1 year old yorkie

Question
I have a 1 year old female yorkie! She had her female surgery, and after that she has completely changed we dont know what happened. She lays her ears back and growls and bites you if you do something she doesnt like, for ex. if she is asleep and you start talking to her and walk over to pick her up she growls at you and tries to bite you. Or just out of the blue for no reason she will lay her ears back and bite you hard, not playing. She has been doing that quite a bit here lately. Also when you go to leave it is a fight to catch her to put her in the bathroom(where we keep here when we leave.) We have never been mean to her, abused her or anything, she is our little girl and we love her dearly but not her behavior.I really need help, she has started biting my family more and more. We just want our little sweet dog back.

Answer
Although rare, developing aggression following total hysterectomy in dogs is seen.  It may be hormonal: perhaps the dog was spayed too close to her cycle or too soon after it; this type of problem can be adjusted with hormonal (short term) therapy.  It may be physical; during surgery it is possible other organs (the bladder especially) are injured. It may be fear conditioned immediately AFTER surgery when the dog was in considerable pain (duh?!) and not adequately medicated, and has learned to associate being handled with horrible physical agony.  Your description of her problem behavior, vis a vis her growling when approached during sleep, her intermittent and (to you) unexplained aggression, etc., all suggest post-surgery psychological trauma, i.e., INADEQUATE MANAGEMENT  of her post surgery pain and psychological condition.

Take her immediately to another veterinarian for full evaluation.  Meanwhile, put a very lightweight house leash on her (use a body harness, not a neck collar) in order to control her movements (especially getting her into the bathroom); she is exquisitely sensitive to being "captured" and obviously associates it with extreme pain (taken from a holding cage just after surgery while not fully sedated, mishandled, etc.). Do not approach her while she is asleep; do not BACK AWAY from her if she suddenly demonstrates fear aggression (laid back ears, growling, snapping), simply stand there until she stops.  Do not attempt to pick her up; do not force interaction with her in order to avoid provoking the fear aggression, because EVERY TIME SHE BITES she learns more about how to "protect" herself and EVERY BITE will be worse than the one before it.  You need the intervention of a certified applied animal behaviorist.  There is NO WAY I can advise you without IN PERSON evaluation of the dog, and there is NO WAY ANYONE can advise you without it.  Call the veterinary college in your geographical area and ask for referral to a Ph.D. or DVM behaviorist.  THIS CAN BE FIXED!  Don't give up.