I have a friend who's a vet tech at our local SPCA and I've got to say he's great.If they get an aggressive dog that their considering putting down he will spend countless hours working with them even on his off hours trying to turn them around.He's had alot of success to.Many dogs have been spared because of his time and devotion.Alot of these dogs including a huge Mastiff have turned around so much that they've been adopted.He personally does follow-ups every month for 6mths to make sure they're doing well.If theres a problem and the person can't handle the dog he will foster them so he can work with them some more and they get one more chance at adoption.As for the comment that it's better to put a dog down rather then having them spend their life in a cage I totally agree,but I don't agree that they should be put down after only 4 weeks simply because of their breed,