Here's what I have for acute first aid - quite different to what else I have that is useful for additional day to day management of horses in my charge:

animalintex poultice,
equiwrap,
gamgee 30cm,
large roll of cotton wool
wound gel
Hibiscrub anti-bacterial scrub
Hydrogen Peroxide dilution
Melolin Non-stick dressings
A selection of bandages including:
Stretch cotton bandages eg Knit-firm, K-band and crepe bandages
Adhesive bandages eg Elastoplast
Elastic conforming self-adhesive bandages eg Vetrap
Tubular bandage
Synthetic orthopaedic bandage
A set of stable bandages
2cm electrical tape
duct tape 10cm wide
A gentian violet or antibiotic spray
Petroleum jelly eg Vaseline
Sudocrem
Wound powder containing fly repellent
skintact 10cm x 10cm,
vetalintex
sterile saline flush wash (I have that in packs but take salt in addition)
salt
bute
needle and vicryl suture
scissors
tweezers
thermometer
large syringe (for saline /wound flush)
shoe pullers
hoof pick
nippers
rubber gloves
clean bowl
clean towel
poultice / protective boot

All packed up in a drawstring bag in the tack room and so ready to go.    We have a checklist in the bag which shows the contents and if anything is used it's marked off and so we know what needs stocking up.

It's duplicated for the horsebox and to save having to keep having to pack up a second kit each time we go somewhere.   The horse box one also contains a pack of electrolytes and some people first aid stuff.