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Puppy Aggression: Why Is My Pup Aggressive All of a Sudden?

I have some good news and bad news.

Can cute, tiny puppies show aggressive behavior? Yes, they can.

Is true aggression common among puppies? No, it’s definitely not and what you’re worrying about is most likely not deep-rooted aggression.

That being said, if your puppy is acting aggressively, that needs to be addressed during training and socialization.

There are many different kinds of puppy aggression and signs can emerge early on.

With patient and focused training, these behavior issues can be addressed before turning into a problem.

Why Is My Pup Aggressive All of a Sudden?

Your puppy may act aggressive all of a sudden as he undergoes different mental stages which can include a fear period, puppy biting, and phases of testing boundaries or discovering rough play.

For many fresh owners, it’s a shock if their puppy acts aggressive and there are some common signs dog owners should look out for below.

Puppy teething: If your puppy bites on your hands, he is probably teething and tries to soothe the pain by chewing.

Pay attention if your puppy is biting on chew toys as often as he bites on your hands. Provide him with a variety of textured chew toys and this issue will eventually go away.

Puppy biting is usually there from the get-go but if your puppy is aggressive all of a sudden, maybe he just crossed the threshold over to that particularly hassling teething stage.

Puppy play: Puppies usually switch roles when playing with one another. One gets chased and then the tables turn.

If one puppy yelps, the others will stop the play. If your puppy is interacting that way with you, then he is probably not showing any signs of aggression.

My Rottweiler loved close quarter play and not every pup does so if yours meets the wrong dog, it may come off as your puppy being aggressive all of a sudden.

Fear and stress: An anxious puppy has his tail tugged between the legs, back crouched, and will try to defend himself.

Fear periods are totally normal for every puppy and can resemble sudden puppy aggression which is why you’ll need to be consistent with socializing your puppy.

Health issues: A puppy in pain will probably growl at you when you touch him. It can also be misinterpreted as food aggression or resource guarding.

How can you spot sudden puppy aggression?

You can spot puppy aggression by observing your dog’s body language which includes: Tail position, ears perked up or laid back, posture, hackles, snarling, and so on.

Consult a behaviorist to find the cause of his distress if the trigger is not known.

5 Signs of Aggression in Puppies

The most common signs why owners deem their puppies aggressive include biting, chasing, jumping, but also more serious behaviors like snarling or snapping at the owner or other dogs.

  • Biting on your hands and feet
  • Chasing you around
  • Jumping and barking at you
  • Growling or snarling
  • Snapping and lunging at you

But aren’t these all typical canine behaviors? Yes, they are! Let’s have a closer look to determine if we can figure out if puppy aggression is really on the table.

Biting can be due to teething, chasing you can signal play, jumping might mean your puppy wants you to interact.

These behaviors are part of play and desirable. However, you’ll want to teach your dog to contain themselves and be disciplined about how far they go.

If your dog is big-time into jumping, you need to address that in your training.

Many people consider puppy aggression because their pup is growling at them.

It’s true, growling paired with snapping or lunging could be a sign of aggression but in general, a growl is just a dog’s way to communicate.

My Rottweiler Amalia growled a lot as a puppy and still does when she’s playing.

But the only instance where she growled at me directly was when I perhaps startled her and tried picking her up from her crate at night as a puppy.

If you act accordingly and if your dog’s behavior is reasonable, you shouldn’t be worried about this behavior as long as it’s not excessive.

Puppy Aggression Towards Other Dogs

Puppy aggression towards other dogs is most likely just reactivity or the puppy is going through a fear period where socialization with dogs will still be crucial.

Puppies love interacting with other dogs, most of the time that includes those who will later only be dog tolerant.

If your puppy is air-snapping at a large, daunting dog they haven’t met before that might seem like sudden puppy aggression but most of the time, it’s nothing.

However, ongoing exposure and training are still key to avoid that turning into aggression.

Puppy Aggression Towards Owner

Puppy aggression towards their owner is uncommon if they came from a responsible breeder but issues such as resource guarding or puppy biting are very common.

If your pup was allowed on the couch back in the breeder’s home and isn’t in yours, there might be some conflict with really persistent puppies.

However, if you’ve done nothing to hurt your pup physically or scarred him mentally, puppy aggression towards the owner is probably not on the table.

5 Types of Puppy Aggression

Puppy aggression can come in the form of reactivity, leash aggression, rivalry, or predatory behavior.

1. Puppy Dominance Aggression

Dominance in puppies is probably the most misunderstood topic when it comes to behavior problems.

Dogs at such a young age cannot develop dominance in a way that an adult dog can and the term is outdated anyway.

They just haven’t learned it yet and the correct term to use here instead would be conflict aggression.

This type of aggression usually occurs out of fear and the puppy will quickly learn which methods will get him to not be confronted with his fear again.

For example, if he starts barking at tall men because he is afraid of them and you quickly walk around and try to avoid them, he will learn that barking means the fear trigger will be removed.

You can learn more about puppy howling and barking here and how to stop it.

2. Reactivity

Reactivity in dogs often results in behavior problems like leash aggression.

Puppies will start lunging or barking at people or other animals and will be very reactive towards their environment.

Reactiveness is not the same as aggression but I wanted to add it in this post as it is a common issue.

Dogs will get overstimulated and react poorly in certain situations. Here you can learn how to train a reactive dog.

3. Leash Aggression

Leash aggression in puppies is usually directed towards other dogs. The leash gives a dog confidence and the urge to protect you and his territory against other dogs.

If you have a small dog, he will probably be most afraid of large breeds. This is fairly easy to train as puppies quickly adapt to what gives them rewards and what doesn’t.

Remember that you do not give in to your puppy lunging and let him bark or even come close to his opponent.

You will want to repeatedly train your puppy how to walk past other dogs.

Show him that there is no reason for him to bark and only reward when you have passed the other dog and your puppy has behaved well.

He will quickly learn that leash aggression gets him nowhere.

Also, distract and redirect while you are in the process of walking by and consistency will eventually lead to your goal.

You will definitely want to look into puppy socialization to make sure this issue won’t occur.

4. Rivalry

Especially if you have children or other dogs in your home who are competing for your attention, sibling rivalry can become an issue.

As we all know, puppies need so much attention physically and emotionally. Rivalry can be about attention, territory, and resources.

If you recognize that your puppy is starting to guard his food or toys, you should definitely look into this post on how to stop food aggression.

And also check out this information with some tips on how to avoid this rivalry.

5. Predatory Aggression

While a puppy develops into an adult dog, he learns everything that will be mandatory for his future, including how to play.

You should not encourage the predatory instinct of a puppy which usually occurs while playing.

Quick movements with your hands trigger that instinct and play biting will become an issue.

Bite inhibition training should be one of the most important steps that you will be teaching your puppy. You can learn everything about that in my article on puppy biting.

How To Stop Puppy Aggression

Avoid your puppy’s triggers as much as possible to prevent conflict while also setting boundaries and teaching basic obedience as well as keep socializing your pup.

Here are a couple of situations where puppy aggression can shine through:

  • Pup gets startled by suddenly being touched or picked up
  • Pup protects food, toys, couch
  • Pup barks at strangers or guests at your house
  • Pup plays too rough wit you or other dogs

The exact steps to fix your puppy’s aggression depend heavily on what your issue is but all of these are usually relatively easy to fix.

Provide him with enough physical and mental exercise, many of the aggression signs emerge from frustration and boredom.

Use mainly positive reinforcement and always reward positive behavior. Create a strong bond with your dog off mutual respect and trust.

Engage in playtime with him and find out what he likes the most instead of focusing on the negative.

Desensitize him to his environment. If he is afraid of men, try to slowly build up trust by asking a friend over and hand feeding him with treats.

Consult a professional dog trainer if the behavior gets worse or doesn’t get resolved. Call a behaviorist immediately if someone gets injured.

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Disclaimer: This blog post does not substitute veterinary attention and does not intend to do so. I am not a veterinarian or pet nutritionist. If your dog shows any sign of illness, call your vet.

About Danielle

Equipped with 5+ years of expertise as a Rottweiler owner, I partner with licensed veterinarians and trainers to share research-backed and actionable advice for you and your furry friend.


Tuesday 28th of March 2023

After his dinner in the evening we take him for a walk He always does a poop and urinates Soon as we get home he races inside and runs around nipping at our heals and jumping and growl barking Very aggressive


Monday 10th of April 2023

Hi Janet, evaluate whether your pup has enough physical and mental stimulation. They can only settle down once their needs are met. Regarding the potty training: You need to stay outside and positively reinforce if your pup goes potty. Stay consistent and this phase will soon be over.

Leonette rupert

Sunday 5th of March 2023

Yes article good. I had to rehome 5mo old blue heeler husky yesterday. He was turning on me. Bit my rear and week later went for my face. No blood but I got chills when happened. Sad because I had 9 dogs in my life not this young but he would stare me down bark pull my cloths nip at ankles which I knew he'd do. But I did not know how to handle his escalation. We played walked fed. Loved on routine. Was training him some and he started changing. Feel like I wasn't good dog mom to this one


Tuesday 7th of March 2023

While diagnosing anything from afar is impossible, it sounds like this may be a case of puppy biting. While aggression is possible in puppies, it's rare especially if bred properly and socialized early on etc. Ultimately, making the decision of whether to rehome or not is extremely difficult.


Monday 21st of November 2022

My pup plays too hard. He bites my ankles and hands VERY aggressively and when I try to course-correct he lunges and bites more. I give him a toy to chew but he keeps coming at me hard.


Monday 21st of November 2022

Hi Amy, you can either redirect your pup or correct with a "no" and end the play session. It's important not to make chasing you even more fun, just leave the room. There are a couple of different ways to achieve this but it all depends on your pup and biting is a natural part of their development. Make sure they have chew toys, exercise, and so on.


Tuesday 19th of July 2022

I can't take my puppy for walks without her jumping and biting my legs feet ankles and it hurts so bad


Tuesday 19th of July 2022

Hi Linda, some puppies have a stronger puppy biting phase than others but it's crucial to teach her how to walk properly. You might want to check out this article on puppy biting.

Positive reinforcement when she's behaving well, an appropriate correction and calmly restricting access, as well as redirection are all ways you can get rid of that in no time.

Hope you'll still have fun on walks, physical and mental stimulation is so important but of course, it should be fun for you too :).

Cheers, Danielle


Thursday 27th of June 2019

Keep up the quality posts! I love to try everything with my dogs.