The state-level rules every owner and walker in Iowa should know. Local leash lengths, licensing and off-leash rules are set by each city — find those on the city pages below.
Iowa is one of the strictest states — "absolute liability" where contributory negligence is not a defense, provocation doesn't help, and there are only two statutory defenses.
Iowa (Iowa Code § 351.28) is one of the strictest in the country. The owner is liable for all damages when a dog attacks or attempts to bite a person (or worries, maims, or kills a domestic animal). The Iowa Supreme Court (Collins v. Kenealy) holds owners absolutely liable regardless of negligence or knowledge of the dog's vicious propensity, and — critically — contributory negligence is not a defense. It even reaches injuries suffered fleeing an attack (running into the street).
There are only two statutory defenses: the victim was doing an unlawful act that directly contributed to the injury (for example, a nighttime trespasser at the back door), and the rabies exception (no liability for a rabid dog's attack unless the owner had reasonable grounds to know of the rabies and could have prevented it). Provocation, or that the victim approached or startled the dog, are not defenses in Iowa. The statute imposes strict liability on the legal owner, but a keeper or harborer who knew or should have known the dog was dangerous can be liable in negligence.
Iowa has mandatory bite reporting (§ 351.38), and leash and at-large rules are local (§ 351.41 preserves municipal power). The personal-injury limit is two years.
This is general information about Iowa law, not legal advice. Confirm current rules with the official state and municipal sources.