Up till he was about a year old, our boxer, Leo, was a happy go lucky pup even with strangers. Then after a football game my husband went to with my brother-in-law, my husband came in the garage with my brother-in-law right behind him. Now our pup hadn't seen my brother-in-law in months and I believe didn't expect him. I think he was startled, went into defense with raised heckles and wide stance barking full out and even peed slightly. With some ham and my brother sitting on the floor as approachable as possible, Leo finally warmed but only slightly. He has never been the same with guests, especially men.