Looks to me like the cop was holding the dog by the collar, and using it to terrorize the women and kids to get them to run, to break up the protest.

Then the dog got away. You can see him with the "oh shit" run after the dog.

Had the cop not been using the dog to instill fear this wouldn't have happened.

The cops were pretty heavy handed there.

What part of this scene does the "To Serve and Protect" motto cover?