Here's what I keep in my doggie diaper bag:
1. Wee Wee Pads
2. Blanket
3. Extra Harness/Leash
4. Bottled Water
5. Dish for Water
6. Nutrical
7. Food/Kibble
8. Dish for Food/Kibble
9. Scissors
10. Tweezers
11. Wet Wipes
12. Tissues/Paper Towels
13. Codie's Front Carrier (in case he gets tired of walking lol)
14. Poop Pick-Up Bags
15. Gauze (to wrap around a cut)
I keep a few other things but here are the ones I remember off-hand.
And the most important thing ... a typed up list of all the local emergency vets, their address, business hours and phone numbers. I also keep a copy of this list in my car, wallet and on my fridge. You never know on a Sunday night when you will need to RUSH to the vet's office!