If any dog shall, without provocation, bite or injure any person who is at the time at a place where he or she has a legal right to be, the owner of such dog shall be liable in damages to the person so bitten or injured, but such liability shall arise only when the person so bitten or injured is upon property owned or controlled by the owner of such dog at the time such bite or injury occurs or when such person has been immediately prior to such time on such property and has been pursued therefrom by such dog.
For the purpose of this chapter a person shall be considered to be lawfully upon the private property of the owner of such dog when he is on such property in the performance of any duty imposed upon him by the laws of this state or by the laws of the United States or the postal laws and regulations of the United States, when reading meters, when delivering milk, when making repairs to any public utility or service upon said premises or when on such property upon the invitation, either expressed or implied, of the owner or lessee of such property.
The owner of such dog shall, however, be entitled to plead and prove in mitigation of damages that he had no knowledge of any circumstances indicating such dog to be or to have been vicious or dangerous or mischievous, and, if he does so, he shall be liable only to the extent of the actual expenses incurred by the person so bitten or injured as a result of the bite or injury.
Nothing in this chapter shall be construed as diminishing any right or liability for injury by dog bites now existing under the laws of this state.