It's like a switch. It happened with a family members pit going after my 3 year old daughter many years ago. No one could believe what they saw, as the dog was so sweet, loving and loyal. Thank God I was right there. Safely outside, it repeated the behavior later when my daughter walked near the door. No taunting or even eye contact. They are great dogs, until they aren't. Very few owners can accept that until it's too late.
How was that family member's vicious dog then dealt with?
Euthanized?
Regards,