Dogster is reader-supported. When you buy via links on our site, we may earn a commission at no cost to you. Learn more.

Dog Training

Why Are Police Dogs Called K9? History & Facts

Chris Dinesen Rogers
By Chris Dinesen RogersUpdated on June 17, 2026
Share
belgian malinois K9 dog

The history of using canines for police and military work goes back to the Romans using Neapolitan Mastiffs on the battlefield as “dogs of war.” However, police dogs are now an integral part of law enforcement, taking on the duties that they outperform humans in. Canines originally became our guardians and livestock herders through the ages. But when required, they acted as police dogs to ensure law and order while assisting in apprehending those lawbreakers.

The term “K-9” is a homophone for the word “canine.” Its first formal but unofficial use was during World War II. Its popularity undoubtedly rose from its ease of use instead of spelling out the word.

Dogster divider_v3_NEW_MAY_24_

The Beginnings of Canine Training Units

Using dogs in police work is a no-brainer. They can smell and detect things better than we can. They can run faster than any human, with Greyhounds clocked at a blistering 45 mph. Canines are also better equipped, with the word “canine” meaning “pointed tooth.” Our early history with these animals is chock full of stories of dogs fighting alongside humans, but they found their way into law enforcement in the late 19th century.

The Belgians recognized the potential for using dogs in this capacity, with the first training facility opening in 1899 in Ghent, Belgium. They didn’t recruit the typical canines we think of for these roles. Instead, wolfhounds and sheepdogs stepped up to the plate. Their size was undoubtedly a point in their favor. It didn’t take long for others, including the NYPD, to learn about their potential.

The trainers used a unique approach. They taught the pups to associate uniformed police officers as friendly and anyone else as hostile. These dogs were the ultimate multitaskers, detecting and bringing down their quarry. Unfortunately, the dogs’ training backfired after many complaints and an accidental shooting. The NYPD disbanded the country’s first canine unit. Several other cities also tried and failed.

Image Credit: sandyman, Shutterstock
Dogster divider_v2_NEW_MAY_24_

The Quartermaster War Dog Program

Police dogs didn’t go away despite the charges of being overly aggressive. Private agencies still used them during the early 20th century. The military also had canines. Law enforcement in London kept dogs as companions when doing their rounds. Germany opened a training facility in Greenheide in 1920, making the German Shepherd Dog their star pupil. Scotland Yard got into the act in 1938.

Then, World War II started. The military saw the potential for the trained canines and secured them for the war effort. An organization called “Dogs for Defense” teamed up with the American Kennel Club to encourage citizens to donate capable canines to join the Quartermaster Corps K-9 Corps. That’s where the police dogs came into their own, and where the first unofficial use of the term “K-9” appears.

The animals adapted well to their new roles after training with the US Armed Forces War Dog Program. More than 10,000 canines went on to serve all branches of the military in 15 War Dog platoons. In London, law enforcement used dogs in recovery missions to locate victims of the Blitz. The K-9 units' service during the two world wars cemented their use in law enforcement.

The dogs performed several vital tasks, including the following:

  • Mine detection
  • Messengers
  • Sentry duty
  • Scouts

They would find similar duties stateside after the war. March 13, 1942, is the official founding of the US Army K-9 Corps.

Dogster divider_v1_NEW_MAY_24_

Resurrecting Canine Use in Law Enforcement

The London Metropolitan Police recruited dogs for their regular duties after the end of World War II. Similarly, the United States resurrected canine use in various capacities, including security details in department stores. These efforts stalled in some areas for the same reasons they failed earlier. However, proponents recognized the need to refine the training methods and capitalize on the dogs’ strengths.

Several cities began training programs, including Dearborn, MI, Portland, OR, and Los Angeles, CA. The Baltimore City (MD) Police Department was the most successful, thanks to the efforts of a veteran of the US Marine’s K-9 Corps. Presumably, the use of the term “K-9” segued into law enforcement because of the widespread attention Baltimore received. Other nearby cities began their own K-9 units.

Image Credit: MAKSYM CHUB, Shutterstock
Dogster divider_v3_NEW_MAY_24_

Modern-Day Police Work

Modern-day police work has led to specialization with K-9 units. Law enforcement had previously used Bloodhounds for search and detection. That usage goes back hundreds of years. However, their tasks have evolved with the times and technology. Police dogs are typically single or dual-purpose animals. Jobs include detection or patrol.

The former involves tracking or finding explosives or narcotics. The canines only train with one type of detection. The latter works with security, clearances, and officer protection. Interestingly, one task resembles the role of guardian dogs, which historically would capture intruders and keep them at bay until the landowner or groundskeeper arrived. Today, we call it suspect apprehension.

The term “K-9” has stuck with law enforcement and the various organizations working with these animals, including the National Police Dog Foundation and the United States Police Canine Association (USPCA). They use multiple breeds in these roles.

Even the unlikely Labrador Retriever has found a spot on the police K-9 units. The London Metropolitan Police used them in the mid-1940s to accompany bobbies on patrol for purse snatchers in Hyde Park. The military continues to use dogs for various duties based on the unique talents of the breed. They have a permanent place alongside soldiers on and off the battlefield.

Image Credit: New Africa, Shutterstock
Dogster divider_v2_NEW_MAY_24_

Final Thoughts

While the formal history of police dogs started rocky, canines have proved themselves to be valuable companions for law enforcement and the military. They are courageous and loyal companions. Many personnel can thank their K-9 units for protecting them during difficult and dangerous times. That day when a wild canid first approached a human was the beginning of a beautiful friendship.

Sources

Featured Image Credit: Sashulity, Shutterstock

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything dog

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.

Chris Dinesen Rogers
Authored by

Chris Dinesen Rogers

What Do Police Dogs Do? (An Overview of Their Work)

What Do Police Dogs Do? (An Overview of Their Work)

Police dogs have become an enigma for many of us in the world. We see the incredible videos on social media of their intense training. We also witness the amaz…

Nicole Cosgrove
By Nicole Cosgrove · 3 weeks ago
10 Police Dog Breeds: With Info & Pictures

10 Police Dog Breeds: With Info & Pictures

It takes a one-of-a-kind blend of talent, temperament, and determination for dogs to excel in the demanding field of police work. Police agencies rely on these…

Nicole Cosgrove
By Nicole Cosgrove · 4 days ago
What Do Military Dogs Do? Overview of Their Work

What Do Military Dogs Do? Overview of Their Work

Everyone knows the saying, "Dogs are man's best friend." Dogs are incredible creatures with many unbelievable qualities. They serve as companions to those with…

Nicole Cosgrove
By Nicole Cosgrove · 2 weeks ago
An Inside Look Into the Life of a Police Dog

An Inside Look Into the Life of a Police Dog

Have you ever seen a police dog in action up close and personal? Recently, I had the chance to not only see one of these heroes practice doing his job, but I g…

Wendy Newell
By Wendy Newell · 2 weeks ago
June 17, 2026

How Long Does It Take to Train a Police Dog? Age & Duration Explained

Dogs have been used as loyal sidekicks for humans for hundreds, if not thousands, of years, and have been used for a variety of jobs, from farming to protectio…

Nicole Cosgrove
By Nicole Cosgrove
How Long Does It Take to Train a Police Dog? Age & Duration Explained
June 23, 2026

How to Become a Police Dog Trainer: Career, Requirements & More

Among the rewarding careers that entail working with animals—veterinarian, dog groomer, zookeeper, etc.—only one requires a unique set of skills, determination…

Nicole Cosgrove
By Nicole Cosgrove
How to Become a Police Dog Trainer: Career, Requirements & More
June 17, 2026

How Is a Drug Detection Dog Trained? Types of Training, Pros & Cons

Dogs have long been known for their keen sense of smell, and this has made them useful in a variety of workplace settings. Drug detection dogs are trained to u…

Nicole Cosgrove
By Nicole Cosgrove
How Is a Drug Detection Dog Trained? Types of Training, Pros & Cons
June 17, 2026

Cadaver Dog Training: Vet-Reviewed Facts, Uses & FAQ

Dogs have been an irreplaceable part of human life for centuries, largely due to their unmatched sense of smell. From hunting far-off game to sensing impending…

Nicole Cosgrove
By Nicole Cosgrove
Cadaver Dog Training: Vet-Reviewed Facts, Uses & FAQ
June 17, 2026

Everything You Want to Know About Bed Bug Detection Dogs

Bed bugs were eradicated in the United States in the 1950s through the late 1990s.¹ Unfortunately, a new strain of bed bugs came about that was immune to DDT,…

Rachel Giordano
By Rachel Giordano
Everything You Want to Know About Bed Bug Detection Dogs
June 17, 2026

How to Train a Working Dog: 9 Vet-Approved Tips

Dogs can do incredible things. You can find dogs working in jobs all over the world. Dogs can be search and rescue animals, helping find people trapped in rubb…

Grant Piper
By Grant Piper
How to Train a Working Dog: 9 Vet-Approved Tips
June 17, 2026

8 Types of Specialized Dog Training: Facts & Pictures

Dog training can be simple or complex, depending on what kind of training you want your dog to have. Basic commands like sit, stay, and lay down are all well a…

Dean Eby
By Dean Eby
8 Types of Specialized Dog Training: Facts & Pictures
June 17, 2026

Scent Training for Dogs: Where & How to Start

Scent training is exactly how it sounds: training your dog to detect and react to different scents. Since dogs are renowned for their superior sense of smell,…

Kathryn Copeland
By Kathryn Copeland
Scent Training for Dogs: Where & How to Start

Love Dogs? So Do We! Join the Dogster Community

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.

You may opt-out at any time. View our Privacy Policy for more information.

The Dogster app on a phone