What is the meaning of "K9" on American police cars!

The word K9 is very popular in the United States, Russia and other countries. In fact, "K9" refers to police dogs and military dogs. This title has a history. During World War II, the United States saw the great role played by military dogs in the battlefield of World War I, so it began to set up its own special forces with 20,000 military dogs to carry out military tasks such as reconnaissance, sentry duty, mine detection and security. But how do you number this unit? So someone thought of the homonym K9 of the English word "Canine". This figure was well received by the government and the public and soon became popular. In the United States, some police dog departments and training bases use the name K9. In addition, police dogs with outstanding achievements will be awarded medals of honor. In Russia, the K9 German Shepherd, who is in charge of the search and rescue mission, will be hung with an armband engraved with two paragraphs in Russian, meaning "Russian Ministry of Emergency Situations". ........................................................................................................................................................................., an active sheepdog search and rescue brigade, our training clothes also say k9. I'll give you a picture of a k9 police car. I cut it from the demand for speed/%ba% ab% b1%F3/album/item/f8879E2F6C33F0381e308951.html.