A dog bite victim in Wyoming can recover compensation under the doctrines of negligence, negligence per se, scienter and intentional tort. There is no state dog bite statute so this is a "one bite state." Individual counties and cities may have ordinances creating strict liability, however.
Strict liability for scienter
When a dog owner or harborer is aware that his dog either has bitten a person without legal justification or has exhibited the desire to do so, the dog owner or harborer thereafter will be held liable if the dog bites a person. "[T]he often repeated statement that “every dog is entitled to one bite” is not and never has been the law. It is enough that the dog has manifested a vicious disposition, and a desire to attack or annoy people or other animals." Prosser, Law of Torts, §76 at 501-502 (footnote omitted), cited in Gannon v. Voss (Wyoming Supreme Court) http://caselaw.findlaw.com/wy-supreme-court/1260744.html#sthash.dGq7LrCn.dpuf
This ground of liability is referred to as "scienter" (i.e., knowledge, in this case meaning knowledge of the dog's viciousness). It also is described as the "common law cause of action," the Restatement cause of action, and the "one-bite rule" although that term is a misnomer. For more, see The One Bite Rule.
No strict liability by statute
The one bite rule is the foundation of dog bite law. It exists in every state. The majority of American states have supplemented it with statutes that make dog owners responsible for all bites including the first one. These so-called "dog bite statutes" sometimes extend to people other than dog owners and injuries other than dog bites. Unfortunately, Wyoming does not have a dog bite statute. Critics have asserted that not having a dog bite statute is at odds with modern American beliefs about personal responsibility, because the one bite rule shields a dog owner from liability each time one of his dogs bites a person for the first time unless it can be proved that the owner knew that the dog had the propensity to bite people without justification. See Criticism of the One Bite Rule. Whether one agrees with these critics or not, it nevertheless is true that a dog bite victim has more to prove in the absence of a dog bite statute.
The state also permits a dog bite victim to recover compensation on the ground of negligence. Negligence is the lack of ordinary care; that is, the absence of the kind of care a reasonably prudent and careful person would exercise in similar circumstances. If a person's conduct in a given circumstance doesn't measure up to the conduct of an ordinarily prudent and careful person, then that person is negligent. For example, letting a stray dog into a day care center is negligence. See Negligence.
The Wyoming Supreme Court has emphasized that the negligence cause of action does not require proof that the dog was vicious or that the owner knew the dog was vicious. Requiring a victim to prove "the scienter element in the negligence claim" would be "contrary to law." Gannon v. Voss (2003) at http://caselaw.findlaw.com/wy-supreme-court/1260744.html#sthash.dGq7LrCn.dpuf.
Negligence per se
Disobeying an animal control law (like a leash law) can result in "automatic" negligence or can be simply evidence of negligence, depending on the law of the state. Wyoming recognizes it as a cause of action in dog bite cases. Williams v. Johnson, 781 P.2d 922, 923 (Wyo. 1989); (Borns v. Voss (2003) at http://caselaw.findlaw.com/wy-supreme-court/1260744.html.
A landlord can be held liable when a tenant's dog bites a guest on the premises, if the landlord had scienter. Roberts v. Klinkosh, 986 P.2d 153 (Wyo.1999).