Food Animal Drugs

Food Animal Antibiotics

Due to the restrictions on antimicrobial use, choosing antimicrobials for food and fiber animals is somewhat simpler than in dogs and cats in many regards.

Primary considerations:

  • are you likely dealing with gram positive, gram negative or both types of organisms?
  • is there a drug labeled for the species and the disease?
  • what drugs are legal in the species?
  • where is the infection? can the antibiotics reach it? what drugs will be effective in that environment?
  • how sick is the animal? can you use a bacteriostatic drug or do you need a bacteriocidal drug?
  • does the animal have any other conditions that would increase the risk of certain drugs? e.g. renal disease or liver failure
  • what drugs should you avoid using in order to save them for human use?

Secondary considerations

  • is the animal milking or likely to go to market soon? what is your withholding window?
  • how valuable is the animal and how expensive is the drug?
  • what routes of administration are available to you and how frequently can the drug be administered?
  • what are the resistance patterns in your area? can you assume certain drugs will be more effective than others?

Selecting antimicrobials (Dr. Alex Bianco)


Drug IV IM/SQ PO Anaerobes Good penetration Use in a dairy cow
Penicillin x x x x
Ampicillin x x x
Cephalosporins EQ/SRC x x (on label only)
Fluoroquinolones EQ FA EQ
Macrolides FA FA/foals
Chloramphenical/Florfenicol FA EQ x x
Tetracyclines x FA x

Swine Antibiotherapy Handbook: (also has good info for other species)

While I tend to assume prophylactic is important, this article suggests that antibiotics are needed pre/postop for Csections, that antibiotics should not be used for elective abdominal surgery.


Procaine Pencillin G is labeled for administration at a very low dose. This label dose is NOT effective and should be avoided. Generally doses of 22,000 – 66,000 IU/kg are recommended rather than the label dose of 6600 IU/kg.

This article does a great job of fairly painlessly explaining why and how pharmacodynamics and pharmacokinetics play a role.

Update on withdrawal intervals following extralabel use of procaine penicillin G in cattle and swine. JAVMA | JAN 1, 2022 | VOL 260 | NO. 1



Antimicrobial resistance learning site

Pharmacology chapter, Dairy Production Medicine ebook

Randomized prospective trials to study effects of reduced antibiotic usage in abdominal surgery in cows. J. Dairy Sci. 101:8217–8223. With careful attention, maybe we can pick which cases get preop antibiotics.

Food Animal Drug Regulations

OSU VMC Antimicrobial use guidelines – great place to start when choosing a drug



Wikipedia– often has very good pharmacological information

For Future Reference | Create a drug reference table

Pharmacology course notes and the online drug monographs


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Large Animal Surgery - Supplemental Notes by Erin Malone, DVM, PhD; Elaine Norton, DVM PhD; Erica Dobbs, DVM; and Ashley Ezzo, DVM is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.