Selected Antimicrobial Information – Equine

Chloramphenicol [Equine]

Restriction Status



Species Usage Dose

For susceptible infections
  • 45-60mg/kg PO q6-8h (extra-label use)
  • 25mg/kg IM or IV q6-8h (extra-label use)
For foals 20-40mg/kg PO or IV q-64h

Brand Name(s)



Chloramphenicol is a bacteriostatic, time-dependent acetamide antibiotic with a very broad spectrum of activity, including Gram-positive and Gram-negative aerobes, and anaerobes. Plasmid-mediated resistance to chloramphenicol develops in Gram-negative bacteria over time. Chloramphenicol is widely distributed throughout the body, crosses the blood-brain barrier, and penetrates necrotic tissues and abscesses. Elimination is through hepatic metabolism, and inactive metabolites are excreted in urine.

Acceptable Uses

  • Treatment of conditions in which broad-spectrum coverage is required (e.g. pneumonia, peritonitis, internal abscesses, cellulitis). Culture and susceptibility are indicated prior to initiating therapy.
  • Treatment of central nervous system infections (e.g. meningitis or cerebral abscesses).
  • Treatment of proliferative enteropathy in foals caused by Lawsonia intracellularis.

Unacceptable Uses

  • Mycobacterium spp. are intrinsically resistant.

Formulations Available within the OSU Pharmacy

  • Chloramphenicol 1g tablet
  • Chloramphenicol 250mg tablet


  • Idiosyncratic, irreversible aplastic anemia is a rare complication of human exposure to chloramphenicol, which can lead to death. Gloves should always be worn when handling chloramphenicol.
  • Chloramphenicol can decrease the clearance of other hepatically-metabolized drugs (e.g. barbiturates, xylazine).


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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.