Aggressively Biting Puppy: What Should You Do?

Puppy fiercely playing tug of war

One of the most frequent questions dog trainers and behaviorists hear from new puppy owners is: "Why is my puppy biting me aggressively?" Many owners, especially those new to having dogs, interpret this behavior as aggression, when more often than not, it's normal puppy behavior. Puppy owners need to learn how to gently guide their pups to more acceptable ways of interacting with people.

Curbing Aggressive Biting Puppy Behavior

No dog owner dreams of bringing home an aggressively biting puppy. While nipping is a normal puppy behavior, once in a while an owner may find themselves with a puppy who has true aggression issues. It's important to learn the difference between aggression and puppy mouthing and nipping. Although the normal behaviors of a puppy can definitely be unpleasant, it doesn't have to become a lifetime habit if you teach your pet that biting and mouthing skin is unacceptable while they're still young.

What Is Normal Puppy Mouthing?

Since puppies don't have hands like humans, they use their mouths to explore their environment. If you watch a litter of puppies, you will see them mouthing and "biting" each other as part of play. Sometimes a puppy will bite down too hard, causing the other puppy to yelp or cry and move away. In this way, puppies teach each other what is acceptable. If a puppy is taken away from a litter too young, they lose this valuable socialization opportunity. Even puppies taken from the litter at an appropriate time will nip and mouth in their new homes as they are teething and learning about their new environment.

Puppies chewing on a male hand

Signs of an Aggressive Puppy

When puppies mouth or bite their owners, this is most often a normal behavior. However, in some cases you can find yourself with a puppy that is actually demonstrating aggressive behaviors. This may be due to poor breeding and genetics, medical issues, or the influence of environmental circumstances that lead to fear, frustration, or anxiety. Puppies who are under socialized can also display aggression if they're uncomfortable around other dogs or people.

Work With Your Vet or Professional

In these situations, it's best to work with your veterinarian and a trained behavior professional to determine the cause of the aggression and work to alleviate it. It's critical to begin this behavior modification work right away. Puppyhood is a critical developmental period for dogs, and what they learn, or don't learn during these formative weeks and months can permanently affect their behavior for the remainder of their life.

Normal Puppy Biting Versus Aggressive Puppy Biting

In general, you will notice key differences in a puppy's demeanor and body language that can clue you in on what's normal behavior and what is concerning.

Behavior/Body Posture




Appear relaxed

Ears will either appear pointed forward and up or pressed back against their head. Dogs with long floppy ears will have muscles along top of ears pushed back and up or forward and up


"Soft" eyes with a normal overall size and pupils

Smaller eyes that appear narrowed


"Loose" mouth that is somewhat open or closed, possible open with tongue out if excited

Muzzle will have lips taught and back, bared teeth, mouth open, possibly panting and drooling


Gentle wagging when relaxed or faster wagging when excited or happy but tail still appears "loose"

Tail will either appear stiff and taut and standing up, or wagging but stiffly. In fear aggression the tail may be tucked under their body.

Overall Body Posture

Relaxed, "wiggly"

Taut and stiff. Fearful dogs will be low to the ground and moving back. Or puppy may have a forward body motion that also is high to make the dog appear bigger and more threatening.


Puppy may make excited barking, and depending on breed, might growl during play - look at overall body language to determine context

Growling with either fearful or aggressive body language


Overall relaxed, "happy", affectionate behavior

Puppy seems either fearful or defensive or may make threatening body language - does not feel "friendly" or relaxed


Puppy may mouth or nip at hands during play or cuddling, usually when hands are presented in proximity to puppy

Triggers might be a harsh tone of voice, looming posture, rapid or forward movement; the presence of high value objects like toys, bones, food bowl; strangers

Bite Pressure

Might simply mouth your arm without pressure to nipping if the puppy is excited, but generally won't break skin.

Can either leave bruising or break skin. Bites may be singular or in rapid succession


Most puppies can be easily redirected with a toy or treat or asked to sit; can learn "leave it" command fairly fast

Attempts to redirect puppy may take longer and puppy may not be as receptive and doesn't appear in an emotional place to learn but seems more in a "fight or flight" state of mind

Play Biting Leads to Aggressive Biting

Since mouthing and biting is a natural behavior among dogs, it's expected that they will engage in this behavior in their new home. If you watch dogs playing, you'll see that they regularly nip each other, and most dogs know not to nip so hard that they hurt the other dog. However, play biting can escalate if the dog becomes too excited or aroused and doesn't have good bite inhibition or impulse control.

Play Biting Can Escalate

Play biting can escalate into something painful when a pup becomes too excited or you engage in "rough housing." If your puppy comes from a breed with a stronger prey drive, such as a terrier, they may be more likely to get over-aroused during excited play and bite down too hard without intending to cause harm. In these cases, working with them on bite inhibition and impulse control can alleviate the problem. You should also avoid overly excited play, and try to find outlets for your dog's energy that work his mind and develop his self control skills.

Reasons for Aggressive Puppy Biting

In cases where the puppy is truly biting out of aggression, there are several reasons why this may be happening in addition to play biting getting out of hand. In these forms of aggression you may also see growling and snapping, as well as aggressive body language. Some more common reasons are:

Resource Guarding

Puppies may guard valued resources like toys, bones, their food or water dish, or entrances and exits. They may only do this to other animals, or to humans in the household. Resource guarding is an ingrained behavior that is exacerbated by fear and anxiety. Sometimes it can also be passed on genetically, which is why meeting the parents of a prospective puppy is so important. Resource guarding can also be made worse in puppies by punishment and inappropriate handling.

Fear Aggression

Puppies with fear aggression usually become this way either due to poor socialization, a genetic tendency inherited from one or both parents, and/or a singularly traumatic experience at an early age. If not properly introduced to new things in the world like other dogs, people, places and noises, they can become nervous and afraid. These puppies will show aggression in a defensive posture because they are scared and want whatever is frightening them to go away.

Territorial Behavior

Lack of proper socialization can also lead to territorial behavior in puppies. It may also occur as a natural behavior in breeds bred for guarding and protective instincts.

Congenital Behavior

Some puppies inherit an aggressive disposition from their parents. In some cases this can be redirected through obedience training, behavior modification and lots of socialization. In others, you should seek the help of a professional behavior consultant or veterinary behaviorist.

Working with a pack of Jack Russell Terriers

Is Dominance Involved?

In the past it was believed that a puppy or adult dog displayed aggression due to the need to show dominance over his human owners or other dogs. Research has since shown this is incorrect, and in many ways a problematic belief when it comes to handling aggression. According to associate certified applied animal behaviorist Katenna Jones, "Aggression is related to fear, anxiety or stress. One key to improvement is understanding the basis for the aggression, learning to spot and listen to early warning signs and finding appropriate ways to manage and redirect the behavior in a positive way."

Adult and puppy dog playing and biting

Training for Behavioral Change

Whether your puppy is biting in play or because he's showing aggressive behavior, it's crucial to stop the biting before it becomes an ingrained habit. Explains Jones, "It all comes down to communication, listening to what the puppy 'is saying' and respecting that. We teach dog owners to manage the situation and provide positive alternatives to the puppy."

Teaching Puppies Not to Bite

In order to teach a puppy not to bite, he first has to understand what is expected of him.

  1. While some trainers advocate never allowing the puppy to put his mouth on you, Jones states that letting the puppy put some pressure on you can help teach him to have a "soft" mouth.
  2. She teaches owners to "allow pressure but not too much. Pretend your skin is a raw eggshell or a potato chip that you want to keep intact. Soft pressure with the mouth is fine, but if the puppy presses hard enough to 'break it' it's pressed too hard."
  3. If the puppy bites too hard, simply stay calm, get up immediately and walk away. In this case you are removing something the puppy values: your attention.
  4. Wait a few minutes and then return to the puppy. If he mouths you too hard again, repeat the process.
  5. She also recommends not following a traditional method of putting a toy in the dog's mouth if he bites too hard, as "this teaches them they get a reward (the toy) for biting too hard." However, she says you should still use this method when redirecting a puppy away from chewing something inappropriate, such as a shoe or a table leg.
  6. It's important to make sure that everyone in your household understands why these steps are necessary, and all must agree to the "rules" from the start. It's not fair to a puppy to be expected to comply 100% when he's getting mixed messages from household members.

Steps to Avoid When Teaching a Puppy Not to Bite

Unfortunately, there's a great deal of outdated advice regarding puppy training and behavior. Most of this advice is based on punishing the puppy for a natural behavior, which can lead to fear and anxiety. A great deal of advice is also ineffective because owners aren't teaching the puppy what they want them to do instead of biting too hard. There are several traditional tips you should avoid.

Tip One: The firm "NO"

Some owners use a firm "NO" when your pup tries to use his teeth on you. This may also include wrapping your hand around his muzzle and saying "No" in a loud, firm voice. Unfortunately, doing this will teach your puppy that your hands are to be avoided and feared, and he may generalize this feeling to you as well. If anything, it may cause the puppy to bite even more, as he will want hands around his face and muzzle to go away.

Tip Two: Time Out

A time out means confining him to his crate or gating him in another room. In theory, this teaches him that he will not be rewarded with more attention when he bites. However, this can teach the puppy to dislike his crate or "safe room" because it is used as a punishment. It also doesn't show him what he needs to do to get rewarded. It's very easy for owners to get the timing wrong on a time out, and the puppy may miss entirely what he is being punished for. Jones also relates that she has seen time outs teach a puppy to "bite and run," creating a chase-me-catch-me game between you and the puppy, which can end up reinforcing the behavior even more.

Tip Three: Avoid Rough Play and Teasing

It used to be that dog owners were told to avoid a rousing game of tug-of-war because it will encourage a more aggressive puppy to become over aroused and bite harder. Holding a toy just out of his reach can also encourage him to lunge for it and make him frustrated. However, tug-of-war can actually be a great outlet for a puppy's energy, and a good way to teach him inhibition and impulse control, but only if you observe a set of rules for play.

  1. Ask your dog to sit or lie down in a stay before you start to play.
  2. Pull out the toy and begin to move it around and encourage your dog to get it. You can pair a verbal cue with this to let the puppy know it's time to tug, like "tug!" or "take!"
  3. In the middle of excited play, put the toy behind your back and ask your dog to sit. Stay calm and wait for him to comply.
  4. If the dog has a hard time letting go of the toy, you can work on teaching him a "leave it" or "drop" cue.
  5. Once the dog sits, praise him and begin to play again.
  6. If at any time he gets his teeth too hard onto your skin, stop play immediately and calmly walk away. You can either put the toy away or leave it and ignore the dog if he picks it up and runs after you trying to get you to keep playing tug.
  7. The key to this game is that the dog learns how to control himself despite excitement; and that biting too hard ends the fun.

Tip Four: Bitter Apple

Bitter Apple is a spray product that discourages dogs from chewing just about anything you spray it on. You can use it on your furniture, your carpeting, and even your hands. The problem with using Bitter Apple is that it doesn't teach your dog what you want, and some dogs aren't bothered by the taste at all. Putting Bitter Apple on your skin is also a recipe for ending up with it in your mouth and eyes, and this is distinctly unpleasant. Think of it like getting a milder form of pepper spray on your tongue!

Tip Five: No Hitting

If you want your pup to modify his behavior, you also need to keep control of yours. This is one traditional tip that you should respect. Although the urge to give your dog a smack when he bites may feel like a natural reflex, avoid it at all costs. Hitting your dog will only feed into his aggression and his natural instinct to protect himself, and will in turn lead to more biting. It also will teach the dog to fear you and damage your relationship with him.

Seek Help to Stop Aggressive Puppy Play

If you want to keep an aggressively biting puppy from growing up into a household menace, the best course of action is to talk to your veterinarian and get a referral to a qualified behavior professional. If not handled properly with positive reinforcement and a modern understanding of dog behavior, a truly aggressive puppy can become worse as he or she becomes more fearful, anxious or frustrated. For the normal puppy expressing natural behaviors, work to redirect him to more appropriate activities and reinforcing him for them. A puppy socialization class should also help lead the puppy to outgrow biting behavior as he moves into adolescence and adulthood.

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Aggressively Biting Puppy: What Should You Do?