I have to have both. A couple years ago I had surgery for a torn retina and had to keep my head face down and perfectly still for a few days. My cats stayed with me the whole time . When one would take a break, the other one would be right there to take over and at night they both stayed with me even though they really didn't like each other that much.
We have an Australian cattle dog that lives for our daughter, She is Meg's self appointed defender and caretaker all in one little bundle of love.

I said it before and I 'll say it again right now, I love ACD's, they are the greatest!!