Can a dog owner avoid liability by arguing I provoked the dog in Ontario?

Yes. Provocation is one of the main ways a dog owner can reduce or defeat liability under the Dog Owners' Liability Act, since the strict liability the Act otherwise imposes is not absolute in every circumstance. If the owner can show that the injured person did something that provoked the dog - teasing it, threatening it, or otherwise behaving in a way that would foreseeably trigger a defensive reaction from an animal - a court can reduce the compensation awarded, or in some cases find the claim is not made out at all, depending on how significant the provocation was relative to the dog's actual reaction.

Whether specific conduct counts as provocation is a factual question courts assess on a case-by-case basis, and context matters a great deal. A young child's actions, for instance, are generally viewed differently than an adult's when assessing whether behaviour amounted to genuine provocation, since children may not understand how a given action could affect an animal. How the dog was behaving beforehand, and whether its reaction was proportionate to whatever provocation actually occurred, are also relevant to how this defence plays out.