This is so sad.
It's large dog owners like this who give them a bad rap... and it's sad and irresponsible to just let your large dog run free if you don't have control of them.
Like on my floor there is a german shepard and a pit in my appartment building and I think this week I've counted 5 other pits, several german shepards, and a few large mixes, ALL of which belong to owners who respect small dogs. (Big building by the way and the only dog friendly one in the city). Each one of them works hard to train thier dogs, and some of them have the decency to warn you if the dog is young and to stay away (imagine that). I have absolutely nothing against large dogs, especially pits etc, it's the owners that drive me absolutely nutts.
Imagine a world where every dog person was responsible.