Several types of bark control collars
Because every dog is different, it takes several types of bark control collars to work for all of them. A lot of people don't want to use a sonic bark collar, or one that shocks the dog before trying something else out. I do have to admit that this method, while not inordinately cruel, a somewhat mean. Were I a dog, I would rather be sprayed in the nose with citronella than shocked or subjected to a piercing tone. Nonetheless, citronella collars don't work for all dogs. Basically, they work by spraying a powerful jet of citronella every time the dog barks. This confuses the dog, and it is Perceived as mildly uncomfortable. For some dogs, this is an effective method of bark control training. Not only does it avoid stressing them out the way that shock collars can, but also does the job more quickly for dogs with a fragile temperament. After all, these kinds of dogs can get freaked out by shock or sonic collars.
It is sad for those of us who like big dogs, but normally the bigger the dog, the tougher the training has to be. Part of this has to do with the fact that bigger dogs tend to be tougher. A bark collar which might be shocking enough to terrorize a little dog simply won't work for them. Along with this toughness, They can also be more stubborn. They are used to being bigger than most things, even sometimes their owners. This means that, unless you show them who is boss by doing something they find unpleasant, they won't listen to you.
Of course, bark training involves a lot more than the bark collar. Almost all dog training involves creating associations between desired behavior and rewards, or unwanted behavior and punishments. Sometimes, bark collars alone can train a dog, but more often some involvement is required by the pet owner or a suitable trainer. The dog has to associate the discomfort or pain received from the bark collar with displeasure on the part of the trainer.
So which one is right for you? I think that the best idea is to start small and work your way up. Sometimes, a dog will be able to resist A minor bark collar, but will quickly understand what is going on when it is substituted for a more unpleasant one. Working with the collars in two phases like this, strangely enough, can actually speed up training.