©Scott Sheaffer, CDBC, CBCC-KA, CPDT-KA, USA Dog Behavior, LLC

Types of Dog Bites

“This is the beginning of serious biting because the dog is choosing to exert enough pressure…”

Certified dog behavior consultants, like myself, are frequently asked to quantify and provide details about human dog bites. We are asked to do this primarily for two reasons: 1) to determine the severity of the bite(s) in order to pursue the proper course of behavior modification and management, and, 2) to properly document the bite(s) for legal purposes (there can be both civil and criminal consequences for owners of dogs that seriously bite humans). Aggressive human dog bites are required to be reported to animal control.

We do this by assigning a specific grade or type to dog bites. In addition to assigning a number grade to dog bites, discussions about dog bites can also include information about bite pressure, number of bites, bite motion, bite location and size/breed of the dog.

The Official Dog Bite Scale

Dr. Ian Dunbar’s Dog Bite Scale is the de facto standard used in the dog behavior consultant community for numerically ranking dog bites. Unfortunately, this scale is ambiguous and vague which makes it a less-than-great tool for grading dog bites. Since it’s the accepted standard, dog behaviorists make it work by adding additional comments along with the official ranking.

Dr. Ian Dunbar Dog Bite Scale

I’ve listed the six levels of dog bites below according to this scale with notes.

Level 1. This isn’t really a bite at all (See what I mean about it being confusing?). It’s any kind of aggressive behavior exhibited toward a human. It could include growling, lunging or air-biting. It’s actually an aggressive incident with no biting.

Level 2. This is technically a bite but it’s primarily just tooth-to-skin with no tooth penetration of skin with the exception of some very superficial scratching. This is not to be confused with play-biting or attention-getting mouthing which is annoying but otherwise benign.

Level 3. This is described as one to four tooth punctures from a single bite that are all less than half the length of the dog’s canine teeth in depth. When observing these bites on skin they usually look like one to four red dots. This bite level using this scale is challenging because it’s difficult to determine tooth penetration accurately.

This is the most common type of serious bite I see. This is the beginning of serious biting because the dog is choosing to exert enough pressure to penetrate a human’s skin. It’s after this level (i.e., Level-4 and beyond) that the possibility of a positive prognosis and outcome for the dog start to erode quickly.

Level 4. This bite is the same as a Level-3 bite except that at least one of the tooth punctures has to exceed half the length of the dog’s canine teeth. Again, it’s very challenging to determine tooth penetration accurately. This level of bite can also include serious bruising (which can’t be seen until later so this isn’t a particularly good indicator at the time of the incident).

The most significant feature of some Level-4 bites is lacerations in both directions extending from the initial tooth puncture. This is extremely significant since it indicates the dog shook its head while biting. When dogs shake their heads while biting, they intend to harm the victim, not just warn the victim as is typically seen in Level 1, 2 and 3 bites. Dogs that bite at this level and beyond are frequently euthanized for safety reasons. The prognosis is poor.

Level 5. This level is technically defined as comprising at least two Level-4 bites. It can also be multiple attacks with at least one Level-4 bite in each attack. Does this sound like something you see in the news? A bad Level-5 bite incident that doesn’t kill the victim can also be referred to as a mauling.

Level-5 bites represent extremely serious safety concerns and the prognosis is extraordinarily poor for the dog. These dogs are almost universally euthanized.

Level 6. This highest-level dog bite, ironically, is the only level that is completely unambiguous. The victim is killed. There are about 35 of these incidents each year in the U.S. The dog is always euthanized as soon as possible.

8 Ways Owners Naively Respond to Their Human Aggressive Dog

After working with hundreds of human aggressive dogs and their owners, I find the following to be true about most owners with human aggressive dogs that have the potential to inflict a serious bite to a human.

They:

Grossly underestimate the bite risk to other humans - made even more significant if their dog is large. Their dog loves them and they can’t imagine that Max would ever really want to hurt anyone.
Deny the civil and even criminal legal issues that can result if their dog bites someone seriously.
Don’t fully appreciate how quickly and seriously their dog can bite. Things can go sideways in a life-changing way in literally under a second.
Ignore the warning signs their dog is giving them that things are headed in a bad direction. Growling, lunging and barking at people over an extended period almost always precede that first serious bite.
Don’t want to use a muzzle on their dog because it might make the dog uncomfortable. This is closely related to the “I don’t want to use behavior medication with my dog as it might change their personality.” I always remind people that we are actually trying to change their dog’s personality with these medications.
Don’t provide an extra level of vigilance and management when their dog is around children. Human aggressive dogs and children are a perfect recipe for really serious problems.
Don’t fully reveal to their veterinarian or behaviorist on their first visit the level of aggression their dog is showing to humans. Believe me when I say that animal professionals really appreciate getting a heads-up on this behavior.
Think they can easily re-home their dog to a loving family or rescue organization that will somehow quickly and easily fix everything.

I Think I Have a Human Aggressive Dog. Now What?

I tell clients who bring human aggressive dogs to me for behavior modification that the two things we need to focus on are management of the dog and treatment. Management simply means that we are going to do whatever is necessary to keep their dog safely away from people while we proceed with dog behavior modification and owner training. We do this for safety reasons and we do it so their dog doesn’t continue to rehearse aggressive behaviors.

I’ve seen many dog owners with human aggressive dogs who seek the help of conventional dog trainers. The truth is that human aggression is not in the wheelhouse of most dog trainers and the owner can end up improperly educated - potentially creating a dangerous situation. If you have a dog that is beginning to show signs of human directed aggression or is well down the road with this behavior, please consult with a full-time independently certified dog behavior consultant.

6 Types of Dog Bites - Updated for 2020