Ontario law does not mince words about responsibility for dog bites and attacks. The Dog Owners’ Liability Act, R.S.O. 1990, c. D.16 (“DOLA”)^[1] imposes strict civil liability on an owner for damages caused by a bite or attack on a person or a domestic animal, with apportionment for the victim’s own fault if any. The same statute also empowers the court to make public-safety orders (muzzling, leashing, confinement, and, in extreme cases, destruction) and contains offence provisions. Read the core rule in section 2 and the related provisions (including section 3 on how this interacts with occupiers’ liability) straight from the statute:

The Statutory Baseline

DOLA’s baseline is simple. Prove the bite or attack, prove the resulting loss, and you have civil liability against the “owner.” Knowledge of viciousness or negligence is not an element. The statute also clarifies two important boundaries. First, where a dog injures on the owner’s premises, civil liability is determined under DOLA (not the Occupiers’ Liability Act). Second, damages are reducible to the extent the plaintiff’s fault contributed to the loss (comparative fault is built into s. 2(3)).

Who Counts as an “Owner”? The Court of Appeal’s Anchor

The most important Ontario case on “ownership” under DOLA is Wilk v. Arbour, 2017 ONCA 21^[2]. The Court of Appeal held that “owner” includes a person in physical possession and control of the dog just before the bite or attack—not only the registered or true owner. That reading flows from the statute’s definition (“includes a person who possesses or harbours the dog”) and the policy that the person exercising real-time control is best positioned to prevent harm. Wilk also explains that negligence claims about animal behaviour remain available but turn on foreseeability and unreasonable conduct—“special circumstances” beyond a sudden, unexpected act by a domestic animal.

The bottom line is that under DOLA, possession/control at the critical moment can make you an “owner”. In negligence, you still need facts showing the risk was reasonably foreseeable and the conduct fell below the standard of care.

Harbourers, Hosts, and Bystanders: Drawing the Line

Earlier jurisprudence helps mark the limits of “owner” status. In Purcell v. Taylor, 1994 CanLII 7514 (ON SC)^[3], the court explained that to harbour a dog you must exercise some degree of care or control, the kind of responsibilities an owner would assume (shelter, feeding, exercising). Simply allowing someone else’s dog to be on your property, without more, does not make you a harbourer and therefore not an “owner” for DOLA purposes.

Likewise, Sgro v. Verbeek, 1980 CanLII 1745 (ON SC)^[4] is frequently cited for the proposition that casual presence or incidental contact is not enough to transform a non-owner into an “owner” under the statute. The law asks who had possession or harbouring in a meaningful, control-based sense.

Employees, Caregivers, and “You Can’t Sue Yourself”

The inclusive “owner” definition can have hard edges for people who work with dogs. In Medeiros v. Petopia Ltd., 2020 ONSC 1562^[5], a kennel employee bitten by a client’s dog sued both the kennel and the dog’s true owner. The decision highlights the way DOLA claims can be complicated where the injured person arguably possessed or controlled the dog at the critical time. Negligence claims may still be considered, but DOLA’s strict-liability route can be blocked if the plaintiff is also an “owner.”

A recent illustration pushes this point further. In Nigro v. Luciano, 2025 ONSC 1362^[6], a professional dog walker was deemed an “owner” under DOLA because she had physical possession and control immediately before the bite. Since one owner cannot sue another under DOLA, her statutory claim failed. The decision underscores the practical risk that caregivers—walkers, sitters, groomers—can land on the defendant side of the DOLA line, depending on the facts, even while still exploring negligence against others if foreseeability and breach can be proven.

Contributory Fault, Trespass, and Other Limiters

DOLA expressly allows courts to reduce damages in proportion to the plaintiff’s own fault (provocation, ignoring warnings, unsafe conduct around a known reactive dog, etc.). It also carves out a narrower rule for criminal trespassers injured by a dog on the owner’s premises. No DOLA liability will attach unless keeping the dog for protection was unreasonable in the circumstances. These are statutory, not judge-made, limitations. They live in the same text that imposes strict liability and are regularly applied in damages assessments and motion practice.

DOLA vs. the Occupiers’ Liability Act: When Both Might Matter

Because DOLA displaces the Occupiers’ Liability Act only where the defendant is an “owner” and the injury occurs on the owner’s premises, claims against non-owners who control premises (condominiums, landlords, event venues) can still proceed in negligence/occupiers’ liability where the evidence supports it. In practice, identify who is an “owner” under DOLA (strict liability applies to them), and who is an occupier but not an owner (negligence analysis applies to them).

Public-Safety Powers and the Pit Bull Regulation

Separate from civil damages, DOLA authorizes public-safety applications in the Ontario Court of Justice to control or destroy a dangerous dog and to impose conditions on owners. Ontario also maintains the Pit Bull Controls regulation under DOLA (O. Reg. 157/05^[7]) governing bans/exemptions, identification, leashing and muzzling of pit bulls. While these provisions don’t decide a civil damages claim, they often surface in parallel proceedings, risk assessments, and compliance obligations after an incident.

Practical Takeaways for Pleadings, Proof, and Mediation

The civil path in Ontario runs on two tracks.

Track one is DOLA’s strict liability. Figure out who the law treats as an owner at the time of the incident and quantify loss, anticipating a reduction for any contributory fault.

Track two is negligence/occupiers’ liability against non-owners with control over the premises or the situation, provided you can make out foreseeability, breach, and causation on conventional principles. Wilk remains the touchstone for ownership and for when negligence adds anything beyond DOLA.

At intake, build the record around control and context: Who held the leash? Who opened the door? Who habitually fed, housed, or exercised the dog? What warnings were given? What training history or prior behaviour was known? Cases like Purcell and Sgro show small shifts in those facts can flip a defendant from non-owner to owner (or vice-versa), with immediate consequences for liability posture and insurance response.

Finally, be candid about role-based exposure for professionals and family members who care for dogs. Medeiros and Nigro remind us that walkers, sitters, kennel staff, and even well-meaning friends can be treated as “owners” for DOLA purposes if they had possession and control at the wrong moment—which can bar a DOLA claim altogether and shift the analysis to negligence against others with knowledge and the means to prevent what happened.

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