Duke is extremely loyal to the Farmer and always treats him with caring love and respect.
While he has a good heart, Duke is also very dumb when it comes to sheep. He is also known to over-do it with return favors when someone saves his life. He can also be very stubborn. He watches over and guards the sheep, lives in the doghouse and enjoys dog biscuits.
Duke is also a know-it-all and a suck up, which makes him the most unpopular member of the Barnyard. However, his best friends do like him and consider him a member of their unconventional family. But there are some times that he does make good points and have common sense.
In the film, he seems to be somewhat of a leader. Now, he just hangs out with Otis and his best friends. He helps out with Otis' stunts and pranks, but doesn't really do the prank. He is loyal to Otis, who saved his life, but Otis is also appreciative for Duke, who saved his life back. Otis often has Duke's back at times, and usually bails him out of trouble, like in the Great Sheep Escape.
His general is rolling over, playing ball, and chasing his tail. Duke shot the original Barnyard safety film, apparently, in the 1950's era, which means that he is at least 50. Duke is also the self-appointed Barnyard safety inspector. Because of this, Pip nicknamed him "McGruff the Crime Dog."
Duke has an arch-nemesis named Baxter, a stray that has tried to steal his identity, dignity, and even his sister Stamps, but was foiled every time. Duke also wants to be the leader of the Barnyard even thinking that he might be a better leader than Otis, but nobody seems to agree with him.
Duke is a white Border Collie with black spots and splotches on his forehead and half of his back and light brown eyes.
- In "Man's Best Fiend," it is shown that Duke loves to play ball.
- Duke was based off of Steve Oedekerk's dog, who he would often think would play poker with the other dogs as soon as he left. This is also what inspired him to create the movie.