What an awful thing to have to witness. I can't believe someone would treat their pet like that. I'm not suprised you didn't say anything I'm sure I'd of been to shocked to respond.
How about walking the same time same route over the next few days and seeing if you can get some film on your mobile phone, discreetly following her to see where she lives and e-mailing the address and video to your dog warden.

__________________


A dog Possesses Beauty without Vanity,Strength without Insolence, Courage without Ferocity, And all the Virtues of Man without his Vices.