I have most of what others have stated - and it's sort of funny, but my horse first-aid kit is usually better stocked than my people kit. I don't know how many times I've used the horse's kit to patch myself up!
Yes, I have gone out to the barn and fetched some first aid stuff from my horse supplies, but have also done the reverse in an emergency= like used human eye drop antibiotics on a horse
I even took a horse to a Hospital emerg department once.
Kinda a funny story. Way back when, all we had were covered stock racks to haul a horse. We loaded a mare, going for breeding, quite a distance away, in the dark. Of course, we had to dot hat by backing against a dirt pile, and on the way in, she had caught a back leg somewhere.
I did not think it was serious, so we set off. When we stopped in Red Deer for coffee,I noticed the wound was bleeding quite a bit, and no, I did not have any emergency supplies with me. Learned a lesson for the future! Of course, easy to keep stuff in a tack compartment of a horse trailer.
Anyway, it was early in the morning with no vet clinics open, thus I told hubby to drive tot he Red Deer hospital. I walked into emerg, and asked, as a professional courtesy, if they would give me some dis disinfectant and bandaging material for an injured friend out in the parking lot.
I was asked as to why I did not just bring the patient in. When I told them it was a horse, they rolled eyes, gave me the supplies and told me to just go!