Selected Antimicrobial Information – Equine

Enrofloxacin [Equine]

Restriction Status



Species Usage Dose
For treatment of susceptible infections
  • 5mg/kg IV q24h (extra-label use)
  • 5-7.5mg/kg PO q24h (extra-label use)

Brand Name(s)



Enrofloxacin is a bactericidal, concentration-dependent fluoroquinolone antibiotic with activity primarily against Gram-negative aerobes, such as Enterobacteriaceae and Pseudomonas aeruginosa. Gram-positive coverage is limited, though enrofloxacin is efficacious against many Staphylococcus spp. Distribution is wide, including into abscesses, and excretion is primarily in the urine with also a lesser component of biliary excretion.

Acceptable Uses

  • Treatment of Gram-negative infections, or when combined with a ╬▓-lactam antibiotic, broad spectrum antimicrobial coverage. This includes Gram-negative pneumonia, osteomyelitis, or septic arthritis.
  • Treatment of intracellular infections, such as Mycoplasma, Neorickettsia, or Anaplasma.
  • Treatment of internal abscesses, such as Corynebacterium pseudotuberculosis infections.
  • Treatment of urinary tract infections.

Unacceptable Uses

  • Gram-positive infections other than susceptible Staphylococcus spp.
  • Anaerobic infections.
  • Should not be used in foals due to risk of articular cartilage damage.

Formulations Available within the OSU Pharmacy

  • Enrofloxacin 100mg/ml injectable suspension
  • Enrofloxacin 20mg/ml oral suspension
  • Enrofloxacin 22.7mg tablet
  • Enrofloxacin 68mg tablet
  • Enrofloxacin 136mg tablet
  • Baytril 22.7mg/ml injectable suspension
  • Baytril 100mg/ml injectable suspension
  • Baytril 22.7mg tablet
  • Baytril 68mg tablet


  • Formulations given PO have been associated with oral ulceration and/or colitis.
  • Ciprofloxacin has been associated with fatal colitis in horses and should not be used.


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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.