Treatment of natural infestations of the biting louse (Werneckiella equi) on horses using triflumuron, a benzoylurea derivative insect growth regulator.

This study evaluates the efficacy and safety of using triflumuron, a benzoylurea derivative insect growth regulator, to treat horses infested with the biting louse (Werneckiella equi). The findings demonstrate that triflumuron is both safe and highly effective in ridding horses of these parasites, even at doses three times the regular amount.

Research Objectives

• The primary goal of this study was to evaluate the efficacy of benzoyl(phenyl)urea insecticides, specifically triflumuron and diflubenzuron, in treating horses infested with the biting louse, Werneckiella equi. These substances are commonly used as lousicides for sheep, but their efficacy on horses had not yet been assessed.
• Additionally, the study aimed to assess the general wellness and dermal safety of the horses during and after the treatment with triflumuron.

Methodology

• Two efficacy trials were run using 25 adult horses naturally infested with the parasite. In these trials, triflumuron was applied as a backline pour-on at a dose of 2.5mg per kg of the horse’s body weight.
• A dermal safety trial was also conducted using 10 adult horses free of the louse. For this safety study, triflumuron was applied at a higher dosage of 7.5 mg per kg of body weight, which is three times the regular clinical dose.
• The horses were monitored over a 14-months period in order to track effectiveness and observe for any adverse effects.

Findings

• In the first efficacy trial, 100% louse-killing effectiveness was accomplished by day 44 after treatment.
• In the second trial, no lice were found on the horses by day 71 after treatment.
• During the safety trial, no adverse effects were observed, indicating that triflumuron was safe to use even at higher dosage levels.

Conclusion

• This research strongly suggests that triflumuron can effectively be used to treat horses infested with the biting louse, Werneckiella equi.
• The study also suggests that triflumuron is safe for use on horses, even at dosages three times the regular clinical dose.
• The findings provide a new method for treating this common equine ectoparasite, offering a potential solution for stable owners and horse caretakers around the globe.