Comparison of chlorhexidine and alcohol-based antisepsis of the distal limbs of horses

Abstract

Background: An alcohol-based rub has been confirmed effective at reducing bacterial counts on equine skin. Skin sites with expected high bacterial burden have not been tested or has a comparison to a common protocol been performed.

Objectives: To determine if ethanol-based antisepsis reduces bacterial counts on the equine distal limb comparable to a current chlorhexidine scrub method and determine the most effective application technique for the product.

Study design: Randomised trial.

Methods: Forty-one horses were used in the study. By horse, each limb was randomly assigned to a treatment group: 5min scrub using 4% chlorhexidine gluconate to a clipped site (CHG); 90s scrub using 80% ethanol to a clipped site (ETC); 90s contact with 80% ethanol applied as a spray to a clipped site (ETS) and 90s scrub using 80% ethanol to an unclipped site (ETUC). Samples were collected pre- and post-treatment and plated in duplicate. Bacterial counts were log₁₀ transformed and averaged between duplicates. A linear mixed model was used to compare mean log₁₀ CFU/mL reduction between groups. A cost-benefit analysis was performed.

Results: There was no significant difference in mean log₁₀ CFU/mL reduction between CHG and ETC in either fore- or hindlimbs. In forelimbs, there was no significant difference in mean log₁₀ CFU/mL reduction between any groups. In hindlimbs, CHG had significantly greater mean log₁₀ CFU/mL reduction than ETUC and ETS. No significant difference in cost-benefit was found between CHG and ETC. Significant differences were noted between CHG and both ETUC and ETS.

Main limitations: Researchers were not blinded to treatment group during sample collection.

Conclusions: This study showed no significant difference in reduction in bacterial counts on the distal limb of horses between CHG and ethonol (ET) when applied as a scrub to a clipped site and there was no significant difference in cost-benefit between these treatments.

Keywords: alcohol-based antisepsis; bacterial count; chlorhexidine; ethanol; horse.