attack dog
noun
1- a dog trained to attack on command and kept for this purpose攻击犬。
1.1
- a person who is very aggressive in their defence or support of someone or something强力捍卫者（或支持者）：
he was accused of being an all-purpose attack dog for the government.
人们指责他是一条在各种情况下都会为政府效力的御用斗犬。