单词tracker dog
n.: 搜救犬网络: 循迹追踪的警犬
（受过训练协助搜寻人或炸药的）警犬，搜救犬:
a dog that has been trained to help the police find people or explosives
The tracker - dog soon smelt the murderer out.
警犬很快跟踪查出了凶手。