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signs of aggressive puppy

Signs Of An Aggressive Puppy: Is My Puppy Normal, Or a True Terror?

All puppies play bite, but some puppies are more intense than others.

It’s rare, but even at a very young age, some puppies have an “edge” to them. As a dog behavior consultant who’s worked with thousands of dogs, I’ve only seen one or two puppies that I would even consider classifying as truly “aggressive” (we’ll talk about one of these pups later).

Nevertheless, I get several calls or emails per week from owners who worry that their puppy is aggressive.

So, how do you differentiate the signs of an aggressive puppy from puppy rough play that’s within the range of normal? We’ll focus today on answering that question for dogs less than 6 months old. Then, I will give some suggestions as to what you can do if you do have an aggressive pup.

What Exactly Is An “Aggressive” Puppy?

It’s very common to see puppies that have an overly rough play style, low bite inhibition, low frustration tolerance, or even mild resource guarding issues. When I get a call about an “aggressive puppy” from a client, it’s almost always a puppy that fits into one of these categories.

While these puppies might fall under the layman’s umbrella of “aggressive,” I set them apart from puppies that seem to be truly behaviorally “off.” Those puppies still may need help from an experienced trainer to prevent further problems down the line, but they should not be confused with puppies that are behaviorally abnormal.


I often explain aggression in puppies to clients through the lens of children.

It’s not very nice for a six-year-old to push his sibling down or hit a friend – but it’s not a huge cause for alarm, yet. However, if that same six-year-old pushes and hits all the time (frequency), is very forceful with those pushes and hits (intensity), or keeps hitting for a long time (duration), that is a cause for concern. This is especially true if the child is not just rude, but seems to have the intent to harm the other child.

Similarly, if your puppy is unusually intense in her painful or threatening behavior, or displays these behaviors frequently and for a long time, this is a cause for concern.

Normal Vs. Abnormal Puppy Behavior

So, an “aggressive puppy” is a puppy that displays an abnormal intensity, frequency, or duration of behaviors such as lunging, snarling, growling, baring teeth, or biting.

But what’s “abnormal”? As I discussed in my article on puppy play biting, “normal” varies. A lot. Normal play biting for a Belgian Malinois puppy would be quite concerning to see in a Shih Tzu.

While what is classified as “normal” play biting can vary depending on breed, age, and other factors, some behaviors are red flags across the board.

It’s almost always abnormal to see a small puppy growl or bare teeth, lunge at dogs or people, or bite and hold onto littermates while they cry. These puppies should see a behavior consultant sooner rather than later.

If you feel like your puppy is abnormally aggressive, it never hurts to contact a certified dog behavior consultant – not just your local obedience trainer – and ask for their opinion. Dog behavior consultants will have knowledge and skill sets that differ from even the most experienced obedience trainers. Some trainers are also behavior consultants, but don’t assume without asking around.


The Paradox of Puppy Aggression

It’s hard emotionally to look at a small, young dog and consider the fact that this puppy might grow into something dangerous. It’s easy to overlook concerning behavior in something so cute and fluffy!

Yet, paradoxically, most animal behavior consultants will say that the younger a dog is when it displays concerning behaviors, the more alarmed we should be.

Some level of over-arousal while on walks, growliness with other dogs, and even growling over shared resources isn’t at all uncommon for dogs 9-18 months old. They’re terrible teenagers! These dogs require training to help them grow out of these naughty behaviors, but this is actually far less concerning than seeing the same behavior in a ten-week-old puppy.

When I see an eight-week-old puppy growl at its siblings over food, or a four-month-old puppy on a leash lunging at other dogs, alarm bells go off. Pre-adolescent dogs should not, for the most part, be reacting to their environment in a highly negative way.

Warning Signs of an Aggressive Puppy: When to be Concerned

If you’re concerned at all about your puppy, it’s never a bad idea to contact a certified dog behavior consultant. They may ask you to film the behavior and send it along, or they may want to come meet you and your puppy in person.

If you’re on the fence about whether or not your puppy is “abnormal,” here’s a starting list of “red flag” behaviors that warrant an experienced eye. This list is not exhaustive and is aimed at puppies under the age of six months.

Puppies that growl (or worse) when you or another dog approaches their food or toys. Resource guarding is a common and natural issue – but it’s unusual to see in young puppies. This problem is more common in puppies that were all fed out of a single shared food bowl, so ask your breeder if your pup was fed that way.

Teaching the puppies to “compete” with their siblings at a young age for food isn’t a good way to help them share later!

Puppies that continue to bite or “go after” playmates even when the playmate has its tail tucked and/or is attempting to get away. Not all puppies are awesome at reading social signals from other dogs. However, it’s concerning to see one puppy blatantly ignoring another puppy’s pleas for play to be toned down.

Puppies that lunge at strange people, dogs, or other objects on walks. It’s pretty normal for most puppies to be interested in their environment. They’re generally loose, waggy, and curious. Some puppies are a bit more reserved – that’s also normal.

What isn’t normal is a puppy that is so scared of something that it thrashes on leash or growls, snarls, or snaps at the offending subject. It’s also highly abnormal for puppies to lunge towards things on walks, especially if their body is stiff and they’re growling, snarling, or snapping.

This is a very concerning behavior for a pre-adolescent dog (and should be addressed in dogs of any age).

Puppies that show their teeth, growl, snarl, snap, or bite with a “hard face” and tense body. There’s a difference between a puppy that’s play biting, or even biting because it’s overly excited, and a puppy that is biting out of a strong negative emotion.

It’s hard to see that difference at first, but aggressive behaviors are often described as having a stiffness, stillness, or hardness to them (we also talk about this in our article on how to safely break up a dog fight). If you feel that your puppy’s behaviors have an “edge” to them, it might be time to call in help.

Puppies that bark constantly, bite during play (but are otherwise relaxed), play growl while engaging in a game of tug, nip at hands or clothing playfully, or pull towards others on walks to go say hi are not necessarily aggressive.

These puppies might be rude and may benefit from training (or some puppy teething toys if your pup’s adult teeth are coming in), but these are not big “red flag” behaviors.

A Case Study in Puppy Aggression

Only one puppy in my time as a dog behavior consultant has been truly concerning – even frightening – to me.

I’ve seen many puppies that growled or snapped around their food, puppies that were very fearful of their environment, and puppies that played or bit far too roughly. These puppies almost all had excellent outcomes thanks to some training interventions.

But this puppy – we’ll call her Halley – was different. She came into the shelter I worked for as a transfer, meaning that a shelter in Texas was overflowing. My shelter in Denver brought in a truckload of dogs per week from the Texas shelter to help the Texas shelter reduce euthanasia rates.

The puppies were in the Denver shelter for under a week – just long enough to get spayed and neutered, get medical clearance, and go up for adoption.

Halley had a few siblings with her. They were cute eight- or nine-week-old hound mix puppies – huge ears, big spots of tan and black and white, soft dairy cow eyes. Halley looked just like Copper from Fox and the Hound.

Cue melting heart (img from Character Wikki)

The second day that the puppies were in Denver, the entire behavior staff got an email about Halley.

The email said that, when animal care staff fed the litter of puppies that morning, Halley turned snarling towards her siblings. She pinned one of her siblings to the ground while the other puppy screamed, but Halley didn’t let up. She latched onto the other puppy’s neck – luckily it was the loose skin on the back and not the throat – and shook.

Halley wouldn’t let go, even when staff banged on doors and shouted to try to startle her. The animal care staff had to spray her with a powered hose to get her to let go of the other puppy.

The puppies were separated, and the behavior staff brought Halley down to hang out in our office for a while. We played with her and watched her interact with us and her environment. We didn’t see much of concern, other than knowing that this cute little puppy had nearly given her sibling stitches over a pile of food.

Eventually, we decided that there was nothing that the behavior team could realistically do in the shelter environment to help modify her behavior around food and other dogs. We reached out to a few rescues with more long-term resources but didn’t have much luck.

Halley was adopted to a couple that was given full disclosure on the incident and several good resources for help. Halley never came back to the shelter; hopefully, this means the couple had success in dealing with Halley’s behavioral problem, although I’ll never be totally sure.

On one hand, Halley seemed to be a normal puppy in many ways. She was quite friendly and curious. But the incident with her sibling over food still haunts me.

I don’t know what happened to Halley, but if she had been a private client of mine, I would expect a relatively long road of behavior modification to help keep other dogs safe around her as she reached adulthood.

How Do I Teach My Puppy Not to be Aggressive?

If you’ve adopted or purchased an aggressive puppy like Halley, it’s time to get some help.

Your first step should be to contact a dog behavior consultant through the IAABC. If there’s no one near you, feel free to reach out to me – I take clients via video chat from anywhere in the world, and I can help.

While you wait for the dog behavior consultant to see you, you’ve got some steps you can take on your own:

1. Video the behavior, if possible. Don’t provoke your puppy into displaying her bad behavior. But if you can catch it on camera, that’s very helpful.

2. Document the times your puppy behaves aggressively. This will help your dog behavior consultant find a pattern. Try to note the time, the situation, and her response in as much detail as you can.

Be as descriptive and objective as possible – say “Ruby lifted her lips and stared at my daughter Karen when Karen reached out with her hand to pet Ruby. Ruby was on the couch sleeping at the time and Karen had her side to Ruby. It was 4:30 pm after Karen came home from school.” That’s much more helpful to your dog behavior consultant than something like, “Ruby gets aggressive when my daughter tries to pet her.”

3. Manage the situation. If you can figure out what triggers your puppy’s aggression, that’s great! Your next step is to set up your home in a way that reduces the likelihood of your puppy becoming aggressive.

For example, if your puppy growls when you touch her food, your job is to avoid touching her food bowl. If your puppy keeps practicing these unwanted behaviors, it’s just going to get harder to go in and “fix” them.

4. Start training: counter-conditioning, desensitization, and forming an alternate response. Now that you can control when your puppy is exposed to the situations that cause her unwanted responses, you can start to change her emotional response to those situations.

Counter-conditioning and desensitization can be tricky to do at first, so don’t rush this step and don’t do it alone if you don’t have to!

Here’s an example:

Penny the puppy lunges and snarls at other dogs on walks. We’ll teach Penny to look at her owner for a treat when she sees another dog instead of lunging and snarling. That’s the alternative response. Pairing a formerly stressful item (the other dog) with treats is counter-conditioning. Doing so slowly and systematically is desensitization.

A sample progression would be:

a. Teach Penny to look at you in exchange for a treat when you say her name and practice this hundreds of times.

b. Go outside and set up a friend’s dog a football field’s distance away. The friend’s dog should be lying down with its back to Penny.

c. When Penny notices the other dog and does not react negatively, say her name and then give her a treat. Retreat a bit from the other dog, take a break, then repeat.

d. Repeat until Penny sees the other dog, then automatically looks at you for her treat.

e. Gradually decrease distance and allow the other dog to move a bit. If at any point Penny lunges, snarls, tenses, or stops eating treats around the other dog, you’re too close. Take a break and start again further away from the other dog.

Counter-conditioning and desensitization can only work with proper management in place. Do not skip step three (managing the situation) and just go straight to the juicy training bits. Counter-conditioning and desensitization is a long, slow process. Be patient. It’s going to be much easier to do with the help of a dog behavior consultant.

What If I Can’t Keep My Aggressive Puppy?

Sometimes, a dog simply isn’t a good fit for a home. The puppy might be too unpredictable or severe in its aggression. The owners might not be up for the time, money, and attention needed for training. The home might just be too chaotic for effective management.

If keeping a puppy in your home is dangerous because the puppy is aggressive, it’s ok to admit that.

There are times when seeking a new home for an animal is the best thing for that animal.

“Till death do us part” is not generally part of your adoption contract. Most adoption contracts (or buyer contracts) will say that if the puppy or dog can’t stay in your home, it needs to be returned to the rescue, shelter, or breeder.

Ideally, you should be able to return the dog or puppy to the rescue, shelter, or breeder you first got it from. This should always be your first step if you cannot keep your dog, especially if it’s in your contract. Some rescues, breeders, pet stores, and private sales don’t have this stipulation. What then?

Before passing your puppy to the next home, it’s smart to get a dog behavior consultant involved. They might be able to help you out and fix the problem. They might not. But they also will be able to give you some feedback on what’s most responsible to do next.

In the case of severe aggression, rehoming the dog might not be responsible. That’s not an assessment or decision for anyone to make for you, but this is an important discussion to have.

Many certified dog behavior consultants will help you weigh pros and cons, but ultimately the final decision is yours.

Dogs and puppies that pose a serious threat to other people and dogs shouldn’t just be shuffled from one home to the next or dropped at a no-kill shelter so that they can live out years in a concrete cell waiting for an adopter that might never come.

So how do you make the decision of what to do next with your aggressive puppy? I’m kind of a flowchart person, so here’s one to help.

Remember, though – in the vast, vast majority of cases, your puppy is not aggressive. Your puppy may be rude or easily frustrated, but she’s not aggressive.

Even if your puppy is aggressive, there are steps you can take to help her going forward. If you can’t give your puppy the support she needs, you will probably be able to find her another home that can help her.

Do you have an aggressive puppy? Do you have questions about whether or not your puppy’s behavior is normal? We want to hear about it!

About the Author Kayla Fratt

Kayla Fratt is an Associate Certified Dog Behavior Consultant through the IAABC and works as a professional dog trainer through the use of positive reinforcement methods. She also has experience working as a Behavior Technician at Denver Dumb Friends League rehabilitating fearful and reactive dogs.

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