Kari did take her in to the vet and she got a clean bill of health.
Did you test specifically for thyroid? (Ideally you should get a 6 panel - it has to be sent to either somewhere in California or the University of Michigan.)
However, assuming there is nothing going on there, my mother said that she had Labs for years as a child. She commented that you have described is very abnormal behavior for the breed. With breeds that were developed as guards or guardians, I would ask about more subtle body language occuring before the bite, but Labs are supposed to be very friendly, easy-going dogs. I would say that this could be an unstable temperament.
Regardless, with little children, I think that your friend is exactly right - she cannot keep Snickers in her house right now. Tell her to take the dog to the vet for boarding, and, in the meantime, try to make arrangements to have her evaluated by a behaviorialist
. If the temperament is unstable, then, IMO, the dogs needs to be put down unless there is a behaviorialist that would like to keep her. (Re-homing such a dog with anyone of lesser qualifications is a disaster waiting to happen; someone will get hurt, and your friend WILL be sued.) If the problem is elsewhere, then you can look into re-homing Snickers with someone who does not have children.
Just my two cents.
Sofia
P.S. Just noticed that it is your birthday today. I'm sorry that something like this came up for you today of all days.Â