If they are healthy probably not much you can do. If they are severely under weight etc. You can call animal control so they can check it out.
That depends on how neglectful the person is and what it's about if they're not feeding their dog or watering their dog properly and the dog is suffering from it then that's animal cruelty if they're just not getting their shots that's the person's decision on whether they want to give their dog shots to protect the dog or not I really don't think there's anything anyone can do about that but as far as abuse on a dog there is something you can do you can call animal control or the police if you feel that someone is harming an animal or neglecting them with food or water or if they have them in a small cage in the Heat or something like that that would be the only way a person would be in trouble for neglect
I wouldn't say refusal to give an animal their shots is "being neglectful". It's a person's right to make the decision whether or not to bring their animal to the veterinarian. Maybe you should just mind your own business...!
I would say call animal control.
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