Thesis Title

A Survey Of Anthelmintic Control Practices Of Horses Used For Trail Riding And Horse Show Competitions

Date of Graduation

Spring 2016


Master of Natural and Applied Science in Agriculture


College of Agriculture

Committee Chair

Gary Webb


Effective parasite control is essential for maintenance of health in the equine athlete. Today cyathostomes are the most common and pathogenically significant parasite to affect horses around the world. Parasite resistance has been escalating within all anthelmintic classes. Objectives of the study were to determine parasite load in performance horses that participated in trail rides or horse shows and to survey parasite control practices utilized by owners participating in these activities. Surveys were distributed to owners of horses at horse shows or trail riding events (n=155) to determine current anthelmintic practices utilized by horse owners. Fecal samples were collected from 277 horses and evaluated for parasite eggs using a Modified McMaster Method. Eighty-two percent of survey respondent stated that they rotated the class of anthelmintic used to treat their horses for internal parasites. Logit model analysis indicated these populations of horses were 9.5% more likely to have a fecal egg count (FEC) ≥400 eggs/gram (p<0.05). Horses were 10% less likely to have a FEC ≥400 eggs/gram if owner stated they had previous knowledge of parasitic resistance in the horse (p<0.03), or when horses were housed on five acres or less (p<0.05). A total of 197/277 horses had been treated with an anthelmintic ≤8 weeks prior to the date the survey was taken. Horses treated more than 12 weeks prior to sampling had higher FEC than horses treated 1-4, 6-8 or 10-12 weeks prior to sampling (p<0.05). Egg counts of the later groups were not different. Therefore, there may be resistant populations of cyathostomes in the horses sampled.


parasite, anthelmintic, equine, cyathostome, performance horse

Subject Categories



© Cassandra Ruth O'Hara


Open Access