A mongrel dog, also known as a mixed breed or a mutt dog, is a dog that is not from a particular breed or is not the outcome of deliberate breeding. The word ‘mong’ is a mongrel, which means ‘mix.’  Most of the mixed breed dogs or mongrels do not have a pure-blooded forebear. There are many crossbreed dogs resulting from the merger of various breeds, and they differ from mongrels as they are deliberately bred.  One good thing about mongrel dogs is that they are less expensive than dogs that are deliberately bred. And even mongrels are less prone to any health problems related to genes.