for starters, if he was trying to eat it, I doubt he would do so by shoving the whole thing down his throat. He would most likely suffocate on it.
Secondly, no blood. Even a kitten has claws. hurting something with claws inside your mouth with your teeth would result in blood one way or another.
It was appearently a *lucky shot* or something.
from the kittens legs you can see that it is not dead.
So, calm dog, meaning no claws in his throat.
No blood, meaning no teeth piercing the cat.
Not limp cat, meaning it is still alive.
Owner had enough time to get the camera and make a shot of that, meaning the scene is going on for some time.
Yeah, that dog might be going overboard, but in that pic noone is hurt.