Topical permethrin may increase blacklegged tick (Ixodes scapularis) repellency but is associated with cutaneous irritation in horses.
Abstract: To evaluate the safety of repeated applications of permethrin concentrations (0% control, 1.5%, 5%, and 10%) to the necks and faces of horses and assess the efficacy and longevity of permethrin as an equine tick repellent. Methods: 5 healthy adult Quarter Horses. Methods: Each treatment was applied to the neck of each horse (0.01 m2) 4 times a day, for up to 10 days. An 8-mm biopsy was taken to evaluate postexposure dermal responses. Any treatments that were not withdrawn were applied to a quadrant of the horse's face 4 times a day, for up to 5 days. For tick bioassays, a treatment was applied to 1 leg of a horse and 5 female blacklegged ticks (Ixodes scapularis) were evaluated as "repelled" or "not repelled" by the treatment. The bioassays were repeated up to 5 days, but treatment application took place only on the first day of the experiment. Results: Histological results of neck biopsies indicated that more repeated exposures or higher concentrations resulted in more dermal damage. Tick bioassays showed that 5% and 10% permethrin had the greatest efficacy and longevity as a tick repellent, but the differences in tick repellency were not significant overall. Conclusions: While there was a nonsignificant trend of higher permethrin concentrations repelling more ticks with longer-lasting residual repellent effects, higher concentrations also produced greater skin damage after repeated exposures. These opposing findings emphasize the need for better tick prevention and control methods that balance safety and efficacy for the equine community.
Publication Date: 2023-02-20 PubMed ID: 36800301DOI: 10.2460/ajvr.22.10.0176Google Scholar: Lookup
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Summary
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This research investigates the safety and effectiveness of using differing concentrations of permethrin, a chemical insecticide, as a tick repellent on horses. Although higher concentrations of permethrin were found to repel ticks more effectively and for longer periods, they also led to increased skin damage in horses, highlighting the need for safer and more balanced tick control methods.
Objective of the Study
- The study aimed to assess the safety of multiple applications of varying permethrin concentrations (0% control, 1.5%, 5%, and 10%) on horses.
- It also sought to determine the efficacy and duration of permethrin as a repellent against blacklegged ticks (Ixodes scapularis) in horses.
Methods Used in the Research
- The researchers recruited five healthy adult Quarter Horses for the study.
- Each treatment was applied four times daily to a section of the horse’s neck for up to ten days.
- An 8-mm biopsy was taken to evaluate the skin’s post-exposure responses.
- Treatments that were not withdrawn were applied to a quarter of each horse’s face, also four times daily, for up to five days.
- In the tick bioassays, a treatment was applied to one leg of a horse, at which point the reaction of five female ticks was assessed as either “repelled” or “not repelled”.
- The bioassays were repeated for up to five days, but treatment application occurred only on the first day.
Results of the Study
- Neck biopsies indicated that more frequent exposures or higher permethrin concentrations resulted in increased skin damage.
- Tick bioassays revealed that 5% and 10% permethrin were the most effective as tick repellent and had the longest residual effects. However, the differences between these and lower concentrations were not statistically significant.
Conclusion of the Research
- The study found a trend of higher permethrin concentrations repelling more ticks for a longer period. However, this also resulted in greater skin damage due to repeated exposure.
- This suggests a need for better tick prevention and control methods that can balance safety and efficacy for horses.
Cite This Article
APA
Poh KC, Cole ZT, Smarsh DN, Springer HR, Kelly K, Kenny LB, Machtinger ET.
(2023).
Topical permethrin may increase blacklegged tick (Ixodes scapularis) repellency but is associated with cutaneous irritation in horses.
Am J Vet Res, 84(4), ajvr.22.10.0176.
https://doi.org/10.2460/ajvr.22.10.0176 Publication
Researcher Affiliations
- Department of Entomology, Pennsylvania State University, University Park, PA.
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA.
- Department of Animal Science, Pennsylvania State University, University Park, PA.
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA.
- Penn State Extension, Pennsylvania State University, University Park, PA.
- Animal Diagnostic Laboratory, Pennsylvania State University, University Park, PA.
- Penn State Extension, Pennsylvania State University, University Park, PA.
- Department of Entomology, Pennsylvania State University, University Park, PA.
MeSH Terms
- Horses
- Animals
- Female
- Dogs
- Ixodes / physiology
- Permethrin / pharmacology
- Permethrin / therapeutic use
- Dog Diseases / drug therapy
- Horse Diseases
Citations
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