What do i do when i see someone hit their animal?

Im a HUGH supporter to fight against animal cruelty. && what ever i can do i help then as much as i can, i hate to see animals be harmed. I always go over a friend of mines house. She has two dogs and now they have cubs. && i was over last night and her brother was feeding the cubs separately and the cub kept running to his fathers plate. & the my friend brother hit it like smacked it && i told him to stop ! that thats animal abuse that its not right. But it seems like he didnt listen because when the mother was trying to run in. He was pushing her face back into the yard where she sleeps WITH HIS FOOT. Like kicking her face, these animals get fed and everything but since theyre so hyper they get hit && every time i see them get hit i say something but it seems like they wont listen to me. I just feel so bad and i dont know what i can do.