Several years ago we decided we would make up a first aid kit for horses that people could take with them on trips into mountains or desert. We had bandages, ointments, local anesthetics, antibiotics, syringes, needles, disinfectants, and analgesics all neatly packed in a plastic case that we bought at a local department store.
People still ask about taking some first aid items along on a pack trip.
The idea of a first aid kit probably was good, but the way we packaged it was not something people could use. Different items may be needed depending on the type of trip, the length of the trip, the distance from available veterinary attention, and the space available in the saddle bags or panniers. The most common injury when riding in rough country is lacerations or puncture wounds, usually to the extremities. Some bandage material and antibiotic dressings are all that you need to handle the injuries until you can get veterinary attention. Furacin dressing has been and still is the standby for use in horses.