But it is not unlikely for them to kill dogs.
Yes but where does this appear in the article? They apparently had themselves two dogs.
Admittedly I don't know where the inhabitants of the London area in question originate from... but again, I think it's unlikely (yet not impossible) for Muzzie kids to have dogs.
"They are said to have set two of their own dogs on the boy after he was stabbed in the heart and leg."
That more-or-less rules out mohammedans ... but as to what religion they actually practice: I suspect that they worship themselves.
Muslims do keep dogs for dog fighting. It's just another form of dog abuse that you do see in Muslim countries. This would appear to be that sort of dog.