I don't know about soy, but I'm sure that someone here will post some info for you soon. If soy won't work, could your son handle other nut butters (like cashew, maybe?) if someone here knows if they are safe for dogs? I just wanted to say that one of my sons has serious food allergies (dairy, wheat & eggs), so I sympathize. I think that it's great that you're looking for treat recipes that your son can handle safely and are good for your dog, also. Maybe you could Google dog treat recipes and see if you come up with something safe, also.