This article is general education, not medical, legal, or behavioral advice. Anyone who has been bitten should get medical attention, and anyone dealing with a dog who bites should consult a qualified professional.
What the bite scale is
The Dunbar dog bite scale, written by veterinarian and behaviorist Dr. Ian Dunbar, is a widely referenced six-level system for describing how severe a bite is by the damage to skin. Trainers, behaviorists, and shelters often use it to describe a dog’s bite history in a consistent way. It rates the injury, not the dog’s intent, and it is not a legal standard.
The six levels at a glance
The wording below is a plain-language summary of the commonly cited version of the scale.
- Level 1: Snapping or growling without any tooth contact with the skin.
- Level 2: Teeth touch skin but do not break it, or leave only minor marks.
- Level 3: One to four punctures, none deeper than half the length of the dog’s canine tooth. There may be small lacerations.
- Level 4: One to four punctures, with at least one deeper than half the length of the canine tooth. There may be deep bruising, or tearing and slashing if the dog held on or shook its head.
- Level 5: A multiple-bite incident with at least two level 4 bites, or multiple attacks with at least one level 4 bite in each.
- Level 6: Death of the victim.
Some versions describe levels 3 to 5 slightly differently, so it is wise to confirm which version a professional is using.
What a level 4 bite means
A level 4 bite is a deep-puncture injury. It usually means the dog bit with real force and did not simply snap and release. Features often described include deep punctures, bruising around them, and tearing if the dog clamped down and shook. These characteristics indicate a dog that did not inhibit its bite much, which is why behavior professionals take them seriously.
Is a level 4 bite serious?
Yes, it is generally considered serious. Deep punctures can push bacteria well beneath the skin, and wounds may involve muscle, tendon, nerves, or blood vessels. Medical care is usually advised, and people bitten may need wound cleaning, possible stitches or surgery, antibiotics, and a tetanus check. Rabies risk should also be considered, depending on the dog’s vaccine status and the region. Scarring or longer-term effects are possible. Bites to the face, neck, hands, or joints, or bites to children, older adults, or people with weakened immunity, deserve extra urgency.
If your dog has been bitten by another dog, a bite of this kind should also be seen by a vet. See our guide on what to do when your dog bites another dog.
What is level 5, and what is the highest level?
Level 5 is a multiple-bite incident with at least two level 4 bites, or multiple attacks with at least one level 4 bite in each. The highest level, level 6, is a fatal bite. These are rare compared with the lower levels, and the scale is a tool for classification rather than prediction. Never leave a dog with a bite history unsupervised with children.
What to do after a serious bite
- Get medical care. Wash the wound with soap and water and seek prompt treatment. For heavy bleeding, apply pressure with a clean cloth and seek emergency help.
- Secure the dog. Keep it confined and away from the person bitten and other animals.
- Share the dog’s vaccination status with the treating clinician.
- Report as required. Many places require bites to be reported to animal control or health authorities.
- Consult a professional. A veterinary behaviorist or experienced behavior consultant can evaluate the dog, and your vet can check for medical causes such as pain.
Prognosis and management
Behavior professionals generally view a dog with a level 4 history more cautiously than one with only level 1 to 2 incidents. Many describe the outlook as guarded or poor under ordinary household conditions, particularly if children are in the home, and typically recommend strict management, such as secure confinement, a conditioned muzzle in risky situations, and keeping the dog apart from triggers. Whether a dog can improve depends on the individual dog, the cause, the context, and the household’s ability to manage it. A professional assessment is needed for decisions like this.
Dogs that are reactive on leash can escalate if they feel cornered or are pushed too far. If you are working with a dog that has shown aggression, read about aggressive behavior on leash and training a reactive dog on walks.
What about legal value or compensation?
There is no standard figure for how much a level 4 bite is “worth.” The scale describes severity, but the outcome of any claim depends on the injuries, medical costs, local law, insurance, and circumstances. For specific questions, speak with a qualified attorney in your area. Owners of dogs kept for guarding or protection often face extra legal responsibilities; see guard dog vs protection dog.
Limits of the scale
- It measures damage, not the dog’s intent or how often it bites.
- Small dogs and large dogs cause different injuries at the same level.
- It describes one incident; context and history matter.
- A single level label does not decide what should happen to a dog.
Used with care, it is a helpful shared language, not a verdict.