Utah Code § 4-25-205

(1) The owner of any cattle, horse, ass, mule, sheep, goat, or swine that trespasses upon the premises of another person, except in cases where the premises are not enclosed by a lawful fence in a county or municipality that has adopted a fence ordinance, is liable in a civil action to the owner or occupant of the premises for any damage inflicted by the trespass. (2) A county representative may intervene to remove the animal and the county is entitled to fair compensation for costs incurred. If the animal is not claimed within 10 days after written notification is sent to the animal's owner, a county representative may sell the animal to cover costs incurred. (3) Notwithstanding Subsections (1) and (2), the owner of any cattle, horse, ass, mule, sheep, goat, or swine that trespasses upon the premises of another person is not liable in a civil action to the owner or occupant of the premises for damage inflicted by the trespass if: (a) the animal enters the premises from an historic livestock trail, as defined in Section 57-13b-102; and (b) the premises that was trespassed is not enclosed by an adequate fence at the time the trespass occurs.