Chihuahua acting moody

Question
Hi, I have a three and a half year old female Chihuahua named Pepper. She is a really sweet dog and loves meeting new people. She has never bitten anyone or never not liked someone.

But recently, she has been acting moody. Three weeks ago, when my brother brought his girlfriend home from college to meet our family, Pepper started acting strange. She liked Tammy and got along with her, but sometimes she would just randomly start howling and whining throughout the day, which she has never done before. Soon after, she began to stay in her bed more, sleep more and curl up on a blanket with her back facing whoever was in the room. She also wanted attention constantly.

After Tammy left the howling stopped, but then my other brother began bringing his son over almost every day over the holiday season, and Pepper became moody again, but didn't howl. We kept Pepper away from my brothers son because she has never been around small children and he is afraid of dogs. At first, Pepper seemed to want to be his friend, but soon she began barking and growling at him and craving attention again.

After the holidays, my brothers son went back to his mother, but Pepper kept barking at the slightest sound, and sometimes even at us, and she still continues to be moody and attention craving. She is also not listening to us much anymore.

Please help. I'm not really sure what to do. The only person Pepper seems to like the most now is me (well, she is my dog) and she sometimes ignores everyone else.

What should I do?

Answer
Whenever a dog shows sudden behavioral changes, the first stop is the Veterinarian.  Your dog might be experiencing some cognitive dysfunction, low level seizure activity, or other neurological problems that was initiated by stress.  She also might be in pain or suffering an illness.  Bring a stool sample with you and describe the situation to your veterinarian.  Seizure disorders are notoriously difficult to diagnose (if that's what is causing this) so the Veterinarian might have trouble arriving at a conclusion if all other tests come up negative.  However, a course of Phenobarbital might bring the dog around to her usual self and that will prove the root cause of the behavior, if the Veterinarian is willing to participate in this "experiment".  You can leave her on the drug for several weeks then wean her off to see if the odd behavior returns.  In the mean time, try putting the dog on leash when she exhibits these behaviors.  The leash is a psychological, as well as a physical, restraint and often helps the dog to calm down.  Have a lot of patience with her.  The holidays are stressful for everyone, not just people!, and she might be reacting to the flow of "strangers" in her space.