Tennessee Code Title 39. Criminal Offenses § 39-17-1363

(1) “Potentially vicious dog” means a dog that may reasonably be assumed to pose a threat to public safety as demonstrated by any of the following behaviors:

(2) “Vicious dog” means any dog that without provocation and off the property of the owner or keeper of the dog, has attacked a person causing death or serious bodily injury, as defined by § 39-11-106, to such person; and

(3) “Violent felony” means:

(1) Is not micro chipped for permanent identification; and

(2) Is not spayed or neutered and is older than twelve (12) weeks of age.

(e)(1) It is an affirmative defense to prosecution under subsection (c), which must be proven by a preponderance of the evidence, that the dog in question is microchipped and neutered or spayed, or that the dog in question was microchipped and neutered or spayed within thirty (30) days of the defendant being charged with a violation of this section.

(2) Medical records from, or a certificate by, a person who is licensed by the person's state of residence as a doctor of veterinary medicine, whose license is in good standing and who has personally examined, inserted a microchip in, or operated upon the dog, indicating that the dog in question has been microchipped or spayed or neutered, shall be sufficient evidence that the dog in question has been microchipped or spayed or neutered.

(3) If the dog in question is microchipped by a different doctor than the doctor who spayed or neutered the dog, medical records or a certificate indicating that both procedures have been performed are required for purposes of this defense.