Collars with electric pulses have been placed on cows' necks to help create wetland habitats in the fens. The 'Nofence' ...

More secure. Also known as GPS dog fences, these function by connecting a dog collar receiver to a central transmitter that outlines a virtual boundary around your yard. When your dog gets close ...

The collars give out a short low level pulse, similar to an electric fence, with livestock quickly learning the extent of their new boundaries and to avoid approaching the "virtual fence line" again.