No, do not use hydrogen peroxide to clean your horse’s flesh wound unless you have no other means of cleaning it. While hydrogen peroxide will kill bacteria in the wound it will also kill healthy tissue. Horse wounds can be treated with Nolvasan, Furacin, Corona, Wound Powder, or a diluted Iodine solution.
These treatments should be applied to the wound if your veterinarian is unable to attend to your horse’s injury within the first four to eight hours. If your veterinarian will be treating your horse’s injury within that time frame flush out the wound with cold water and cover it so that it stays clean and doesn’t dry out.