While parasite resistance is currently a hot topic in the equine community, another form of resistance is taking its toll on horses worldwide: antimicrobial resistance. According to Imogen Johns, BVSc, MRCVS, Dipl. ACVIM, lecturer in equine medicine at the United Kingdom’s Royal Veterinary College in Hertfordshire, the amount of bacteria that has developed resistance to antibiotics since the drugs become commonplace in the 1930s and ’40s is "sobering." She presented on the topic at the American College of Veterinary Internal Medicine Forum, held June 15-18 in Denver, Colo.

At the time of their inception into society, antibiotics were considered miracle drugs, contributing to an increased human life expectancy by eight years. But Johns pointed out that antimicrobial resistance (AMR) began to occur within a relatively short time of widespread antibiotic use. This wasn’t originally a problem since 29 new drug classes were developed between 1929 and 1969; however, since then, lack of discovery of new drugs poses a sobering contrast to the rapid and rising resistance of bacteria.

Bacteria can pass resistance genes on to future generations, as well as acquire resistance to multiple drugs–even those to which the bacteria have not been directly exposed. The result of this is the development of "super bugs." Acquired antimicrobial resistance is now a serious public health concern that needs to be addressed, Johns noted.

The link between AMR in humans and animals tends to focus on food-producing animals medicated for therapeutic reasons or for growth promotion. These animals can potentially transfer antibiotic-resistant bacteria via the food chain (i.e., the humans that consume the animals could be consuming resistant bacteria). If authorities implement antibiotic restrictions for all veterinarians (which is a future possibility) and not just those ministering to food-producing animals, the implications could mean changes in how we manage equine health in the future