Noun

1. A trained police dog.
   • 2003, Nicholas H. Dodman, If Only They Could Speak: Stories About Pets and Their People, page 248

     Police working dogs (K9s) often have extremely close bonds with their handlers.

   • 2003, Trevor J. Orsinger, The Firefighter's Best Friend: Lives and Legends of Chicago Firehouse Dogs, Page 90

     Originally a K9 dog for the police department, Captain was asked to resign for unknown reasons.

   • 2005, Priya Kapoor, Nandita Jaishankar, VIPs: Very Important Pets, page 71

     Apollo, part of the New York Police Department K9 Search and Rescue team was on the scene of the disaster just 15 minutes after the disaster

   • 2006, Asa Nonami, Juliet Winters Carpenter, The Hunter: A Detective Takako Otomichi Mystery, page 134

     The Saitama Prefectural Police Department, for example, had no K9 units of its own, and relied on contract dogs exclusively.