A dog’s natural instinct is to protect his home & property. A dog that is unsupervised or out of reach cannot be corrected for barking (or digging, or chewing…).   In order to work with barking, therefore, the dog must be supervised and easily reached during times of (possible) barking.  

To facilitate teaching not to bark, you do NOT have to wait for the situations of barking to happen. Enlist help, and set up the situation! Practice several times in a row to teach. The easiest way to work with barking (as with anything) is to have the dog on a leash (or umbilical leash – a little safer).  That way, it is easier to catch and correct (and praise!) the dog.


Methods to teach a dog not to bark:

First, pick a word or phrase that will be your command to stop barking.  Suggestions can be: “Quiet!”, “Enough!”, “No Bark!”, “Hush!”, “That’ll Do!”.   
I never use “Shut Up!”, and I prefer not to use “No”.
Set up for barking, and have a leash on the dog.  When the barking happens, take the leash (step on the leash if you have to “catch” the dog or just have the leash in your hand to start!), give a firm tug horizontally to the floor and firmly use your word. 
When the dog is quiet, calmly & quietly praise (“GOOD quiet”).  Sometimes a tiny soft-moist treat can reinforce your praise (brought down to the dog’s level).
If the pop on the leash doesn’t help, you can incorporate a squirt bottle into the equation. Give a sharp series of squirts right in the face, firm command to quiet, and, for extra measure, have the dog SIT.  Your correction should only be as firm as it needs to be. You can also use a small “shaker container”.  Do not use these tools to threaten.
I like to teach a command for “guard barking” – my command is “Who’s there?” My dogs will run to the door and bark.  I tell them “Good who’s there!” and then I will use my quiet command to tell them that is enough.  I use this to get my dogs to respond to the doorbell or knock.
If I have an excessive barker, or to make my point of QUIET clearer, I will enforce a firm DOWN.  This is a leadership gesture on my part (I am the leader, and you comply with my wishes) and also a dog in a down generally does not bark.  You can make sure the dog remains in a down by stepping on the leash.
Although you have no way to correct barking when you are not home, you may want to leave a tape recorder or video camera on to see when barking happens, what causes the barking and the duration of the barking.  Guard barking, for example, is handled a little differently than lonely or random barking.

Barking is a normal dog behavior.  In excess, it can be irritating.  If controlled, barking can be useful!

Pam Young, LVT CDBC CPDT  
Dog Gone Good LLC
Dog Behavior Consultant
Personal Dog Trainer