Help, My Dog Keeps Attacking My Other Dog!

Can I Stop My Dogs From Hurting Each Other?

"I have three dogs: one female (mother) and two males (her pups). The female is 8 years old, and the other two are 6 years old.

One of them, Tyson, is most likely the alpha (when my father is not around). Whenever we get a delivery to our house, Tyson jumps to the gate and barks. When the other two get close, he doesn't let them bark and jumps to the other male until, eventually, they start fighting and hurting each other. Sometimes, he just growls if the other male is just moving, and I don't understand why.

They don't go on walks and never really have contact with other humans. I blame my father because he was supposed to get only one more dog, but he kept the two males.

My father is somewhat aggressive, and he used it as a teaching method. They obey my father instantly and not the rest of the family. I was too young when we had them, so I couldn't train them like they were supposed to. Our dogs love us deeply but I wish they could not hurt each other like that and stop being so aggressive. Their breed is Cane Corso."—Mariana

Dog Aggression Is Disturbing and Can Be Complex

Hello Mariana, I am sorry to hear that your dogs are not getting along. It sounds like the main trigger for Tyson's behavior is delivery people approaching your property, but you have also described that sometimes Tyson attacks your other male dog just "for moving."

Given that you own large, powerful breeds and they are hurting each other, it's imperative to make safety top priority.

You are right to be concerned about the whole situation, and I can understand your fear about your dogs harming each other. Cases of intrahousehold dog aggression (fights among dogs sharing the household) can be complex.

Let's delve deeper into what may be happening and, most importantly, some important safety precautions to reduce these attacks from occurring until professional help can be sought.

Why Is My Dog Attacking My Other Dog When We Get a Delivery?

Pinpointing exactly what is causing a dog to attack another dog often requires taking a careful behavioral history; however, if the behavior consistently takes place in a specific context, we can tease out some possibilities.

Some potential triggering factors to consider here are a dog's tendency for territorial behaviors, its associated heightened state of arousal, and the potential for redirected aggression. Let's take a closer look at all of these.

Territorial Behaviors

Barking, lunging and growling at unfamiliar people approaching the home is a common problem seen in dogs manifesting fear and territoriality.

Several factors, including genetics, socialization deficits, learning history, hormones, and neurophysiological components, contribute to the development of territorial behaviors in dogs.

One prominent distinguishing factor is that territorial behaviors tend to occur around a dog's perceived territory (the dog's "turf," so to speak).

Typically, the dog will manifest territorial behaviors towards delivery people approaching the home and yard but may not care about their presence in other settings (such as on walks, especially neutral areas, where the dog is not walked habitually).

Territorial behaviors are known to increase in intensity the closer the unfamiliar person approaches the boundary line (fence, gate). Smaller territories may be protected more intensely compared to the larger ones.

Typically, territorial behaviors begin around 6 months of age or older as the dog approaches social maturity.

It's important to note that although territorial behaviors often involve offensive posturing and appear to originate from a state of "boldness," there is often a fear or anxiety component at play.

"Fear-motivated aggression is the most common diagnosis in dogs aggressive toward unfamiliar stimuli, even when elements of territoriality are present," points out board-certified veterinary behaviorist Dr. Lore Haug in a journal published by Elsevier.

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Territorial behaviors are associated with high arousal levels, which can trigger aggressive responses, as discussed below.

Heightened States of Arousal

When dogs are presented with a threat (such as an intruder approaching their perceived territory e.g. a delivery person), it triggers a reaction.

This reaction to a threat is linked with emotional arousal, considering how incoming threats activate the dog's sympathetic nervous system, triggering heightened levels of arousal along with feelings of alertness, nervousness, and readiness for action.

While the ability to quickly detect and react to threats (the so-called fight or flight response) is known to have evolutionary benefits, problems start when the reaction is disproportional and/or occurs consistently.

Time after time, the dog gets more and more aroused and with lower latency (the dog gets aroused more quickly) at the sight of delivery people approaching their perceived property and risk getting stuck in an arousal loop, leading to chronic stress.

This is due to the persistence of neural circuits that occur as a result of repeated activation. In a nutshell, the more a dog gets aroused and practices a problem behavior, the stronger the neural pathways supporting this aroused state and behavior become, further reinforcing the problematic neural circuits. Soon, aroused behaviors become habitual, which may pave the path to trigger stacking.

The Role of Frustration

Cane Corso are dogs with a natural predisposition for guarding. Fences and gates can trigger feelings of barrier frustration as these boundaries leave no doubt as to the extent of the dog’s property, giving these naturally protective dogs a clear barrier to patrol.

Additionally, when dogs are prevented from reaching the target that triggered their aggressive response (the delivery person), they may get highly aroused and frustrated, which may trigger them to displace their aggression toward a more convenient target.

Redirected Aggression

A dog's overarousal at some point may reach a boiling point, where it spills into aggression, which is basically redirected from one target to another one that just happens to be nearby.

Redirected aggression in dogs, also known as displacement aggression, is a phenomenon where a dog attacks another dog (or even a person) who happens to be near the trigger but without being directly related to it.

Because of the intensity of the behavior and its impulsiveness, safety in these cases is a main concern, especially when dealing with large, powerful breeds.

Why Is My Dog Attacking My Other Dog When He Moves?

When we understand in which specific context a dog attacks another dog (as in the case of an aggressive response predictably occurring in the presence of delivery people), this situational aggression is often more straightforward to treat and easier to manage considering its identifiable and predictable patterns.

The issue becomes more intricate when dealing with a dog who attacks another just for the mere act of "moving." This presents as a more complex issue, which may be indicative of a broader, less predictable pattern of aggression, which may or may not be tied to specific stimuli.

In these cases, an in-depth evaluation is needed to tease out and understand what underlying motivations and triggers may be at play.

A Generalized Response

We must consider that as a dog gets to practice aggressive behaviors repeatedly, these behaviors (and their attached emotional responses), may evolve and generalize over time, leading to the dog acting aggressively in an increasing range of situations.

At some point, a dog may therefore shift from attacking another dog when in presence of a trigger (the approach of delivery people in this case), to attacking whenever the other dog is simply near the gate or outside, even if no delivery person is present.

This can further escalate to the point where the aggressive dog attacks the other dog just for being in the same room or even just for "breathing" in the most severe cases.

Sometimes, there may be a learned component at play. For example, a dog may learn that through its aggressive behavior, it can effectively control or limit the movements of the other dog, which reinforces the behavior over time.

Generally, the broader and more generalized the aggression, the more challenging the situation is to manage because it is less predictable and more deeply ingrained.

The Importance of a Thorough Evaluation

Please consider that these are only speculative insights. A professional evaluation is needed to better pinpoint the dynamics at play.

It may be possible that the attacks are carried out for other reasons, more than just "the mere act of moving," and that these reasons can be identified and managed.

For example, we know that dogs may react with aggression in several specific contexts that involve some type of "movement," for example, a dog may attack another dog when that dog:

• Is moving towards a valuable resource (such as food, toys, bones)
• Is moving towards a valuable person (such as a dog moving towards the owner/favorite person which may trigger in the other dog jealousy-like, protective aggression)
• Is moving towards a valuable area (such as a dog's preferred resting spot, areas where food is often kept)
• Is moving through a tight passageway (as it happens with dogs fighting through doorways)
• Is moving in an erratic way (as it happens with seizures, uncontrolled movements during sleep)

We must also consider that repeated exposure to high arousal levels and triggers can cause a dog to become overreactive, triggering aggression triggered by seemingly minor movements.

In some cases, a medical issue may be at play which contributes to lowering a dog's threshold for aggression, making the dog more irritable and prone to aggression.

Therefore, to address the root cause and reduce aggressive incidents, a thorough assessment of the dog's history, environment, and interactions is needed.

Be Aware of Dogs "Ganging Up"

How Can I Stop My Dogs From Fighting?

Stopping dogs from fighting is important considering all the associated risks. Equally important is to consult with a dog behavior professional considering the complexities associated with cases of intrahousehold dog aggression.

The following are some general guidelines to help reduce the chances of fighting until a behavior professional can intervene.

Identification of Triggers

At this point in time, we know that the arrival of delivery people evokes high arousal levels in your dogs, and therefore, the arrival of these strangers induces aggressive responses.

We also know that the movements of your other dog seem to trigger aggressive responses which are problematic. However, more details are needed to see if it is possible to tease out any additional triggers that may be evoking such responses and whether they can be potentially controlled. This will require intervention of a professional for an in-depth assessment.

Avoidance of Triggers

Several precautions can be implemented to prevent fighting. These precautions accomplish several goals: 1) they prevent your dog from rehearsing problematic behaviors, 2) they prevent your dog from gaining reinforcement from sending intruders away, and 3) they increase safety. There is actually an additional goal: trigger avoidance also protects your other dogs' emotional wellbeing, considering that dogs need time to recover from a dog attack.

The avoidance of triggers is known as environmental management, and in a case like yours, it may entail the following approaches (or a combination of them):

• Separating the dogs prone to fighting (this may entail the use of baby gates, kennels, pet fencing or closed doors). This is likely the safest option considering the incidents where Tyson attacks your other dog as a result of mere movement.
• Keeping Tyson away from the other two dogs during deliveries (or other high times of stress). While it may be tempting to just separate Tyson from your other male dog since it sounds like he's the one often targeted, it's important to consider that oftentimes, in cases of redirected aggression, the victim of the attack happens to be the closest one, so your female dog may be at risk too.
• Covering windows with window film or placing barriers to prevent seeing delivery people from indoors so as to lower arousal levels.
• Meeting delivery people away from the home.

Work Alongside a Dog Behavior Professional

Considering the complexity of your case, it's important to consult with a board-certified veterinary behaviorist. A board-certified veterinary behaviorist is a diplomat of the American College of Veterinary Behaviorists.

These specialists have made behavior problems their area of specialty. Being that they are veterinarians who have completed a residency in the discipline of veterinary behavioral medicine, they can help screen out any potential medical problems which should always be considered before starting any behavior modification plan.

Once the potential for medical problems has been ruled out, then an integrated treatment that includes a customized behavioral modification program can be started based on the individual dog.

You can find a board-certified veterinary behaviorist near you by visiting this website: find a diplomate near you.

What If There Are No Veterinary Behaviorists in My Area?

It's unfortunate, but veterinary behaviorists aren't easy to come by. If there are none in your area, consider that some veterinary behaviorists offer veterinarian-to-veterinarian telehealth consults.

Another option is to see if you have a certified applied animal behaviorist in your neck of the woods. Here is a directory: CAAB directory.

While some dog trainers/behavior consultants are experienced enough to work on aggression cases, it's crucial that they employ force-free, humane training and behavior modification methods, rather than punishment-based techniques based on outdated alpha dog and dominance fallacies.

You may find some force-free dog trainers/behavior consultants from the Pet Professional Guild's directory: find a PPG professional or the International Association of Animal Behavior Consultants: find an animal behavior consultant/dog trainer. Make sure they are experienced and comfortable in taking aggression cases.

Say No to Punishment

Dogs who are not listening when in highly arousing situations are often assumed to be defiant, disobedient or "dominant." However, what's really happening is that their limbic system (the emotional portion of the brain) is overriding the cortical system (the thinking portion of the brain).

The use of punishment under the form of corrections, whether physical (shock collars, alpha rolls, physical interventions) or verbal (yelling, stern tones of voices) is not without side effects and risks creating the potential for more problems down the road.

For example, a dog who has been punished for barking at the approach of strangers and/or in the presence of other dogs may intensify the dog's reaction, considering that punishment may increase arousal levels and further reinforce in the dog the belief that approaching people are "bad."

What May a Behavior Modification Plan Entail?

Every behavior case is different and may require a different approach. The following are only some examples of what a behavior modification plan for cases of interhousehold dog aggression may entail:

• Ruling out medical conditions. This may be necessary for all the dogs sharing the household to ensure no medical issues are causing or contributing to the problem.
• Identifying triggers (the so-called antecedents)
• Environmental management (erecting barriers, separating the dogs to prevent them from rehearsing problematic, overly aroused behaviors)
• Muzzle training (a gradual acclimatization to wearing a bite-proof basket muzzle may be needed as a preliminary step)
• Desensitization (low-intensity exposures to triggers with the goal of building a dog's coping skills and increasing the dog's threshold)
• Counterconditioning (creating positive associations with the low-intensity triggers)
• Training (impulse control training, general foundational training for steadfast responses when cued at the earliest signs of arousal). Training offers a trifecta of benefits, considering that it's a form of mental enrichment and helps strengthen the dog and owner bond while increasing the dog’s skill set. For example, hand targeting can help reorient a slightly aroused dog and help move him away from a potentially problematic situation. The task is easy enough to train and perform, considering that simple tasks can be performed successfully at slightly higher arousal levels. Ask a professional for guidance on how to introduce this cue in increasingly distracting environments.
• Family involvement. All family members should be involved in the training. Although dogs may form social hierarchies amongst them, dogs adapt their behaviors to specific situations. "Dogs don’t see people as other dogs, but rather social companions of a different species," explains Meghan E. Herron, board-certified veterinary behaviorist. When dogs aren't listening, there may be several factors at play such as lack of training, unclear expectations and lack of consistency. Dogs may respond to some family members out of fear, but such fear may fuel further arousal and other problematic behaviors.
• Exercise/mental stimulation to ensure all the dogs' needs are met. Walks may help as long as they don't trigger further arousal. Steps can be taken to reduce stress on walks (e.g., walking in areas with a low probability of encountering triggers). Dogs may be grossly deficient in being offered sufficient stimulation. Games, food puzzles, chew toys, and Licki mats may help, but they may need to be offered to the dogs separately so as to prevent conflict/fights among dogs.
• Relaxation techniques. Dogs who are hyper-aroused may not know how to relax and self-regulate. A relaxation protocol needs to be in place, starting from an area that is free of distractions. Dogs prone to high arousal should also receive sufficient sleep and the dog's sleeping location may matter. According to a study, dogs who slept indoors spent 80 percent of the night in behaviorally defined sleep. In contrast, this ratio went down to 70 percent for dogs sleeping outdoors in a yard, and even 60 percent for dogs sleeping outdoors in a non-fenced area.
• Calming aids/medications. The goal is to help lower the dog's arousal levels so that the dog is capable of cognitive functioning. When dogs are in a hyper aroused state, they are often incapable of effectively learning and may not make sufficient progress in a behavior modification program at least until the high arousal levels have been reduced.
• Patience and consistency. It's important to understand that changing dog behavior requires time and improvement may not occur in a linear fashion, but there may be ups and downs along with setbacks. The process may sometimes feel overwhelming to owners, but breaking down the interventions into stages (management, foundation training outside of the triggering event, and behavior modification exercises/training in the presence of the triggering event) can help.

Can Behavior Modification Treat Intrahousehold Aggression?

How likely a behavior modification program is going to work varies based on a variety of factors such as the likeliness for injuries, the seriousness of the bites, the size of the dogs, the dogs' responsiveness to training, owner commitment and the ability to manage the situation.

The prognosis for cases of redirected aggression tend to be poor to guarded in cases where a dog is easily aroused and the situation/trigger is difficult to avoid, explains board-certified veterinary behaviorist Dr. Gary Landsberg in the book: Practitioners, An Issue of Veterinary Clinics of North America: Small Animal Practice.

In challenging cases, where management strategies are challenging to implement, or the safety of household members and other pets is at risk, rehoming the dog into a home without other dogs may be considered. However, this decision should be made in consultation with a veterinary behaviorist after exhausting all other management/treatment options so as to ensure it is the best course of action for a particular household.

For Further Reading

These articles may help gain a deeper understanding on the topic of behavior modification and provide some general tips.

• Common behavior modification mistakes: this article covers 10 common mistakes when implementing behavior modification and how to address them.
• Causes of behavior changes in dogs: behavior changes in dogs often happen as a result of internal and external triggers.
• Tips for managing a multi-dog household: these are general tips on how to pave the path to a more harmonious relationship among dogs once medical causes are ruled out and after working with a professional.
• Do Cane Corso get along with other dogs? This article specifically discusses some common causes as to why Cane Corso may not get along with other dogs.
• How to stop household dogs from fighting: some general tips to manage and reduce chances for future fights under the guidance of a professional.
• Side effects of punishment-based training: even reportedly "mild" forms of punishment can negatively impact dogs and how they perceive the world around them.

References

• Haug, Lore. (2008). Canine Aggression Toward Unfamiliar People and Dogs. The Veterinary clinics of North America. Small animal practice.
• Beerda, B., Schilder, M. B., Janssen, N. S., & Mol, J. A. (1996). The use of saliva cortisol, urinarycortisol and catecholamine measurements for a noninvasive assessment of stress responses in dogs. Hormones and Behavior, 30, 272–279
• Kabaila A. The effects of current training techniques and environmental factors on dog behavior. Anim Welf Sci Ess 2004
• Behavior: A Guide For Practitioners, An Issue of Veterinary Clinics of North America: Small Animal Practice by Gary Landsberg
• S.S. Campbell, I. Tobler Animal sleep: a review of sleep duration across phylogeny Neurosci Biobehav Rev, 8 (1984), pp. 269-300
• Sleep-wake cycles and other night-time behaviours of the domestic dog Canis familiaris [1993] Adams, G.J.; Johnson, K.G.; From the journal Applied animal behaviour science ISSN : 0168-1591
• Can Sleep and Resting Behaviours Be Used as Indicators of Welfare in Shelter Dogs (Canis lupus familiaris)?
• Starling MJ, Branson N, Cody D, McGreevy PD. Conceptualising the Impact of Arousal and Affective State on Training Outcomes of Operant Conditioning. Animals (Basel). 2013 Apr
• Zsido, Andras. (2023). The effect of emotional arousal on visual attentional performance: a systematic review. Psychological Research. 88
• Veterinary Information Network: Stress and Anxiety - How Do They Impact the Pet?
• Scientific American: Mental Rehearsals Strengthen Neural Circuits
• Behavior: A Guide for Practitioners Kenneth M. Martin DVM, Julie K. Shaw RVT, KPA CTP, VTS (Behavior), in Veterinary Clinics of North America: Small Animal Practice, 2014

If your puppy or dog shows signs of potential aggression (lunging, barking, growling, snapping, biting), please consult with a dog behavior professional for direct in-person guidance. Articles, videos, and general information provided online are not meant to replace in-person training/instruction. By using this service, you are waiving any liability claims or other types of claims related to any of your dogs' behaviors against you or others.

© 2024 Adrienne Farricelli CPDT-KA, Dip.CBST