Selected Antimicrobial Information – Equine

Gentamicin [Equine]

Restriction Status



Species Usage Dose
For susceptible infections in adult horses 6.6mg/kg IV q24h (extra-label use)
For susceptible infections in foals <2wks 12mg/kg IV q36h (extra-label use)
For susceptible infections in foals >2wks 6.6mg/kg IV q24h (extra-label use)
For susceptible uterine infections 2.0-2.5g diluted in 200-500mL sterile 0.9% NaCl, infused into the uterus q24h for 3-5d during estrus
For regional limb perfusion 1g or 1/3 the systemic dose diluted to 30-60 ml with sterile 0.9% saline

Brand Name(s)

Gentocin®, Garamycin®


Gentamicin is a bactericidal, concentration-dependent aminoglycoside antibiotic with efficacy primarily against Gram-negative aerobic organisms, and some Gram-positive aerobes such as Staphylococcus spp. Gentamicin is not effective against anaerobic bacteria. Distribution is throughout the extracellular fluid, and penetration into cells and tissues is poor. Excretion is primarily in urine. There is a significant post-antibiotic effect.

Acceptable Uses

  • Used in combination with a ╬▓-lactam, provides broad-spectrum coverage for treatment of pleuropneumonia, septic arthritis, or osteomyelitis.
  • Treatment of streptococcal and non-enteric Gram-negative infections, including Pseudomonas aeruginosa.
  • Treatment of septic arthritis or other localized infections when used in antibiotic-impregnated polymethylacrylate beads, intra-articular injections, or regional limb perfusion.
  • As an alternative to amikacin.

Unacceptable Uses

  • Inactivated in the presence of purulent or necrotic material (e.g. abscesses).
  • Anaerobic infections.

Formulations Available within the OSU Pharmacy

  • Gentamicin 100mg/ml injectable suspension
  • Gentamicin Sulfate 100mg/ml intrauterine infusion suspension


  • Nephrotoxicity (acute tubular nephrosis) is a significant side effect that can be avoided by following dosing recommendations, minimizing duration of therapy, maintaining hydration status of patient, minimizing concurrent use of nephrotoxic drugs, and seeking alternative antimicrobial treatment in patients with pre-existing renal disease. Therapeutic drug monitoring can help optimize dosing and minimize trough concentration to help avoid nephrotoxicity.


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OSU VMC Antimicrobial Use Guidelines Copyright © 2018 by The Ohio State University College of Veterinary Medicine is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.