Why Do Dogs Bite?

sheltie growling at maleGiven the right circumstances — all dogs will bite.

Oh no, you say. Not my little Fluffy! Never!

If little Fluffy hasn’t bitten someone so far, it’s because little Fluffy has been lucky enough not to be put in a situation that causes little Fluffy to bite. And maybe little Fluffy will continue to be lucky for the rest of her life. Let’s hope so. Upwards of one million dogs — and, therefore, people — a year aren’t so lucky (roughly the number of reported dog bites per year).

What Causes Dogs to Bite?

There are, in fact, many situations that may cause a dog to bite: Dogs are most likely to bite when threatened, angry, hurt, or afraid.

Like humans, dogs have two primary reflexes: fight and flight. When a dog is not able to take flight to protect itself (run away) then it is left with the option of biting out of fear or the need for self-protection. When a dog needs to defend or protect its territory, possessions, or people, it may fight — up to and including bite.

There are a multitude of variations on these themes. Following are some of the specific classes of aggression taken from Borchelt, P.L. and Voith, V.L. 1982. “Classification of Animal Behavior Problems,” Vet. Clin. North Am. Small Anim. Pract. 12:571-585:

  • Dominance aggression: aggressive behavior usually directed to family members who take something from the dog, pet it, hold it, pick it up, or disturb it while it is resting.
  • Defensive or fear aggression: directed to family or strangers who approach too quickly or too closely when the dog is afraid.
  • Protective/territorial aggression: directed to strangers to approach the owner or the home of the owner.
  • Predatory aggression: directed to small, quickly moving animals and children, especially where more than one dog is involved.
  • Pain-elicited aggression: directed to family or strangers who approach or touch when the dog is in pain or injured.
  • Punishment-elicited aggression: directed to family or strangers who hit, kick or verbally assault the dog.
  • Redirected aggression: directed to family, strangers and animals who approach or touch the dog when it is aggressive in another context

Factors That Determine Whether a Dog Will Bite

A report by the American Veterinary Medical Association, Task Force on Canine Aggression and Human-Canine Interactions, entitled A Community Approach to Dog Bite Prevention, refers to five factors commonly associated with dog bites:

  • Breed and “parents” of the attacking dog: this refers to aggression as a type of behavior that has been bred into certain breeds of dogs, and characteristics of the “sire” and “bitch” that produce an individual dog.
  • Socialization of the dog: how the dog has been desensitized to stimuli, especially stimuli produced by children. Poor socialization results in less inhibition to bite and engage in other undesirable behavior.
  • Training of the dog: the nature, degree and quality of training. A dog that has been trained to threaten people is an obvious danger, but so is a dog that has been poorly trained or not trained at all.
  • Health of the dog: whether the dog was sick or injured. When a dog is sick or injured, or in pain, biting can result for a number of reasons.
  • Behavior of the victim: this includes any behavior (i.e., a baby rolling over on a bed), not just provocation (i.e., hitting the dog).

What You Can Do to Lower the Chances of Your Dog Ever Biting

  • First and foremost — know your breed; i.e. if you have a herding breed then you wouldn’t let young children run around your yard, etc.
  • A close tie for first is to socialize and train your dog. Thoroughly socializing your dog in a variety of environments with a variety of people and behaviors helps desensitize it to situations that could make other dogs bite. Training your dog helps teach your dog self-discipline. And a good recall and a strong “Leave it” command are worth their weight in gold.
  • Do not leave your dog chained.
  • Do not leave your dog unattended with children.
  • Educate your children and your children’s friends on how to behave around dogs.
  • Don’t let your children approach or pet unfamiliar dogs — and never a dog on a chain.
  • Don’t let other children approach your dog uninvited.
  • Do not let your dog roam free.
  • If you have two or more dogs, educate yourself on the nature of pack behavior.
  • If your yard is fenced, do not let your dogs race along it barking at passers-by.
  • If your dog has resource guarding issues, get help immediately.
  • If you’re having strange workmen doing work, don’t leave your dogs unattended, or better yet, put your dogs safely away.
  • Neuter your dog.

To keep this in some perspective, here’s a quote from Janis Bradley of, Dogs Bite: But Balloons and Slippers Are More Dangerous:

Dogs can be dangerous. And they are more dangerous to children than to adults. But here’s the reality. Dogs almost never kill people. A child is more likely to die choking on a marble or a balloon, and an adult is more likely to die in a bedroom slipper related accident. Your chances of being killed by a dog a roughly one in 18 million. You are five times more likely to be killed by a bolt of lightning.

Bottom line — to keep your dogs safe, education, socialization, and training are the best defenses!

Two good books to help you better understand and train away from dog aggression are: How to Right a Dog Gone Wrong: A Road Map for Rehabilitating Aggressive Dogs, and The Culture Clash: A revolutionary new way to understanding the relationship between humans and domestic dogs.

Dogs don’t come trained knowing what we expect of them. In order for them to fit well (and safely) into our families and societies, they need our guidance to do so. A dog that gets this leg up can provide us with a lifetime of joy. Sadly, many dogs are destroyed every year that wouldn’t need to be if the owners had taken the time to train their dogs and educate themselves. Help your dog avoid that fate. If you have a dog that is showing any aggressive tendencies, get help immediately. Do not wait. The sooner you address the behavior, the less chance it has of becoming an ingrained way of responding. And the less chance you’re giving your dog to bite.

Other posts on this topic:

Part 1: What You Can Do to Avoid Getting Bitten By a Dog — Or 10 Common Mistakes People Make in Greeting Dogs

Part 2: What You Can Do to Avoid Getting Bitten By a Dog — Learn How to Read a Dog’s Body Language


18 thoughts on “Why Do Dogs Bite?”

  1. We have a 2 yr old rescue German Shepherd, who has been with us for 3 months. We have two children aged 11 and 9, he is such a softie with us but aggressive on the lead when he sees other people or dogs!! Anyway he today bit my son’s friend when he came into the house and broke his skin which required butterfly stitches, we are devastated, he has never done this before…he has been round my young niece and nephews and never any problem, why has he done this? There was no provocation by the boy.we feel now we need to get rid of him, but we don’t want to…we love him so much but are scared he could do it again! What shall we do???

    1. Ursula, firstly, it sounds like your dog needs more obedience and training work. You need to find a good trainer as quickly as possible to help you with both the biting and the on-lead aggression issues. Your whole family will need to participate so that you can understand what his triggers are and work with those.

      It’s extremely likely that he gave tons of signs as to what was going to happen, but if you don’t know what the signs are, you aren’t going to know how to help him avoid making bad decisions.

      After a qualified trainer works with him and evaluates him, that trainer would be in a position to advise you as to whether it’s a good idea for you to keep him. Wishing you good luck…

  2. People so often don’t realize what a responsibility a dog is. They don’t train it. They don’t neuter it. They abandon it if they move. Dogs trust and depend on us, and we owe it to them to recognize that they aren’t stuffed toys.

    We also have a responsibility to teach our children dog safety, just as we teach them street safety. Dogs are part of the human community and our job is to teach our kids how to get along with others.

  3. My partner and son(6years old) welcomed a rotti bitch 3 1/2 years old named “posh” into our lives on saturday just gone, i came home from holiday on monday, and have been home with “posh” and my 3year old daughter all week, posh and i have made a great bond she listens to me and i feel comfortable around her, my daughter was nipped by Posh last night when i was taking her to the toilet, i was carrying her and Posh was sniffing her feet, i didnt realise that Posh was right behind me and i put my daughter down and Posh barged pass me and bit her and then took off, i was shocked we immediately put Posh outside and told her off!! She is fine with my son but she seems to act strange about my daughter i dont know what to do we want to keep her but i dont know how to deal with this situation if you have any ideas on how to re-introduce posh and my daughter and stop this from happening again id appreciate it thanks

    1. Michele, this is beyond what I’d feel comfortable dealing with through comments. There’s not enough information for me to make an assessment.

      Your best bet would be to find a trainer in your area (New Zealand?) who works with dogs who may have biting issues. This is potentially very dangerous. Please get professional help right away.

  4. Andrew in Los Angeles

    Thank you! So far I’ve narrowed it down to territory, fear and something to do with being an alpha – but I hope your expertise here may help others too. I couldn’t be the only fellow that dogs want to bite. thank you again.

  5. Andrew in Los Angeles

    In just the last couple of months I’ve had two scary run-ins with dogs and wish I knew what the reason was. The first just a couple of months ago. I was visiting a client for the first time and the dog came out and bit me hard on the leg – this was chalked up to the family’s new baby as it must have been protecting the family. But then today – visiting another new client, and an extremely tame labrador retriever with no aggressive history came after me and snarled like a big pit bull. All I had done was properly held out the back of my hand as one is taught when you’re a kid. I didn’t know little black labs had it in them! Anyway – how to prevent this. And from what I’ve read I’m somehow scaring them? I’m the least scary guy anywhere. Any suggestions would save me a lot of stress later!

  6. I’m working now with a fluffy little dog who was teased by children until she finally bit in self defense to keep from being injured. Then the idiot adults took her to the shelter. Hopefully we can reprogram her.

    1. That’s so often the problem — the kids don’t know how to behave around dogs and the parents often don’t have the time or ability to train. It’s usually not long after that, they realize it’s one more thing they’d rather not deal with. Lucky she was taken to the shelter and not the vet’s to be put down. She’s landed in good hands.

  7. Then there’s the dog that just bites out of excitement and gets you because you’re standing in front of her intended target:) Hence the four cornered bruise.

  8. jenn in holland

    Wow. an excellent post.
    I appreciate the honest approach to talking about dogs and the way they think/work.
    I love dogs, as do my kids, but I have tried to teach them all along that dogs think differently than we do and we have to approach them with that respect. Just because we want to wrestle and snuggle with every pup we meet doesn’t necessarily mean that they want to do so with us!
    So, it’s about training people as well as training dogs, isn’t it? I am so glad you took the time to do that!

    1. Jenn, you’re very right — it’s at least as much if not more about training people.

      I wish all moms would give their kids the advice you’ve given yours. I run into this a lot when I take Kiera for walks. Her looks are deceiving; she looks sweet and inviting. But she’s a working herding dog who doesn’t have much of a sense of humor when she’s on duty. And she’s definitely not interested in being petted by people she doesn’t know. I’ve often had to run interference for her.

  9. Thanks for educating people on this. I’m no expert but when someone tells me their dog never bites I have to wonder–I mean dogs are still animals and even kids bite sometimes.

    Prevention is better than dealing with tragedy.

    1. Michelle, thanks for bringing up this fantastic point! So often people are in blissful ignorance or denial about their dogs, that I wouldn’t be quick to use anybody’s judgment except my own.

      The best advice is just to pass on going up to other people’s dogs unless you know them very well.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top