A "dog-gone" hard decision

Yesterday, my little dog bit my 2 year old son, Mason in the face. I have no idea what may have caused this attack to occur. I was sitting in my living room talking to a friend on the phone. Mason was playing in our playroom (which isn't really seperated from the living room). The dog was also in the playroom, but he was not lying in an area where I could see him. Mason got up from where he was playing and walked out of my field of vision over to where the dog was lying. Seconds later I heard the dog growl aggressively and I knew he had bit my son.

The dog bit Mason on the cheek right next to his mouth. While the wound was pretty minor, I don't feel comfortable with the fact that the dog seemed to think it was okay to bite him in the first place. In addition, this is not the first time the dog has bitten Mason. Common sense would tell someone that if it probably won't be the last. And I don't want to wait and see how bad it might be next time. At the same time, I ot Dexter as a puppy four years ago, and I love him very much.

In general, he is a great dog. He is not an overly sensative or aggressive dog. He doesn't shed or bark. He is completely house and crate trained. He is very sweet, he loves to sit on your lap or lie next to you on the couch, but he also gives you your space when you need it. He wasn't even a beggar (that is until I left him at my mom's house a few years ago when Paul and I went to Boston on vacation - he learned how to beg there. He also learned how to surf that summer!) The only bad thing about the dog is that he would bite my husband when he felt threatened by him. I know that the reason is does this is because my husband would hit him as a puppy. Paul always had a reason for hitting him, but the dog didn't always know that. For instance, Dexter would pee on the floor and hours later Paul would find the pee and go find Dexter and hit him. To Dexter, it seemed he was getting hit for no reason what-so-ever. He didn't remember that he'd peed on the floor hours ago and that Paul had just found it. So, naturally, the dog started to defend himself. Dexter never turned on me, so I wrongly assumed that he wouldn't turn on the children either.

Now I am faced with a hard decision. Do I find the dog a new home, or do I gamble with my children's safety? The thing that really bothers me is that each time Mason was bit, he wasn't really provoking the dog that bad. The first time Dexter bit Mason was when Dexter was trying to eat something off the floor and Mason told him "no" and reached down to pull him back. The second time, I don't know exactly what happened, but Mason didn't say anything to Dexter. I am guessing that maybe Mason layed down next to Dexter and scared him. I know what the right decision is, but knowing doesn't make it any easier. I know I need to find the dog a new home.