I'm rather surprised at the difficulty in obtaining a good commercial animal first aid kit. Petco doesn't carry any such thing, nor does WalMart or Target. Amazon has a few, but they're massively overpriced for what they come with. Human first aid kits are relatively cheap, but they come with tons of stuff that are useless on animals, like Band-Aids and Tylenol (which is toxic to many animals). So the only real solution was to build our own.
Here's what we've stocked in ours:
Large and small gauze pads
Gauze roll bandage
Flexible adhesive tape in several sizes
Small package of cotton swabs
Pain relieving first aid spray
Bottle of hydrogen peroxide
Bottle of hand sanitizer
Bottle of eye wash
Digital rectal thermometer
Plastic covers for thermometer
Small tube K-Y (for the thermometer)
Tick removal scoop
All this fits nicely into a Sterilite 7.2 Qt clear plastic container.
I should probably add a trauma pad, a small package of cotton balls, one of those emergency "space" blankets and a first aid manual for animals. Can anyone think of anything else I've missed?