Antimicrobial dosing for common equine drugs: a content review and practical advice for veterinarians in Australia

Background Appropriate dosing with antimicrobial agents is critical for effective treatment and to prevent the development of antimicrobial resistance. Methods A review was undertaken of equine journal articles (Equine Veterinary Journal, Equine Veterinary Education, Australian Veterinary Journal, Australian Equine Veterinarian, Journal of Veterinary Internal Medicine and Journal of Equine Veterinary Science) between January 2015 and August 2018. Those with dosing regimens for procaine penicillin G, gentamicin or trimethoprim‐sulfonamide in adult horses were examined and evaluated. Pharmacokinetics and ‐dynamics of these drugs were also reviewed. Results & Conclusion The most frequently reported doses for penicillin, gentamicin and trimethoprim‐sulfonamide were 20–25,000 IU/kg, 6.6 mg/kg and 30 mg/kg, respectively. Veterinarians treating equine patients in Australia should be aware of the current recommended doses and inter‐dosing intervals to ensure efficacy in therapy and to preserve the usefulness of these antimicrobials for the future.