First, buy a plastic bucket that holds at least a quart of water and mark a line on the outside in indelible ink that shows you the fill line for a quart. Or buy a quart sized plastic water bottle. Prepare baggies of table salt (1/2 tablespoon each) that you can add to a quart of water to scrub and cleanse a wound. The kit should also have the following supplies:

• Tamed iodine antiseptic wound scrub (such as Betadine)
• Gauze sponges to scrub up a wound
• Broad-spectrum topical antibiotic ointment (examples: Silvadene, Neosporin and Nolvasan)
• Wound dressings (examples: Telfa, Combipad and Surgipad)
• Conforming roll gauze (Kling)
• Self-adhesive stretch tape (3-inch or 4-inch roll of Elastikon tape)
• Blunt-tipped bandage scissors
• Oral broad-spectrum antibiotic tablets (Trimethoprim-Sulfa tabs)
• Topical eye ointment (nonsteroidal form)
• Rectal thermometer
• An Easy-Boot

These materials are the bare minimum for tending to a wound until your horse can receive professional veterinary attention. Ask your veterinarian what other supplies you should carry based on your individual needs, for example, garden hose sections to help your horse breathe in case of an allergic reaction to a toxin, such as snake bites. You might also wish to carry a small dose of injectable flunixin meglumine (Banamine) or sedative like xylazine (Rompun) or detomidine (Dormosedan) to control colic pain if veterinary help is not available. Be sure your vet shows you how to use these drugs.