To a chicken, there are only two questions in life: can I eat it? or can it eat me?
We have an elderly Boston terrier who, after a couple of half hearted attempts to play chase our chickens (for which he was scolded), ignores our flock. At first, the chickens were very wary of him, but they realized pretty soon that he wasn't going to try to chase and eat them. So they pretty much ignore him, too.
One day, our dog was stretched out snoozing in the sun on the deck. The chickens regarded him. The began to come closer, warily. They craned their necks, eyeing him. They ventured closer, showing an interest in him that I had never seen before.
I think they were trying to figure out whether he was dead so they could eat him. He snorted in his sleep, and then they scattered.