Oregon Revised Statutes Animals § 608.015

(1) As used in this section, “open range” means an area wherein livestock may lawfully be permitted to run at large.

(2) A person who permits a horse, mule, ass, sheep, goat or animal of the bovine species to trespass on land enclosed by an adequate fence and situated on open range shall be liable to the owner or lawful possessor of the enclosed land for damage done by the animal. The person seeking to recover the damages shall plead and prove that the fence of the person consisted of structures, masonry, hedges, ditches, rails, poles, planks, rivers, streams, ponds, lakes, wire fences, natural or artificial barriers of any kind or any combination thereof. The adequacy of the fence shall be determined by reference to the customs and practices of good husbandry in the particular area with reference to fences. The question of the existence of the fence and the adequacy thereof are questions of fact.

(3) Nothing contained in subsection (2) of this section is intended to modify the provisions of ORS 608.310 to 608.400.