The first thing you want to do is make sure you have a first aid kit available for the horse in advance. The first aid kit should have all the important constituents necessary for emergencies and small cuts. You always want to make sure that you have first aid readily available. You will want to make sure you have all the important tools you need, and you will want to know how to use them.
A commercially available first aid kit for horses will cost between $39 and $80. You will want to make sure the kit has a thermometer so that you can check the temperature of the horse. All horses should have a standard temperature of 99 to 115 degrees. The first aid kit should also come with a stethoscope so that you can monitor the heart rate of the horse. You can listen clearly to the heartbeat just under the elbow on the left side of the horse.
All first aid kits should have a flashlight, in case you have an emergency in the dark. You will also want to have electrolytes in case the horse becomes dehydrated. Warming up water and adding a small teaspoon of electrolytes can encourage water consumption by your horse. The first aid kit should also have neosporin, iodine, and hydrogen peroxide. Avoid using the hydrogen peroxide on wounds as it will destroy benign tissue.
You will also want to have wire cutters handy in the event the horse gets stuck in a gate or wire. You will also want to use a twitch which can calm your horse and keep him controlled in situations where it will be in great pain. You will also want to make sure you have a knife cutting bandages and other materials. You will want to make sure you don't injure your horse when handling the knife.
You will want to use the iodine solution to clean out any thick wounds. Any wounds which will be treated by a veterinarian within a hours of the injury should not have medications applied, and should only be flushed with iodine or clean water to prevent them from drying.