Why would a dog bite someone for no reason?

Common Reasons Why Dogs Bite

Every year in the United States, 800,000 dog bites are severe enough to need medical treatment; 17 are fatal. Fifty percent of all American children are bitten by a dog before the age of 13. Literally every dog has the potential to bite.

Children are the most common victims of dog bites, followed by senior citizens, according to the American Veterinary Medicine Association (AVMA). Its website also has an excellent list of teaching points for children about dog safety, including not to approach unknown dogs, never to pet a dog without getting permission from the dog’s person and what to do if attacked. Go over them so you can share them with kids you know. You may learn something yourself that might ensure that your own or someone else’s dog doesn’t get into trouble over something that could have been prevented. It’s worth a few minutes of your time.

Luckily for us, most don’t. Understanding what causes this phenomenon might help you to avoid becoming next year’s dog-bite statistic. The following are a few common reasons why dogs bite.

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Dominance aggression

In cases of dogs who bite due to dominance aggression, members of the dog’s human family are most often the victims. Innocently attempt to move a dog off the bed to change the linens; push down on his rump to ensure compliance with a sit command; step over a dog who’s resting inconveniently in the doorway and the dog erupts in a “you’d better not do that” vocal warning, followed by a bite.

In each situation, the dog believes that he is in charge – that his humans have not earned the status to tell him what to do. Dominance aggression is most commonly – but not exclusively – seen in unneutered males and in confident breed types, such as rottweilers, chow chows, Lhasa apsos, English springer spaniels, Old English sheepdogs and Rhodesian ridgebacks, to name but a few. Obedience training as early as possible can abate a dog’s tendency toward dominance aggression, but dogs who are naturally and intractably dominant aggressive must be closely monitored and kept clear of situations known to trigger the negative behavior. Hollywood trainer Shelby Marlo, author of “Shelby Marlo’s New Art of Dog Training: Balancing Love and Discipline,” states, “Management is underrated. There is nothing wrong with knowing the dog’s limitations and living within those boundaries.”

Protection of valuables

The protectiveness some people seek when acquiring a dog can prove to be a liability. Some dogs believe the only way to protect their valuables is through an act of aggression. A dog’s list of valuables may include food, toys, territory (a house or a car) or even their human family members. Dogs have been known to “protect” one family member from another, driving crying children away from their mothers or chasing amorous husbands out of bedrooms.

The protection of territory is most often seen in males of guarding/herding breeds, such as German shepherds and rottweilers, while certain cocker spaniels and Labrador retrievers – females more often than males – put on ferocious displays over toys and chewies resulting in punishing bites to hands and faces.

Again, early training and/or lifelong management are the only solutions.

Fear aggression

Who knew? Little girls who love all things cuddly can be threatening — or so it seems to our German Shepherd, Tucker. He is generally a submissive guy. Yes, he barks a lot, but the other end is wagging, so it seems to be his way of saying hello. The only time I’ve seen him growl at someone is when a couple of fourth grade girls rushed toward him, wanting to pet him. And thereby hangs my lead-in to saying a bit about National Dog Bite Prevention Week, which is this week, May 19-25, 2013.

Tucker might succumb to fear biting when approached suddenly by rowdy little kids.
Dogs bite for many reasons. For Tucker, it’s the fear factor. Those scary little girls frightened him. Some dogs have territorial issues, while others might not feel well. I understand this. I sometimes would like to bite someone’s head off when I don’t feel well.

The fear aggression response is most often directed toward strangers. Veterinarians learn early in their careers: when in doubt, muzzle. Like people, dogs are naturally fearful of unfamiliar and potentially threatening situations. A dog raised in a quiet adult household will be distraught by noisy, fast-moving youngsters. The dog may bark and lunge to drive them away and deliver a stinging nip to children who do not heed the warning.

There is no particular breed or gender predilection for fear aggression, but these biters commonly lack early socialization to a wide variety of people and experiences. ASPCA Vice President of Behavioral Medicine, Amy Marder, V.M.D., states that “with a dedicated owner and a responsive dog, fear aggression can be greatly improved.”

Maternal aggression

The first two to three weeks after a female dog gives birth, her puppies rely on her for all they need to survive: warmth, nutrition, stimulation to prompt elimination and protection. Even the most outgoing, well-trained dog may show signs of maternal aggression if she feels her newborns are at risk. No training is indicated here, rather an awareness of the new mother’s innate need for a safe space. By limiting visitors to the whelping box to one to two adult family members during those first couple of weeks, the new mother will stay relaxed and focused on the job at hand. There will be plenty of time for socialization once the pups’ eyes are open and they are toddling about under their own steam.

Redirected aggression

An attempt to break up a dog fight is the most common scenario for this category of biting. Two canine opponents are barking, posturing and biting at each other when all of a sudden hands reach in and grab at collars, tails and hind legs. The adrenaline-pumped dogs blindly whip around and land oral blows to body parts of the interrupters.

Fights are best broken up by loud noises or strong blasts of water when available. However, sometimes that is not enough. If you must lay hands on fighting dogs, stay as far away from the mouth as possible and move swiftly and decisively.

Pain-induced aggression

While pain-sensitive breeds like Chihuahuas are common perpetrators, any dog may bite if hurting, depending on the degree of pain. An otherwise gentle dog will bite a beloved owner’s hand trying to soothe, bandage or examine wounds. Like us, each dog has a unique pain threshold and tolerance. A sweet floppy-eared dog suffering from otitis externa may bite on getting his ears tousled; a dog with hip dysplasia may turn on a handler pressing down on his hips to enforce the sit command.

Of course, any dog can be provoked to bite by overly zealous physical disciplining.

Pestered beyond limits

There are dog biting incidents that don’t fit into the aforementioned categories. Perhaps a new category is required, called “Pestered Beyond Limits.” Bites in this category are often prompted by children (or adults) who simply don’t understand that even a dog has limits. Hug a sleeping dog, blow puffs of air in his face, put a rubber banded knee-sox on his nose to turn him into an “elephant dog,” ride him like a pony, stuff him inside a pillowcase just to see if he’ll fit, poke, prod, tickle him, and sooner or later, the dog will say “NO!” the only way he knows how – through a bite.

There are three keys to bite prevention:
learn to understand canine behavior
take the time to socialize and train all dogs – the younger the better
teach children to respect all dogs, starting with their furry buddies at home.

If you are approached by a menacing dog:

do not attempt to run
stay quiet, and remember to breathe
be still, with arms at sides or folded over chest with hands in fists
avoid eye contact

Playing

Dogs also bite when they’re playing, and frankly, it’s not a good idea to play tug of war and wrestling games with your pup. What starts as a playful nip could turn into a serious bite, particularly when it involves a child or an elderly person with fragile skin. Even offering a dog a treat with your fingers can be a problem. My dad’s neighbor offered his beloved dog a piece of meat, and lost three fingers. He was a dentist, and his mistake cost him his career. Best to put the food down or use the flat of your hand.

Why Dog Bites Happen And How To Stop Dog Biting

Approximately four and a half million people are bitten by dogs in the United States every year and one-fifth of them end up needing medical attention for their wounds. Children are the most common victims with half of bite wound victims being under the age of thirteen. Children are much more likely to be severely injured by dog bites due to their small size and not being aware of how one should act around a dog. Most dog bites occur while interacting with familiar dogs thus the need to educate people and their children on how to avoid dog bites. It is important to understand that any dog has the capacity to bite and that by understanding the common reasons why dogs bite it is possible to prevent them.

1. Dog Possessiveness Can Cause Dog Bites

Protection of property is a common issue and “property” in this case can be anything from toy, food, territory or even a human being. Guard dogs and herding breeds tend to be the worst offenders but this behavior can arise in any dog. Start training early to minimize this kind of possessive behavior. Teaching the “Leave it” command works well in preventing toy aggression. Food aggression can be avoided by teaching your dog to wait while you put their food down. Teach them to sit or lie down and then remove their food and then put it back. Approach the food bowl and occasionally add treats to the food so they understand that someone approaching the bowl is not a bad thing. Teach children not to bother dogs that are eating or enjoying a treat such as a bone.

2. Dog Fear Can Cause Dog Bites

Fear is usually directed towards strangers such as veterinarians and postal workers or in unfamiliar situations. Never approach an unfamiliar dog and teach your children to do the same. Fear bites can occur when a dog is startled at home therefore teach children never to sneak up on a dog or bother a sleeping dog. Early socialization is important so that the young dog is exposed to many different people, animals and situations minimizing the risk of a phobia developing. For example, make your first visit to the vet a simple social visit to get a feel for the clinic and meet the veterinary staff. Leave some treats and a note in the mailbox asking your postal worker to give a treat to your puppy.

3. Dog Pain Can Cause Dog Bites

Pain can cause the friendliest dog to bite. If your dog has hip dysplasia, severe otitis or any chronic injury, instruct your children to stay away from the sore areas and be gentle handling the dog. If your dog becomes snippy for no reason consider pain as a possible cause and schedule an appointment with your regular veterinarian for a physical.

4. Maternal Instincts Can Cause Dog Bites

The most well-trained dog can become a biter when she has puppies. Be aware of and respect the maternal instinct around a bitch that has whelped recently. Teach children not to approach a young puppy around the mother and use caution yourself when handling puppies. Make sure the mother and puppies have a place where they can feel safe with minimal distraction.

5. Prey Drive Can Cause Dog Bites

Another instinct to be aware of and is sometimes triggered by running or cycling past a dog resulting in a chase. Be aware of your environment if you are jogging or cycling and if you see a roaming dog try to avoid crossing paths. If a dog does give chase then the best things to do is stop moving and stand tall facing the dog. Be aware of the dog but do not make eye contact which can be seen as a challenge by the dog. They may come up and sniff you but will eventually find you uninteresting and move on to find something else. If a dog knocks you over then curl up in a ball protecting your face hands and neck and be still. Teach children to do the same and set up a mock “stray dog” drill.

Dog Bite Warning Signs

Knowing the common triggers that cause dog bites will empower you to avoid these situations. Dog bites are always preceded by behavior that an astute observer can use as a warning and then take steps to reduce the dog’s stress or fear. Ears are typically pinned back, the fur along their back may stand up and you may be able to see the whites of their eyes. Yawning is not an attempt by the dog to appear casual but to show off their teeth and should be considered a warning sign as well. Non-social “stand-offish” behavior such as freezing in response to a touch or look followed by direct intense eye contact back from the dog is another clear sign that he may bite.

How to Stop Dog Biting from Happening

Dog bite prevention begins at home with your own dog by being a responsible dog owner. If you do not intend to breed your dog then having them spayed or neutered will help decrease the risk of bite-related behaviors. Exercise and play with your dog on a regular basis to reinforce the human-animal bond and to expend excess energy that might otherwise be directed towards nervous energy. However, avoid aggressive games such as wrestling and tug of war which can lead to dominance issues. Train your dog well, they should know the basic commands such as sit, stay, come and leave it. Don’t allow your dog to roam free where they can be a danger to other people.

Do try to socialize your dog and expose him to many different people and situations but take care not to overwhelm him. Keep your vaccinations up to date for a worst-case scenario. In most states a dog can be destroyed if they bite someone and they are not up to date on vaccines. Seek professional help from your veterinarian if your dog shows any signs of aggression. If you have children take the time to educate them on how to act around dogs, what to watch for and what to do if a dog attacks.

How to Stop Dog Bites

Jenna Stregowski is the Pet Health and Behavior Editor for Daily Paws and The Spruce Pets. She’s also a registered veterinary technician with over 20 years of expertise in the field of veterinary medicine.

Updated on 11/24/20
Reviewed by

Dr. Monica Tarantino, DVM, is a small animal veterinarian and writer with five years of general practice, emergency medicine, and geriatric pet health experience. She is certified as a Fear Free doctor. Dr. Tarantino is part of The Spruce Pets’ Veterinary Review Board.

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If your dog bites someone, you will probably find yourself worried and upset—the last thing you want is for your precious pet to cause harm. It is important to take swift action if a dog bite occurs, as you do not want this to become a recurring behavioral issue with your dog.

Most often, dogs bite people when they feel threatened in some way. It’s a natural instinct that is still present in domesticated dogs, no matter how nice they are. But, you can prevent your dog from biting someone, especially if you know why they might bite. Training and socialization are two solutions if you find your dog has the intent to bite, and below, you’ll find tips for how to stop dog bites and what to do if your dog does bite someone.

Why Do Dogs Bite?

As mentioned, dogs can bite people after feeling threatened in some way. It is important for everyone who interacts with dogs to understand what may provoke this aggressive behavior.

Dogs may bite in defense of themselves, their territory, or a member of their pack. Mother dogs will fiercely protect their puppies as well.
Startling a dog, such as waking one up or a child suddenly approaching from behind, can provoke a dog bite. Hurting a dog even if by accident like pushing on sore hips in an older dog can provoke a bite as well.
Running away from a dog, even if it’s during play, can provoke it to bite. They may think it’s part of the fun at first, but even that can turn to aggression quickly.
Dogs who are in a fearful situation may bite whoever approaches them. This may be something as severe as being abused or abandoned, or it may be something you perceive as ordinary, such as a loud noise.
Injury and illness are a common reason as well. If a dog is not feeling well, they may not even want to be approached or touched by their favorite people.

How to Stop Dog Bites

As a dog owner, you must take responsibility for training your dog and keeping them under control at all times. You are responsible for your dog’s behavior and are the first line of defense in preventing dog bites. It’s important to do whatever you can to keep your dog from biting, and these tips can help:

At the very least, put your dog through basic training. Continue a training program throughout your dog’s life to reinforce the lessons you’ve taught them.
Socialize your dog from a young age as recommended by your veterinarian. Start this when they are a puppy and be consistent throughout their life! Socializing your dog includes allowing them to meet and interact with different types of people under calm and positive circumstances, including children, disabled persons, and elderly people. It also means, exposing your dog to various situations on a regular basis, such as other animals, loud noises, large machines, bicycles, and anything else that might cause fear. If your dog is not well socialized or displays any signs of fear or aggression, work with a professional trainer prior to attempting any of the above. The trainer can help lay out a plan to safely and slowly socialize your pet if possible.
Learn your dog’s body language, as well as key signs that may lead to a bite. When you’re around people, pay attention to your dog and know when aggression is building up. Stop it or remove your dog from the situation before it escalates.
Do not discipline your dog with physical, violent, or aggressive punishments. Opt for positive reinforcement before resorting to the use of aversives. Remember to reward your dog for good behavior.
Always keep your dog on a short leash or in a fenced area. Know your dog well before letting it off-leash in permitted areas. Keep your dog in your sight at all times. If you know your dog can be fearful or aggressive, do not put them in situations where they may become fearful and bite another person or pet. Instead, err on the side of caution and work with a professional trainer who can guide you.
If you suspect or know that your dog has fearful or aggressive tendencies, always warn others. Do not let your dog approach people and other animals unless the situation is highly controlled. Be mindful of your dog’s limitations and do not place them in situations that will stress them or put them or other people at risk. Work with a trainer if you know your dog has fearful or aggressive tendencies. They can discuss the appropriate use a basket muzzle if necessary.
Keep your dog’s vaccinations current (especially rabies) and visit your vet routinely for wellness check-ups.

How to Interact With Dogs

Dogs are cute and often friendly, so it’s easy to get excited when you see one. However, they can quickly turn on someone they don’t know. Even if you don’t have a dog yourself, it’s important to know proper behavior for interacting with dogs and how and when to approach one.

All children and adults should learn how to keep themselves safe around dogs. Most importantly, dog owners must be responsible for their dogs. Fortunately, responsible dog ownership and education of the public can keep everyone safe.

Never try to approach or touch an unfamiliar dog without first asking for the owner’s permission. If an owner is not present, do not go near the dog.
When meeting an unknown dog, allow the dog to come to you. Allow it to sniff you. Do not reach to pet it unless the owner has given permission. If the owner and dog cues are appropriate you can, crouch down or turn to the side. Always let it sniff your hand before you pet it.
Do not put your face close to an unknown dog; this includes «hugs and kisses.»
Understand dog body language. Most dogs will show specific warning signs before biting. But some may not.
If you are cornered by a dog, remain still and avoid eye contact. Never run or scream. When the dog stops paying attention to you, slowly back away.
If you’re knocked over by a dog, fall to your side in a fetal position, covering your head and face. Remain very still and calm.
Never approach a dog that is eating, sleeping, or caring for puppies. Dogs in these situations are more likely to be protective and can become startled.
Never leave young children or babies alone with a dog for any reason.
Do not approach, touch, or attempt to move an injured dog. Instead, contact a veterinary professional or animal control for assistance.

If a Dog Bite Occurs

Don’t delay, if your dog bites someone, take the following steps:

Remain calm.
Confine your dog to a crate or another room.
Help the bite victim wash the wound thoroughly with warm, soapy water.
Be courteous and sympathetic to the bite victim. Avoid laying blame or getting defensive. This does not mean you need to admit fault. Remember that what you say may be used against you later if a legal or civil action is taken.
Contact a medical professional for the bite victim. Depending on the severity of the bite, an ambulance may be needed. No matter how minor the bite is, the victim should seek medical care. Dog bites that look mild on the surface can get serious very fast.
Offer to contact a friend or family member for the victim.
Exchange contact information with the victim. Provide your insurance information, if applicable.
If there were witnesses, obtain their contact information.
Contact your veterinarian and obtain your dog’s medical records.
Inform local authorities of the incident and comply with their orders.

Dog Bites and the Law

Dog bite laws can vary greatly depending on the local jurisdiction. It is important that you research the laws in your area, so you know what to expect. The following conditions typically apply in dog bite cases:

You will need to show proof of your dog’s rabies vaccination history.
A quarantine period may be required. The period will likely be longer if the rabies vaccination is not current.
Depending on the situation and your dog’s history, it is possible for your dog to be designated a «dangerous dog.» You may have to comply with specific laws regarding the handling of your dog.
Laws may require that your dog is euthanized if your dog is considered «dangerous,» if the injury was very serious, or if a fatality occurred. Also, you could be held legally responsible and face criminal charges.

Your Role After a Dog Bite

The dog bite victim may choose to press charges or file a civil suit against you. In either case, you should immediately hire an attorney.

You may or may not be legally ordered to cover the victim’s medical expenses. Ethically, it may be a good idea to offer up front to pay. This shows the victim that you are accepting responsibility for your dog. It may even help you avoid a messy lawsuit. Above all, it is the ethical thing to do, even if you have an explanation for the dog bite. In reality, proving your dog was provoked or somehow justified will be difficult unless it can be proven that the victim was committing a crime. This simply may not be an argument that is not worth having.

If you are fortunate enough to get to keep your dog, it is your responsibility to prevent this type of thing from happening in the future. Take steps to prevent your dog from biting again. In most cases, a dog bite can be easily prevented by taking the proper safety measures.

If you are able to determine what triggered the bite, try to keep your dog from getting into the same situation. Work with your dog to adjust its reaction to the trigger. It is absolutely essential to work on training and socialization with your dog as soon as possible after the bite. The best plan is to contact a professional trainer and possibly a veterinary behaviorist.

Many dogs with aggression can be helped through training, socialization, and behavior modification. Sadly, in some cases major aggression cannot be reversed and the most humane thing to do is euthanasia. Of course, this is the last resort.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet’s health history, and can make the best recommendations for your pet.