sheep.  

 Misuno will collect and analyze fecal samples for fecal egg count (FEC) every month through the summer, two to three times during the winter, and once again in the spring. Deworming with EqvalanÒ (ivermectin), which has been donated by Merial Canada, will occur only if testing reveals a high FEC, and a follow-up count will be undertaken a week later to ensure the treatment has been effective.

Farm owners will complete a detailed questionnaire providing information about their management practices. “There are so many variables like what is the previous deworming program, what’s the population density of the pasture and how dry or wet is the pasture — all of these things become quite complicated and that’s why we need this pilot study,” explains Clark. “We need to work out how to do this on a much bigger level.”

The researchers plan to use their results to design a larger study that will randomly select horses from individual farms and will provide veterinarians with the knowledge they need to advise horse owners on the most effective deworming practices for their region.

“People are prepared to spend money and maintain their horses in the maximum state of health,” says Clark. “We want to gather information so we can give people firm recommendations that will ensure the health of their animals.”

Clark emphasizes the importance of the initial project and says that veterinarians in the Prairie area will be given those results so they can start making recommendations that will enable horse owners to make informed decisions about their deworming protocol.

“There might be a real change in the way that people view deworming. We’ve always thought of just treating everything on the farm the same way. Maybe we have to start treating each horse individually: getting those fecal egg counts done and then deworming only the horses that need treatment.”

Clark points out that responsible deworming practices benefit everyone: “First of all, it will ensure that the horses have optimum health. Then if we can reduce the amount of money horse owners have to spend, that is obviously a benefit for them. And finally, if we use the drugs more effectively, there will be no resistance problems and the horses will stay healthy for years to come.”


Lynne Gunville is a freelance writer and editor whose career includes 25 years of teaching English and communications to adults. She and her husband live at Candle Lake, Sask.

reprinted with permission of Horse Health Lines, news publication for the Western College of Veterinary Medicine’s Equine Health Research Fund. Visit www.ehrf.usask.ca to sign up for Horse Health Lines’ e-newsletter.