Here refers to a person who loses the use value, will be killed or leave a worse fate than others. This sentence first came from Historical Records. I think it's similar to what it means now. People usually use running dogs to describe traitors, traitors and others who want to betray their country for glory and flattery, which is nothing more than mocking them. The people they are loyal to now are using their existing values. When they are really useless, they will definitely end up worse than others.
The original meaning of this word is derogatory. When we watch War of Resistance against Japanese Aggression's plays, we are sure to hear the slave's side. Those traitors are often called Japanese lackeys, and we can know whether the word is good or bad.
In fact, the meaning of this word is similar to that of a slave or an accomplice. Are used to describe a kind of alienated power, which corrupts people for money, power, debauchery and so on. It makes people lose face, lose their senses and even become insatiable. So don't let others use this word to describe themselves. We should do something beneficial to society and the country and repay the country.