I took Buddy to puppy classes to socialize him and he was good with the big
dog's. Actually he was good with all dogs until he turned 1yr. Then he changed.
He didn't tolerate large dogs at all. It's been 4 yrs since and we still work
on his behavior when one is approching. It seems he picks and chooses who
he wants to be friends with. He does have large dog friends but strange ones
I have to be on top of him to correct his aggressive behavior. He's come
along way.