Researchers from the Department of Large Animal Sciences at the University of Copenhagen in Denmark, led by Casper Lindegaard DVM, PhD, compared the effects of hot iron branding and microchip transponder injection on horses by measuring the aversive behavioral reactions associated with pain. The research is published in the July 2009 issue of the American Journal of Veterinary Research. In the experiment, four observers scored the behavioral reactions of 7 adult horses, and levels of inflammation and stress hormones was assessed.
The horses that were branded using a hot iron elicited a much stronger aversive reaction that is associated with pain than those injected with a microchip. Chemicals released by the horse in response to pain or inflammation were also much higher in horses that were branded. However, interestingly neither method increased the level of stress hormones.
Branding of horses and livestock as a means of identification has occurred since the ancient Egyptians, and other modern techniques include freeze-branding, tattoos, earmarking, and ear tagging.