A key strategy for reducing antibiotic use in equine practice is to limit prophylactic administration and only treat horses with evidence of infection. 

“Every time we prescribe an antibiotic, we are creating a potential risk of resistance, both the pathogen causing the disease and the natural flora of the patient,” said Pamela Velarde, DVM, a resident in large animal medicine at Cornell University College of Veterinary Medicine’s Department of Clinical Sciences, in Ithaca, New York. “Minimizing the use of the World Health Organization’s list of high-priority and critically important antimicrobials (HPCIAs and CIAs) in our veterinary patients is imperative, and antibiotics in general should only be prescribed when infection is documented and clinically significant.” 

Velarde and colleague Gillian Perkins, DVM, Dipl. ACVIM, recently completed a retrospective study of antimicrobial prescribing practices at Cornell’s Veterinary Teaching Hospital to identify areas of possible improvement. They presented their findings at the 2024 American Association of Equine Practitioners Convention, held Dec. 7-11, in Orlando, Florida. 

In 2021 about one-third of equine patients seen at the hospital were prescribed systemic antimicrobials—including a small percentage of HPCIAs—to treat infections affecting the musculoskeletal, upper respiratory, reproductive, gastrointestinal, and other systems. 

“Out of the 543 horses prescribed an antibiotic, no evidence of infection existed in almost half of the horses,” said Velarde. “Only a small percentage (< 15%) of the horses prescribed an antibiotic had confirmed infections based on culture.” 

For horses undergoing surgery, all were treated with antibiotics, including many horses that had what were considered “clean” surgeries (i.e., elective procedures performed on clean, nontraumatic, and noninflamed surgical sites that didn’t involve opening up the abdomen). 

“Key findings of our data were that approximately a third of the horses were prescribed antibiotics, and culture and sensitivity were only infrequently done,” she said. “Overall, limited prescriptions included HPCIAs. These data suggest that we can do a better job of antimicrobial stewardship for cases with no evidence of infection and for clean surgeries. We need to continue to critically evaluate if horses in these scenarios should be prescribed antimicrobials at all.” 

The next phase of this study is to establish antimicrobial stewardship guidelines for the hospital using a three-tiered approach following WHO guidelines on medically important antimicrobials: increasing justification for use, need for culture and sensitivity, and approval by the Infection Control Committee.