how to fix aggresive behavior
I am new to the forum and just was looking for input on aggression. I have a 1.5 year old male GSD, he is very timid and shows aggression sometimes. He is most aggressive when a new guest comes over to the house he will bark, raise his hair, wag his tail, and sometimes nip at the guest. I muzzle him at first when he does this, than he seems to calm down sniff the guest and let them pet him and etc. At home I can control it with the muzzle because he seems to understand that the muzzle comes out if he acts bad. But in a case like tonight when I was at my parents and was not prepared when my cousin came over he started barking and wanted to attack my cousin. I do not understand this because at the doggy daycare they tell me how friendly and nice he is. And at the dog park he acts fine with people who approach me or him. Any kind of suggestion would be much appreciated.