What Am I Mixed With?

I'm trying to find this little guy a home, but I am having trouble trying to determine what he is mixed with. He was a stray that wandered into my garage and I know he is part Chihuahua, but much larger in comparison to the other two Chihuahuas that I own.

I can't figure out the other part and I need to be as specific as possible with my flyer description. Please help.

By Christina Bras S.