It should also be noted that it's best to keep your pet on leash in public places because he is apt to run uncontrollably if left to his own devices. (dogs.lovetoknow.com)
They can be aggressive with other dogs and should be kept on leashes in public places. (puppiesndogs.com)
Not to mention the fact that in most municipalities it is even unlawful to keep a dog off leash in a public place. (puppy-training-solutions.com)