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Dog aggression is a serious and potentially dangerous behavior. The snapping, snarling, lunging, and barking are impossible to ignore and the last thing you want to see in your dog. It’s extremely stressful to own a dog that exhibits these behaviors. Aggression can also erode the dog-human bond, and often leads to isolating the dog from people and other animals. But although aggression can be easy to recognize, it can be harder to define. What is dog aggression exactly, and what is the motivation behind it?

Read on to better understand your dog’s aggressive behavior. The knowledge will ease your emotional burden, make you a stronger advocate for your dog, and help you teach your dog better ways to cope.

What Is Dog Aggression?

Dog aggression is often an “I know it when I see it” type of behavior. However, the definition can vary according to who you ask. An ethologist might say aggressive behavior is behavior directed toward the elimination of competition. You can also label it as any harmful or threatening behavior used by a dog.

Dog aggression expert and certified dog behavior consultant Michael Shikashio, CDBC, likes to simplify things by focusing on the function. “I define aggression as behavior used to increase distance from or eliminate a provocative stimulus or threat,” he explains. Typically these behaviors are used by dogs to avoid an escalation of conflict, increase distance from a target, or cause damage to the target.

In other words, the dog exhibiting aggressive behavior wants more space even if they have to attack the threat to get it. It’s not rough dog play, even though people sometimes struggle to distinguish playing from dog fighting. It’s also different from predation, where the goal is to get closer until the dog can catch and eat the prey.

Dachshund puppies playing together in the grass.

When to Get Help With Dog Aggression

Dog aggression is difficult to handle without professional help. First, safety is your primary consideration. Second, it’s emotionally charged, which can make it challenging for you to assess the situation. For example, are you stressing your dog with your actions, or are you missing early warning signs?. Management and behavior modification techniques must be suited to the underlying cause. Finally, the more your dog practices aggressive behavior, the harder it will be to change.

Seek the help of a professional at the first sign of aggressive behavior. In fact, most aggression is driven by fear, so intervening early if you have a fearful dog is best. Don’t wait for aggression to escalate to a bite or attack. A veterinary behaviorist, animal behaviorist, certified behavior consultant, or professional dog trainer with experience handling aggression can teach you management techniques, help you identify your dog’s triggers, and develop a treatment plan to help your dog cope better with those triggers.

Remove the Emotion if Your Dog Exhibits Aggressive Behavior

Understanding aggression as distance-increasing behavior takes some of the emotional baggage away. Rather than thinking about words like “harm” and “violence,” consider your dog’s desire for space and safety. They are looking to protect themselves or what they consider to be their property from something or someone they perceive as a threat.

It’s important to remember that aggression isn’t an abnormal behavior for dogs. Given the right circumstances, every dog is capable of aggression, just as every person is. Therefore, Shikashio warns against labeling your dog as aggressive. He says you should describe the behavior as aggressive instead of describing the dog as aggressive. After all, your dog isn’t aggressive all the time. There are certain circumstances that trigger aggressive behavior.

What Causes Dog Aggression?

Fear is the number one cause of aggressive behavior in dogs. For example, a dog that is afraid of strangers may consider a delivery person at the door a threat and, therefore, attack. But dogs can exhibit aggressive behavior for a variety of other reasons, including:

  • Pain: the dog defends against touch or movement that might intensify that pain
  • Resource guarding: the dog protects items they consider valuable, like bones or the food bowl
  • Guarding territory: the dog defends what they see as their domain, like the backyard
  • Protection: the dog guards a human against a perceived threat, or a mother dog defends her puppies
german shepherd mother dog playing with puppy on wooden floor
©Julia Sha/Getty Images

The key element linking all these situations is the dog feels unsafe or threatened and wants something or someone to go away.

Recent research in the journal Scientific Reports supports the idea that fear is a critical element in dog aggression. After collecting owner questionnaires for over 9,000 purebred dogs, the authors found that dogs exhibiting aggressive behavior were more often male, small in size, the owner’s first dog, the only dog in the family, and fearful. In fact, highly fearful dogs were more than five times likelier to exhibit aggressive behavior than non-fearful dogs.

The study also found that the probability of aggressive behavior increased with age and differed between breeds. Rough Collies, Toy Poodles, Miniature Poodles, and Miniature Schnauzers had the highest odds of aggressive behavior whereas Labrador Retrievers, Golden Retrievers, and Lapponian Herders had the lowest odds. Interestingly, Staffordshire Bull Terriers, a breed often stereotyped or targeted by breed-specific legislation, had low odds of aggressive behavior in the study.

Different breeds tending to have different temperaments may partly explain breed differences in aggressive behavior. That’s due to generations of selective breeding for particular qualities, some of which include aggression used for a purpose. Think about livestock guarding dogs, protection dogs, police dogs, and military dogs—we’ve selected for breeds used for these purposes to display aggression in certain circumstances. Therefore, Shikashio takes a dog’s breed into consideration, as it may mean a higher likelihood of aggression. However, he believes each dog is unique.

More importantly, he also looks at the individual dog’s underlying motivations and emotions, such as fear, rage, anger, frustration, stress, anxiety, and arousal. He says these can act as fuel in a gas can, and the more fuel in the can, the more likely a trigger will act as a match, igniting an explosion. For example, in a dog that guards their food bowl, the gas can could be fueled by the dog’s hunger, a juicy steak in the bowl rather than kibble, strangers in the home, and a painful flare-up of arthritis. The match, or trigger, could be a person reaching for the bowl while the dog is still eating. With all of those circumstances fueling the situation, the dog is more likely to react aggressively once triggered. Therefore, it’s important to look at what’s motivating the dog. The outward signs of aggression are all symptoms of the underlying issue. It’s the causes, like pain and fear, that need to be addressed first.

Australian Shepherd being trained by a dog trainer outdoors.
©encierro -

Recognizing Early Warning Signs of Dog Aggression

Is there a way to predict aggressive dog behavior before it occurs? Most of the time, yes. Shikashio uses a teapot analogy. When a teapot on the stove begins to boil, the whistle goes off. That’s the dog reacting aggressively. But before that whistle, when the teapot is still getting warm, if you listen closely, there are little crackles. Those crackles are the early warning signs. “If we pay attention,” he explains, “then we can pull the pot off the stove before there’s even any risk of getting burned.”

So how do you recognize the warning signs of aggression? By paying attention to your dog’s body language, behavior, and vocalizations. These are how dogs communicate that they feel uncomfortable, threatened, or unsafe. For example, one reason dogs may growl is to tell others to back off. It’s a warning sign—your dog is stressed and, as such, you should never punish growling behavior. Warning behaviors like growling tell you that the current situation is more than your dog can handle—the crackles of the kettle—so it’s time for you to step in and ease your dog’s discomfort before the situation escalates.

Dogs displaying signs of stress don’t always escalate to aggression. But it’s important to respect what your dog is communicating, so you can intervene to help them feel safe and prevent them from feeling the need to ramp up their behavior. The earlier you recognize what’s happening, before your dog needs to growl, for example, the better you can advocate for your dog. Here are some signals to watch for:

  • Head turn: the dog looks away by turning their head
  • Whale eye: the dog looks away with their eyes and therefore the whites of the eyes show
  • Freezing: the dog goes still
  • Tail flagging: the dog’s tail is held high and waved stiffly back and forth
  • Tucked tail: the dog’s tail is held down between the legs
  • Lip licking: the dog licks their lips unrelated to eating or drinking

But Shikashio notes that every dog is different, so you need to know your own dog’s unique signs. “Not every dog is going to go through yawning, lip licking, freezing, all those typical lower-level signals that we’d see, so learning what an individual dog does is so helpful in predicting if an aggressive response is going to happen,” he says.

How Do You Treat Aggression in Dogs?

Never punish aggressive behavior. Yelling at your dog or physically confronting them will only exacerbate the situation and can result in further aggression such as biting. It’s simply not safe. But just as importantly, it won’t help your dog feel better about the situation. In fact, they will be more likely to react aggressively next time around. The same goes for growling and any other warning sign. Respect what your dog is telling you and empathize with their emotions. Reach out to a behavior professional for assessment and development of a behavior modification program.

Collie standing in the yard with a ball.
© 2014 Charles Mann via Getty Images

There are many ways to modify aggressive dog behavior. A behavior professional will help you find the right technique for your particular dog. However, Shikashio says the vast majority of the time, desensitization and counterconditioning are helpful. That’s because desensitization involves gradually exposing a dog to their trigger at a distance and at low levels of intensity. Then, counterconditioning changes a dog’s negative association of the trigger to a positive association. Shikashio describes the process as a “treat party” whenever the dog sees their trigger at a distance. “Doesn’t matter what you’re doing for behavior – you can look at the thing, you can look at the sky, you can sniff the ground – but the treats are going to keep happening while this thing is in the environment, 100 yards away.”

Counterconditioning involves classical conditioning or learning the association between events. But Shikashio likes to include operant conditioning in his treatment plans, too. Operant conditioning is where the dog learns the consequences of their behavior. Using a technique called differential reinforcement, Shikashio has his clients mark and reward their dogs in the presence of the target for doing a behavior that isn’t aggressive, such as looking at the target or going to their bed. This teaches the dog an alternative way of behaving while also building a positive association with the target.

Behavior Adjustment Training (BAT) for Dog Aggression

There are other techniques for modifying aggression, such as Behavior Adjustment Training (BAT), which was developed by Grisha Stewart, MA, CPDT-KA, KPACTP, and Constructional Aggression Treatment (CAT), which was developed by Kellie Snider, MS. If your dog is exhibiting aggressive behavior, or is simply showing signs of fear or stress, it’s essential to get help from a professional. Aggressive behavior can be exceedingly dangerous and puts you and your dog at risk. A professional can give you guidance about what to do, how to do it, when to do it, and how to manage setbacks.

While you’re working on modifying your dog’s aggression, it’s important to manage your dog and their environment to reduce any opportunities they have to practice. Every time your dog practices aggressive behavior and gets the desired outcome — whether that’s your hand retreating from the food bowl or a stranger walking away from the door — it reinforces they should keep repeating it. Shikashio explains that if aggression works to make a scary thing go away, the dog is going to remember that and go for that next time. “Because when you think about it, safety is more important than anything else.”

Plus, each time your dog experiences their aggression triggers, their stress levels increase, making it more likely they’ll escalate from warning signals like freezing or tail tucking to aggressive behaviors like snarling, snapping, and biting. So, as you work on behavior modification strategies to reduce your dog’s aggressive behavior, it’s also important to teach them how to better cope with stress, and to manage their environment to eliminate as many triggers as possible.

©V&P Photo Studio -

Along with behavior modification, it’s important to rule out any medical causes for your dog’s aggression. Along with pain, conditions like psychomotor epilepsy and hormonal imbalances can lead to aggression. Your veterinarian can also determine if medication may help reduce your dog’s aggression. For example, medications that reduce anxiety can help your dog cope with their triggers and make them more responsive to your behavior modification techniques. The more tools you have in your toolbox, the better you can help your dog.

Is There Hope for Dogs That Exhibit Aggressive Behavior?

Owning a dog that exhibits aggressive behavior (or even a reactive dog) is truly stressful. Simply managing the situation day to day can be exhausting. Many owners of aggressive dogs feel trapped, as they can’t participate in the world with their dogs in the ways they might want to or might have planned to when they acquired their dog. Safety is a constant concern, and owners can often feel guilty that they may have let their dogs down or failed them. These are all valid feelings. If you have a dog that exhibits aggressive behavior, do all you can to help your dog while remaining confident in the knowledge that you are a good dog owner and your dog is more than just their aggressive behavior.

However, despite exhausting every strategy, sometimes a truly aggressive dog doesn’t improve. There might be a safety consideration, such as an unpredictable dog with a bite history. In these cases, you may face the extremely difficult decision of whether to opt for behavioral euthanasia. This is when a dog is humanely euthanized because of severe behavioral issues, and it may be your only option for a truly dangerous dog, or a dog whose quality of life is suffering as a result of its aggressive behavior. It isn’t something anyone likes to talk or think about, and it’s an extraordinarily difficult decision wracked with guilt, stress, anger, and other emotions. Don’t decide alone. Although they can’t make your decision for you, consulting with behavior professionals will help to give you an objective assessment of your dog’s behavior and all possible options.

But for most dogs, using all the tools at your disposal — behavior modification, management, medication — can help you reduce the aggressive behavior or at the very least make it more manageable. Aiming to fully eliminate it from your dog’s repertoire may be an unrealistic goal. Shikashio suggests focusing on the journey over the destination. It will help you empathize with your dog and see them for who they are as you guide them along and work with them. “You can walk this path with your dog, but it’s never going to necessarily end. You’re not always going to get to that end stage goal, and you don’t have to. You’re making progress, you’re helping the dog, and you’re taking this path together … towards just having a better quality of life.”
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