Dog Sayings

Matt Yglesias wonders where the saying "sick as a dog" come from, seeing as how most modern dogs are not sick very much.

Myself, I've started saying "hold your dogs" sometimes instead of "hold your horses". Dogs, I know. They are very, very impatient. Horses? No idea. I suppose they must be impatient too, hence the saying, but who knows anything about that? Why should I continue to propagate a saying that is meaningless to me?

Updates

I figure: if I read you all the time, I should link you. So I went to add some stuff. Google's now in charge, so I upgraded the blog to take advantage of their stuff. So now it looks a little funny, but its tolerable at least. I'll get the formatting touched up eventually.