The Six Dog Bite Levels – Ian Dunbar’s Scale


Cassandra Nguy

Dog bites are dangerously common and can result in serious injuries if left unchecked. Injuries can range from simple scratches to death and dismemberment, each with separate calculations that affect a victim’s settlement. The law categorizes injuries into six dog bite levels, and knowing them is key to covering your damages.

Dr. Ian Dunbar, a veterinarian and animal behaviorist, created the scale that calculates a dog’s bite into six levels. Below is Ian’s Dunbar Scale categorizing dog bite levels based on trauma, skin contact, punctures, and tissue damage. Each level increases by how severe the bite punctures skin.

According to the AVMA, more than 4.5 million people are victims of dog bites yearly in the United States. The Center for Disease Control stated that over 800,000 dog bite victims receive medical attention, and over half are children.

If you experienced a traumatic dog bite attack, reaching out to an attorney may help you know your settlement rights. LegalASAP is connected to hundreds of law firms working with thousands of experienced attorneys across the United States. If you need representation as soon as possible, call us for quick legal help.

Free Personal Injury Evaluation

Hurt in a wreck that wasn’t your fault? Don't settle for less! Click here to speak with a nearby attorney for FREE about your claim.

Level 1 – Aggression With No Contact

A dog with their fangs out, showing aggression and displaying a level 1 dog bite.

A level 1 dog bite involves no contact, but shows aggressive behavior. For instance, a dog may snarl, growl, or attempt to lunge without physical contact. The first level is a pre-bite incident that can escalate if the dog shows more discomfort or aggression. This level may not be immediately dangerous, but it’s best to stay cautious.

Presume the owner doesn’t give their dog the proper training to socialize with strangers around them. The dog’s behavior may escalate if let loose without the owner’s supervision, which may cause further harm.

Level 2 – Tooth Contact With No Puncture

Someone's hand inside a dog's mouth, indicating a level 2 dog bite.

A level 2 dog bite involves contact with teeth with no punctures, only causing redness or bruising. There typically isn’t bleeding with a level 2 dog bite, but there may be skin nicks less than one-tenth of an inch deep. A dog may inflict a level 2 dog bite to warn with their teeth.

There are only lateral movements, not vertical, with slight skin scratches. Level 2 bites aren’t dangerous on their own, but they do require attentive care. Although this level isn’t as severe as the other higher levels, it may inflict emotional distress to unexpected victims.

Level 3 – Shallow Wounds

A hand suffering a level 3 dog bite, with slight scarring.

A level 3 dog bite attack will inflict 1-4 bites that puncture, with none exceeding deeper than half the length of the canine’s teeth. The victim may experience tearing of the skin, but no severe tissue damage. It may leave lacerations in one direction as the victim tugs their body or the owner forcibly separates both parties.

Level 3 bites are moderately harmful and signal a canine’s aggressiveness without showing severe hostility. This can threaten the victim’s health and often requires immediate medical attention.

A dog capable of leaving a level 3 bite attack needs professional behavioral help with strict owner management routines to stop future injuries. Immediately seek medical attention and a legal advisor if you or someone you know experienced a level 3 dog bite.

Every state has specific laws that are different when it comes to dog bite incidents. LegalASAP can connect you with a dog bite attorney within your state to help properly compensate you for your injuries.

Level 4 – Deeper Punctures

A level 4 dog bite on a leg, with a ruler to the right to show size of bruise.

A level 4 dog bite deals with 1-4 punctures and at least one wound exceeding one length of the canine’s teeth. A level 4 dog bite is categorized as severe to cause substantial tearing of skin and muscle tissue. These bites are sometimes critical enough to impact the nerves, blood vessels, and bones.

Level 4 dog bit attacks are dangerous enough to potentially leave victims in disfigurement or disability. Further symptoms include:

  • Deep bruising
  • Severe bleeding
  • Trauma
  • Multiple lacerations in both directions (due to the dog swaying its head from side to side)

This level can also kill a child at its severity, so proper training, socialization, and supervision is required to prevent future victims.

Also, it poses a serious threat to public safety, facing legal repercussions, hearings, and possible considerations of euthanasia in certain states. Experiencing a level 4 dog bite without a doubt will require immediate medical attention. An owner’s dog capable of a level 4 bite will require immediate professional behavioral assistance.

Dog owners who keep a level-4 biter may be required to sign a form that states:

  1. They’re aware their dog may inflict another level-4 bite and that only adult visitors come in contact with their dog.
  2. When children or guests visit, the dog should be adequately contained to ensure safety.
  3. The dog is required to be muzzled before leaving the house and should not leave for any reason besides visits to the veterinary clinic.
  4. Any dog bite incidents should be reported to the appropriate authorities

Level 5 – Multiple Deep Wounds

Level 5 dog bite incidents will inflict multiple wounds, with at least two being level 4 injuries. A level 5 dog bite can also result from separate incidents with a level 4 bite per attack. Level 5 dog bites show extensive tearing of skin and muscle tissue. This can damage nerves, blood vessels, or bones, possibly causing disfigurement or disability.

Other symptoms from a level 5 dog attack can potentially be life-threatening, causing illness, infection, or even death. Dogs who inflict a level 5 attack are considered extremely dangerous and may face legal consequences like euthanasia.

Level 6 – Death

A level 6 dog bite occurs when the dog takes the life of the victim. Symptoms lead to massive tears of the skin and muscle tissue, severe bleeding, and damage to nerves, blood vessels, or bones. This is the highest level a dog bite can reach, and it’s certain the dog will be put down as a result.

Is the Owner Liable for High-Level Dog Bites?

In most states, yes. The owner is almost always liable for any injuries or damages their dog inflicts upon victims on any level of bite attacks. The owner is responsible for providing attentive care and socialization training for their dog.

Every state has statutes on how to deal with dangerous dog bites. Sometimes, the victim may be at-fault for trespassing on the owner’s property. Or perhaps the owner tried to defend themselves, resulting in them not having to face civil or criminal penalties.

Should I See a Doctor for My Dog Bite Injuries?

It’s a must to see a doctor within 24 hours after a dog has bitten the victim and broken skin. Dog bite levels 3-6 require immediate medical attention since these are much more severe than minor scratches. The possibility of the bite getting infected rises over time. Thus, it’s better to get the wound checked right away.

Legally Protect Yourself With a Personal Injury Attorney

Going through a dog bite incident is traumatizing and can be deadly if not taken care of. No matter the severity of the bite, it’s best to seek immediate medical and legal help. LegalASAP is a network partner with 500+ law firms across the U.S. and connected with thousands of experienced attorneys willing to help you with your case.

Some of our attorneys work with contingency fees, meaning there’s no cost to you if you lose your case. Don’t wait, and protect yourself by contacting LegalASAP to assist you with all legal matters. You can fill out this free short evaluation form, and one of our agents will reach you as soon as possible.

Cassandra Nguy

Cassandra Tran Nguy is a legal writer living in Los Angeles, California. She graduated cum laude from California State University, Northridge with a B.A. in English Creative Writing and a minor in Marketing. Visit her online profile at