Definitely get into an animal behaviorist. We went through this in late 2009 with our beloved dog, who was 7 was the time. Out of nowhere he bit our 3 y on the hand, a warning bite. We did a full medical workup after that, nothing. I kept them separated unless I was directly within arm's reach, one day he did it again, I was right there and was powerless to stop him, it was so quick. He went after her face that time, right under her eye, she turned just in time and he barely got her, thank goodness. He was just lying there on the couch, jumped up and jumped at her. One of DD1's friend's little sister had just been severely mauled by a "friendly" neighbor's dog that the child frequently played with a couple months prior, tore her cheek apart, she is quite scarred now so that was very much in my mind.Â
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Anyway, I kept him completely separate from all children, it was very difficult to do, we finally got into the top behaviorist in our area. We had a long appointment, went through his entire life, history, any behaviors. She pointed that things that I only saw as quirks, and basically said that she hated to do it but she would only suggest euthanizing him. That he could never be trusted around children again, that this just wasn't out of the blue, it had been a long time coming, we just had no idea. He had never been aggressive towards people, other dogs, yes. It broke my heart, I was going to do it, I felt like it was between my child and my dog, but the child wins. At the last minute we actually we able to find him a home with DH's coworker's parents. They were an older couple so no children and had years of experience working with aggressive dogs. He is doing well there, I still miss him daily, just typing this out has me bawling.Â