yappy chihuahua

Question
I have a two year old Chi pup who lately has begun barking at any noise that even remotely sounds like a door knock. She is an angel in every other way, but this barking is so shrill. My old male chi was never a yapper but now he has started yapping as well. We have an old Dalmatian female who is quiet and a Husky male who is quiet, however the pup can get all of them yapping when she "thinks" she hears a noise. The male chi is the alpha. My pup is quite timid. I understand she may be letting me know that someone is coming to "her" house, but I'd rather do without the barking if possible. My second question is hopefully easier.. I have been using a can with some pennies in it as a training aid, and it works beautifully. I have seen the same advice on this site. Now I hear that it makes them afraid of loud noises, which the chi puppy is (thunder, vaccuum etc). So, my second question is: can or no can? She responds very well to praise. I use the can only in situations where I absolutely can not get her attention (for example when she darts outside into the front yard and street). Thanks for your help.

Answer
The Chihuahua BARKS and is extremely sensitive to sound.  Your dog has acquired a conditioned response to door knocks because they have been followed by entry of a "stranger" or (even worse) "friend" often enough to have created this reaction.  Your other dogs are responding to her "alarm".  STOP USING THE PENNY CAN IMMEDIATELY.  This device is PUNISHING your other dogs and this might very well have heavily contributed to their growing hilarity to your younger Chi's conditioned response.  Penny cans are a HUGE NO NO unless carefully (CAREFULLY) conditioned and used scantily after instruction by someone who knows what they're doing.

The strongest re-conditioning you can do is to extinguish ANY KNOWN REWARD to the door knock, meaning no one....NO ONE....can knock at your door.  You need to install a battery powered doorbell (and then closely observe this Chi so that she does not have the opportunity to acquire a conditioned response to that sound.)  Once two or so weeks have passed without any obvious reward to "door knocking" sounds, you can then recondition (or attempt to) the dog.  Between now and then, use positive reinforcement training to teach her one strong behavior (such as "sit" but use a made up word) she can perform 100% of the time with success; this should take approximately 2 to 3 weeks (the same amount of time your doorbell is taking the place of door knocking.)  Teach her this obedience "trick" (behavior) in several very short trials each day until she automatically performs it EVERY SINGLE TIME (ten out of ten, with no failure, not ONE.)  Food reward (part of positive reinforcement training, learn about it from karen Pryor's web site or reading Patricia McConnell Ph.D.) consistently (every time) while she is learning and for at least 3 weeks after she has offered consistent success.  Following this 3 week period, providing you are doing everything correctly, your dog should be ready for the next phase.  Introduce the "knock" (you can knock on anything, won't matter) WITH the food reward WITHOUT asking for a "sit".  Do this repeatedly for at least 30 trials over the course of several days.  Your dog MAY (MAY!) acquire the knock as a cue to food reward and you MAY (MAY!) be able to use the knock as the cue that food reward is coming, after giving her the command to "sit".  Response perseverance might make this impossible;  some dogs have to self extinguish their sensitivity to strong cues (like door knocks and door bells) and this can take many months.  Some dogs can accept the new "cue" (the original problematic stimulus) as the precursor (cue) for reward.