Here's a breakdown:
* Military Code: In the military, units are often designated with letters to simplify communication and identification.
* K for Canine: The letter "K" was assigned to canine units, likely because it's the first letter in "canine."
* K-9: This abbreviation became widespread, especially in law enforcement and military contexts, to refer to working dogs.
So, "K-9" doesn't directly relate to the dog's physical characteristics or its species. Instead, it's a military code word that has been adopted by various organizations.