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Does your dog bark at people who come to the door or lunge toward neighbors when they pass by your fence? Perhaps your dog has even snapped at or bitten somebody. Your dog’s behavior makes it clear they don’t want visitors in their home or yard. But you should be the one deciding who is welcome, not to mention this constant vigilance is stressful for your dog. Territorial aggression may be a natural way for your dog to protect their property. But, it’s dangerous and difficult to manage without professional help.

What Is Aggression?

First, how can you tell if your dog is being aggressive? After all, that barking and lunging could be reactivity – your dog overreacting to everyday stimuli. Aggressive behaviors are typically those used by dogs to increase distance from a target, avoid escalation of a conflict, or cause damage to the target. They can include behaviors such as growling, lunging, snarling, snapping, and biting. Recent research in Scientific Reports concludes that fear is the number one cause of aggression. But no matter the motivation, the dog’s underlying emotion is feeling unsafe or threatened.

If your dog is exhibiting any kind of aggression, from resource guarding to territorial aggression, it’s essential to seek professional help. A behavior consultant, animal behaviorist, veterinary behaviorist, or professional dog trainer (with experience treating aggressive behavior) can help you identify your dog’s triggers, develop a behavior modification program to address the aggression, and establish management techniques to increase safety.

Bulldog sticking its nose through a fence.
©Grigorita Ko -

What Does Your Dog Consider Their Territory?

Dr. Sagi Denenberg, a veterinary behaviorist at North Toronto Veterinary Behaviour Specialty Clinic, says dogs observe three zones in space. The first is their home range. That’s the largest space the dog considers familiar and can include streets, parks, and areas the dog regularly visits. Dogs recognize this space, just as you might say, “This is my city.” However, they don’t defend it.

However, dogs may defend the other two zones. The smallest is the dog’s personal space, which extends from 5 to 6.5 feet around the animal, depending on the specific dog. But the zone of concern for territorial aggression is the area the dog considers exclusively “mine.” That might be the yard, the house, even the street outside the living room window. It all depends on the specific dog and what they consider their home.

What Is Territorial Aggression?

Territorial aggression is behavior aimed at repelling intruders from what the dog perceives to be their territory. The goal is not to hurt the intruder, although the dog might do just that. Instead, their goal is to get that intruder on the other side of the territory line. Dr. Denenberg says all dogs, including small lapdogs, have a degree of territorial behavior. That’s because of their heritage. Dogs have been bred for all kinds of purposes, such as hunting, tracking, sledding, and so on. But way back in the early days of domestication, guarding was a dog’s primary purpose and that has stayed in their DNA. Breeds like Anatolian Shepherds, Great Pyrenees, Komondorok, Kuvaszok, or Central Asian Shepherd Dogs are livestock guardian breeds that were developed to perform the specific purpose of defending a flock or herd of livestock on their territory from large predators, for example.

You probably appreciate that your pet dog barks to let you know when a stranger comes to your door. You might even have selected a dog for the purpose of helping to safeguard your home. But territorial aggression is levels up from this alerting behavior. Plus, it can be dangerous when it occurs in your home. The dog will label everyone with whom they’re unfamiliar as an intruder, not just the people that you find threatening. That means the delivery person, your new friend from work, or any other innocent stranger are equally at risk. Dr. Denenberg notes that your dog may also consider the street their territory along with your personal property.

Thankfully, you can foresee when your dog could behave with territorial aggression. People and other dogs they already know can come and go freely. But if your dog exhibits this behavior, then until your dog accepts a new individual, they’ll predictably try to keep them out. If the stranger retreats, the aggression will diminish, but if the stranger stays, your dog’s aggression will rise. “They will warn the individuals moving toward the line and escalate as the individual comes closer,” says Dr. Denenberg.

Australian Shepherd puppy looking out the window waiting.
Mark Herreid/Shutterstock

Rule Out Any Health-Related Causes of Aggression

As territorial aggression can be connected to a dog’s heritage and DNA, Dr. Denenberg warns it can be hard to modify. But with proper treatment and management, owners can expect a decrease in the frequency of the behavior. However, it’s never going to completely disappear, particularly in a breed developed to be a guardian or protector breed. “Not reacting when there’s someone at the door goes against the dog’s genetics,” he explains.

But how can you manage the behavior? First, rule out any health reasons for your dog’s behavior. Certain health conditions, even common ones like painful osteoarthritis, can lead to aggression. It’s important your dog gets a clean bill of health from your veterinarian. Recent research, such as a study in the academic journal Animals, has pointed to a possible connection between diet and aggression. For example, tryptophan (an amino acid found in protein) and fatty acid levels in a dog’s diet may impact their behavior. Another study in the Journal of Veterinary Behavior found that one dog’s aggressive behavior relapsed through dietary change alone. So, it’s worth discussing your dog’s diet with your veterinarian if other common veterinary causes have been ruled out.

How Can You Manage Territorial Aggression in Your Dog?

First things first: enlist a professional to help you develop a management plan. Safety needs to be a priority as any kind of aggression can lead to harm to others as well as put the dog at risk for behavioral euthanasia. “Keep the dog under control (leash and closed door or gates), fence properties, and a basket muzzle. I often place sticky notes inside the door to remind owners not to open the door when the dog is present,” Dr. Denenberg advises.

It’s also important to ensure the dog’s enrichment needs are met. That means proper mental stimulation and adequate physical exercise. It’s also key to provide sufficient resources such as toys and food. Dr. Denenberg says this reduces the risk of aggressive behavior as the dog won’t feel the need to protect those items along with the property if there are enough of them to go around. And in younger dogs, proper socialization can help teach them to feel comfortable around other animals and strangers, which can help reduce the need to defend the territory from them.

Finally, a professional will help you develop a behavior modification program. Dr. Denenberg believes techniques like desensitization and counterconditioning are the answer. If your dog gets multiple repetitions of intruders at the threshold of the home, such as the door or the edge of the property, along with positive associations with those repetitions, in time your dog will become more accepting of strangers on the property. Such a program, says Dr. Denenberg, can help reduce the intensity and frequency of the territorially aggressive behavior by teaching the dog to accept more people.

Related article: Aggression in Dogs: Signs, Symptoms, Treatments
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