Hello, my dog chased, attacked and nearly killed a deer while hiking in the woods yesterday. She is a 1.5year old German Shepherd mix with a history of completely non-aggressive behavior toward dogs or people. She has chased many (hundreds) of deer before while hiking with me but has never come close to catching one. This particular deer seemed very small, slow and weak. My question pertains to this level of aggression. This was an isolated incident however, it was rather disturbing to see her face covered in blood and the deer wobble away losing blood from bites to the neck. If anybody with dog behavior experience would like to give me any advice here as to how to interpret this incident please comment. Otherwise, others should weigh in here and share their experiences. Looking for advice as well. Thank you.