Massachusetts Dog Bite Law

How dog bite liability works in Massachusetts

Massachusetts has one of the broadest dog statutes in the country. General Laws chapter 140, section 155 does not say "bite". It says that if any dog does "any damage" to the body or property of any person, the owner or keeper is liable¹. Courts have applied it to a dog that knocked a man to the sidewalk and broke his hip, and the Superior Court's model jury instruction tells jurors that an injury "is not limited to a bite"². The Supreme Judicial Court described the statute in Rossi v. Del Duca (1962) as imposing liability without proof of fault or of any known dangerous propensity⁶.

The statute has a twist on the burden of proof. Under the model instruction, the injured person must prove that they were not trespassing, committing another tort, or teasing the dog². For a child under seven, the statute flips that: the child is presumed innocent of all three and the owner must prove otherwise¹. Friendly play with a dog is not teasing².

Liability runs to the "owner or keeper", and to a parent or guardian if the owner or keeper is a minor¹. A keeper is someone with possession of the dog who has assumed custody, management and control; merely letting a dog stay on your property is not enough⁷². That is why landlords usually fall outside section 155 and are judged by the older common-law rule, which asks whether they knew or should have known the dog was dangerous⁶.

Massachusetts reaches further than most dog statutes: it covers knock-downs and property damage, and it binds keepers as well as owners¹². A bite just over the line in New York, Connecticut, New Hampshire, Rhode Island or Vermont is judged by that state's law, so compare the pages. The deadline here is three years, and a bitten child has until three years after turning 18³⁴.

The Massachusetts dog bite statute

If any dog does any damage to the body or property of any person, the owner or keeper is liable for it; if the owner or keeper is a minor, the parent or guardian is liable¹. There is no exception for a first bite and no need to prove negligence². Liability does not attach if the injured person was committing a trespass or other tort, or was teasing, tormenting or abusing the dog¹. A child under seven is presumed not to have done any of those things, and the defendant carries the burden of proving otherwise¹.

• Law: Mass. Gen. Laws ch. 140, § 155 (Liability for damage caused by dog)
• Injuries covered: Any injury the dog causes (bites, knock-downs, chases)
• Where: Anywhere
• Who is liable: The owner, or a keeper or harborer
• Damages: All damages, under the ordinary rules

Other ways to prove liability

Section 155 expanded the common law rather than replacing it². A claim against someone who is not the owner or keeper, such as a landlord, a property owner or a business, runs on common-law negligence: the plaintiff must show the defendant knew or reasonably should have known the dog had dangerous propensities, because the common law treats dogs as ordinarily harmless⁶. In Nutt v. Florio (2009), the Appeals Court allowed a negligence claim against landlords to reach a jury where neighbors had complained about an aggressive, unleashed dog⁶. Because the statute is so broad, most claims against the owner itself are brought under section 155.

Defenses owners raise

Trespassing

A person who was trespassing when injured cannot recover under section 155¹. Entering someone's land can be privileged, though, if it is or reasonably appears necessary to prevent serious harm, as the Supreme Judicial Court explained in Rossi v. Del Duca (1962)².

Provocation

No recovery if the injured person was "teasing, tormenting or abusing" the dog¹. The phrase covers wrongful acts meant to irritate the dog; friendly play does not count (Malchanoff v. Truehart, 354 Mass. 118 (1968))².

Committing a crime

The statute also bars recovery by a person who was committing "other tort" at the time, which reaches wrongful conduct beyond trespass¹. A child under seven is presumed not to have been doing so¹.

Other defense

The defendant was not the owner or keeper. Mere presence of the dog on someone's property, or putting up with it, does not make them a keeper; harboring with custody, management and control does²⁷. A veterinary technician who had custody of a dog under a contract with the owner was treated as a keeper in Salisbury v. Ferioli, 49 Mass. App. Ct. 485 (2000)².

Police dogs

Section 155 has no exemption for police dogs. A separate section requires the state, city or town to indemnify a law enforcement officer sued for damage caused by a dog the officer was caring for as part of official duties¹⁸.

Shared fault

Modified comparative fault (barred at 51%) (Mass. Gen. Laws ch. 231, § 85).

Massachusetts reduces damages by the injured person's share of negligence and bars recovery only if that negligence is greater than the total negligence of the defendants⁵. By its words the statute applies to actions "for negligence"⁵. The Superior Court's model instruction for section 155 claims contains no step for reducing an award by the plaintiff's share of fault². Under section 155 the victim's conduct matters through the statute's own exceptions: trespass, another tort, or teasing the dog¹. The same section 85 abolished assumption of risk as a defense in negligence actions⁵.

How the five fault systems compare: provocation, trespass and shared fault.

Massachusetts dog bite statute of limitations

3 years (Mass. Gen. Laws ch. 260, § 2A)

Tort actions must be started within three years after the cause of action accrues, which for a dog bite is normally the day of the injury³. If a city, town or the state is responsible (for example, a municipal dog), the claim must first be presented in writing to the public employer within two years, and suit must be filed within three years¹⁷.

Children. If the injured person is a minor, the three years run from the day the disability ends, that is, from the 18th birthday, so suit can be brought until age 21⁴. A parent's own claim for the child's medical bills may run on a different clock.

Work out your own date with the dog bite claim checker, or compare deadlines in every state.

Damages

A section 155 plaintiff can recover past and future medical expenses, physical and mental pain and suffering (including anxiety, embarrassment and mental anguish), permanent scarring or loss of bodily function, lost earning capacity and loss of enjoyment of life². Section 155 sets no cap and provides no double or punitive damages; the model instruction tells jurors the award is meant to compensate, not to punish¹². Property damage, including a pet injured by the dog, is recoverable too².

Landlords and property owners

A landlord who does not own or keep a tenant's dog is not liable under section 155⁶. The landlord can still be liable in negligence if they knew or reasonably should have known the dog had dangerous propensities and failed to act reasonably, given the landlord's duty to protect tenants from reasonably foreseeable harm⁶. In Nutt v. Florio, 75 Mass. App. Ct. 482 (2009), repeated complaints to the landlords about a tenant's aggressive dog were enough to send the claim to a jury⁶.

Insurance

As of October 2026, no Massachusetts law limits insurers' use of dog breed in homeowners or renters underwriting. The Senate's version of the PETS Act (S. 3028), passed on March 19, 2026, would ban breed-based underwriting, rating and renewal decisions; the bill has been in a House-Senate conference committee since July 2026¹⁵¹⁶. An owner whose dog is declared dangerous can be ordered to carry at least $100,000 of liability insurance⁸.

More on coverage, breed exclusions and renters policies: dog bite insurance.

The 2012 animal control law

Much of the owner-side law on this site dates from Chapter 193 of the Acts of 2012, An Act further regulating animal control, approved on August 2, 2012¹⁴. It rewrote the definitions in section 136A, replaced section 157 with the hearing-and-appeal system described on the dangerous-dog page, and added section 157A's criminal penalties for ignoring an order¹⁴. The same act wrote the breed rule into section 157: no dog may be declared dangerous because of its breed, and no city or town may regulate dogs in a breed-specific way¹⁴⁸. The civil liability rule in section 155 was not part of the 2012 rewrite and reads as it did before¹.

When a dog injures your dog

Section 155 covers damage to "property" as well as people, and the model jury instruction applies it to a dog or other animal injured by a dog¹². The owner or keeper of a dog that attacks another dog is liable without proof of fault, subject to the same trespass and teasing exceptions². Under Irwin v. Degtiarov, 85 Mass. App. Ct. 234 (2014), the owner of the injured pet can recover reasonable veterinary bills even when they exceed the pet's market value, and even if treatment fails². The law does not compensate the owner's grief or loss of companionship, though (Krasnecky v. Meffen, 56 Mass. App. Ct. 418 (2002))². See what to do when a dog attacks your dog.

Bite reports and quarantine

Every physician who treats a dog bite, and the person in charge of a hospital that treats one, must report it within 24 hours to the inspector of animals of the town where the bite happened, or to the dog officer if the town has no inspector¹⁰¹³. Under the state rabies rules, anyone who knows of a domestic animal that has bitten or scratched a person must report it immediately to the municipal animal inspector¹¹.

After investigating, the animal inspector issues a written order placing the dog under a 10-day quarantine, whatever its vaccination status¹¹. The inspector approves the place of confinement, which is usually the owner's home; the dog may be leash-walked by an adult, and the quarantine ends only when the inspector sees the dog and releases it¹¹¹². The owner pays the cost of quarantine and of any euthanasia¹¹. The quarantine order is a public-health measure and, in the state's words, is not proof of a bite¹².

Dangerous-dog hearings, euthanasia orders and criminal penalties are covered on Massachusetts dangerous dog law.

Questions about Massachusetts dog bite law

Is Massachusetts a one-bite state?

No. Section 155 makes the owner or keeper liable for any damage the dog does, even if it never bit anyone before and the owner took precautions¹². The one-bite idea survives only in claims against people who are not owners or keepers, such as landlords, who are liable only if they knew or should have known the dog was dangerous⁶. See the national guide to the one-bite rule.

Does the Massachusetts law cover a dog that knocks someone down without biting?

Yes. The statute speaks of "any damage" a dog does, not bites¹. The model jury instruction says an injury may include a laceration, fracture or concussion, and cites a case in which a dog tangled in a man's legs and he broke his hip².

Who has to prove the victim was not teasing the dog?

Under the Superior Court's model instruction, the injured person must prove they were not trespassing, committing another tort, or teasing, tormenting or abusing the dog². If the victim was under seven, the law presumes they did none of those things and the owner must prove otherwise¹.

My dog bit someone in Massachusetts. Will it be put down?

Not automatically. A bite leads to a 10-day rabies quarantine, usually at home¹¹¹². Euthanasia can be ordered only after someone files a complaint and the town's hearing authority holds a public hearing and declares the dog dangerous; it is one of seven possible orders, and you can appeal to the district court within 10 days⁸. See my dog bit someone.

Can I sue a dog walker or kennel in Massachusetts?

Possibly, if they were the dog's keeper at the time. A keeper is someone who has possession of the dog and has taken on its custody, management and control⁷². Briefly holding a dog does not make someone a keeper, but the Appeals Court treated a veterinary technician with contractual custody of a dog as one².

Official contacts

Sources

1. Massachusetts General Laws ch. 140, § 155 (liability for damage caused by dog), Massachusetts Legislature. Checked 17 October 2026.
2. Superior Court Civil Practice Jury Instructions, Instruction 9.00: Dog Liability (May 2024), Massachusetts Trial Court (mass.gov). Checked 17 October 2026.
3. Massachusetts General Laws ch. 260, § 2A (tort actions, three years), Massachusetts Legislature. Checked 17 October 2026.
4. Massachusetts General Laws ch. 260, § 7 (minors and incapacitated persons), Massachusetts Legislature. Checked 17 October 2026.
5. Massachusetts General Laws ch. 231, § 85 (comparative negligence), Massachusetts Legislature. Checked 17 October 2026.
6. Nutt v. Florio, 75 Mass. App. Ct. 482 (2009) (opinion text), Animal Legal & Historical Center, Michigan State University College of Law. Checked 17 October 2026.
7. Massachusetts General Laws ch. 140, § 136A (definitions: keeper, dangerous dog, nuisance dog, hearing authority), Massachusetts Legislature. Checked 17 October 2026.
8. Massachusetts General Laws ch. 140, § 157 (nuisance or dangerous dogs), Massachusetts Legislature. Checked 17 October 2026.
9. Massachusetts General Laws ch. 140, § 157A (non-compliance with order; transfer of dangerous dog), Massachusetts Legislature. Checked 17 October 2026.
10. Massachusetts General Laws ch. 112, § 12Z (reports of dog bites), Massachusetts Legislature. Checked 17 October 2026.
11. 330 CMR 10.00: Prevention of the Spread of Rabies, Massachusetts Department of Agricultural Resources. Checked 17 October 2026.
12. Protocol for Domestic Animal that Bites / Scratches a Person or another Domestic Animal (owner instructions, 2025), MDAR Division of Animal Health, Rabies Program. Checked 17 October 2026.
13. Reporting Bites by Domestic Animals (healthcare providers, Nov 2024), Massachusetts Department of Public Health. Checked 17 October 2026.
14. Acts of 2012, Chapter 193: An Act further regulating animal control, Massachusetts Legislature. Checked 17 October 2026.
15. S. 3028 (194th General Court), An Act promoting pet equity, treatment, and safety: bill history, Massachusetts Legislature. Checked 17 October 2026.
16. Animal Anti-Cruelty Legislation Passes Unanimously in the Senate (March 19, 2026), Massachusetts Senate. Checked 17 October 2026.
17. Massachusetts General Laws ch. 258, § 4 (claims against public employers), Massachusetts Legislature. Checked 17 October 2026.
18. Massachusetts General Laws ch. 140, § 155A (indemnification of officers for police dogs), Massachusetts Legislature. Checked 17 October 2026.
19. Massachusetts General Laws ch. 140, § 156 (killing dogs under certain conditions), Massachusetts Legislature. Checked 17 October 2026.