An electronic collar is a device worn around the neck of a pet that provides a mild electric shock or vibration as a form of training or control mechanism. Full definition
The studies of electronic collars (including the one mentioned above) found their use carries risks for animal welfare even when the trainer is experienced. (academyfordogtrainers.com)
To this day, several studies looked at the stress levels of dogs on whom electronic collars were used. (topdogtips.com)
Some trainers use negative rewards like electronic collars to administer a mild shock to the dog, which stops as soon as he sits. (animals.howstuffworks.com)