As Ann wrote above, *any* 2 dogs together can be dangerous if triggered. Doesn't matter what breed.
My Yorkies boys are close in size and have the potential to harm each other. They love each other, but they are 2 strong males and they do have their moments when they get overly feisty with one another.
I would not risk leaving a visiting dog alone with my dogs.
__________________ Kristin, Max and Teddy |