Dog "defending" the baby (By biting my wife)
I have a problem where our English Springer Spaniel has started biting my wife when I'm holding our baby son. I have noted he acts protectively towards other members of the family, in particular biting my father-in-law when he gets near my mother-in-law. However the baby is now six months old and the biting has only started now. I am guessing it's some kind of protective behaviour.
I am at a bit of a loss, because I have a two-year old toddler who Phoebe is extremely tolerant with. She's "inherited" so I don't know much of her background. I believe she is still trainable, since I've managed to get her to stop jumping (on me so far only). Tempereament-wise she's usually very tolerant, but prone to the unexpected behaviour described above.
What is strange about it is that during the day Phoebe and the other dog spend the day with my wife and the two children, mostly without incident. When I'm home they tend to follow me around.
What do I do?