If you go out to your barn and find your horse has a nasal discharge or snooty nose and a cough, you may find out when you call your veterinarian that antibiotics will not be prescribed over the phone.  The reason for the signs could be dust, allergies or viral infection and antibiotics will not be helpful, plus – and this is significant - incorrect use can lead to antimicrobial resistance.  The development of bacteria resistant to anti-microbials is a major problem in humans and animals.  I have talked about this issue in cattle, but this is a concern in all animals including horses. Once bacteria become resistant, we have lost our ability to control their proliferation.  Dr. Wendy Vaala indicates in The Horse that without antibiotics, we will be treating infectious diseases like they did in the 1900s, which was not successful as many people and animals with infections did not survive. 

New antibiotics are first tested in humans and if it is unsuitable for humans, then it may be considered for use in animals.  The CDC indicates that 50% of the time antibiotics are used incorrectly, dosed improperly, or taken for the incorrect amount of time.  And it is not only animal medicine playing a role in antimicrobial resistance. Human medicine is also involved as some organisms can spread from human to human and from human to animals.  Bacterial organisms Salmonella, staph, clostridium difficile, and group A strep are becoming resistant in humans and horses, and Rhodococcus in foals is becoming resistant.  If you call your vet because your horse has a cough or an abscess in the hoof and you want antibiotics without your vet examining the horse, your vet may decline. It is not because your vet doesn’t want help, but is trying to decrease overuse of antibiotics.