Hi there. I'm sorry about your chicken. I know how worrisome an infection can be. I just had a hen get a terrible infection after a stray dog bit her on the back. My vet gave me chlorhexadine to flush the infected area daily and this herbal poultice called Golden Yellow to put on it to dry it out and help with scab formation. It worked wonders. I'm not sure if your vet has any in-stock but you could maybe ask him to order it for you, or do a google search for "golden yellow poultice." Seriously, this stuff saved my chicken from an infection that ate through her muscle to the backbone.
In terms of what you can do at home, I would go ahead and get some sterile saline to flush the wound rather than using cold water from the hose (probably doesn't feel too good and may not be as clean as you'd like it to be). Also, isolate her from other chickens and keep her in the house in a dog crate or something like it to keep flies from getting on the wound and laying eggs in it. Make sure you check the wound thoroughly for any maggots that might be in it and remove them. There are some great posts on here about maggot removal if you end up with that problem. Make sure she is eating well and supplement her food to get her interested if her appetite isn't what it should be. Good luck! Hopefully someone with more experience with wound care will reply before too long.
