You may see this phrase in an insurance letter, a landlord dispute, or a call with an adjuster: "The owner had no prior knowledge the dog was dangerous," or "There was no previous bite." That usually points to the one-bite rule, a rule some states use to decide when an animal owner is legally responsible for an attack. In general, it means an owner may avoid liability the first time an animal seriously harms someone if there was no reason to know the animal had dangerous tendencies. A prior bite is the classic example, but warning signs can also include lunging, snapping, or past aggression.

That rule matters because insurers and defense lawyers sometimes use it to make injured people think they have no case unless the dog attacked before. That is not always true. Even in one-bite-rule states, a claim may still exist under negligence, leash-law violations, or unsafe handling of the animal.

In Iowa, this is a trap to watch for. Iowa Code § 351.28 generally imposes strict liability on a dog owner for damages caused when the dog attacks or worries a person, with limited exceptions such as the injured person committing an unlawful act that directly contributed to the injury. So Iowa does not rely on the classic one-bite rule the way some states do. If fault is disputed, Iowa's modified comparative fault rule, Iowa Code § 668.3 (2024), can still reduce or bar recovery if the injured person is more than 50% at fault.