The most important thing to do is not panic. You need to be able to think clearly, make good decisions, and most importantly, try to have a calming effect on your horse.
If possible, move your horse and yourself to a safe place to make an initial assessment of the injury. Trying to assess and treat a horse in an unsafe environment can lead to additional injury for both you and your horse. If possible, tie your horse up. If your horse is uncontrollable or is thrashing about remember that your safely come firsts. You cannot help your horse if you are in need of medical attention too. Try to calm him down verbally. If a barn buddy or family member is present, it may be best to have them call your veterinarian so they can relay information while you continue to work with your horse.
During your initial assessment you will want to look for serious injuries. These would include: broken bones, puncture wounds, deep cuts, eye trauma, and heavy bleeding. All of these will require the immediate attention of a veterinarian.
If there is heavy bleeding, or bleeding that is squirting or pulsing out, you must stop this bleeding first. Wrap the bleeding wound with a pressure bandage. If the bandage becomes blood soaked DO NOT REMOVE IT. You do not want to release the pressure. Simply add more gauze on top of the bandage and wrap it with more vet wrap. If you cannot wrap a bandage around the wound you will have to hold the gauze in place with heavy pressure. Again, if the gauze becomes blood soaked do not remove it; add more gauze on top without relieving pressure.
Once you have controlled the bleeding; take your horse’s vital signs so they can be relayed to your veterinarian. You will need to take your horse’s pulse, respiratory rate, and temperature. You may also want to check your horse’s gums. The gums should be a healthy deep pink color. This will help the veterinarian determine the severity of your horse’s injury, how quickly they will need to respond, and aid them in helping you prior to their arrival.