A mobility assistance dog is a dog trained to assist a physically disabled person who has mobility issues, such as wheelchair dependency or poor balance. Roles include “providing balance and stability” picking up and carrying objects, and (controversially) pulling wheelchairs. A mobility assistance dog can also be trained to open and close doors, and operate light switches, and can “have a major positive impact on the lives of recipients”. These dogs usually wear a special vest so that the owner can attach a cane-like handle. This allows the dog to guide the owner and assist with their balance.