What is scarlet oil?
I think vital signs are important to know or have handy in your kit: Horse Vital Signs: Temperature, Pulse and Respiration
This site tells you the values and how to take them. When you are in an emergency, this is vital (pardon pun) information for your vet. Also, keep a watch with a second hand with you or in your kit. You can also purchase a stethoscope and have your vet show you a think or 2 about listening for bowel sounds. These are great skills to develop if you have horses. Learn how to take vitals, especially the pulse (in several different locations). Oh, and know where to stick the thermometer! In addition, people often do not learn how to properly bandage a horse until they have to. I think if you can learn to wrap polos, then you can get the hang of bandaging. There is nothing like a terrible bandage job that hinders a wound from healing.