For purposes of sections 54-617 to 54-624:

(1) Animal control authority means an entity authorized to enforce the animal control laws of a county, city, or village or this state and includes any local law enforcement agency or other agency designated by a county, city, or village to enforce the animal control laws of such county, city, or village;

(2) Animal control officer means any individual employed, appointed, or authorized by an animal control authority for the purpose of aiding in the enforcement of sections 54-617 to 54-624 or any other law or ordinance relating to the licensure of animals, control of animals, or seizure and impoundment of animals and includes any state or local law enforcement officer or other employee whose duties in whole or in part include assignments that involve the seizure and impoundment of any animal;

(3)(a) Dangerous dog means a dog that, according to the records of an animal control authority: (i) Has killed a human being; (ii) has inflicted injury on a human being that requires medical treatment; (iii) has killed a domestic animal without provocation; or (iv) has been previously determined to be a potentially dangerous dog by an animal control authority, the owner has received notice from an animal control authority or an animal control officer of such determination, and the dog inflicts an injury on a human being that does not require medical treatment, injures a domestic animal, or threatens the safety of humans or domestic animals.

(b)(i) A dog shall not be defined as a dangerous dog under subdivision (3)(a)(ii) of this section, and the owner shall not be guilty under section 54-622.01, if the individual was tormenting, abusing, or assaulting the dog at the time of the injury or has, in the past, been observed or reported to have tormented, abused, or assaulted the dog.

(ii) A dog shall not be defined as a dangerous dog under subdivision (3)(a)(iv) of this section, and the owner shall not be guilty under section 54-622.01, if the injury, damage, or threat was sustained by an individual who, at the time, was committing a willful trespass as defined in section 20-203, 28-520, or 28-521, was committing any other tort upon the property of the owner of the dog, was tormenting, abusing, or assaulting the dog, or has, in the past, been observed or reported to have tormented, abused, or assaulted the dog, or was committing or attempting to commit a crime.

(iii) A dog shall not be defined as a dangerous dog under subdivision (3)(a) of this section if the dog is a police animal as defined in section 28-1008;

(4) Domestic animal means a cat, a dog, or livestock. Livestock includes buffalo, deer, antelope, fowl, and any other animal in any zoo, wildlife park, refuge, wildlife area, or nature center intended to be on exhibit;

(5) Medical treatment means treatment administered by a physician or other licensed health care professional that results in sutures or surgery or treatment for one or more broken bones;

(6) Owner means any person, firm, corporation, organization, political subdivision, or department possessing, harboring, keeping, or having control or custody of a dog; and

(7) Potentially dangerous dog means (a) any dog that when unprovoked (i) inflicts an injury on a human being that does not require medical treatment, (ii) injures a domestic animal, or (iii) chases or approaches a person upon streets, sidewalks, or any public grounds in a menacing fashion or apparent attitude of attack or (b) any specific dog with a known propensity, tendency, or disposition to attack when unprovoked, to cause injury, or to threaten the safety of humans or domestic animals.