How do i return a mouse to petsmart?
They may take a return but will not "treat it and return it" to you. They may exchange for a different one or return your money. IMO, if you're adamant about keeping it for its safety, you need to quarantine it away from the other mice and treat with a sulfa product (usually found in the bird section of the pet store) or Dri-Tail used for diarrhea for rodents. Either should work. Keep her warm, dry and well fed.
Love my Newf
You just take it back. But how stupid are you putting it with your other mice? What ever it has your other mice now have and they could end up DEAD!