The state-level rules every owner and walker in Pennsylvania should know. Local leash lengths, licensing and off-leash rules are set by each city — find those on the city pages below.
Pennsylvania is a two-tier hybrid — strict liability for a bite victim's medical costs, negligence for everything else, and a leash or confinement violation is negligence per se.
Pennsylvania's Dog Law (3 P.S. § 459-502(b)) splits liability by type of damage. Medical costs → strict liability: the owner or keeper pays all medical bills for a bite or attack regardless of fault or history, with no free first bite (only defenses: provocation, trespass). All other damages (pain and suffering, lost wages, scarring) → negligence: the victim must prove the owner was negligent, or that the dog was previously declared dangerous. The statute names owner or keeper, so a walker or sitter (a keeper) is squarely inside both.
Pennsylvania's Dog Law (§ 459-305) requires owners and keepers to keep dogs confined or under reasonable control at all times. Under Miller v. Hurst (1982), an unexcused violation of that duty is negligence per se — the gateway to the full, non-medical damages. So a leash or confinement failure is exactly what converts a medical-costs-only case into a full-damages case against whoever was controlling the dog. (An owner may still show the dog escaped despite due care.)
A dog can be declared dangerous (§ 459-502-A) for a severe injury, an off-property animal kill, use in a crime, or an attack; the designation requires $50,000 liability insurance, a proper enclosure, muzzle and leash off-property under a responsible person, and signage — and violations are criminal (up to five years for severe or fatal cases). All dogs three months and older must be licensed, and rabies vaccination is required from three months.
Pennsylvania applies modified comparative negligence — a victim more at fault than the owner recovers nothing — with no cap on compensatory damages. The personal-injury limit is two years.
This is general information about Pennsylvania law, not legal advice. Confirm current rules with the official state and municipal sources.