Even if animals were afforded a full set of rights backed up by a constitution of some sort and enforced by goverment, where they were no longer considered property there would still be abuse. Human beings abuse each other daily, new laws regarding animal rights wouldn't deter the abusers to any great extent. They'd just hide it better.
In a nutshell, I think pet owners have an obligation to provide their pet with it's basic needs.
I just watched a comedy show where someone said I had the right to remain silent, but I didn't have the capacity? was it? (they were drunk).
Anyway, changing the legal definition of our pets would only cause a lot more trouble, it wouldn't mean all their problems (and our social problems) would be magically solved.
I think everyone here agrees animals shouldn't be abused or neglected or denied food/water/vet care/attention, regardless of their status (house pet, farm animal, wild animal) and all living things do deserve respect and love. But not everyone "gets" that, and making laws won't change that either. It won't help, it will make things worse. There are already laws in place for the welfare of animals and to help them have justice should they need it, energies would be better spent trying to figure out how to make the existing laws and enforcement work better and help more animals.