Why Would a Dog Suddenly Attack Another Dog?
Why does my dog attack my friends dog?
Why Did My Dog Attack My Friends Dog?
"I am writing to seek your advice regarding a concerning incident involving my dog Zeke and my friend's dog Diesel.
The dogs have met each other before and have always gotten along fine. We went camping this weekend, and they played together happily at first. Diesel showed some jumping behavior towards Zeke, but this eventually stopped.
On the second day, during breakfast, Diesel seemed somewhat standoffish with Zeke, hiding behind me for head rubs while I gave Zeke my direct attention and rubbed him.
The day progressed without issues until we returned to camp after a long hike and sat in chairs. Diesel wanted to be on my lap, while Zeke, who is typically not an affectionate dog, approached me a couple of times and placed his paw on me. Thinking he wanted to join me, I tried to include both dogs by allowing them both on my lap. However, after a few minutes, Zeke jumped off, and Diesel returned to my lap.
Around 30 minutes later, while we were prepping our meals, we decided to feed the dogs. Diesel was fed inside the RV, while Zeke was fed outside. Zeke has been trained to be desensitized during meals and has no issues with people touching his food.
When my husband thought Zeke was done eating, he placed his bowl up high. Unfortunately, we didn’t see what exactly happened after that, but minutes later, Zeke went after Diesel, growling and very aggressive. It seemed that he wanted to attack Diesel, but I didn’t see the incident.
My friend's husband got up in fear and yelled at Zeke, who initially stopped but then attempted to go after Diesel again. We separated the dogs for approximately 30 minutes and attempted to reintegrate them, but Zeke was still visibly bothered, so we put Zeke on a leash while my friend held Diesel on her lap, and both dogs eventually fell asleep.
As soon as Diesel woke up, Zeke sat up, positioned himself in front of me, and started growling. We commanded him to lay back down away from Diesel's sight
I am unsure whether I did something wrong, if Diesel's behavior triggered Zeke, or if Zeke was simply tired and fed up with Diesel's energy. Zeke has never had any problems with other dogs before, so this incident was quite scary for all of us.
I would appreciate any advice you can provide on what we could have done differently in this situation or if this is something I should be aware of moving forward. Thank you so much for your time and assistance. I look forward to hearing your expert advice on how to handle this situation."—Sylvia
Dealing With Unexpected Dog Aggression
Hi Sylvia, thank you for reaching out for support during this challenging time. It can be deeply distressing when our dogs, with a perfect track history of getting along with other dogs, start showing unexpected behaviors that concern us. I am glad that no physical harm was done to the other dog, as things may have gone much worse.
As concerned as you may be, remember that even well-behaved dogs may occasionally exhibit aggressive behaviors, and this incident doesn’t define your dog’s entire character. Numerous variables can trigger behavioral responses akin to those you have detailed. While pinpointing the exact dynamics may remain somewhat elusive, we can explore some possibilities.
Why Did My Dog Attack Another Dog for the First Time?
The interactions among dogs can be complex. Things get further challenging when we are missing some puzzle pieces about the events leading up to the incident.
What happens right before a dog reacts is what we call the “antecedent.” In the ABC model of behavior, which stands for antecedent, behavior and consequence, the antecedent is what evokes a behavior, and the consequence is what maintains the behavior.
For example, in the case of a dog who barks at the mailman, we may know that the sight of the mailman placing mail in the mailbox (antecedent) is what evokes the barking (behavior).
The consequence in this case is the mailman leaving (which reinforces the barking behavior), and therefore, we know what triggers the behavior and what maintains the behavior, preventing it from extinguishing.
Consequently, understanding both the antecedent and the consequence is pivotal in comprehending the factors that initiate a behavior, thereby facilitating a targeted approach to modifying the behavior.
However, it is not always possible to definitely pinpoint the antecedents. For instance, there may be a multitude of variables at play, the antecedents may be subtle or internal, or the behavior may occur infrequently or unpredictably (as in your case), making them difficult to observe.
In these cases, it is possible to formulate some hypotheses based on the best available evidence. Following are some possibilities.
Medical Issues
Anytime a dog behaves in an uncharacteristic way, it’s important to rule out a potential medical disorder. For example, a dog in pain may engage in unusual aggressive behavior since agonistic behavior serves the purpose of avoiding contact with humans or other animals.
Pain can lower a dog’s general threshold for aggressive behavior, causing them to have a “shorter fuse” as they attempt to protect themselves
A dog may initially engage in nonviolent signals, such as turning the head, stiffening and giving a hard stare, but if these early preludes to a bite (as seen in Kendall Shephard’s “ladder of aggression") are ignored, the dog may lash out which may appear like a sudden impulsive exhibition of aggressive behavior without warning.
Such dogs are often reported to have a Jekyll and Hyde type of temperament. The aggressive behavior is often noticed when the dog in pain is approached and often when lying down.
The good news is that when pain is identified, the prognosis is excellent, with all cases reported to have a positive outcome once the pain is addressed (Beaver 1983).
Pain is only one possible reason for unexpected behavior changes in dogs. There can be several other possible medical disorders responsible for causing dogs to behave in uncharacteristic ways.
Course of Action: A vet visit is always a good first step to determine whether pain, discomfort, illness or other medical problems may contribute to a dog’s sudden aggression.
Resource Guarding of Food
It may be possible that some form of resource guarding was at play since this incident happened shortly after eating.
It could be that Zeke was guarding the food bowl even if it was put high or perhaps there were some small remnants of food on the floor.
Although Zeke has been desensitized to people touching his food or food bowls, this conditioning doesn't necessarily carry over to include other dogs.
Course of Action: In cases where there is a tendency to resource guard food, management is paramount. Feeding both dogs separately in a very controlled environment may be all that is needed to prevent future conflict.
Because dogs may also guard empty food bowls (and their surrounding space), it’s important to keep these completely out of the way and ensure there is no food around. Even sealed baggies, closets where food is stored and areas around them, can evoke fights.
It may also be a good idea to not introduce dogs in areas where they were recently fed. The dogs should be given some time following meals to be introduced again.
It’s important to consider that dogs who resource guard dog food or food bowls may also resource guard human food, food that is accidentally dropped or anything that is considered edible or “scented” and found occasionally on the ground, such as animal carcasses or animal poop.
Resource Guarding of People
Just as dogs may resource guard food, they may also resource guard people, almost as if they were a prized possession like a food bowl or a valuable bone.
The behavior you mention about Zeke usually not wanting to cuddle and suddenly seeking attention may signal some subtle competition going on.
Also, Diesel’s standoffish behavior when around you and Zeke may suggest that Zeke may have displayed some intimidating body language that caused Diesel to possibly approach cautiously, or perhaps they already had some conflict going on prior that went unnoticed.
If these incidents therefore took place when Diesel approached somebody, there may be chances that Zeke has started resource guarding the people he cares about and that the behavior has escalated at some point if Diesel trespassed some boundary.
Zeke's positioning in front of you growling towards Diesel is a typical stance of a dog who resource guards people, although it could be that he simply felt more secure with you being around. What appears like a people-guarding behavior is something that needs to be teased out to ensure it’s not something else.
Course of Action: It’s important to avoid giving attention to any dog if a dog is prone to resource guarding a particular person. Any type of favoritism can cause “jealousy” and competition among two dogs. If any early signs of conflict are noticed, it’s important to quickly redirect the dogs by using an obedience cue.
A Matter of Social Fatigue
Spending two whole days along with another dog may lead to tiredness and the onset of cranky behaviors in dogs. This tiredness and crankiness may escalate to aggression. Let’s take a look at some possible dynamics.
Extended periods of interaction with little time to rest and downtime can be mentally and physically exhausting for dogs. Dogs may get overstimulated and overwhelmed by the constant social interaction which may lead to irritability and fatigue.
The more time the dogs spend together, the more chances that their social dynamics may also change. While at the beginning it may be fun to play and disperse energy, minor irritations may be ignored. As tiredness sets in, though, the dogs may get less and less tolerant of each other
This increased tiredness and prolonged overstimulation can cause the dogs to get into conflicts for things such as resources, human attention and sometimes even space, which may escalate into aggression if not managed.
Course of Action: Some dogs may feel tired after just 20 minutes of playdates with friends, and then they may be ready to nap or relax. Other dogs may take more, but they all need some breaks. To prevent excess overstimulation and social fatigue, it’s important to recognize early signs of fatigue, stress and irritability. Careful attention to a dog’s body language is important.
By providing the dogs with breaks, separated rest areas and some time apart, it is possible to mitigate some of these issues.
In-person guidance from a dog trainer/behavior professional can be helpful so as to learn how to better manage a dog’s social interactions and ensure that dogs spend quality time together without feeling stressed.
Different Energy Levels
Different energy levels among dogs can lead to conflict, especially when one dog is repeatedly communicating his desire to be left alone, but these requests "go to deaf ears" so to say.
Disparities in energy levels may cause the dog wanting to play to feel more and more frustrated while the other dog gets more and more stressed as he can’t seem to find a way to communicate their need for boundaries.
When too many “leave me alone signs” are ignored, tension can rise and the dog with lower energy may reach a breaking point.
Course of Action: Find playmates that match your dog’s energy levels and monitor carefully for signs of tiring. Providing breaks and safe spaces can help give the dogs a chance to relax. Training fluent responses to important cues such as “leave it” can help manage undesirable behaviors and redirect the dogs as needed. Play and interactions should always be supervised so as to recognize early signs of stress.
The Impact of Trigger Stacking
Trigger stacking refers to the phenomenon where a dog reacts to the cumulative effect of multiple stressors taking place prior to the aggressive event. The dog’s reaction may seem to take place “out of the blue,” but in reality, there was a backdrop of stressful events taking place one after another leading up to the explosive reaction.
Dogs are animals that thrive on routines, and any novelties added into their lives and/or unsettling and disruptive events may serve as a tipping point.
If there has been a lot going on lately in your dog’s life, with many changes recently taking place, the additional stress of a camping trip can cause a dog to reach his breaking point.
Course of Action: Reduce exposure to triggering events as much as possible. Give the dog time to acclimate to a new place. Invest in calming aids (e.g. pheromone collars/diffusers, calming treats) to reduce the stress associated with changes. Recognize signs of early stress in your dog and intervene as soon as possible to prevent your dog from reaching his tipping point.
Giving Time for the Dogs to Recover
After an attack, it’s important to give each dog some time to chill. Arousal levels are very high and stress hormones such as cortisol take some time to lower.
According to a study, increased cortisol levels are associated with an increase in the amygdala’s activity, which is the fear center in the brain, which means dogs may be more reactive while cortisol levels return to baseline (van Stegeren et al., 2007).
Too early reintroductions may therefore lead to more conflict, and in several cases, full reintroductions should be avoided and steps should be taken to offer less stressful and more structured interactions where it is possible to create positive associations.
For example, parallel walks may be an option so that the dogs get to do something together, but without feeling stressed about too close exposures. With one dog per handler, it is possible to feed the dog’s treats as they look at each other and remain happy and calm. If one dog appears stressed, distance should be increased so that the dog feels relief. Here is a general guide on parallel walks for dog-to-dog reactivity.
Here is more about how to help a dog recover after a fight.
Moving Forward
As seen, there are several potential scenarios that could have triggered the aggressive episodes. Pinpointing the exact underlying cause may not be easy, considering that we don’t know exactly what may have happened and there may be some overlapping factors at play. Following are several strategies to prevent future incidents.
The Use of Management
When the exact dynamics of what may have triggered a fight are not clear, it’s best to err on the side of caution and take a more conservative approach by implementing management. How much management will need to be in place may vary depending on various factors such as the dogs' level of stress, how resilient the dogs are in “getting over a fight,” the ability to avoid triggering events, etc.
Management entails the avoidance of any potential triggering situations. Plans should therefore be in place to prevent future incidents. Examples of management in a case like yours may entail various degrees of avoidance, such as:
- Feed the dogs separately.
- Avoid giving attention to one dog when in the presence of another dog and avoid any favoritism.
- Address energy level disparities.
- Interrupt play if one dog is giving signs of no longer wanting to interact.
- Provide opportunities for the dogs to have breaks from each other.
- Always monitor the dog’s interactions and watch their body language.
- Provide familiar items on camping trips, such as the dog’s own beds so as to reduce stress to use when taking breaks from each other.
Recognition of Early Signs of Stress
Before a dog lashes out and attacks another dog, there are usually preceding warning signs taking place. When dogs interact with other dogs, it’s important to recognize signs of fear, stress, anxiety and the many nonverbal precursors of aggression, points out board-certified veterinary behaviorist Dr. Amy Pike.
Signs that signal a defensive stance are the ears kept flat, lip licking, panting, wrinkled brow, wrinkled nose, rapid blinking, cowering, avoidance of eye contact, and a tucked tail.
Signs that signal an offensive stance include a tail that is held high, the body leaning forward, direct staring, ears kept erect and a stiff, tall posture.
Seeking the Help of a Professional
For successful reintroductions, it may be important to work alongside a dog behavior professional. He or she can monitor the dog’s interactions, help identify problematic body language and help train fluent responses to obedience cues so as to interrupt interactions before a situation deteriorates.
If you're struggling to figure out what may be triggering your dog’s behavior, especially if it persists and generalizes to other dogs, early intervention is important.
Concluding Thoughts
Despite having a track record of behaving appropriately, dogs can sometimes behave in unpredictable ways, especially when they are placed in an unfamiliar place and are exposed to potentially stressful situations.
The fact that this is the first time that Zeke has exhibited this behavior is a promising sign, as this may be an isolated incident triggered by a specific circumstance.
Recognizing this early on is important as many dogs can learn to overcome such issues when addressed before it becomes a long-term pattern and generalizes to other dogs.
The good news is that dogs are capable of changing and with the right approach, love, patience and professional guidance as needed, you and your dog can work through this challenging time and any potentially problematic behavior can be nipped in the bud.
Best of luck, and here’s to many more safe and enjoyable adventures with your canine companion!
References
- Camps, T.; Amat, M.; Mariotti, V.M.; Le Brech, S.; Manteca, X. Pain-related aggression in dogs: 12 clinical cases. J. Vet. Behav. 2012
- Clinical indicators of occult musculoskeletal pain in aggressive dogs
- Barcelos, A.-M., Mills, D. S. and Zulch, H. (2015) Clinical indicators of occult musculoskeletal pain in aggressive dogs. Veterinary Record
- Mills, D.S.; Demontigny-Bédard, I.; Gruen, M.; Klinck, M.P.; McPeake, K.J.; Barcelos, A.M.; Hewison, L.; Van Haevermaet, H.; Denenberg, S.; Hauser, H.; et al. Pain and Problem Behavior in Cats and Dogs. Animals 2020
- van Stegeren, A. H., Wolf, O. T., Everaerd, W., Scheltens, P., Barkhof, F., & Rombouts, S. A. (2007). Endogenous cortisol level interacts with noradrenergic activation in the human amygdala. Neurobiology of learning and memory
- Carrier, L. O., Cyr, A., Anderson, R. E., & Walsh, C. J. (2013). Exploring the dog park: Relationships between social behaviours, personality and cortisol in companion dogs. Applied Animal Behaviour Science
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.
© 2023 Adrienne Farricelli CPDT-KA, Dip.CBST
