Selected Antimicrobial Information – Equine

Oxytetracycline [Equine]

Restriction Status



Species Usage Dose

For treatment of anaplasmosis 6.6mg/kg IV q24h for 5-7d, diluted and given slowly (extra-label use)
For treatment of Potomac Horse Fever 6mg/kg IV q12-24h for up to 5d, diluted and given slowly (extra-label use)
For treatment of Lyme disease 6.6mg/kg IV q12h for 7-10d, diluted and given slowly (to be followed by treatment with doxycycline for 1-2mos.)(extra-label use)
For treatment of proliferative enteropathy 6mg/kg IV q12-24h for 2-4wks, diluted and given slowly (extra-label use)

Brand Name(s)

Biomycin®, Terramycin®


Oxytetracycline is a bacteriostatic, time-dependent tetracycline antibiotic with a broad spectrum of activity against many Gram-positive and Gram-negative aerobes. It is not effective against Proteus spp. or Pseudomonas spp. There is activity against some anaerobes, but efficacy against Clostridium spp. is variable. Intracellular organisms are highly susceptible. Distribution is wide, except to the central nervous system. Oxytetracycline undergoes entero-hepatic recycling and is primarily excreted in urine.

Acceptable Uses

  • Treatment of anaplasmosis (Anaplasma phagocytophilum), Potomac Horse Fever (Neorickettsia risticii), and Lyme Disease (Borrelia burgdorferi).
  • Treatment of proliferative enteropathy in foals caused by Lawsonia intracellularis.

Unacceptable Uses

  • N/A

Formulations Available within the OSU Pharmacy

  • Oxytetra 100mg/ml injectable suspension
  • Oxytetra 200 mg/ml injectable suspension


  • Oxytetracycline has poor oral bioavailability.
  • Rapid IV administration can result in hypotension and collapse or renal tubular necrosis.
  • Oxytetracycline is also used for the treatment of flexural limb deformity in foals due to its non-antimicrobial effects, including attenuation of matrix metalloprotease activity, anti-fibrotic effects, anti-collagenase effects, and anti-inflammatory effects.


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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.