Early on in Japan the method used to train dogs to search out drugs was to give the drugs to the dog. After it was addicted, its own strong craving would entice it to hunt for the contraband.
早期日本訓練緝毒犬的方法是，讓狗服毒，等狗兒上癮以後，自然對找尋毒品有強烈的慾望。