What Set Them Off? Making Sense of Your Dog's Reactivity
For some dogs reactivity triggers are less obvious and require us to become detectives. photo: AdobeStock
Maisie was a sweet Golden Retriever whose guardian reached out to me about Maisie suddenly barking and lunging at other dogs. Most of the time, Maisie was friendly and social so these outbursts seemed random. They were also embarrassing to her person, who couldn’t figure out what was setting her off.
Before developing a training plan, we needed to determine what was triggering Maisie's behavior. Her guardian began tracking each incident, noting where they were, what the other dog was doing, and how Maisie responded. Within a week, a clear pattern emerged. Maisie’s reactions only happened in her immediate neighborhood, only when she was on leash, and only with dogs larger than her. Once we had those details, we could build a plan that avoided surprise blowups and focused on helping her feel safe around big dogs on familiar turf.
What Are Antecedents and Why Do They Matter?
For many dogs, the cause of reactivity is immediately apparent. It might be a specific breed, a dog behind a fence, intact males, or “dog enemies” they've had run-ins with before. These triggers will reliably provoke a predictable reaction. But for some dogs, the triggers are less obvious and require us to become detectives, gathering clues and connecting the dots. If your dog reacts to other dogs on walks, it may seem random, but there’s almost always a pattern.
Before we can begin training, we need to understand what’s setting the stage for the reaction. These are called antecedents: the events, conditions, or contexts that come before a behavior and influence how it unfolds. Keeping a detailed log helps us understand which situations tend to trigger your dog.
Ultimately, the goal is to minimize reactions, not just by avoiding triggers entirely, but by managing exposure in a way that sets your dog up for success. We want to prevent unplanned encounters that lead to a reactive outburst. Every time your dog rehearses the barky-lungy behavior, it strengthens that habit and makes it harder to undo. Repetition builds patterns, and patterns become default responses. But what’s predictable is preventable. Identifying antecedents is the first step toward real change.
How to Track Your Dog’s Antecedents
While today we’ll focus on dog-dog reactivity, the same data-gathering principles can be applied to other types of reactivity, including reactivity toward people, bicycles, runners, or what have you. The process of identifying antecedents is the same across various contexts and will help create clearer, more effective training plans, regardless of the trigger.
The goal is to identify what’s happening before your dog reacts. Some antecedents are immediate, like turning a corner and finding yourself face-to-face with an off-leash dog. Others are more distant, such as skipped meals, lack of rest, earlier excitement, or underlying pain or injury that prime your dog to be more sensitive to triggers.
The important thing is to log each incident soon after it happens while details are fresh. You can use a notebook, your phone, or a printed log or chart - whatever helps you stay consistent. When logging incidents, include:
✓ Distance from the other dog
✓ Time of day (morning, afternoon, evening, etc.)
✓ Distance from your house (e.g., near home vs. farther away)
✓ Familiar location or new environment
✓ Location and setting (e.g., quiet street, busy park, backyard, inside car)
✓ Where you were in the walk (e.g., just leaving the house, mid-route, or returning home)
✓ Was your dog on- or off-leash?
✓ Was the other dog on- or off-leash?
✓ Was the other dog male or female? Spayed or neutered?
✓ Was the other dog a puppy, adolescent, adult, or senior dog?
✓ What was the other dog doing (e.g., walking calmly, running, barking, sniffing, sitting still, playing, staring)?
✓ How did the other dog appear (e.g., suddenly, from behind a fence, from a distance, etc.)?
✓ Who was present (humans and other dogs)?
✓ Who was holding the leash?
✓ Were food, toys, or treats present?
✓ Did you interact with the other dog or their owner?
By noting the details that happen before your dog reacts - the antecedents - you’ll start to see patterns and be able to identify the events that set the behavior in motion.
Recognizing When a Trigger Is Too Much
Part of tracking antecedents is noticing when a trigger is too close or too intense. Common early warning signs include lip licking, yawning, stiff posture, prolonged staring, ears pinned back or held in a high-alert position, pulling on the leash, or refusing treats. If you notice your dog shifting into a tense or alert state, it’s your cue to create distance or adjust the environment before the reaction occurs.
Want help spotting these signs? This video walks you through what “under the threshold” looks like - and why it’s so important to catch those subtle cues early.
Reactivity Ladder: A Rough Guide to Trigger Difficulty
The below “reactivity ladder” provides a general guide to some of the more common triggers for many dogs, in rough order of increasing difficulty. But remember that every dog is different, and your dog’s reactivity ladder may look very different.
Dogs at a distance
Dogs sitting or lying down
Small or older dogs walking slowly
Dogs walking away
Dogs ignoring your dog, head or body turned away
Dogs approaching head-on
Dogs that remain in sight for an extended time
Dogs behind barriers (e.g., fences, windows)
Dogs with pointy ears or high tails (e.g., Huskies, German Shepherds)
Certain breeds your dog has had a bad experience with
Intact males (especially if your dog has had prior conflict with one)
Dogs moving quickly, running, or playing
Dogs barking while running or playing
Dogs making direct eye contact, especially if staring
Dogs approaching with the intent to interact (playful body language)
Dogs approaching head-on
Dogs approaching with intent to interact (hard stare, stalking, high tail)
Rowdy, bouncy, high-energy dogs
Groups of dogs or multiple dogs together
Other reactive dogs
Trigger Amplifiers
Certain conditions can make even a mild trigger feel more intense for your dog. A tight leash, tension in your body, narrow sidewalks, sudden appearances, slippery footing, being in a crowd, or loud noises can all increase stress and reactivity.
The cumulative effect of past negative experiences in a particular location, such as your neighborhood or a familiar park, can also heighten your dog’s reactivity. When a location is associated with repeated stressful events, even lower-level triggers may feel more intense.
Don’t overlook the possibility of pain or underlying medical issues as a contributing factor. Dogs are remarkably good at hiding discomfort, and many can be in pain without showing obvious signs. In fact, undiagnosed pain is one of the most frequently missed causes of reactivity. Even subtle or intermittent pain can impact how your dog responds to the world around them. What may appear to be a behavioral problem could actually be your dog protecting a sore joint, avoiding movement that aggravates discomfort, or reacting defensively to prevent physical pain.
Pain is a powerful antecedent, and it’s one we can’t afford to miss. If your dog’s reactivity developed suddenly or changed noticeably, a comprehensive veterinary workup is a necessary first step.
Trigger Stacking
Sometimes reactivity isn’t just about the dog in view. Rather it can be the cumulative effect of everything else that’s already gone wrong that day. This is called trigger stacking: when multiple stressors (big or small) pile up over time, lowering your dog’s threshold and increasing their likelihood of reacting. A missed nap, a skipped meal, allergy flare-ups, earlier arousal, houseguests, and changes in routine can all quietly add to the load until that final last-straw moment hits during a walk.
Collecting and analyzing data about your dog’s reactions becomes even more powerful when shared with your trainer. Once you have clarity on your dog’s specific triggers and thresholds, you can proceed with systematic desensitization and counterconditioning. A force-free behavior consultant can guide this process.
You don’t have to track your dog’s reactive incidents forever, but even a week or two of careful observation can reveal more than months of guesswork. Managing your dog’s environment to keep them under the reactivity threshold reduces stress for both of you and creates more opportunities for learning and calm behavior.
All behavior happens for a reason, even reactivity. Once you start to understand what triggers your dog’s reactions, you’ll be able to plan ahead, reduce surprises, and respond with confidence instead of feeling caught off guard. And that’ll make life a whole lot more pleasant for both of you.