Bite Levels:

Was It Just a Little Bite or More?

Meet Veterinarian and Animal Behaviorist-Dr. Sophia Yin

Ever since she was a child, Sophia wanted to be a veterinarian, and in 1993, her dream came true. But once out in private practice, she quickly realized that more pets were euthanized due to behavior problems than medical ones. She went back to school to study animal behavior, and earned her Master's in Animal Science in 2001 from UC Davis where she studied vocal communication in dogs and worked on behavior modification in horses, giraffes, ostriches, and chickens. During this time she was also the award-winning pet columnist for the San Francisco Chronicle. Upon receiving her degree focused on animal behavior, Dr. Yin served for five years as a lecturer in the UC Davis Animal Science Department. Through these and an eclectic collection of other animal behavior experiences, she came to realize the true secret to successful behavior modification.

Sophia learned that every pet needs a human who can lead. Not like a boss, but like a partner in a dance—someone who gives clear signals, rewards desirable behavior as it occurs, removes rewards for inappropriate behavior immediately, and sticks to the plan consistently until the new, good behavior is a habit.

Evaluating Bite Levels in Dogs

By Dr. Sophia Yin, Friday, June 1st, 2012

As the 75-pound male shepherd mix squatted to urinate on the floor just 10 minutes into our consult, I hinted to the owners who were seated between the urinating dog and me, “The paper towels are hanging on the post right next to Ferdinand.” Since the owners were way closer to the paper towels than I was and theirs was the dog pottying inside the behavior consult room, I assumed they would clean up the mess. Not so! So, I decided I’d better clean it up myself.

Although the dog was presenting for fear (aggression) to unfamiliar people, I’d already greeted the dog, he was comfortable taking treats, AND the owners had marked in the preconsult records that he had never bitten anyone before. As I got up to walk past the owners toward the papers towels and the accident, I noted Ferdinand’s demeanor. He was relaxed and still interested in exploring the room. Fearful dogs suddenly can become scared and reactive when the person they’re nervous around changes posture, moves suddenly, or approaches them, especially head-on. Ferdinand showed no such signs of anxiety or reactivity.

Furthermore, although the owners had brought him in on a muzzle, they had asked to take it off now that he was in the room and looked comfortable. They said that he only was fearful of some people. They reiterated that, as the preconsult form stated, he had never bitten before. We decided to let him explore the room while dragging his leash, so that I could evaluate his uninhibited behavior in the new environment.

As I dropped the paper towels onto the floor and then stepped on them to sop up the dog’s mess, I continued to question the owners about Ferdinand’s history. “How many aggressive or reactive incidences does he have per week? How do you handle the situations? What’s his response to your handling technique?”

When all the urine was soaked up, it was time to collect the paper towels and dispose of them. Normally when I’m in the room with a dog who’s fearful and reactive, the dog would be on leash. In addition, I might avoid facing him head-on even to pick up something off the ground. But, based on the owners’ experience, Ferdinand was not likely to react at this point. Plus he was over 10 feet away. I casually bent down to pick up the paper towels. Then I hear, “Bark! Bark! Bark!!” and feel teeth on both sides of my head.

The owners quickly had him by the leash and pulled him away from me so it wasn’t a serious or even scary event for me. Plus, I was pretty sure that there were no marks on my head. However, that didn’t stop me from being peeved.

I emphasized to the owners, “You know that counts as a bite.” I thought to myself, “When you told me he had no history of biting, you forgot to include that you didn’t count the times that your dog rushed a person and grabbed a body part in their mouth as a bite!”

Based on the response of this dog, I could tell this wasn’t Ferdinand’s first time acting like this. He’d clearly had some practice sessions barking, lunging and putting his teeth on skin. A first timer facing the same level of threat or scariness—me leaning over from far away while not looking at him—might run up and bark at me but would just snap or nip with his front teeth, rather than actually grabbing my head like he was trying to taste a cantaloupe with his teeth. If he’d had tons of practice or intent to harm he’d have actually bitten down or clamped on in the same way he does when he mangles his tug toys. Or if he was scared out of his mind by my movement he would have kept biting, even if it was only a soft bite owing to lack of enough confidence to bite hard. But it was still a bite; the owners should have known that it could happen and should have had Ferdinand on leash or still wearing his muzzle.

How could the owners have been so naïve about their dog’s behavior? Usually when people think about bites and aggression, they think about mauling or think the dog has to intend to be mean. However, Ferdinand’s biting behavior, although mild, was cause for concern.

“Some Bites Can Kill”

Surprisingly, even with serious bites, sometimes it doesn’t click for owners. Says, Dr. Emily Levine, a veterinary behaviorist at Animal Emergency and Referral Associates in New Jersey, “I recently saw a 2 or 3 year old intact male English Bulldog in a behavior consult. The dog was staying at the owner's mother’s house. She thought the dog was crated. She went to open the door for her friend who was there holding her baby. The dog saw the visitor, ran straight towards her and bit her legs. The dog bit through muscle down to bone. They owner had a difficult time getting the dog off of the visitor. The visitor needed 90 stitches and will likely need plastic surgery,” continued Dr. Levine.

You would think that a person would clearly see how dangerous this situation is; however, according to Levine, this family had no real experience with aggressive dogs. Says Levine, “The owners had been instructed by Animal Control to quarantine the dog, which they did, but because they never received a visit from the Animal Control Officer at the end of the 10 day quarantine, the owner thought that perhaps this degree of bite was not out of the norm.” In the owner’s view, since the Animal Control Officer didn’t seem concerned enough to make a return visit, the bite must not pose any future threat.

Luckily the owner did seek a behavior consult. “Once they were educated about the fact that this was a very severe bite and after I went through the risk and benefits of a behavior plan, they decided that the risks outweighed the benefits for them.

They understood that even if they were extremely vigilant and did a great job with the behavior modification plan, fantastic results are not a guarantee.

“They realized that this could happen again and that this dog could literally kill someone,” says Levine. “If the person he had attacked was a short person or a child, it would have been the neck he grabbed hold of.” The owners decided to euthanize their dog.

Although aggressive behavior can be modified in a huge range of cases, behavior modification is not like fixing a clock or a television set where you make a few changes and then it’s good for another five years. Dogs are living animals and behavior is something you can never guarantee 100%. Based on her findings with this particular dog and family, Dr. Levine says, “I believe the owners did the right thing. I fully supported this choice.”

Different Level Bites

One way to find out how serious a bite may be is to acknowledge that different levels of bites exist. Bite levels range from minor to so severe they lead to death.

Dr. Ian Dunbar first developed this bite levels system. I’m providing my modified description of these levels here.

Level 1 (pre-bite): the dog snaps or air bites but makes no contact with the person. Now people tend to say, “The dog tried to bite me but I moved away.” I say, “Give me a break.” Humans have sloth-like reactions compared to the speed of a biting dog and dogs have pretty good aim when trying to grab things. If the dog actually meant to bite (rather than just give you a warning), you would have the holes to prove it. Owners should take this air snap as a sign that someone wasn’t paying attention to their dog’s earlier signs of displeasure or fear. Owners should get help before this sort of pre-bite behavior progresses to an actual bite. Avoid punishing these warning signs or the dog may progress to biting without warning. Instead, learn the signs of fear and anxiety that the dog probably showed prior to this situation and learn to spot the common inappropriate human actions that may have contributed to the snap.

Level 2 (near-bite or highly inhibited bite): the dog snaps and makes tooth contact on skin but there’s no actual puncture. Often the dog runs up to or lunges for a person but just puts front teeth in contact with the skin in a sort of near-bite. In other cases, the dog actually opens his mouth and clamps but in an inhibited manner such that no skin is broken. Again the owners should ask, “What earlier signs did we miss to warn us that this could happen?” The owners should realize, the near-bite or inhibited bite could turn into a real bite down the road.

Level 3A: the dog bites once and punctures skin, but the puncture is shallower than the length of the canine tooth. Even though this bite may not be severe, it is still reportable. And painful, too. Reporting is mandatory if the victim is treated in a hospital. Once your dog has actually bitten at this level (or higher) he will always be considered a liability, even if, with behavior modification, he is 99.9% improved.

Level 3B: the dog bites multiple times leaving skin punctures shallower than half of the canine. Multiple bites generally mean the dog is in a higher arousal state. That is, the dog is reacting without thinking between bites.

Level 4: the dog bites once with punctures deeper than the length of the canine (the dog bit and clamped down) or the bite produces slashes in both directions from the puncture which indicates that the dog bit and shook his head. This type of bite is very serious. While any of the lower bite levels should act as a neon sign telling the owners to seek help from a qualified and educated behavioral modification specialist (link to my site), the level 4 bite says, “Man, you should have gotten help three years ago. This has been building up even longer than the level 3 bites.”

Level 4 bites are way harder than level 3 bites and now show no inhibition in strength. A dog biting at this level presents a screaming liability to the owners, both in terms of money and family members because this type of bite can kill a child.

Level 5: The dog gives multiple bites with deep punctures. Dogs who bite at this level generally have had practice biting at levels 3 and 4. Some dogs are so fearful that a scary event triggers a high arousal state and they get stuck in a reactive mode, continuing to bite hard.

Level 6: The dog kills the victim or consumes their flesh. It’s important to realize that even little dogs and puppies can bite hard enough to kill infants and small children, just the way little knives can. Dogs can bite this hard due to fear, but they can also bite and cause death due to over aroused play.

What Should You Do If Your Dog Bites?

Now that you know dogs can bite at different levels and early snapping and low level bites can, and often do, lead to more severe bites, you can start addressing the biting earlier, as soon as you see warning signs. Hopefully, the situation won’t escalate into something life-threatening for your dog or others.

For information on how to prevent dog bites or the types of behavior modification that are safe or appropriate, go to Help, My Dog Bites! How to Deal with Dogs who Bite.

Download the Canine Bite Levels Poster.