IME citronella collars work for the right dog.

I LOVE citronella bark collars! A humane and effective way to stop your dog from barking.
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Bark collars are an effective way to train a dog not to bark excessively. They use one of three methods of correction to dissuade a dog from barking; a small and harmless electric shock, a citronella spray, or an ultrasonic tone. Bark collars are usually triggered by the sound of the dog barking, the vibration of the dog’s vocal cords, or a combination of both, and the best bark collars will have a range of different correction levels so that the collar can be set at an intensity that will suit the temperament of the dog.
See our quick picks for the best citronella dog collars, or read below for full reviews and info
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Before making a purchase you should ensure the collar is comfortable especially if it is to be worn every time. It should not aggravate the dog. For it to be useful, it has to be tolerated. Consider the temperament levels of the dog. Some dogs are calm and restrained thus require simple control methods like the Citronella spray or low voltage shocks. Consider the dogs’ size and the environment for the collar use. Compare the prices for the collars and choose the favourable one. This citronella bark collar is made especially for small dog breeds with a neck size up to 22″.
Photo provided by FlickrPetsafe Gentle is the basic dog citronella collar. All you have to do is put it on your dog.
Photo provided by FlickrPetSafe/Premier GentleSpray Gentle Spray Humane Citronella Dog Bark Collar
Photo provided by Flickr
I have two dogs whose barking has gotten terrible and I'd like to correct it before the babies get here. I have collars that spray citronella in their faces when they bark (and they really work if only your DH will keep the collars on them). If the dogs are near me, I get a small whiff of the citronella. Is this harmful to the babies?That led to the development of the citronella anti-barking collar. After being attached to the dog's neck, the collar automatically releases a squirt of citronella fragrance under the animal's nose every time he barks.I have two dogs whose barking has gotten terrible and I'd like to correct it before the babies get here. I have collars that spray citronella in their faces when they bark (and they really work if only your DH will keep the collars on them). If the dogs are near me, I get a small whiff of the citronella. Is this harmful to the babies?The problem with the citronella collar is that the dog will eventually habituate to the smell. That's because dogs get used to the odor after a while, and the more accustomed the animal becomes to the scent, the less it will bother him.Everyone knows that the way to discipline or deal with misbehaved cats is to spray them with a bottle of liquid, usually water. Most people do not think to apply the same principle to dogs, but it can be done. Now obviously water does not work, but you can use things like Citronella or lemon juice to help discipline your dog. The best way to go about using Citronella is to buy a Citronella dog collar. These collars works best for stopping your dog from barking unnecessarily, but they can also be used to do other disciplinary tasks, like preventing your dog from running past a certain area. Citronella collars are very much like shock collars obviously without the actual shock part, but they work very similarly.The best way around the habituation phenomenon is to alternate the use of the citronella collar with an , so that the dog wears the citronella device no more often than once or twice a week.