Our 4.5 year old German shepherd has really changed her temprement since we brought DD home (11 weeks old)
She is great in the house and with the baby(although I would never leave any animal alone with my tiny girl), The problem is outside...I used to be able to let her run free in the garden,did'nt even have to close the gate,she would have a bark at people/dogs going past but now she is really aggresive and last week jumped over the fence and took a jack russell by the throat,luckily it was ok
I cant trust her off the lead now either,anyone know of any re-training techniques???
At the risk of sounding like the MNPets broken record...
Pop her to the vet and ask them to refer you to a good behaviourist. She is taking her duties a bit too seriously by the sound of it! I would recommend you don't try out anything you hear/read on the internet as it is easy to make a confused dog much worse!
Presumably before this she was a reliable dog? If so then she should be again, just get some help and put the time in!