A guy that stays around the corner from me has a real psycho of a dog. It's some kind of terrier, i'm not exactly sure. Anyway, he got it from his daughter, she and her b/f lived together. He's a real nutcase, and so is his whole family. They actually raised the dog to attack other dogs, i'm not sure how, but it certainly worked. Anyway. the guy ended up in jail, so the daughter moved back home (around corner from me) and she brought the dog.
To give an example, I was walking my dog (since died), a cocker spaniel, to the shop. It was sitting in a car, the driver window was open, the dog was in the back. It spotted my dog and in a flash, lept out the driver window, and literally landed on my dog, and they started fighting. The thing was nuts, i got caught by it as I pulled them apart, because the only way I could do it was grab both of their mouths, pull them apart, then pick up the psycho an put him back in the car. Other wise, they just got caught biting each other. My dog wouldn't/didn't harm anyone or anything, but obviously did when it had to.
It's a reflection of the kind nature of the guy that stays round the corner. The daughter couldn't be bothered with the dog, but he took it on, even though he wasn't a 'dog person' and even though the dog was completely nuts. It was strangely fine with humans though, but went mental with other dogs.
The guys back garden is fenced, so the dog couldn't get out when it was there. Once, another dog walked past, and it darted IN TO the fence, then, whilst going nuts, tried to force (not dig: FORCE) it's way under the fence. It got stuck, it broke 2 ribs, but still tried to get under the fence, still going nuts. The owner had to drag it out from under the fence. I'm pretty sure it also broke a leg, either that or hurt it badly. Afterwards, after it had got all patched up by the vet, the thing could barely move, it hurt itself so badly, just trying to get to another dog.
That was about one year ago. The dog now INTERACTS with my g/f's dog. It walks with it, they seem like friends. It's calmed down a lot. A little love, respect and stability goes a long way. I doubt it will ever be completely sane, but it's came a long way. The owner could of got that dog put to sleep at anytime, but persevered, and it's pretty much a good pet now...