What kind of dog does K-9 refer to?

K-9 doesn't refer to a specific breed of dog. It's a term used for any dog trained to assist law enforcement or military personnel.

While certain breeds like German Shepherds, Belgian Malinois, and Labrador Retrievers are commonly used for K-9 work due to their intelligence, trainability, and physical abilities, the term K-9 applies to any dog trained for these purposes, regardless of breed.