An "unrestrained dog" refers to a dog that is not controlled or held back by a leash or any other means. It is free to move around or act without any restrictions. Full definition
However, even in states that are not legislating on the issue, pet parents are getting the message that unrestrained dogs in moving cars pose a number of dangers. (petbusiness.com)
City officials said the abrupt decision was prompted by owners not cleaning up after their pets, as well as the threat unrestrained dogs pose to children and other park visitors. (articles.orlandosentinel.com)
It could be that more people were bitten by male dogs because more male dogs were accessible (roaming for example)-- indeed, unrestrained dogs roaming off the owner's property were responsible for a quarter of the bites recorded in the study. (thehappypuppysite.com)