Like us, older dogs can experience lower energy levels, less tolerance for exercise, increased pain, reduced mobility, and cognitive deterioration. This can influence how they learn and behave. Normally, this happens because of underlying medical conditions, rather than age itself. Lower energy and exercise tolerance can leave dogs feeling less able to cope. Age-related conditions like canine cognitive dysfunction syndrome (like Alzheimer's in dogs) can leave them feeling confused, anxious and more likely to use aggressive behaviours. Pain strongly influences the use of aggressive behaviours. Conditions such as Arthritis, which cause long term pain, are likely to be more noticeable in older dogs due to disease progression. The fear of getting hurt, and the limited behavioural responses due to reduced mobility (like moving away) can make aggressive behaviours more likely. Less flexibility with routines and difficulty adapting to new environments. Changes in sleeping, eating, drinking, or toilet habits linked to medical conditions are more common in older dogs. Although medical conditions can be worrying, your dog may never have to deal with any. And not all dogs suffering from medical conditions will use aggressive behaviours. This is why regular vet visits are essential. If you see any changes in your dog , seek professional help from your vet and our behaviour services. It could help to prevent future aggressive behaviours.

Dog aggression: causes, warning signs and how to help

Are you worried about why your dog is displaying aggressive behaviour? Find out how you can help them right away.

39 min read

Illustration of a man thinking about a dog that is in a yellow speech bubble

Reviewed by:

Behaviour team

Aggression is generally used to describe a group of behaviours when there is a perceived risk of harm. This includes biting, lunging and growling. If your dog uses aggressive behaviour, we know how upsetting this can be.

You likely feel lots of different emotions, but please don’t feel alone. We’re here to help.

Resolving aggressive behaviour can feel impossible at times, but with the right training and support, things can get better.

Jump to section

Our phone lines are open Monday to Friday 8:30am to 7:30pm; Saturday, Sunday and bank holidays 9.30am to 5pm.

Tips while waiting for help

Prioritise safety - avoid triggers or situations that cause your dog to use aggressive behaviour. This might mean keeping them physically separated from the trigger.

Management options like baby gates can help with separation in the home. Avoid incidents when out by hiring secure fields to walk in.

Make an appointment with your vet to rule out underlying medical problems.

Keep a record of your dog’s behaviour: where it occurs, when it occurs and other potential influences.

What happens on the call

When you call our Behaviour Support Line, our team will listen carefully, offer practical advice, and help you find the best way forward for you and your dog.

Our trained experts keep up-to-date with the latest science and offer immediate, personalised advice over the phone. We’ll ask a few questions about your dog and what’s been happening, and you’ll have the space to explain in your own words what you need help with. Whatever challenges you’re facing, you’ll get kind, non-judgemental support.

In many cases, a free telephone consultation will give you all the support you need. We’ll also follow up with an email so you have clear, helpful information to refer back to.

If needed, we may also recommend one of our other behavioural services. We’ll talk you through what this involves, answer any questions, and help you arrange the next steps.

Quick wins: what to do if your dog shows aggression

If your dog shows aggressive behaviour, your priority is to keep everyone safe and help your dog feel calmer.

Pause and create space. Stop what you’re doing and give your dog space. Increase the distance between your dog and whatever is causing them to respond this way. Calmly move away from noise, crowds or busy areas to help them relax.
Safely separate. Use leads, baby gates, doors, or other barriers to prevent close contact. At home, calmly move your dog behind a gate or into another room. Outdoors, change direction or move behind a visual barrier like a parked car.
Stay calm. Avoid telling your dog off so the behaviour doesn't intensify.
Seek support. Seek medical attention in the event of injury to humans. As well as getting injuries to your dog checked by your vet, they should also have a full health check to rule out any underlying medical problems.
Witnessing or experiencing dog aggression can be traumatic. Seek support if you or anyone involved is struggling with the emotional impact.
Contact a qualified behaviourist. Our behaviour services include clinical behaviourists, behaviour coaches and qualified experts. We can also offer free, immediate safety advice by phone.
Make a record of the incident. This will help you to avoid similar situations and triggers in future. A behaviourist can also use this information to create a plan of support.

What is aggression in dogs?

Dogs are naturally very social and cooperative animals. When they behave aggressively, it’s usually because they feel that they, or something they value, is under direct threat.

When dogs feel threatened, they usually try to increase the distance between themselves and whatever the perceived threat is.

They might:

avoid the thing that is worrying them by moving away
show ‘appeasement’ behaviours to diffuse the threat or situation, e.g. ears back, lip licking, tail under, rolling onto their back, cowering
show aggressive behaviour, ranging from a bark or growl to a bite.

Their response will depend on:

past learning and what’s worked before in a similar situation
the choices available to them at the time, e.g. moving away might be their first choice, but this might not be possible
how ‘intense’ the dog feels the threat is.

If we can recognise and respond to early signs of fear or discomfort in dogs, they’ll be less likely to communicate by lunging, baring teeth, snarling, growling, snapping, or biting.

Dogs that use aggressive behaviours often are sometimes called ‘dominant’ or ‘reactive’. These labels aren’t helpful, as they imply that it’s part of the dog’s personality and can’t be changed. Instead, aggressive behaviours are an emotional or pain-led response to a trigger. They happen because of how a dog feels, and feelings can be changed.

Common signs of aggression

Generally, dogs use aggressive behaviour when they feel threatened and need space. Dogs showing aggressive behaviour should be given space immediately.

You may see some or all the following:

Barking – low pitch vocalisations that are short in duration. They start and end abruptly with one bark normally followed by another in rapid succession.
Growling – a deep, rumbling vocalisation that is much longer in duration than a bark. Aggressive growls are low-pitched and the volume can increase significantly.
Stiff body posture – tension in the muscles of the body cause the dog to appear rigid. There is likely to be little to no movement. Weight may be shifted forwards or backwards.
Staring – a direct, and fixed, intense stare at the perceived threat. The eyes are likely to be wide with dilated pupils. Often referred to as a ‘hard stare’.
Raised hackles – hair raised along the spine – this is a physiological response and not something the dog can control. This could be the full length of the spine, only at the shoulders or only at the base of the tail. Can also be a sign of overarousal.
Snapping – a fast open and snapping shut of the jaw that is close to contacting the target of the behaviour but doesn’t. This behaviour often happens as the dog jumps forward and is often misunderstood as a dog trying to bite but ‘missing’. The behaviour is a warning to give the dog space, or they might follow up with a bite that makes contact.
Baring teeth – tension in the face and ears while pulling the lips back to show teeth.
Lunging – a sudden leap or jump towards a perceived threat. As with snapping, the goal of the behaviour is to increase the distance between the dog and the target by threatening physical conflict.
Biting – considered by most people to be the most aggressive behaviour. Biting occurs when the teeth of the dog contact the perceived threat.

These behaviours may be used in combination with other signs of fear and anxiety, and don’t always get stronger gradually. Some dogs might vary which behaviours they use and in what order depending on what has worked in the past. The pictures below show what a combination of behaviours might look like.

Image 1 of 2

illustration of a dog showing aggressive behaviour such as: staring, snarling, tail help up and out, tension in the body, weight forward and forward, upright ears

illustration of a dog showing signs of aggression such as: tail tucked, ears back, head low, growling, showing teeth and leaning away

Understanding your dog's body language

Dogs are always communicating. They use facial expressions, body language and vocalisations to show their feelings. It’s extremely rare for there to be no other warning signs before a dog behaves aggressively.

It’s important to know your dog well so you can intervene early and stop them from feeling the need to use increasingly aggressive behaviours. To do this, we need to understand their body language and recognise when they feel anxious.

How to understand your dog's body language

Signs your dog is feeling anxious

If your dog feels anxious or fearful, they might turn away, tuck their tail, cower, freeze or stare. They’re trying to communicate how they feel without using aggressive behaviour. We can respond to these signs by giving our dogs space or creating distance from the potential threat. If these signs are missed or ignored, your dog might escalate to using aggressive behaviour such as growling, snapping, lunging, or biting to get their message across.

Signs of anxiety and fear

Have a go at watching your dog. Can you work out their likes and dislikes from reading their facial expressions and body language? How do they show you what they’re feeling?

Feeling confident with your dog body language skills? Take our fun quiz!

Most common triggers for dog aggression

Aggressive behaviour is often led by strong emotions. If we know how our dog feels, it’s easier to understand why they behave a certain way. This is the first step in changing their behaviour.

Fear and anxiety – most common reasons for aggressive behaviour. The goal is to drive the perceived threat away. This can happen when a dog is startled, anticipates something scary, faces a known scary trigger, or encounters something unfamiliar.
Frustration – occurs when a dog’s needs or expectations aren’t met. They’re unable to get to or move away from something, or if there are barriers to what they want. For example, a lead preventing social interaction.
Pain – a big factor in dog aggression. The aggressive behaviour could be a reflexive response to sudden, acute pain or because of a longer-term illness or injury causing chronic pain. The aggressive reaction is defensive behaviour by the dog so they can protect themselves and avoid further pain. Dogs in pain or discomfort are less resilient and tolerant of others.
Resource guarding – occurs when a dog is worried about losing access to a favoured resource. This could be food, toys, people or rest spaces. The goal is to drive the perceived threat away.
Overstimulation – dogs get overwhelmed, too. When things mount up, we might see aggressive behaviour. The behaviour seems unpredictable, but it’s a result of lots of triggers and stressors building up – we call this trigger stacking.
Learnt response – dogs learn from every situation. They can learn that aggressive behaviour works to make a threat move away, which creates a sense of safety and relief. Dogs repeat behaviours that work. The more dogs repeat aggressive behaviours over time, the stronger and more habitual they can become.

Why do dogs become aggressive?

Aggressive puppies and young dogs

Dogs are naturally social animals. When they show aggression, it’s normally a sign they’re feeling scared, stressed or threatened by something.

There are many factors that can influence our dog’s behaviour, including genetics, early learning, continued learning through life, and physical health and wellbeing.

Inherited traits – like us, all dogs are individual with a unique genetic makeup. Some dogs may be more anxious than others, or prone to frustration. However, having a genetic predisposition doesn’t guarantee a dog will behave in a particular way.

Maternal stress – stress experienced by the mother during pregnancy can negatively affect her puppies. They may be more anxious and less resilient as a result. This highlights the importance of getting a puppy responsibly.

Socialisation window – a dog’s early experiences during critical development periods (typically between 3 to 14 weeks of age) have a lasting impact on their emotional stability and ability to cope with fear and frustration. Positive and neutral experiences during the first four months of life help to build confidence and establish what is ‘normal’. Negative experiences and things not experienced during this time may result in fears being established and problems developing into adulthood.

Play biting and mouthing – puppies explore, learn and play with their mouths. This can sometimes look (and feel) like aggression, but it’s normal puppy behaviour. We need to teach them what they’re allowed to chew on and how to play appropriately.

Social behaviour – puppies can learn unhelpful behaviour from dogs that struggle to communicate. Good role models have long lasting, positive effects on social behaviour.

Rule changes – puppies get a certain amount of leeway for behaviour perceived as rude by both humans and other dogs. For example, puppies might be allowed to jump up at people and get lots of attention for this. As they grow this may change and the dog might become confused or frustrated that they’re no longer allowed to greet in this way.

Overarousal – young dogs can become overstimulated and overwhelmed quickly. Rising levels of excitement, frustration or stress can lead them to bark, jump and mouth as they struggle to cope. This appears aggressive, but it’s normally a sign of needing a good rest.

Trauma – bad experiences when young can have long-lasting effects.

Fluctuating hormones – adolescent dogs may become more easily frustrated, impulsive and less able to manage their emotions. Things that didn’t worry them as puppies might suddenly seem scary. With the right support, these fears are usually temporary.

Training methods – punishment-based training methods can cause emotional states that lead to dogs using aggressive behaviours. Research also suggests that inconsistent training methods are linked to the use of aggressive behaviours.

Older dogs

Like us, older dogs can experience lower energy levels, less tolerance for exercise, increased pain, reduced mobility, and cognitive deterioration. This can influence how they learn and behave. Normally, this happens because of underlying medical conditions, rather than age itself.

Lower energy and exercise tolerance can leave dogs feeling less able to cope.
Age-related conditions like canine cognitive dysfunction syndrome (like Alzheimer's in dogs) can leave them feeling confused, anxious and more likely to use aggressive behaviours.
Pain strongly influences the use of aggressive behaviours. Conditions such as Arthritis, which cause long term pain, are likely to be more noticeable in older dogs due to disease progression. The fear of getting hurt, and the limited behavioural responses due to reduced mobility (like moving away) can make aggressive behaviours more likely.
Less flexibility with routines and difficulty adapting to new environments.
Changes in sleeping, eating, drinking, or toilet habits linked to medical conditions are more common in older dogs.

Although medical conditions can be worrying, your dog may never have to deal with any. And not all dogs suffering from medical conditions will use aggressive behaviours. This is why regular vet visits are essential.

If you see any changes in your dog, seek professional help from your vet and our behaviour services. It could help to prevent future aggressive behaviours.

Rescue dogs and new environments

The first few days after you bring your rescue dog home can be the hardest. Everything is new and this can leave dogs feeling overwhelmed and vulnerable. They’ll have lost access to the people and places they could trust and feel safe in. With time, they’ll adjust to their new routine, family and home. Allowing your new dog to do this at their own pace will reduce the likelihood of aggressive behaviours developing.

Other contributing factors include:

Some rescue dogs may have little to no experience of living in a home, so may feel scared or excited.
New smells, sights and sounds can be confusing and disorientating.
Unfamiliar environments can make dogs feel vulnerable. They don’t know where to go to feel safe if they’re worried.
Exposure to new triggers or to old triggers in new places they’re unfamiliar with.
Getting to know and trust new people can be daunting. Relationship building takes time, and the dog might feel overwhelmed if rushed.
Some dogs may be more worried about being left while they find their feet. They might need help to feel relaxed at first. Or they could focus their anxiety on a single person.
Family and friends are likely to be keen to meet your dog. This could be very overwhelming, especially in the early days.
Dogs often have preferred routines and may need time to adjust to change.

We have lots of advice on training at home that may be useful for your new addition to the family.

If you have any concerns, speak to our Behaviour Support Line to see how we may be able to support you.

Changes in routine or environment

Generally, dogs are creatures of habit that thrive when they know what is expected of them. Having a good routine helps them learn, be confident and feel safe. Creating a routine can be particularly useful for young dogs and anxious dogs.

Once a routine is established, it can be harder for dogs to adapt to changes and be flexible. They may need more time to adjust – especially as they get older. Gradually adding some variation to your dog’s daily routines helps build resilience to change. Variation can also benefit dogs that need novelty and change to prevent boredom.

Common aspects of doggy life that can be included in a routine:

food
walks
going to the toilet
play
training
rest/relaxation
sleep
time together.

Change is an inevitable part of life. Dogs find change harder than we do, although some deal with it better than others.

In a dog’s life they might come across some, a few, or all the following types of change:

New homes and holidays – even a temporary relocation can be stressful for some dogs. There’s a lot of change to their daily routine, and plenty of unfamiliar sights, sounds, and smells.

Visitor anxiety – some dogs get very excited when visitors arrive, while others might feel like their space is invaded. They may need time, complete separation or a safe space to relax in to help them cope.

Owner stress – dogs have spent thousands of years learning to read us. As a result, they’re often strongly influenced by how we feel. If we get stressed, it’s quite likely that our dogs will pick up on it and feel unsettled as a result.

New family – when dogs first move to a new family, it can take time for them to settle. They may feel anxious while they get used to their new home.

New baby – babies bring big changes. They’re noisy, make unfamiliar smells and mean owner attention is now shared. There may be changes to your dog’s routine and visitor numbers. Your dog may feel anxious, excited, worried, confused or frustrated.

New job – a new job can affect your dog in lots of ways. For example, changes to mealtimes, walks, a change from working from home to working in an office, walking in different places and reduced time together.

Loss of another pet – dogs can form strong bonds with other animals as well as their human family. The loss of a companion can leave the surviving dog clingy, anxious or more sensitive to things going on around them.

Frustration – without a routine, it’s hard for your dog to know what you expect of them. If we’re working, for example, we probably expect our dogs to settle down and relax. If this isn’t a routine though, they don’t know this and might become frustrated at the lack of interaction or activity.

Food aggression and resource guarding

Dogs can show aggressive behaviours when they fear losing something they value. What a dog finds valuable depends on the individual, so this behaviour could apply to anything. But food, toys and chews are the most common.

In some cases, this behaviour might be extended to worrying about losing access to loved ones. We call this type of aggression resource guarding. This behaviour could be directed towards humans, dogs or other animals.

Dogs that resource guard may show some or all the following behaviours:

standing over something they value, with a very stiff and still posture
taking something and running away with it
hiding an item (for example, burying it in the garden, in their bed, or behind the sofa)
eating very fast
lowering their body posture
growling when approached
swallowing items.

If your dog resource guards, seek expert help from your vet and a clinical behaviourist. Resource guarding can be linked to health problems, so a clean bill of health is important before any training can take place. Avoid telling your dog off or removing an item they might guard as this could make them more worried and intensify their behaviour.

Redirected aggression

Redirected aggression can happen when a dog becomes overwhelmed by their emotions and can’t reach whatever is causing them to feel this way. Redirection is often a result of frustration but can also be a result of fear or overarousal (high excitement or stimulation). If a dog can’t reach or respond to the trigger in the way they want or expect to, they may redirect their feelings into aggression towards someone or something nearby.

A highly social dog that is restricted by a lead may become frustrated if they can’t reach another dog. Especially if they expect to interact with all dogs they see. This frustration can lead to redirected aggression. The aggression might be directed towards their owner, the lead, or may result in an aggressive display towards a nearby dog. This is why context is so important when working with aggressive behaviours.

The behaviours that you might see are:

jumping up
barking
lunging
snapping
ragging the lead
grabbing at clothing
growling
nipping
freezing
biting.

Check out our advice on how to stop unwanted behaviours.

It’s important to remember that the more often your dog uses a behaviour, the more likely it is to become a habit. For the best results in resolving this behaviour, we recommend speaking with a qualified professional.

How to stop aggressive behaviour in dogs

Aggression shown in the home can be very upsetting. Especially when it’s directed at you or your family. There are lots of reasons why dogs might behave this way. Try to identify why your dog is behaving this way and remember that it’s not personal.

Aggressive behaviours are your dog’s way of saying they’re struggling and need help. With the right support, aggressive behaviours are not only manageable, but can be dramatically improved.

It’s important to recognise that under the Dangerous Dogs Act 1991, it’s against the law to let a dog be dangerously out of control. This applies in public and in private. For example, a park, your home, or a neighbour’s house. This section of the law is not breed specific and applies to all dogs.

Aggression in the home

Towards adults in the home

If your dog shows aggressive behaviour at home, prioritise safety. Seek help from a clinical behaviourist, like our behaviour support team. Early intervention stops the behaviour from getting worse. This reduces the likelihood of the behaviour becoming fully established and habitual.

In addition to the quick wins and daily habits on this page, here are our additional tips that might help:

As much as possible, avoid the situations or interactions that cause your dog to show aggressive behaviour.
Use management to reduce exposure to triggers. For example, baby gates to prevent access to the front door or feeding your dog in a separate room.
Tidy up all items that could cause conflict between your dog and other members of the family as soon as you’re finished with them. For example, empty food packets, children’s toys and plates of food.
Provide a safe space for your dog so they have somewhere they can retreat. They should not be disturbed while using it.
Train your dog to be relaxed left alone before you need to separate them.
Avoid fussing your dog if they’ve become sensitive to handling. Make an appointment with your vet to rule out illness or injury.
If your dog wants attention, stroke them for a few seconds, then pause and remove your hand so they can choose to stay or move away.
Keep changes to routine minimal to avoid upset or anxiety.
If your dog is struggling, allow plenty of rest and opportunities to do what they love best, like enrichment. This will help to reduce overall arousal and stress.
Forcing them to push on and risk exposing them to triggers can increase the likelihood of aggression.

Towards children in the home

Children are usually less likely to notice the warning signs that dogs use.

If your dog is showing aggression to the children in your home, keep them completely separate from one another. They should not interact without professional, qualified guidance from a clinical animal behaviourist.
Even if your dog has never used aggressive behaviours towards your children, they should never be left alone together. Interactions should be closely and actively monitored for safety.
Encourage your children to recognise the signs of anxiety in dogs. Teach them how they should respond.

Find more detailed information on living happily together with dogs and children.

Towards other dogs in the home

Even the best of dog friends need a break from each other sometimes. Like us, tension can build without time apart, and competition for resources can bring challenges.

If your dogs get into conflict, there are some immediate steps you can take.

Separate your dogs - be careful to not put your hands between them. If they don’t respond to you calling them, you can try making a loud, non-human noise.
Stay calm and positive. Encourage your dogs to move either side of a solid barrier.
Avoid telling your dogs off or leaving them to ‘work it out themselves’. Each of these options risks intensifying the behaviour.
Check for injuries if physical conflict has occurred and seek veterinary help if needed. Remember, if there has been a dog bite, the surface wound can look relatively minor, but damage to deeper structures can be much more severe. So, it’s important to get your dog assessed by a vet.
Give the dogs involved time and space away from each other to cool off. Offer an appropriate enrichment activity each to help them relax.
Call our free Behaviour Support Line for immediate advice on your specific situation. They can also connect you with our clinical behaviourist team to resolve any underlying behaviour concerns.
We recommend getting both dogs checked by a vet to see if underlying medical factors might be affecting either dog’s behaviour.

Daily habits that help:

Ensure there is at least one bed and water bowl per dog plus a few extras. Keep access to spaces and resources wide and clear.
Supervise interactions and watch your dogs’ body language for signs of stress.
If you notice signs that either dog is stressed or anxious, like walking away from the other dog or lip licking, increase the distance between them. Call one dog away and encourage them to relax in their individual beds.
Separate your dogs when you’re unable to supervise them puppy pens, baby gates and crates can be useful or put your dogs in different rooms.
Give food, toys and chews when dogs are separated. Anything given when the dogs are together should be low value to minimise competition.
Reduce frustration by not fussing and playing with one dog in front of the other
Offer daily breaks from each other. For example, separate walks, play sessions or grooming.
Support the path of least resistance and enable your dogs to avoid one another if they want to.

Towards visitors to your home

If your dog shows aggression to visitors, it’s best to seek expert help.

In the meantime, the most important thing is to make sure everyone is safe. Here are our top tips:

Ensure safety. Keep visitors separate from your dog. They might need help to relax alone at first. A safe space could help with this. Avoid visitors walking past your dog.
Keep them busy. While your dog is alone, use enrichment, food toys and long-lasting chews to encourage calm behaviour.
Manage your visitors. Where possible, try to avoid visitors for the time being. If visitors do come, try to find out their expected arrival time, then settle your dog in advance. Ask them to call or message when they arrive if your dog reacts to the doorbell.

You can set up a safe space for your dog straight away and start teaching them how to relax alone if it’s something they struggle with. With time, patience and professional support you, and your dog, will be relaxed when there’s a knock on the door.

At home aggression prevention plan

If you understand your dog and can tell when they’re worried, you’ll be able to respond appropriately. This will help to keep you, your dog and others safe.
Always closely and actively supervise any interactions between dogs and children. They’re not always able to tell how a dog feels.
Avoid disturbing dogs while they’re sleeping, relaxing in their safe space, or eating. These are times when conflict is more likely.
Identify what triggers, if any, your dog has that causes them to use aggressive behaviour.
Limit your dog’s exposure to triggers. If your dog is aggressive to delivery drivers, you could try blocking their view of the person approaching with window film. Or you could collect your delivery from a drop-off point. If a delivery driver does come to the door, make sure your dog is safely behind a baby gate or door before they arrive.
Regular vet visits help to spot illness or injury as early as possible. If you notice changes in your dog’s movement, behaviour, eating, drinking or toilet habits, get them checked out straight away.
Seek the support of a behaviourist, especially if your dog’s behaviour is affecting either of your welfare, or anyone else’s. We can help with this.
Always make sure your dog has the choice to move away from anything they’re not comfortable with.
Teach cues for hands-off management. For example, a ‘leave’ command is useful if your dog picks things up. Teaching a ‘touch’ or ‘off’ cue can move them without force.

Aggression outside the home

Dogs that show aggression outside of the home are often referred to as ‘reactive’. They’re normally worried or frustrated by things they see on a walk. For example, people and other dogs.

If your dog is aggressive outside of the home, you’re likely to see some or all the following:

lunging, barking, growling or snarling at another person or dog
frantically bouncing around - they may try to get out of their collar or harness
nipping another dog they’re walking with
grabbing your clothing or body and shaking it
ragging on their lead
jumping and snapping at you or another person or dog
biting another person or dog or redirecting that aggression towards you.

You can find in depth advice on how to help your dog if they show aggressive behaviours outside the home on our reactive dogs page.

Reactive dogs: why it happens and how to help

When to seek professional help

Vet check

Changes in a dog's behaviour are often influenced by their physical health, even when there are no obvious signs of pain or illness. Some medical issues are subtle, develop gradually, or are masked by dogs coping well, so even very attentive owners may not notice anything wrong.

You should seek veterinary advice if your dog suddenly starts to display aggressive behaviour or if there are changes in your dogs usual behavioural responses.

A visit to your vet is a supportive first step. It could rule out any medical causes or fix the behaviour. Knowing your dog is healthy will make any behaviour support and training clearer, fairer, and more effective for you and your dog.

To help your vet assess your dog's behaviour, it can be helpful to bring along any videos, diaries or notes you have to your appointment at the vets. Speak to your vet when booking if you think it'd be useful to have a detailed conversation before the physical exam.

Professional behaviourist support

We understand that it can be difficult to manage aggressive behaviour, and that it can put a strain on relationships, as well as your ability to relax. If you need help working out why your dog is showing signs of aggression, or a friendly listening ear, our experts are just a click or call away.

Contact our Behaviour Support Line, request a call back from an expert, or book a support package now. We help thousands of dog owners every year. Our team can offer a wide range of support depending on what you feel is best for you - even if it's just to check you're on the right track.

Real owner stories: you're not alone

Rupert, a two-year-old Labradoodle, used aggressive behaviour to communicate how he was feeling. Understandably, this left his owner, Margaret, feeling increasingly worried and overwhelmed.

Calling our free Behaviour Support Line gave Margaret the chance to talk things through with someone who really listened. Our behaviour experts offered practical advice straight away, along with a referral for further support.

I was so desperate for help and have spent over £1,000 on trainers. This is the first time I felt truly listened to and understood. Thank you so much for providing this service.

Margaret, Rupert's owner

Contact our behaviour services

Whether you’re facing a tricky behaviour or feeling completely overwhelmed, we’re here to help. Our team of experts can offer advice, training and support.

Call us on 0303 003 6666

Get in touch today

Our free telephone service is open Monday to Friday 8:30am to 7:30pm; and 9:30am to 5pm on weekends and bank holidays.

FAQs about dog aggression

Is my dog being aggressive or just playing?

If you’re worried your dog is using aggressive behaviours when playing, here are a few things you can do.

Stop and give space. If they run back and re-start the game, no harm is done. If they relax a little, you made the right call.
What is your dog’s body language saying? Do they look tense? Is their body posture low or very stiff? Wiggly bodies are a good sign of being relaxed.
Are they showing signs of anxiety, like lip licking, yawning or moving away?
Try to pinpoint what you find concerning with their play. Growling can be normal so isn’t the most reliable indicator.
Do they have a history of resource guarding? Does your dog freeze over toys or try to stop anyone else from getting them?
Add regular, short breaks to play to prevent tension and allow your dog to disengage. Try tugging for a few seconds before a short break of a few seconds. Remember to swap the toy you’re using for treats, so you don’t need to take it away from them.
There’s a myth that dogs shouldn’t win a gentle game of tug. But it’s okay to let them win. Winning games is great for building confidence, builds bonds between you, and acts as a reward. Losing frequently would be demotivating and quite frustrating. Allow your dog to play in the way they enjoy most. For example, shredding them (keep a careful eye to make sure nothing is ingested). This can help to reduce their arousal and help them to calm down.
Ask for help. You don’t need to try to work this out alone.

We have tons of free advice on our website, and understanding your dog is a great place to start to help you spot your dogs playful signs! so go have a browse.

Why is my dog aggressive all of a sudden?

Sudden changes in behaviour can mean that all is not well with your dog. A common reason is an underlying medical condition. The first step should be to visit your vet for a full health check. If your dog gets a clean bill of health, speak to a qualified behaviourist.

What should I do if my dog growls at me?

If your dog growls at you, stop what you’re doing and give them space.

Growling is a normal part of dog communication. There is often a difference in how growls sound. For example, growling as part of aggressive behaviour sounds like a long, low rumble that comes from deep inside. A play growling is likely to sound quite different and may be accompanied by other vocalisations. This can vary between individuals. Understanding your dog will help you recognise how they feel. In any circumstance, giving your dog space is the least risky option. Continuing when they’ve asked you to stop risks them escalating their behaviour.

If your dog growls, avoid telling them off. This could damage your bond, make them feel more worried, or cause them to escalate their behaviour. Growls are an early warning system. Telling them off for growling may stop them from doing it, but the emotion behind the growl will remain. This could lead to them biting without warning instead.

If you know why your dog growled, avoid a similar situation occurring again. If you’re unsure why your dog growled or you need behaviour support, our friendly behaviour services team are just a phone call away. We have experts on hand for immediate advice, and behaviourists and behaviour coaches for practical support if needed.

Why is my dog aggressive to my other dogs?

Dog-to-dog aggression can be challenging at times – whether that’s in the home or outside of it. And there’s lots of reasons why a dog might behave aggressively towards another dog. This page has information on multi-dog households.

Check out our reactive to dogs info if your dog sometimes behaves aggressively while out and about.

If you’d like to speak to a professional for support and advice, our Behaviour Support Line experts are ready and waiting for your call.

My dog bit someone - what now?

We understand how traumatic it can be if you experience or witness a dog bite. You might be feeling guilty, scared and worried for both the other person and your dog.

If your dog bites someone, take the following steps:

calmly secure the dog behind a barrier or on a lead
separate your dog and the person to reduce stress
seek medical attention for injuries, and veterinary advice for your dog
avoid telling your dog off —this can worsen fear and aggression
in the following few days, keep the environment quiet to allow your dog to recover
seek professional support.

Can neutering help with aggression?

Neutering is the general term used for the surgical removal of the reproductive organs in both male and female dogs. We normally refer to neutered males as castrated and neutered females as spayed.

Studies show both benefits and risks to behaviour associated with neutering, but results are conflicting. There are many factors that influence the likelihood of an individual showing aggressive behaviour. While hormones are a factor, neutering won’t account for inherited traits, environmental factors, developmental factors or prior learning. Whether this is beneficial, detrimental, or of no consequence depends on the dog concerned.

For further advice, speak with your vet about the neutering process and our behaviour services for behaviour questions.

Is it ever too late to help an aggressive dog?

Dogs are always learning. This means that their feelings and behaviours can change throughout their lives. It’s equally true that the more a dog practises a behaviour, the more likely they are to use it in the future. Especially if the outcome is successful from the dog’s perspective.

Aggressive behaviour is normally a display of how a dog feels. This means that dogs that use it regularly may not be having their needs met. If we help these dogs, not only is safety improved for all, the welfare and behaviour of the dog can be dramatically improved. It’s certainly never too late to try.

When considering what help a dog displaying aggressive behaviour needs, it’s important to manage our own expectations. A dog who is afraid of other dogs might have shown aggressive behaviour for a long time. It’s not realistic to think they’ll become sociable with all dogs they meet. It might be possible to walk past dogs on the other side of the street without a reaction, though.

It's a sad fact that some dogs experience things in life that traumatise them. The welfare of these dogs may be poor and opportunities for help limited. The best way to be sure is to speak with your vet and a clinical behaviourist. They’ll be able to guide you through all options available.

Should I punish or discipline my dog for aggression?

If you tell your dog off for using aggressive behaviours:

they may become more stressed or worried. This could lead to them intensifying their aggressive behaviour
it can damage your bond, and they may become afraid of you
their negative feelings towards the trigger may increase
they may no longer communicate when they’re worried which removes your warning system that something is wrong.

Will a vet euthanise an aggressive dog?

In some cases, euthanising an aggressive dog might be the kindest option available. Dogs that regularly use aggressive behaviours, will be struggling emotionally. This severely affects their welfare. The good news is that there are many options for support available before this point is reached.

If your dog shows aggressive behaviour, it might be difficult to believe things can get better. Most dogs can be supported though, and the emotions driving their behaviour can be changed. If you’re asking yourself whether euthanasia is the best option for your dog, please call us. We have professional experts and clinical behaviourists that can support you at all stages of your journey.

What is the most common reason for aggression in dogs?

Most cases of aggressive behaviour come from fear, anxiety, and medical concerns. While most aggressive behaviours are designed to avoid physical conflict, they must still be listened to.

If behaviours intensify, it shows that the dog’s feelings are also intensifying. An increase in the intensity of aggression normally shows that the dog’s fear is significant, and they’re clearly stating their need for space.

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