I have had dogs all my life (60 years) and I have never ever had an aggressive dog until now. I have had 6 Great Danes, but never had one show any type of aggression to a person. I have a male Dane that we have had since he was 12 weeks old. He is 8 years old and has started to be aggressive. First if he was in the kennel and people were in our yard he would growl and bark. This was maybe 2-3 years ago. When we let him out around people he was fine. Then about 6 months ago he was on the leash with my husband and a neighbor was walking by and put his hand out to him and my Dane nipped his hand, but did not break the skin. Then in July we were camping and our granddaughter was in the camper with our Dane and Bassett Hound. She had them both on the sofa bed with her and was snuggling. She got up to go to the bathroom and the dogs got down. She started to fold up the sofa bed and accidentally stepped on the Dane's paw and fell pushing him with her foot as she fell. He grabbed her arm and bit down and shook it. This caused wounds enough that we had to go to the ER for stitches. Then last weekend a friend who the Dane has been around numerous times was visiting and the two dogs were in their large fenced area. He raised his arm pointing at something and the Dane aggressively went for his hand. I don't know what to do. I love my dog, but I no longer trust him with anyone and don't want to run the risk of him hurting anyone else. What are your thoughts?