Well Nuishyboy - It seems that this connected with stress. Dogs eat their young when in a great stress situation.
But I think it is the dog who is stress by being no longer the baby in the household. So I suggest that you sit with your dog and get him to look at you. Then explain to the dog that it is a different situation and is now needed to guard the baby and not try to harm it. Praise him for being a help in the house and is say how it is really needed in the new role. As you do this hold mental image of what you are saying.
Dogs, like us, need to have things explained to them - as of course babies also.
Tony