My dogs behavior has changed

Question
Hi there,
About 5 months ago my husband and I divorced.  I now live in an apartment and he remains in th ehouse.  Since our 4 year old schnauzer/pomeranian mix was my dog, I took him with me.  He is a wonderful, people-friendly dog.  Since the move, he has become more nervous.  Recently, my job has me working long hours, so Buddy has been spending the weekdays at my ex's (our old house).  Also, I had to go out of town, so he was there for that.

Recently, he has started barking at people, and even growled at my step-daughter. At a holiday open-house, he growled at every person who came to the door.  This is completely opposite of how Buddy is with people normally.  He loves a party, loves the attention.  I am really worried abouthim, as he is my best friend.  Can you tell me what you think?
Thanks!
Rachel

Answer
Your dog is caught in the middle of emotional turmoil, yours (and no one can blame you!)  He is also quite confused and moving him back to his old "home", even though apparently necessary, most likely aggravated this condition.  Also, you have absolutely no idea what went on while he was staying with your ex.  Is it possible your ex neglected him or in some way interacted with him around visitors that created a problem?  I can't answer that question; you can.

In future, you must find a safe, secure kennel or pet sitter: be certain to get multiple references on both.  If it's a kennel, be sure you can go in at any normal business hour to view the premises.  If kennel owners don't allow this, don't use the kennel.  If a pet sitter (either in her home or yours), be sure your dog LIKES the person and be certain to carefully check MANY references.  You can't run the risk of leaving the dog with your ex again; regardless of how this situation began, you need to be in total charge of its rehabilitation, with no interference, one-upmanship, or hidden agenda.

I can only offer suggestions here, not being able to see the dog's front door aggression personally.  Because active dog to human aggression is involved, you absolutely need the professional advice of a certified applied animal behaviorist.  You can get referral by calling the veterinary college in your geographical area or by calling around the higher end veterinary offices.  Be sure the person has real credentials, not make-believe letters after their name given them by the training organization to which they belong.  The WRONG approach can make this situation far worse.

Using positive reinforcement training, teach Buddy one solid behavior ("sit", but use a unique word); this will take approximately two weeks to form a solid 100% response to your cue (command).  During this time, do not allow Buddy to greet anyone at the door; keep him in another room behind a closed door until your visitor is settled in your home; then allow Buddy out on lightweight nylon "house tab" (leash).  Instruct your visitor to ignore Buddy, no matter what the dog does.  When people respond to growling, they educate the dog further in its use, something you want to avoid.  Once Buddy has obtained a 100% reliable response to your cue for "sit", enlist the aid of a couple of friends (one at a time) over the course of a few hours and have them come to the front door.  When the doorbell rings, ask Buddy to "sit" (and keep him on house tab); open the door only after he is seated.  If he breaks the sit, close the door in the face of the "visitor".  Keep doing this until Buddy has maintained his sit, then allow the "visitor" to enter.  Again, the "visitor" must ignore Buddy.  You must observe the dog's body language to determine what he is feeling, what impulse he is acting on.  Allow the "visitor" to interact with Buddy ONLY if the dog responds to the "visitor's" cue to "sit", and keep the interaction short.  This is all a stopgap measure until a professional is able to attempt to determine what Buddy is afraid of, and why; no one may be able to answer that question, but whatever occurred to Buddy while he was in the home of your ex may have precipitated this and he now has a conditioned fear response to visitors.  Your holiday open house, allowing multiple people in/out of your home, is called "flooding" and this sort of event can worsen a conditioned fear response.  Do not allow Buddy to be present for any further such events until the aggression has been successfully treated.  Don't give up on your dog (and I know you won't.)  Try to understand that your emotional upheaval is communicating directly to your dog (through your body language and other behaviors).