I think there was a member on here (Sharonandtink?) that lost her little girl because she ate some cat food. I believe there is something in the food that dogs cannot digest...but don't quote me on that because I can't remember the exact situation. I think it's only dangerous if consumed in large amounts, but to be safe my cat food stays FAR away and high up from my dogs, because I don't want to risk it! 
 
Your baby will probably be fine but I wouldn't let him do it on a regular basis...