As used in this chapter, the following items shall have the meanings indicated:
As applied to a dog, off the premises of the person owning or keeping or harboring it and not securely fastened to a tether, leash, cord or chain, or the like, held by its owner or other person capable of controlling said dog.
Any dog, bitch or spayed bitch.
Any dog which has attained the age of seven months or which possesses a set of permanent teeth.
As applied to the proprietorship of a dog, includes every person, family, firm or corporation having a right of property in such dog and every person, family, firm or corporation who has such dog in its keeping.