Dog Attack Survivor

Hello. This is my son who was attacked by a dog. Brantley is 5 years old,  he  is the youngest of 4. The dog pictured was a sweet and protective dog of his of 3 years. We have no idea why his dog turned on him and attacked him .. Only thing we can think of is Marley had taken a piece of her steak from her dish and took it to the bedroom where my kids were watching tv..even though she has never been aggressive about her food either. He is on the road to recovery and about to start kindergarten. Thank you for your shares