Sick as a Dog

I've come down with some kind of virus this past week, and I've been feeling pretty ill ever since Monday night/Tuesday morning. In honor of my sickness, I decided to do some research into the meaning of the phrase "sick as a dog." There doesn't seem to be a consensus on the phrase's origin or how it came about, but here are some of the suggestions I found as to its meaning:

-"Could it be that the dog is the only animal that we have the "opportunity" to see vomiting?"

-"It is probably no more than an attempt to give force to a strongly worded statement of physical unhappiness. It was attached to a dog, I would guess, because dogs often seem to have been linked to things considered unpleasant or undesirable; down the years they have had an incredibly bad press, linguistically speaking (think of dog tired, dog in the manger, dog’s breakfast, go to the dogs, dog Latin — big dictionaries have long entries about all the ways that dog has been used in a negative sense)"

-"Because dogs eat just about anything they find, they often get sick. So it's fitting to describe someone who is not feeling well as being "sick as a dog.""

Now I will resign myself to my sickbed and leave you to ponder the situation.