The pound will put him to sleep so if you can call the huimane society. But if they only thing she is diong is letting her dog shit on your lawn I dont think they would take the dog in the first place. She has to be neglecting the dog, beating it, or letting it run loose in order for the pund to take it. Although you could still get her for tresspassing and I would do that, oh and I would do the shit in the mail box just to get my point across. Make sure its after the mail runs and the shit is placed nicely on top of her mail