I take it you mean equine?
I have:
Thermometer
Animalintex
Vetwrap
Scissors
Cotton wool
Elastic and a polo type bandage
Hydrogen peroxide
Sterile wound cream
Arnica tablets
Calendula cream
Gel that has Arnica and Witch hazel in it
Salt (to make saline with)
Zinc oxide cream (like sudofed)
Latex bandage
Suncream
Mag Phos tablets
Weight tape
Tea tree oil
Purple spray
Milton fluid
I keep things simple,
scissors, Thermometer, stethoscope, syringes, Hibiscrub, vet wrap, Poultice, sudocreme or equivalent (what ever is on offer at the time) Aloe vera gel, Bute, ACPs.
I buy anything else as needed. I used to keep all sorts of lotions and potions but they just go out of date and clutter the place up. If what ever it is is so desperate that it can't wait for you to go out and buy it then you should call the vet anyway and they'll bring you what you need.
Two things that haven't been mentioned so far are epsom salts and gaffa tape. Along with animalintex, vetwrap and hydrogen peroxide these are essentials when dealing with an abcess. I always make sure i have witch hazel and arnica gel, wound cream and purple spray aswell.
Yes Gaffa tape alway have pleanty in...it's no fun driving to B&Q in a rush late at night to get more...two dressing changes a day and a grumpy horse that pulls off the poltice soon leaves you short!
Bandages
Plasters
Tape
Thermomiter
Bute
Gauze
Hibi scrub
Oxytetryclin spray
Iodine
Slings
Steri Strips
Salt
Vet wraps
Scissors
Face mask for humans! Resusitation aid