I have only yorkies but my brother has a boxer named Vito and he gets along very well with Abbie.  She was not quite a year and he was just about a year old when they met last summer.  She was playing with him like she was a big dog and he was drooling all over her because he was so excited. And Max just stayed on the couch like the "adult" and barked occasionally like he was reprimanding them for acting so crazy.  It was so funny to watch