IMO, it doesn't matter what you have in your first aid pack
if you don't know how to administer first aid. I think everybody needs a
course in first aid every couple of years just to keep fresh. First aid
for people will give you a lot of savvy about taking care of your horse in an
emergency situation.
That said, here's some stuff I keep on hand in the
barn.
Sanitary napkins for covering bleeding
wounds.
Banamine (refrigerate)
Dipyrone (ditto)
Empty large syringes
(without needles) for washing out wounds. I got a huge bag of them from
the blood bank, free)
We ride for a Mounted Patrol Unit and in our packs we
take:
paper and a pencil with duct tape wrapped around
it
compass
aspirin (1st aid for heart attacks)
mini pads
adhesive tape/vet wrap
bandaids
sugar (for diabetics)
alcohol swabs
safety pins
string
CPR mask
emergency blanket
matches
power bar
All this stuff fits in a tiny pack.