Why is it so difficult for equine veterinarians to change prescribing practices? That’s the question Clare Ryan, DVM, PhD, Dipl. ACVIM-LA, from the Department of Infectious Diseases, at the University of Georgia’s College of Veterinary Medicine, in Athens, posed during her presentation at the 2024 American Association of Equine Practitioners Convention, held Dec. 7-11 in Orlando, Florida. One reason, she said, is that changing behavior is challenging.

“Things always come up that keep us from making changes that we know are important … we are busy!” she said. “And with push back from clients when we try to change our behavior, it can be even more difficult, especially when trying to step away from the higher-tier antibiotics toward first-tier antibiotics.”

Ryan used ceftiofur as an example: “It’s a fantastic drug,” she said. “A third-­generation cephalosporin with activity against both Gram-positive and -­negative microbes approved for Streptococcus equi respiratory infections and, of course, effective for many off-label conditions. It is widely available, affordable, convenient to administer, especially if needed long-term, and usually has few adverse effects.”

A big downside, Ryan said, is the significant impact cephalosporin resistance has on treating serious infections in humans. The potential impact is so big, the World Health Organization classifies ceftiofur as an HPCIA (highest-priority critically important antimicrobial), meaning it should be used sparingly in equine practice.

“The University of Georgia has an antimicrobial stewardship committee to help guide prescribing practices for hospital veterinarians, and they have a tier system,” Ryan explained. “In this system, ceftiofur is tier 2, not first-line therapy.”

When is it appropriate to use ceftiofur? Ryan described a litmus test to find out:

1. Is ceftiofur effective at treating the bacteria causing the infection? Enterococci, Pseudomonas, and Salmonella are inherently resistant to cephalosporins.
2. Is the cultured organism’s minimum inhibitory concentration (MIC) above the reported MIC break point?
3. Can ceftiofur reach adequate concentrations at the infection site? It cannot in the meninges, placenta, or joints.
4. Are reasonable alternatives available, such as beta lactams (penicillin, ampicillin), sulfas, tetracyclines, or gentamycin, that are not HPCIAs?

For which clinical conditions is ceftiofur use appropriate? Ryan explained the Gram-positive respiratory infections it is labeled for (at times combined with an aminoglycoside for Gram-negative coverage), urinary tract infections, and potentially some cases of endometritis with Gram-­positive organisms.

“If treating foal bronchopneumonia, fresh wounds/lacerations, following choke, for surgical prophylaxis, or strangles, we really should be looking for the lower-tiered drugs,” she said.

Further, she emphasized that we should reach for nonantibiotic therapies and employ vaccination, improved husbandry, and biosecurity protocols to prevent disease.

How can you start making changes in your antibiotic-prescribing habits?

“Be curious about antimicrobial stewardship,” said Ryan. “Start by picking small things and implement one at a time. Don’t think you’re going to suddenly be a perfect antimicrobial steward in one afternoon.”

Also, find a like-minded colleague and develop your own antimicrobial use guidelines, holding each other accountable and leading the way for other practitioners to follow suit.