Bobrow, a direct question...
Are you afraid to tackle these ''dog abusers'' directly? Feel free to say yes, they might be violent drug abusers for all I know.
If not, should you not be taking some direct action, as you feel so strongly about it?
At the very least you should bombard the RSPCA, or the local Police Officer with phonecalls until action is taken.
No one does anything in this world without being harassed these days.