What would you do in this worst case senario with your dog?

I would rinse the gash and try to get all of the dirt/debris out, then I would secure a bandage by wrapping gauze around the dog's middle section. I would try to splint the leg to keep it from moving and causing more damage. I would then leave all the supplies and (assuming I could) I would carry the dog back to civilization no matter how long it took. I wouldn't leave the dog unless absolutely necessary because I would be worried it would try to follow and injure itself even more.