Disturbing Moment in Hengelo

I met a friend for lunch today and after a nice, post-lunch cup of tea and a chat, I left her apartment and headed for the train station. On my way there, I saw a little girl -- she couldn't have been more than 8 or 9 -- walking her big yellow Labrador Retriever. My attention always focuses on animals when I'm out and about so I was watching them when the little girl suddenly stopped. Her dog dutifully stopped beside her. (Dutch dogs tend to be very well trained.) But this is when the disturbing part began.

The little girl started walking again, and even though her dog also began walking, she grabbed his leash and yanked on it with all her might. Then she smacked the dog. Then, she used the leash as a whip. Then she grabbed the dog's collar and roughly pulled the dog after her.

Meanwhile, I'm yelling at her from the opposite side of the street. I quickly crossed over and called out to her. She glanced behind at me and continued to abuse her dog. I yelled again and told her to be nicer to her dog. She barely glanced at me and picked up her pace -- all the while smacking this poor dog and pulling violently on his leash.

She turned a corner and I stopped to call M (to ask what I should do... Do I find a policeman?) He told me to confront her and ask her where she lives (so I can talk to the parents) or find a cop. But of course, when I entered the street where she'd gone, she had disappeared.

I have to say, this is one of the most upsetting things I've seen in awhile and it immediately raised all kinds of questions for me. Is this how her parents treat the family pet and so she's just mimicking their behavior? Is she being treated this way and so she takes things out on the dog? Or was it just fun for her to abuse this poor animal? And finally... why was I the only one that said anything to her? There were dozens of people on the street who must have noticed what was going on.