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Antibiotic Resistance in Horses

Updated: 10 hours ago



The objective of a recently published article was to discuss the controversies surrounding antimicrobial use in critically ill horses. It is well known that increasing bacterial antimicrobial resistance in the human population is not only a very concerning problem but has changed the way in which antibiotics are used and prescribed and how patients are treated. The goal has been to decrease bacterial resistance from developing to “reserved” antimicrobials (an antimicrobial not recommended as a “first-line treatment”) currently in use in human medicine today.


Unfortunately, veterinary medicine has followed a similar trend, making antimicrobial treatment more difficult in critically ill foals and adult horses. Decisions need to be made regarding the most effective drug to treat the patient, taking into account the disease being treated, the duration and necessity of treatment, and whether the disease is infectious or noninfectious. The researchers looked specifically at three examples of critically ill horses: purulent infections (abscesses of the respiratory system and the abdomen), neonatal septic (blood-borne infection) foals, horses that had colic surgery, and horses that had colitis (inflammation of the colon). The source of their data was extensive PubMed searches from 1970-present, focusing on terms and keywords pertinent to their study (ex., horse, foal, antimicrobial, prophylaxis, to name a few). While they found that there were few“evidence-based” recommendations for the use of antimicrobials in horses, they were able to come to the following conclusions:

  • Antibiotic combinations remain the basis for treating purulent infections.

  • Antimicrobial treatment for compromised foals should not continue beyond recovery of the foal.

  • Continuation of prophylactic antimicrobials (used to prevent a disease) >3 days is likely unnecessary after colic surgery: a shorter duration might be equally effective.

  • Antimicrobial prophylaxis in adult horses with diarrhea is “unlikely to be beneficial.”

In an effort to slow the development of resistance to antibiotics, the human and veterinary communities need to rethink how antimicrobials are being used to treat their patients. With few oral antibiotics available to treat horses and certain antimicrobials needing to be “reserved” for only the most targeted cases, it is necessary to change the way in which antimicrobials are being prescribed and used. This may mean that horse owners will also have to adjust their way of thinking about how their critically ill horses are being treated. Owners will need to understand and accept new treatment options that will get their horse well without compromising any further the effectiveness of the antibiotics currently available for use in equine medicine.


Scientific Article: Dunkel B. DVM,PhD, DACVIM, DECEIM, DACVECC and Johns, I. BVSc

DACVIM. “Antimicrobial use in critically ill horses”, J. of Vet Emergency and Critical Care 25(1) 2015,pp. 89-100.



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