Obviously, the most dangerous of all training tools is the choke chains and prong chains. If used on a dog that has not been trained properly can even claim life within a second chance. If used by an inexperienced handler the choke chains can lead to serious injury.
Records have shown evidences of canine injuries due to the misuse of choke and prong chains. Serious choke/ link chain injuries such as oesophageal damage, tracheal injuries, ocular vessels injuries, necks sprain, laryngeal nerve paralysis, misalignment of the cervical vertebrae, horner's Syndrome, transient foreleg paralysis and hind leg ataxia etc. have been documented in the veterinary record in March 1999.
The Kennel Club and RSPCA, however, still considers the choke chains as legal training tool – provided they are used by "experienced handlers". This policy, by itself sounds vague, because there's no parameter to count the experience of a handler. Most significantly accident can happen at any point of time even though they are used by experienced people.
Electronic dog training collar, however, has proved to be quite humane and a thousand times safer than the prong and choke chains. The device works on a static stimulation system. The dog gets a static stimulation by a device attached to the collar. The device is operated by the trainer by a remote transmitter. One pressing the button of the transmitter the device generates a static stimulation or an ultrasonic beep upon which your dog is trained to act.
Get more information about dog training collar at http://dogtrainingcollars.com