Dog Sniffs Other Dog Then Attacks [Solutions to Keep Your Dog Safe]

Zack Keithy, our author, is a certified veterinarian technician (UC Blue Ash) for over 6 years (contact him here). The articles written here are based on his expertise and experience, combined with a review by our expert vet reviewers including Dr M. Tarantino. Learn more about us here.

I think you would agree with me that one of the scariest things that a dog parent can witness is their pet exhibiting sudden aggression.

From growling and snapping to biting and fighting with other dogs, none of these is something we wanna see in our lifetime.

Why does it happen though? Here’s the thing:

There can be a wide range of reasons why a dog sniffs other dog then attacks. The trigger could be an underlying illness, territorial behavior, or trying to guard its resources. By understanding the reasons behind such behavior, we can properly address and prevent it.

In this post, I will go through in more detail the various reasons and also offer you ways to work around it, so be sure to read till the end!

Medical Questions? Talk to a Veterinarian 24/7.
Connect one-on-one with a licensed vet who will answer your questions in minutes.

Ask a Vet Now or Schedule a home visit

*Article may contain affiliate links to retailers like Amazon and Chewy. Learn more on our disclosure page.

Navigate this post
  1. 9 Reasons for Sudden Aggression in Dogs
  2. Identifying Aggression Signs and Triggers
  3. Bullying and Intimidation at Dog Parks or Daycare Centers
  4. Ways to Help Dogs Get Along Better
  5. The Potential of the Gut Microbiome Causing Aggression
  6. Managing Dog-to-Dog Introductions
  7. Training and Equipment That Might Be Helpful
  8. What to Do if Dogs Get Aggressive With Each Other?
  9. When to Seek Professional Help?
  10. Frequently Asked Questions (FAQs)
  11. In Conclusion: Dog Sniffs Other Dog Then Attacks
Dear Dog Owner

9 Reasons for Sudden Aggression in Dogs

Reasons for Sudden Aggression in Dogs

Dogs, even the least well-trained ones, don’t turn aggressive toward other people or dogs out of the blue.

If your pet sniffs another dog and then launches an attack, there’s a reason behind it. 

I’ll cover 9 reasons that this happens.

1. Illness or injury

Just like humans, dogs can get irritable and aggressive when they’re not feeling well.

If your dog is suddenly displaying aggressive behavior, it’s important to consider whether it might be sick or injured. 

Pain and illness can be underlying factors that trigger aggression in dogs, causing them to growl, snap, or bite unexpectedly. 

You can try to look out for common medical conditions such as lacerations, arthritis, fractures, internal injuries, and tumors.  

Another reason could be canine cognitive dysfunction. It’s a syndrome in dogs that affects the brain and cognitive function. 

We can view it as something similar to dementia or Alzheimer’s disease in humans.

If you have an older dog, the likelihood of this happening is higher.

2. Resource guarding

Is your dog quick to snap or growl when another dog tries to approach their favorite toy or food bowl? Does your dog stare at you when it eats?

These are all signs of resource guarding.

Some dogs can display such tendencies and become aggressive when they feel their valued possessions are being threatened. 

Doggy says, consider reading this next: Why is my dog covering food with a blanket?

3. Household stress

As you might well know, our dogs can easily get stressed out by changes in their surroundings.

Moving to a new home, a new baby arriving, or even changes in their daily routine can all make them feel anxious. 

And guess what?

This stress can sometimes lead to aggression towards other dogs or even people!

And that is why it’s so important to create a relaxed and stable environment for your furry friend. 

4. Frustration

Ever seen your dog get frustrated when they can’t have what they want?

Yes, dogs can feel frustrated or annoyed too. 

It’s when they can’t get that toy, treat, or attention they’re craving, it can trigger aggressive behavior.

5. Annoyance

You might wonder how does a dog get annoyed?

Well, this can be triggered by various factors such as being repeatedly bothered, disturbed, or provoked by other dogs, humans, or environmental stimuli. 

For example, a dog being pestered by another dog, teased by children, or bothered by loud noises may start to show signs of irritation, which can manifest as aggression such as biting another dog’s legs.

Biting or growling could be your pet’s way of communicating their discomfort or frustration. 

6. Redirected arousal

Redirected aggression occurs when a dog is aroused or displays aggression towards one stimulus, and then redirects that aggression towards another stimulus due to interference. 

For instance, if your dog is barking at a squirrel in the yard and you try to intervene, they may redirect their aggression toward you.

This can happen because the dog’s emotions are heightened at that point in time.

They may not be able to differentiate between the original trigger and the interference, resulting in an unintended outburst of aggression.

Doggy says, consider reading this too: How to stop your dog from licking other dogs privates

7. Fear

You could say that this is similar to our flight or fight response.

Dogs can become aggressive when they feel scared or threatened.

For example, if a dog is approached too quickly by a stranger or another dog, it may respond by growling, snarling, snapping, or biting as a way to protect itself. 

This type of aggression is often rooted in fear and is a defensive response.

It can also be triggered by loud noises, unfamiliar environments, or past traumatic experiences. 

8. Dog-dog dominance

Ever heard of the term ‘top dog’?

Some dogs may display aggression towards other dogs as a means to establish dominance or protect their social status within a group. 

This can happen at places like dog parks or daycare centers, where dogs may bully or intimidate others.

Your pet may growl, snarl, or try to assert its dominance by posturing over another dog to show they are the leader. 

I should say that this type of aggression is pretty rare though, as aggression is mostly triggered by fear.

9. Territorial behavior

Dogs are naturally territorial creatures, and some may exhibit aggression when they feel their territory or personal space is being threatened. 

This can occur both inside the home and in outdoor settings. 

If your pet feels that another animal or person is invading their space, they may respond with aggressive behaviors such as growling, barking, or lunging. 

Hey there, sorry to interrupt but I wanted to tell you about an online vet service I’ve been using for years.

An in-person visit with one is great, but it’s not always an option.

Now, thanks to technology, you can speak to one without leaving your home.

Remote access
Avoidance of travel
Reduced stress for pets
Immediate access to experts
Quick response time
Schedule appointments easily

Got something to ask a vet?
Talk to one anytime, 24/7.


* Don’t use this service for emergencies.

Alternatively, a vet can come out to you instead (exclusive to our readers: use THEVETS15 for 15% off).


Thank you. The rest of the article continues below.

Doggy says, you might be keen to read this too: My dog wants to stay inside all the time!

Identifying Aggression Signs and Triggers

How can you tell if your dog is about to become aggressive?

Well, there are telltale signs to watch out for.

If you are seeing any of these, you need to take action to prevent the situation from getting worse.

Stiff body posture

If your dog’s body appears tense, with rigid muscles and a lack of relaxation, it could be a sign of impending aggression.

Growling and snarling

These vocalizations can be a warning sign that your dog is feeling threatened or uncomfortable. Listen for low rumbling sounds or the baring of teeth.

It’s their way to intimidate or warn others to stay away.

This can be accompanied by a wrinkled nose or raised lips, showing the teeth in a threatening manner.

Ears pinned back

When your dog’s ears are flattened against its head, it can indicate fear or discomfort. This may happen when your dog feels threatened and is preparing to defend itself.

Direct eye contact and a hard stare

If your dog is making direct eye contact with a fixed and intense gaze, it’s a pretty sure sign of aggression.

Lunging or snapping

Your dog may suddenly lunge forward or snap at another dog or person when they feel threatened or provoked. 

Biting or nipping

This is the most extreme form of aggression, and it can cause serious harm. If your dog bites or nips at others, it’s a clear indication of aggression and should be addressed immediately.

Tail position

A high or rigid tail often held straight up or straight out, can indicate aggression or excitement. However, a wagging tail does not always mean a dog is friendly, as it can also signal heightened arousal.

Dominant body language

Behaviors such as standing over another dog or person, placing a paw on them, or leaning in aggressively can be signs of impending aggression.

Blocking or guarding

Dogs may block access to resources such as food, toys, or their owners, and guard them aggressively. This can involve standing in front of the resource, growling, or snapping to protect it.

Doggy says, you might be keen to read this too: Dog biting other dog’s tail

Bullying and Intimidation at Dog Parks or Daycare Centers

Dog parks and daycare centers are the most common places where dogs can interact and play with other dogs.

Unfortunately, these can also be places where bullying and intimidation behaviors can occur. 

This happens when some dogs try to establish dominance or protect their social status within a group by displaying aggressive behaviors like growling, lunging, or snapping.

Dogs that feel threatened or anxious may then use aggression as a way to assert themselves and maintain their position or protect their territory.

As a responsible fur parent, you must keep a close eye on your pet’s interactions at dog parks or daycare centers. 

The moment you notice any signs of bullying or intimidation, such as stiff body posture, direct eye contact, growling, or other aggressive behaviors, you should quickly intervene and separate the dogs to prevent any potential escalation.

Doggy says, you might be keen to read this too: Why do Havanese lick so much?

Ways to Help Dogs Get Along Better

Ways to Help Dogs Get Along Better

I get it. If your dog’s been “naughty” for some time now, it gets really tiring and frustrating.

Here’s the thing though: It’s possible to help your pet get along better with other dogs.

Here are some simple tips and tricks you can follow to address aggression. 

Learn dog body language

Dogs have their way of communicating, and it’s all in their body language. 

Keep an eye out for wagging tails, perky ears, and relaxed body postures, which usually indicate happy and relaxed dogs. 

On the other hand, raised hackles, stiff bodies, and direct eye contact may signal tension or potential aggression.

By learning to decipher their body language, you can intervene proactively and prevent conflicts among your furry friends.

Remove underlying stressors

It’s important to identify and address any factors that may stress out your dogs in their environment.

This could include things like resource guarding, overcrowding, or lack of personal space. 

By eliminating or reducing these stressors, you can create a calmer environment for your dogs.

For example, if your dogs are prone to resource guarding during mealtime, you can feed them in separate areas or use food puzzle toys to reduce competition and minimize conflicts.

Avoid trigger stressors

We all have things that push our buttons, and dogs are no exception! 

Pay attention to situations, places, or other dogs that consistently trigger aggressive behaviors in your dogs.

It could be a certain park, a particular dog, or a crowded area. 

Avoiding these triggers or managing them effectively can prevent conflicts and promote positive interactions among your dogs.

Increasing exercise and interaction

Exercise can work wonders for our furry friends! 

Regular exercise and social interactions provide an outlet for dogs to release energy and reduce tension, which can contribute to better dog-to-dog interactions. 

Make sure your dogs have plenty of opportunities for playtime, walks, and positive socialization, and watch those tails wag with joy!

Manage anxieties

If your dogs have anxieties or fears that contribute to their aggressive behaviors, all the more you need to manage them effectively.

The best way to do so is through desensitizing and counter conditioning which I cover in more detail below.

Create a routine

Dogs thrive on routine and predictability.

Establishing a consistent daily routine for your dogs can provide them with a sense of stability and calm, which can reduce stress and promote positive interactions. 

Set regular feeding times, exercise routines, and training sessions to create a structured environment where your dogs feel secure and at ease with each other.

Teaching loose leash walking skills

Walking your dogs on a leash can sometimes trigger tension and aggression.

Teaching them loose leash walking skills can help them walk calmly and comfortably in each other’s presence, reducing the likelihood of leash-related conflicts. 


Gradual desensitization is a technique that involves exposing your dogs to situations or stimuli that trigger their aggression in a controlled and gradual manner while rewarding calm behavior. 

This process helps your dogs learn to cope with their triggers and reduces the likelihood of aggressive reactions.

For example, if your dog becomes aggressive towards other dogs when on walks, you can gradually expose them to other dogs from a distance where they remain calm, and reward them for their calm behavior with treats, praise, or play. 

Over time, you can gradually decrease the distance between your dog and the trigger, continuing to reward calm behavior until your dog becomes more comfortable and less reactive.


Counterconditioning is a technique that focuses on changing your pet’s emotional response toward triggers and it involves pairing the trigger with positive experiences, such as treats or playtime, to create a positive association.

For example, if your dog becomes aggressive because of their fear of thunderstorms, you can start by playing calming music or providing a safe space for your dog during a storm. 

While the storm is happening, you can reward your dog with treats, playtime, or other enjoyable activities.

This way, your dog begins to associate the sound of thunderstorms with positive experiences and may become less fearful over time.

Doggy says, you might be keen to read this too: My dog killed a groundhog

The Potential of the Gut Microbiome Causing Aggression

The gut microbiome is like a little community of tiny organisms that live in a dog’s digestive tract.

Recent research shows that these tiny organisms might not just affect the dog’s physical health, but also their behavior and mental health. 

Some studies suggest that an unhealthy gut with harmful bacteria or an imbalance of different types of bacteria could potentially contribute to changes in the dog’s brain chemistry and behavior, including aggression. 

While researchers are still figuring out the details, there’s evidence to suggest that taking care of a dog’s gut health through diet, probiotics, and other interventions might have a positive impact on their behavior, including reducing aggression. 

Managing Dog-to-Dog Introductions

Introducing your pet to another dog in a controlled and positive way can help prevent aggression as it promotes good interactions, socialization skills, and positive associations.

It allows dogs to learn how to behave around each other and helps detect and address any signs of discomfort or aggression early on. 

Follow these steps for a smooth and successful dog-to-dog introduction that promotes positive interactions and minimizes the risk of aggressive behavior.

Choose a neutral location

Pick a neutral location, such as a park or a quiet area, where neither dog feels territorial or possessive.

Keep both dogs on a leash

Keep both dogs on a leash initially to have control over their movements and prevent any potential incidents.

Allow them to sniff and greet each other from a safe distance.

Use calm and relaxed body language

Your body language plays a key role in setting the tone for the introduction. Stay calm, relaxed, and confident to help your dogs feel at ease.

Keep the initial interaction brief

When introducing your dogs to each other, keep it short and sweet!

Limit the first interaction to just a few minutes, and make sure it’s positive. 

Praise and reward positive behavior

Praise and reward both dogs for positive behaviors, such as calmness, friendly gestures, and appropriate social cues.

Be sure to use treats or toys to reinforce positive behavior.

Observe body language

During their interaction, you should pay close attention to the body language of both dogs.

What you don’t want to see are signs of discomfort, stress, or aggression, such as stiff body postures, growling, or raised hackles.

Gradually increase interaction time

If the initial interaction goes well, you can then gradually increase the time the dogs spend together while continuing to monitor their behavior closely.

Introduce off-leash play in a secure area

Once both dogs are comfortable with each other on-leash, you can consider introducing off-leash play in a securely fenced area.

Needless to say, always supervise the play session until a point where you can confidently say that they are well integrated and developed a bond.

Training and Equipment That Might Be Helpful

When it comes to managing dog aggression, having the right training and equipment can be a game-changer!

Let’s check out some must-have tools that can help keep things under control and promote positive behaviors.


q? encoding=UTF8&ASIN=B000H594RS&Format= SL500 &ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=dailydogdrama 20&language=en USir?t=dailydogdrama 20&language=en US&l=li3&o=1&a=B000H594RS


q? encoding=UTF8&ASIN=B007S9JOLC&Format= SL500 &ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=dailydogdrama 20&language=en USir?t=dailydogdrama 20&language=en US&l=li3&o=1&a=B007S9JOLC

Head halter

q? encoding=UTF8&ASIN=B00074L4W2&Format= SL500 &ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=dailydogdrama 20&language=en USir?t=dailydogdrama 20&language=en US&l=li3&o=1&a=B00074L4W2

Basket muzzle

q? encoding=UTF8&ASIN=B07DVD29QZ&Format= SL500 &ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=dailydogdrama 20&language=en USir?t=dailydogdrama 20&language=en US&l=li3&o=1&a=B07DVD29QZ

Exercise pen

q? encoding=UTF8&ASIN=B000H8YTJI&Format= SL500 &ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=dailydogdrama 20&language=en USir?t=dailydogdrama 20&language=en US&l=li3&o=1&a=B000H8YTJI

Calming chew

q? encoding=UTF8&ASIN=B077MDJ58Y&Format= SL500 &ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=dailydogdrama 20&language=en USir?t=dailydogdrama 20&language=en US&l=li3&o=1&a=B077MDJ58Y

Leash and harness

A leash and harness give the ability to guide and redirect your dog’s movements, helping to prevent unwanted behaviors like lunging or aggressive approaches during walks.

Head halter

The head halter is like a gentle steering wheel for your dog’s head! It helps you redirect your dog’s attention and movements, making it ideal for managing dogs that tend to pull or show aggressive behaviors on walks.

Basket muzzle

The basket muzzle acts as a safety shield for your dog’s mouth. It allows them to open their mouth, pant, and drink water while preventing biting. 

Baby gates or exercise pens

Baby gates or exercise pens create safe spaces or designated areas to keep dogs separated and prevent potential conflicts.

Calming aids

Calming aids come in different forms like pheromone diffusers, collars, chews, or supplements, and can help reduce anxiety and stress in dogs.

What to Do if Dogs Get Aggressive With Each Other?

Have you actually seen two dogs get into a fight before? Some are pretty harmless and they get away from each other in a matter of seconds.

However, there are times when the emotions really run high and they are biting and not releasing their grip.

I can tell you, most dog owners do not know what to do in such a situation and when you’re so flustered, it’s easy to make a mistake.

Below, you will find some steps and advice that will work in most cases, but in an extreme case like I mentioned, you should use the last method right away.

Stay calm

Take a deep breath and stay cool!

Remember that your dog may view you as the top dog and take their cues from your actions.

Dogs can pick up on your energy, so staying calm helps prevent the situation from escalating and allows you to handle it more effectively.

Interrupt the aggression

Diverting the attention of your pet when they show signs of aggression may help prevent things from getting worse.

Use a loud noise like a clap or a firm “NO!” to interrupt the growling.

This will help break your dog’s focus and potentially stop the aggressive behavior in its tracks.

Separate the dogs

Obviously, your dogs won’t be able to hurt each other if you separate them.

You can physically prevent them from reaching the other by using a baby gate or a leash.

Doing so will prevent further conflicts and allow your pet to calm down.

Use the wheelbarrow method

If you need to separate two dogs physically, you can use the wheelbarrow method.

This maneuver will require two people to grab the hind legs of each dog and pull them away from each other.

This hold will allow you and your companion to keep the dogs separate and prevent them from lashing out and injuring each other.

Choke the offending dog

The title might sound crazy but let me explain.

If you attempt to hit the dogs or use external stimuli like water or an air horn, you’re just going to aggravate the dog further.


Instead, using a leash to form a self-closing loop and putting that around the dog’s neck, you can temporarily choke the dog, during which it will release its grip, and you can then move the dog elsewhere.

Alternatively, if you’re able to, you can slip your palm underneath its collar, pull it up, and give it a bit of a twist. This action too will choke your dog enough for it to release its grip.

When to Seek Professional Help?

Dealing with dog aggression can be tough, but you can always reach out for help.

If your dog’s aggression isn’t improving despite your best efforts, or if you’re worried about safety, it might be time to call in the experts.

A certified dog trainer or a veterinary behaviorist can provide specialized guidance and create a customized plan for your furry friend.

They can help if your dog’s aggression is persistent or escalating, or if you’re feeling unsafe or overwhelmed. 

Not just that, but you can also rule out any medical causes and address anxiety or fear-related aggression.

Frequently Asked Questions (FAQs)

Are certain dog breeds more prone to attacking other dogs?

Yes, some dog breeds may have a higher likelihood of displaying aggressive behavior towards other dogs due to genetics, upbringing, and socialization, but it’s not solely determined by breed. Training and socialization will still play a bigger role in whether your pet will exhibit aggressive tendencies.

Why does my dog become aggressive after sniffing another dog during walks?

Dogs may become aggressive after sniffing another dog due to fear, resource guarding, or other triggers that cause them to feel threatened or anxious. This can be curbed through proper training and socialization.

Can neutering or spaying help reduce the likelihood of my dog attacking others?

Yes, neutering or spaying may have some impact on reducing aggressive behaviors in dogs, but it’s not a guarantee. Other factors such as genetics, training, and environment also play a significant role in the likelihood of your dog attacking others.

In Conclusion: Dog Sniffs Other Dog Then Attacks

I know it can be scary and frustrating when your dog is reactive and shows lots of aggression, but I can assure you that with proper training and management, you can help your dog overcome this behavior!

For more fetching content and tail-wagging tips, check out these other posts too:

Share this post!
Zack Keithy
Zack Keithy

Hey, I'm Zack, the Chief Editor here. I was formerly a Certified Veterinary Technician (CVT) for a good 6 years before moving on to greener pastures. Right now, I am still heavily involved in dog parenting duties, and it is my desire to share all our knowledge with fellow dog owners out there! Connect with me on LinkedIn, or read more about Canine Care Central!


  1. I have recently taken on a 7 year old male maltipoo who was neutered 3 weeks ago. He has had very little interaction with other dogs and has little idea of walks apart from up and down a street and a garden, but gets on with my Yorkie and Yorkie mix. He has learned some recall, but runs to other dogs, sniffs then lunges on them barking and growling. Some dogs snap back and he walks away, others don’t react and he has the upper hand. Obviously owners aren’t happy and I wouldn’t be either if the situation was reversed. He is on a training lead when out in the fields and will follow me but doesn’t always react to commands s.g. Calling his name or “come”. Please could you give some advice as to what to do in this situation. Thankyou.

    • Hey Janette, sorry to hear about your situation. The post has a lot of tips that you can use, and I highly recommend you to check them out. But what’s most important is to stick to at least one method and be consistent. And that means doing it day after day. You should see improvements over time. And the great thing is that you have 2 other dogs which you can “use” as a means of socialization. I would also encourage you to seek out other dog owners to interact with their dogs (under close supervision of course) where you can conduct proper training. If you really do not see any improvements after 2-4 weeks, I would then recommend finding a professional trainer. Sometimes, we simply do not have the right skills or “eye” to figure out what’s wrong, and that’s where a professional comes in. Best of luck and keep me posted!

Comments are closed.

no more bad dog breaths banner