dog licensing won't work. only law abiding citizens will do it and scum like these won't. Thus the law abiding citizens get hit with another tax they could do without.
I personally believe that all dogs of this kind of breed should be banned, or there should be stringent laws on keeping them. People who already have them before the ban takes place should be forced to muzzle their dogs in public. Any dog caught without a muzzle should be seized immediately and owners should be banned from keeping any animals in future and jailed for having a dangerous weapon. Muzzles don't hurt the dogs and law abiding people will comply, and their dogs will be safe from confiscation (as it's not their fault they already have these dogs and they are not violent so i don't see the need to cause unnecessary heartache by confiscating them).
Hope your dog is ok snapper. i've seen an attack like this on tv. when you see dog fights, the dogs are usually weight matched, but seeing one attack a dog that is not a fighting breed is truly terrifying, and you realise just how horrific these attacks are.