Retrospective assessment of perioperative antimicrobial use for elective arthroscopy in horses.
Authors: Muntwyler Noah, Dubois Marie-Soleil, Weese J Scott
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Perioperative Antimicrobial Use in Equine Arthroscopy Prophylactic antimicrobials are fundamental to preventing surgical site infections in equine arthroscopy, yet evidence suggests current practice may deviate substantially from evidence-based recommendations. Muntwyler and colleagues reviewed medical records from 150 horses undergoing elective arthroscopy at a single institution between 2016 and 2018, examining the timing, dosing, and duration of preoperative, intraoperative, and postoperative antimicrobial administration. Whilst nearly all horses (99.3%) received preoperative antimicrobials, only 40% were dosed within the critical 60-minute window before surgical incision—a concerning gap given that adequate serum and tissue concentrations at the time of first incision are essential for prophylactic efficacy. Drug choice significantly influenced timing adequacy: penicillin-based regimens failed to maintain therapeutic levels in 35% of cases due to their short half-life, whereas trimethoprim-sulphadoxine proved more reliable, and body weight was independently associated with underdosing for penicillin and trimethoprim-sulphadoxine but not gentamicin. Postoperatively, antimicrobial use was highly variable, with 77% of discharged horses prescribed continued treatment at home for a median of three days—a practice not typically supported by prophylaxis guidelines for uncomplicated elective cases. For equine practitioners, these findings underscore the importance of protocol standardisation, particularly regarding antimicrobial selection based on pharmacokinetics, precise dosing calculations relative to body weight, and careful timing of administration to ensure optimal surgical prophylaxis whilst reducing unnecessary exposure that drives antimicrobial resistance.
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Practical Takeaways
- •Ensure antimicrobial doses are administered within 60 minutes before surgical incision for optimal prophylaxis; consider trimethoprim-sulfadoxine as it maintains therapeutic levels longer than penicillin
- •Weight-based dosing protocols for penicillin and trimethoprim-sulfadoxine need review and standardization to prevent underdosing in heavier horses
- •Postoperative antimicrobial use should be limited to one dose for clean elective arthroscopy rather than extended courses; develop clear institutional protocols to reduce unnecessary antimicrobial exposure and resistance risk
Key Findings
- •99.3% of horses received preoperative antimicrobials, but only 40.2% received doses within the recommended 60-minute window before surgical incision
- •35.1% of horses receiving sodium penicillin had first incision performed more than two half-lives after drug administration, compared to only 0.8% of those receiving trimethoprim-sulfadoxine
- •Body weight was significantly associated with underdosing for penicillin (P=0.0075) and trimethoprim-sulfadoxine (P=0.002) but not gentamicin
- •77.2% of discharged horses received postoperative antimicrobials (median 3 days), indicating prolonged prophylaxis beyond elective arthroscopy guidelines