The most common breeds of dogs that qualify for K9 units are German Shepherds and Belgian Malinois. However, other breeds may fit the bill, specifically those known for tracking, trailing, and detecting items.
The dogs first need to pass obedience training and respond to commands seamlessly. Then, the handler takes them through intense K9 training. Since they were puppies, handlers train the dogs to bite fabric and then they advance to "bite suits". And the handlers get together on a regular basis to continue training. They mirror real-life applications to train the dogs.