We got a new dog 2 weeks ago, he is very good most of the time. He will sit, stay, lay down, and come. However he hates men. If any man comes over the house he will growl and bark constantly! He will do this until the man leaves. The man might stay for half hour, and the dog will not stop barking and GROWLING!!! The dog Tucker will not listen to the word NO if a mans is over. Tucker knows the word no, and listens to it any other time except when we have guests. We tried to have the man give a treat whenever he comes over, but Tucker wont take his favorite treats from any men. He does not mind the hubby of the house, but any other guys he hates. No matter how many times the same man comes over, Tucker will not get use to him. Hes fine with women and kids. He will bark at them when they first come into the house, but will stop after he sniffs them. However sometimes he barks or growls at certain boys. If where out with Tucker and a man gets near us he starts the barking and growling hair on his back standing up. We thought about doggy school, but the trainers a man. I know Tucker would be fine with all the other dogs. I am just worried he would bark the whole time with all the people there. What can I do?