Antimicrobial use in equine patients at a veterinary teaching hospital in the northeastern United States reveals opportunities for enhanced stewardship.

Overview

• This study evaluated how systemic antimicrobial drugs are used in horses at a veterinary teaching hospital over one year to find ways to reduce unnecessary antimicrobial use and promote better stewardship practices.

Study Purpose and Design

• Aim: To assess the frequency and context of systemic antimicrobial prescriptions in equine patients and identify targets for reducing unnecessary use.
• Methodology: Retrospective review of electronic medical records from 2021 at a northeastern U.S. veterinary teaching hospital.
• Data included all equine visits where systemic antimicrobials were administered.
• Statistical analysis: Negative binomial regression was used to understand factors influencing the rate of antimicrobial prescriptions.

Key Findings on Antimicrobial Use

• Antimicrobials were prescribed in about one-third of equine visits (33.5%, 543 out of 1,622 visits).
• Most visits where antimicrobials were used involved the administration of up to three different drugs (89.1%).
• Higher prescription rates were noted in horses with confirmed or suspected infections and in those that died or were euthanized.
• The highest-priority critically important antimicrobials, which should be reserved for serious situations, were infrequently used (only 13.6% of antimicrobial prescriptions).
• Horses undergoing clean surgeries (surgeries without existing infection) typically received antimicrobials on the day of surgery, but many received treatment for more than 24 hours post-surgery, which may be unnecessary.
• Almost a quarter (24%) of nonsurgical patients received antimicrobials despite no evidence of infection.
• Diagnostic cultures to identify the causative bacteria were rarely performed (only 15.7% of cases), limiting tailored antimicrobial use.

Interpretation and Recommended Improvements

• Systemic antimicrobials were frequently used but there is potential overuse, especially in cases without infection and in extended perioperative periods for clean surgeries.
• The low use of highest-priority important antimicrobials suggests clinicians are appropriately reserving these drugs, avoiding them as first-line treatments.
• Recommendations include:
  • Better documentation of why antimicrobials are prescribed, including justification, specific drug types, treatment duration, and reasons for modifying therapy.
  • Reducing the use of antimicrobials around the time of clean surgeries, particularly limiting treatments beyond the day of surgery.
  • Increasing the use of bacterial cultures to guide targeted antimicrobial therapy instead of empirical treatment.

Broader Context and Importance

• Antimicrobial resistance is a major global health issue, threatening the effectiveness of drugs used to treat infections.
• Veterinary use of antimicrobials contributes to resistance development; therefore, veterinarians play a key role in stewardship by critically assessing their prescribing habits.
• By aligning antimicrobial use with current evidence-based guidelines, clinicians can reduce unnecessary antimicrobial exposure, slowing resistance emergence and preserving drug efficacy.