I have a two year old spayed female chihuahua and I would like to have a friend for her. I had a cat for a few weeks, but sadly, I had to re-home her because I discovered I was allergic. The dog has to be under twenty-five pounds, but I’d like to branch out from a chihuahua. What would be the best breed (or combination of breeds) that would fit under twenty five pounds and would be good for a smaller environment?