Store these items in the trailer so you always have them on board!
Equine First aid kit
Spare Tire/Jack/Tire Iron
Three emergency triangles/flares
Flashlight with spare batteries
Electrical tape and duct tape
Knife for cutting ropes in emergency.
Water - 5 - 20 gallons. Enough for drinking, cooling the horse if overheated, or washing of wounds in the event of injury.
Spare halter and lead rope
Spare light bulbs
Spare fuses if applicable
Broom, shovel, fork, manure disposal bags