Sick as a Dog

Factual Questions
#1

The other day, I was telling my daughter a story of a time that I was very sick. I used the phrase “sick as a dog”. She asked me about when and how that phrase came to be. We have two dogs, that never get sick as often as we do.

So to answer my daughter’s question, please explain sick as a dog.

Thanks.

#2

Just a WAG, but I think dogs instinctually retire to their bed to “lick their wounds”.

You can see a sick dog, and recognize him as such. They lay there and whimper.

#3

A little googling gave me this explanation.