I have a LOT of stuff in my kit...from vet wrap, and vet RX, to Banamine, and penicillin. And yes, even though I have boarded mostly for the last 4 years, I ALWAYS have my own kit ready and available.
A side on Banamine (which I ALWAYS have on hand), it is best given IV...it can cause some issues when given IM, so if your vet is willing, have them show you how to inject it into the vein. Of course in an emergency it doesn't matter, but not only will it act faster given IV, but you reduce the muscular effects that it can have.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."