What is the origin of the idiom "treated like a dog" and when to use it?

The origin of the idiom "treated like a dog" can be traced back to ancient times when dogs were commonly associated with negative connotations. Dogs were often seen as lowly creatures, sometimes subjected to mistreatment, neglect, or used for menial tasks. The phrase likely emerged from the observation of such treatment towards dogs and was later applied figuratively to describe how people were treated in a similar manner. This phrase is used to convey the idea of being treated as inferior, demeaned, or given little regard for one's well-being or dignity.