Already have animal bug? I can't recruit the DG dog

Trying to recruit the dawnguard dog but keeps saying I have a animal, I only had barbas and meeko and that dog you buy, all of whom I dismissed, I even went to meekos shack to murder him to make sure I had no followers, any ideas on how to fix this bug or did I forget something?

The DG dog probably does not want to be the next murder victim once you are tired of him like you are tired of meekos? :)