Critically injured chicken, please help.

We have a small chicken that my dad bought last year and we love her dearly, especially my dad. He lives alone and she's his best friend. I don't know too much about chickens, but she has a great personality and is very lovable. Earlier today my beagle went out as she usually does and in a few short minutes she attacked and critically injured our chicken. She has been attacked by a cat before and was seriously injured then, but recovered quickly. This time she has a hole in her neck. I can see a pecan she ate and it's blocking the hole for now. It's drying up okay. She is warm and isolated for the time being and is still able to move around. What do we do next? Do we need to clean out the injury with something like peroxide? Should we call the vet? Would the vet remove the pecan piece and sew it up or would he leave it alone? We're all really distraught. We love 'Miss Stingy' dearly and we want to do anything we can to keep her from dying. Any suggestions would be greatly appreciated.