Keep the horse as calm and still as possible while you wait for veterinary help.
Do not walk him or allow him to take a single step on his own. Instead, ask others to make the area around him as safe as possible. If it will help, offer the horse hay and water and/or bring another horse to stand nearby. You may be tempted to hold up the injured limb to keep the horse from putting weight on it, but keep in mind that 10, 15 or even 30 minutes may pass before help arrives. You might also put yourself at risk if the horse is unstable. If he is holding up the limb himself, it’s best to just let him be.
Stay with the horse.
Use your cell phone or scream for help if you must. Do not let go of the horse, even if you think he can’t move. Horses have turned minor, survivable fractures into catastrophic ones by escaping their handlers and running off in a panic.
Control any significant bleeding.
If the fracture is open and spurting bright red arterial blood, apply direct pressure with a towel, saddle pad or even your shirt to staunch it. This may be painful for the horse, so be extremely careful. There is no need to apply pressure if the wound is only trickling darker blood.
If you are capable and have another person to help, apply a Robert Jones bandage
If you have another person to help, are confident in your wrapping abilities and your horse is standing calmly, you can apply a Robert Jones bandage, which uses thick padding, hard splinting materials and several layers of wraps to stabilize the leg. This is not something you can learn on the spot, however. Practice the technique beforehand so you’ll be prepared in an emergency.
Send someone to check the other horses
If the fracture occurred in a field, it could have been the result of a fight. Send someone to check the other horses in the herd for signs of injury. Also, if your veterinarian might have trouble finding you, recruit a helper to guide her to your location.