Hi Shaggs,
Your photos remind me of my son and a white shepard we had. Very similar relationship. Our dog Keemo, seemed to welcome the newborn into our house. We went through all the orientation trainers recommend.
We got Keemo as a stray when he was a pup, he looked like he could be your dog's brother. Our son was born 7 years later.
Keemo and my son Trevor got along great. When Trev ate yogurt, Keemo would clean up after him. Things were really going well. At around 18 months, Trev was on the floor with a chunk of a whole wheat bagel and Keemo attacked him. Luckily I was only two feet away and screamed no at him, but it was too late. Keemo had bitten him on the face, with his canines going completely through Trev's face.
I picked up my son and we rushed him the the ER.
The reality is Dogs are pack animals and your family is his/her pack. The dog will see the new member as being below them in the pecking order. Believe me. We had no warning this could happen. I have many pictures just like yours.
We had a well respected local trainer come to work with us, but in the end our eight year old Keemo wouldn't be submissive with the child. I had to put him down. We tried new homes, but he was too set to socialize away from our family and he pined for us. It was terrible.
Please watch carefully when your child is with your dog. I wouldn't have believed our Keemo could get agressive at all. He was very submissive with my wife and I.
Good Luck, and please watch carefully. Any sign of aggression, even a low growl, or ears back should serve as a warning. Our trouble signs started when Trev could cruise tables . When he stood upright, keemo saw him as a competitor for his place in the family.
My son carries permanent scars.
Take care,
John