I really need some advice. I'm at a loss. I have a 6 month old chocolate lab, and earlier today we were at my sister's house my lab was playing with her 2 Chihuahuas. They were getting along great so we left them to play in their 20x20 kennel. We went to the store and was gone for about an hour. When we got back we found that both of her dogs were dead. It appears that my puppy killed both of them. He is not aggressive at all but the Chihuahuas were. We don't know what happened. Not sure if they jumped on him and he defended himself or if he was playing and it was an accident. We just don't know what happened. Since this happened my lab has been acting like a normal puppy and don't seam aggravated or anything. Does this mean that my puppy is ruined now that he has killed or can he still be trained to be a good dog. My heart is breaking any advice will be greatly appreciated.