did you dig down 12ft or trench in 12ft not being funny,but you say you heard the dog sounding was that from the entrance it had to be.If you did'nt block up any tubes while digging theres a chance she is still alive,maybe just stuck,go back out and if you can try with another dog all the better if not leave a coat or something like that outside.If it comes out she might stick around,hope you get her back safe.