A longtime police horse will be retiring this Saturday, Lancaster police announced. Duke, the 22-year-old Percheron, will be clopping down from his position as a police mount after 18 years of service at Saturdayâs âCoffee With a Copâ event at the Pennsylvania College of Art and Design Art Park at North Prince and West Chestnut streets at 10 a.m., the police department stated in a post on social media. The equine officer will be retiring to a private farm âwhere he will be able to enjoy his golden years,â police said. He will retire as the longest-serving police animal in Lancaster police history.