Dogs on leads will almost always bite as they can't get away! The easy way to seperate dogs fighting is to grab the collars and twist, chokes the buggers an they let go. I always choke the other dog first tho, makes sure the aggressor gets battered a bit more and it may learn not to pick a fight next time! Most staffs have the aggression bred out of them now but i've met a few nasty ones around here but thats purely down to chavs having them to look "ARD INNIT" I have a working JR (kills things for fun!)and they have a bad rep due to people who have not socialised their dog and can't control them, they are aggressive lil fuckers at times but mine is as soft as shit. Mine was aggressive till i made a point of socialising him with strangers dogs. I never have my terrier on a lead, he will go up to any dog and sniff it's arse it's what dogs are meant to do. If the other dog picks a fight then it best look out as both me and my dog will knock the shit out of it! Theres no such thing as a bad dog.....just bad owners! by the way sparky yorkies were bred to hunt rats and are fuckin good at it given the chance