There are currently three types of bark collars to help prevent your dog from excessive barking. First off is the Citronella bark collar which utilizes the strong smell of the citronella plant. The Citronella bark collar is electronic, and basically sprays citronella onto a dog's muzzle when the dog barks. Next is the E-Collar which shocks the dog whenever it tries to make a sound. Lastly, the ultrasonic anti-bark collar basically uses the whistle concept of high pitched noises humans can't hear to affect a dog as they can hear it.
