In history, dog days were popularly believed to be an evil time when the sea boiled, the wine turned sour, and dogs grew mad. All creatures grew languid, and man risked acquiring diseases such as burning fevers, hysterias, and insanity. It seems like the making of a Stephen King movie to me!
In latter years, the stock market is referred to as suffering from the Dog Days of Summer. Some of the stocks become volatile while others only seem to wilt. The stocks are called "dogs."
Upcoming in future weeks, I will contemplate many more dog phrases.
Man's best friend has certainly left his mark on our daily use of language.