Witnessed a neighbor's child being abusive toward their dog--do I tell the parents?

My neighbors 8-year-old son is quite mean to their dog, but he does it because he has seen his parents do the same. If you've seen the parents abusing the dog then I would anonymously tell the proper authorities. If it's just the daughter, and the parents aren't to stand-offish, I would tell them. I would try not to make it sound like you're accusing them of anything but just informing them of what's going on.