Signal called Splitting. Seeking professional advice from local organizations, dog trainers, or veterinarians. Use of a mechanical device such as a bark collar. There are several types, all of which use a collar device that produces a response to barking that the dog notices: Citrus spray ("citronella") - dogs as a rule do not like citrus. At the least, it is very noticeable and disrupts the pattern through surprise. These collars spray citrus around the dog's muzzle when it barks. (Sometimes these devices make a "hissing" noise before spraying, as an additional deterrent – see "Combination and escalation devices" below) Sonic/ultrasonic (including vibration) - these collars produce a tone which humans may or may not be able to hear, in response to barking. Over time, the sound becomes annoying or distracting enough to deter barking, although this may not always work. Electrical - these collars produce a mild stinging or tingling sensation in response to a bark. It is important that such devices have a failsafe mechanism and shut off after a certain time, to prevent ongoing operation. Combination and escalation devices - many sound and/or electrical collars have combination or escalation systems. A combination system is one that (for example) uses both sound and spray together. An escalation device is one that uses quiet sounds, or low levels of output, rising gradually until barking ceases. Escalation devices are effective since they "reward" the dog for stopping sooner by not having "all-or-nothing" action, so the dog can learn to react by stopping before much happens. Note: Various bark collars have been both praised and criticized; some are considered inhumane by various people and groups. Electrical devices especially come under criticism by people who consider them torturous and akin to electrocution. However most Societies for the Prevention of Cruelty to Animals agree that in a last resort even an electric collar is better than euthanasia if it comes to an ultimatum, for a stubborn dog that will not stop any other way. It is generally agreed that understanding the communication and retraining by reward is the most effective and most humane way. Surgical debarking The controversial surgical procedure known as 'debarking' or 'bark softening' is a veterinary procedure for modifying the voice box so that a barking dog will make a significantly reduced noise. It is considered a last resort by some owners, on the basis that it is better than