He doesn't mean to hurt him.
My dog has this chronic ear infection that I have to constantly treat. Sometimes when my boyfriend would try grabbing him, he'd accidentally grab his tender ear. What I had to tell him is that he needs to be more gentle with the dog.

"Kicking" is an expression. "He'd try to kick my dog away" is used in the same sense as if someone said "You should kick your lazy boyfriend out of your house" - you are not literally kicking.

For the hitting, it's the kind of "hitting" a lot of people do to their dogs because they think it's "training" - a flick to the nose, a pat on the bum. I don't agree with it because I know it's not good training, but a lot of people don't. That's how his parents raised and trained their dogs, so that's what he believes is necessary to train a dog.
But the same is up to debate when it comes to children - some people think spanking your child from time to time is alright, and a lot of people do it, but a lot of people also don't think hitting a child at ALL is the way to go.

Most people you ask have received a slap on the butt or two growing up. Do you automatically consider that abuse?