Why is My Dog Aggressive Towards Other Dogs?

Nov 26

Written by Lauren Tsao, MS, CDBC, CPDT-KA

As a new dog owner, you may find yourself asking, "Why is my dog aggressive towards other dogs?" This is a common concern since the pandemic, and you're not alone in your quest for answers. Aggression in dogs is a behavior issue that can feel overwhelming and even alarming for dog owners. Whether your dog is growling, snapping, or lunging at other dogs, understanding the root causes of these behaviors is key to addressing them effectively. Aggression is often a sign of deeper issues, including fear, pain, or environmental stressors.

In this blog post, we’ll explore the causes of dog aggression towards other dogs, how to identify aggression-related behaviors, and actionable steps to address these issues. By uncovering the underlying reasons behind your dog’s behavior, you can create a pathway toward positive change.

What Does Dog Aggression Look Like?

Aggression refers to a range of behaviors that dogs use to communicate discomfort or defensiveness. These behaviors can range from growling and barking to lunging or biting.

Aggression in dogs often stems from one or more of the following factors:

Fear or Anxiety: The dog perceives a threat and reacts defensively.
Territorial Behaviors: Protecting their space or resources.
Pain or Discomfort: Physical issues can heighten irritability and reactivity.
Environmental or Learned Triggers: Previous negative experiences or inadequate socialization.

Understanding aggression as a form of communication helps us respond with compassion and effective strategies rather than frustration or punishment. Before diving into solutions, it’s important to recognize the signs of aggression. Dogs often communicate their discomfort or agitation through body language before escalating to more overt behaviors.

Common Signs of Aggression:

Stiffened body posture.
Intense staring or “hard eyes.”
Growling, snarling, or showing teeth.
Lunging or snapping at people or other animals.
Tucked tail or pinned ears.

By identifying these signs early, you can intervene before the behavior escalates, helping both your dog and others feel safer.

Common Causes of Aggression in Dogs

1. Fear and Anxiety

Fear and anxiety are among the most prevalent causes of aggression in dogs. When a dog perceives a threat, whether real or imagined, they may respond defensively in an attempt to protect themselves. This behavior is often misunderstood as dominance or bad temperament, but fear-based aggression is typically rooted in a dog’s attempt to create distance from something that frightens them.

How Fear-Based Aggression Develops:

Poor Socialization During Puppyhood
During critical socialization periods (typically between 3 to 16 weeks of age), puppies learn to navigate their environment, interact with people and other animals, and adapt to various stimuli. Dogs that miss out on these experiences may grow into adults who feel unprepared or unsafe in new or unpredictable situations. For instance:
- A puppy raised without exposure to other dogs may grow up to fear unfamiliar dogs.
- A lack of positive interactions with other dogs during early life can lead to fear or aggression during dog-to-dog encounters.
Past Trauma or Negative Experiences
Dogs with a history of abuse, neglect, or frightening incidents are more likely to exhibit fear-based aggression. Examples include:
- A dog who was harshly punished for barking at dogs may associate dogs with negative outcomes.
- A rescue dog that had to fight for resources may react aggressively in situations where they feel cornered or threatened.
- A dog that has been in a fight with other dogs, even if they “won” or “started it”.
Unfamiliar Situations or Stimuli
Even well-socialized dogs can develop fear-based aggression if they encounter situations that feel overwhelming or outside their comfort zone. For example:
- Loud noises like fireworks or thunderstorms can create lasting fear associations.
- Dogs introduced to new environments (like a veterinary clinic or grooming salon) without gradual acclimation may react fearfully.

Recognizing Fear-Based Aggression:

Dogs often display subtle signals before escalating to overt aggression. Recognizing these signs is key to preventing incidents:

Body Language: Tucked tail, lowered ears, showing whites of eyes, shaking, urination, defecation, or cowering.
Vocalization: Whining, growling, or barking in a high-pitched tone.
Avoidance Behavior: Attempting to flee, hiding, or moving away from the trigger.
Defensive Actions: Lunging, snapping, or biting if escape isn’t possible.

Owners often misinterpret these behaviors as stubbornness or disobedience, but they’re actually signs of a dog trying to cope with their fear.

2. Territorial or Protective Instincts

There are disagreements about whether or not territorial aggression is anything more that fear aggression. My stance is that it is likely a sub-category, which is still likely rooted in fear or insecurity, but may present slightly different. In my experience, many of these dogs have a medical component influencing their behavior, particularly if this type of behavior suddenly appears.

How Territorial Aggression Manifests:

Territorial aggression often emerges when a dog perceives an intrusion into their space. These reactions can include:

Barking or Growling: A common response when someone or another dog approaches their yard, home, or vehicle.
Lunging or Snapping: Escalation occurs if the dog believes the intruder is too close.
Blocking Access: Standing between the perceived threat and their territory or family members.

This behavior isn’t limited to strangers or strange dogs. Some dogs may even show territorial aggression toward familiar people or pets, especially if they feel their space is being invaded.

Protective Aggression vs. Territorial Aggression:

While territorial aggression focuses on defending a physical space, “protective” aggression arises when dogs feel the need to safeguard their family members. This might include:

Defending Family Members: A dog growling or barking at another person or dog approaching their owner.
Guarding Safe Areas: Dogs may show heightened aggression when people or other dogs approach an area they deem “safe”. If these are areas in which the dog feels safest, they can display aggressive behaviors to protect their safety bubble. This generally includes dogs that are more aggressive in the home, than when on walks or out in public. However, they can also be more specific, like “guarding” only certain rooms, beds, crates, etc.

Example of Territorial Aggression:

Imagine a dog barking aggressively at another dog walking past their yard. From the dog’s perspective, these passersby are "intruding" on their territory, even if the humans see no harm in their presence. The barking serves as both a warning to the "intruder" to get out of their space. When the other dog walks by, your dog’s barking can be reinforced because they may believe the barking worked to get the other dog to leave.

If left unchecked, this behavior can escalate, with the dog lunging at fences or gates or becoming reactive even when inside the home.

3. Pain or Physical Discomfort

Pain or physical discomfort is one of the most overlooked and misunderstood causes of aggression in dogs. When a dog is experiencing discomfort, even a gentle touch or a routine interaction can become unbearable, prompting defensive or aggressive behaviors. Understanding this link is crucial to addressing aggression effectively and compassionately. In my experience, all dogs involved in the aggressive episodes should be assessed for medical conditions, particularly in cases of inter-household dog aggression. I commonly see that at least two of the household dogs end up having medical issues that are heightening or causing the aggressive behaviors.

Why Pain Can Lead to Aggression:

Dogs, like humans, will protect themselves when they are in pain. Pain-related aggression often arises as a defensive response, especially if the dog anticipates discomfort from an action, like being petted, played with, or picked up. This form of aggression is not rooted in malice or dominance, but in self-preservation.

Pain can lower a dog’s tolerance for stress and triggers, making them more reactive in situations they might have previously handled well. For instance:

A dog with arthritis might snap if someone accidentally touches a sore joint.
A dog with an undiagnosed injury might growl or lunge when asked to perform tasks that exacerbate their pain, such as climbing stairs or jumping onto furniture.

Medical Conditions That Can Contribute to Aggression:

Pain-related aggression can stem from a variety of medical conditions, including:

Joint Issues: Conditions like arthritis, hip dysplasia, or joint hypermobility can cause chronic discomfort, leading to irritability and defensive aggression.
Injuries or Trauma: Cuts, bruises, or fractures may prompt a dog to react aggressively if touched near the affected area.
Neurological Issues: Conditions such as intervertebral disc disease or spinal injuries can cause pain and heightened sensitivity.
Dental Problems: Tooth pain or oral infections can make a dog reluctant to eat or have their face touched, potentially leading to growling or snapping.
Chronic Illness: Conditions like ear infections, gastrointestinal pain, or skin allergies can cause ongoing discomfort and contribute to changes in behavior.

Recognizing Signs of Pain-Related Aggression:

Dogs in pain often give subtle cues before escalating to aggressive behavior. Look for the following indicators:

Body Language: Flinching, stiff posture, or guarding a specific area of their body.
Changes in Behavior: Reluctance to engage in activities they previously enjoyed, such as playing with other dogs or going for walks.
Aggression During Routine Activities: Growling or snapping during grooming, petting, or handling.
Avoidance: Hiding, withdrawing, or avoiding touch altogether.

4. Frustration or Barrier Aggression

Frustration or barrier aggression is a form of aggression that arises when a dog is physically or emotionally prevented from accessing something they want. This could be another dog, a person, or even a toy. The inability to reach the object of their desire leads to pent-up energy and stress, which can result in aggressive behaviors like barking, lunging, growling, or even redirecting aggression onto nearby objects, animals, or people.

What Causes Frustration or Barrier Aggression:

Physical Barriers:
Leashes, fences, crates, or gates often trigger this form of aggression because they prevent the dog from reaching their target. For example:

A dog barking and lunging at another dog on the opposite side of a fence.
A leashed dog pulling toward a passerby, barking and growling when they cannot approach.

Emotional Barriers:
Dogs may experience frustration when they perceive a lack of control over their environment or when their desires are thwarted. For instance:

A dog seeing a toy but being unable to reach it due to a physical block.
A dog restrained on a leash during a walk when they want to greet another dog or chase a squirrel.

Unmet Needs:
Dogs that don’t receive sufficient mental or physical stimulation are more likely to display frustration-related behaviors. Lack of exercise, play, or enrichment can build tension, making it harder for them to handle obstacles calmly.

How Frustration Aggression Manifests:

Frustration aggression can look different depending on the situation and the individual dog. Common signs include:

Intense barking, lunging, or growling when restrained.
Redirecting aggression onto nearby objects, people, or animals (e.g., biting the leash or snapping at a handler).
Pacing or pulling frantically against the leash or barrier.
Whining, high-pitched barking, or vocalizing out of frustration.

For many owners, this behavior can be mistaken for dominance or hostility, but it’s actually a response to emotional overwhelm and lack of access to a desired goal.

The Role of Dynamic Dog Assessments

Aggression in dogs is rarely a standalone issue. It’s often a complex behavior influenced by a combination of factors, including physical discomfort, emotional stress, past experiences, and environmental triggers. These underlying causes are frequently subtle and easy to miss, even for experienced dog owners. This is where Dynamic Dog Assessments come into play, offering a comprehensive and thorough approach to uncovering factors involved in your dog’s aggression.

Unlike one-size-fits-all training methods, we provide an individualized approach to tackling aggression. This detailed evaluation ensures that we don’t just address the symptoms of aggression, but target the underlying causes for lasting results.

For example:

A dog exhibiting leash aggression may not just need leash-training techniques. They might also require pain management for an undiagnosed joint issue identified during the assessment.

This proactive and thorough process equips you with the tools to support your dog’s emotional and physical well-being, fostering a more harmonious relationship between you and your dog.

Photo shows dog with pink bow on in a yard.

If your dog is showing signs of aggression, don’t wait for the behavior to escalate. Our Behavior Guidance Calls with Dynamic Dog Assessments provide a thorough evaluation of your dog’s physical and behavioral health.

📞 Contact us today to schedule your Behavior Guidance Call and take the first step toward understanding and addressing your dog’s aggression. Contact me today to schedule a Behavior Guidance Call. I offer in-person sessions in the Jackson, MS metro area and virtual training help worldwide. Together, we can create a safer, happier environment for you and your dog.