I have a 5 yr old Boxer that enjoys the chickens, and they don't seem to mind. Every once in a while he will run full speed right though the middle of the flock, and watch them scatter around scolding him. It's pretty funny. Other than that he just lays around nearby and watches them free range in the yard.
My favorite story was what I thought at first just another occurrence of his weekly sprint through the flock.....except he didn't stop, but kept going full speed into the fence row where two small foxes busted out and sprinted away.
He chased for a bit and then trotted back to the flock. They never stopped picking at the grass through the whole episode.
He did get one chick when it was about 3 weeks old. I heard a fee startled peeps, and the dog came trotting out of the garage showing off his chick that he was holding by its butt. It was facing forward and just peeping away. They trotted around the driveway one time before i could get to them. He dropped the chick and I don't think even a feather was lost, but after I scolded him. He has never touched another one.
It was kind of funny though. The chick looking straight ahead looked like a hood ornament on the dog.