The state-level rules every owner and walker in Missouri should know. Local leash lengths, licensing and off-leash rules are set by each city — find those on the city pages below.
Missouri makes the "owner or possessor" of a dog strictly liable for a bite — so a walker with possession is a named liable party — under pure comparative fault.
Missouri (Mo. Rev. Stat. § 273.036, since 2009) makes the owner or possessor of a dog strictly liable for a bite, without provocation, when the victim is on public property or lawfully on private property — regardless of the dog's history or anyone's knowledge. Owners and possessors are also strictly liable for property or livestock damage. Because possessor is in the statute, a walker or sitter who has possession of the dog at the time of a bite is a named liable party alongside the legal owner.
Non-bite injuries (knockdowns) fall under negligence, where a leash-ordinance violation is strong evidence. Missouri applies pure comparative fault even to strict liability: a victim's own fault reduces recovery proportionally but never fully bars it unless they are 100% at fault.
The core defenses are provocation (read narrowly — petting or walking past is not provocation) and trespass. There is no statewide leash law — leash and dangerous-dog rules are local. The personal-injury limit is an unusually long five years (§ 516.120).
This is general information about Missouri law, not legal advice. Confirm current rules with the official state and municipal sources.