I'm as sick as a dog!

Have you ever wondered where that saying comes from? I always have. I wonder what a sick dog feels like. They probably feel just as sick as a person, except they have a floppy tongue to worry about. I wonder if dogs ever feel like sleeping all day and drinking lots of water. Funny thing about dogs is that they always do that! Maybe that's why we say we are as sick as a dog because dogs always act sick! I think I have uncovered a deep and dark secret! Well tata for now because I am off to do boat loads of homework. And now i wonder where that saying comes from....