Leash Reactivity Explained: Trigger Stacking, Genetics, and How to Help Your Dog

Living with a reactive dog can make walks feel miserable. It can be frustrating, embarrassing, and at worst—even dangerous. Many reactive dog parents come to me at a complete loss for what to do, and some have already been through multiple trainers or feel like they’ve “tried everything” with no improvement.

The missing piece in these cases is almost always the same: not understanding the factors shaping the behavior or the nuance behind your dog’s triggers.
Let’s dive in.

What Leash Reactivity Really Is

When dog trainers use the term leash reactivity, we’re typically referring to dogs that bark or lunge on leash at various things. The list of things they react to varies widely, but we commonly call them triggers. What’s really happening underneath these outbursts is rooted in arousal modulation—basically, how well your dog can handle a sudden spike of excitement, frustration, or fear when a trigger appears.

Common triggers include other dogs, fast-moving objects, anything that startles them, men, people with hats, and other animals.

But here’s the part most people forget: barking, chasing, and rushing toward things in the environment is often in the dog’s genetic job description.

Some dogs were intentionally bred to bark at, chase, and kill vermin.
Some were bred to control movement—especially sudden movement that “doesn’t belong.”
Some were bred to alert at anything relevant in their environment.
And lots of dogs bark when they feel frustrated, excited, or scared. Some even bark just for the sheer joy of barking (yes, hounds, I see you).

So, you can see why a cookie-cutter recipe for every leash-reactive dog is destined to fail. A frustrated dog may not respond to the same strategy that works perfectly for a fearful dog. A dog bred to control movement may react differently on leash than a dog with intense prey drive—even if both dogs are lunging and barking at something.

This is where nuance matters, and understanding it will benefit you tremendously.

The Nuances of Triggers

Triggers aren’t one-size-fits-all, they come with different intensity levels. Think of them on a spectrum.

Take skateboards, for example:

• A stationary skateboard = low intensity

• A skateboard suddenly popping into view with a rider flying toward you = extremely intense

• A skateboard 300 feet away, rolling away from you = somewhere in the middle

Dogs work the same way. A calm dog sniffing the ground might barely register to your own dog. But a frantic, barking dog popping around a corner within a few feet? That’s a totally different level of intensity.

And let’s not forget micro body language cues. Dogs communicate constantly with tiny shifts most humans never notice: eye shape, ear flicks, tail height, muscle tension, posture. Your dog picks up on all of it. That’s why your dog may feel neutral around stable dogs but lose their mind the moment they sense even a hint of threat from another dog.

Trigger stacking is real—and powerful.

Triggers can feel ten times more intense when they show up back-to-back. If your dog has one explosive reaction, and then encounters another trigger—even a mild one—shortly afterward, the second reaction can feel much bigger.

This is called trigger stacking.

Some sensitive dogs feel the effects of a stressful event for up to 48 hours. They’re more alert, jumpy, or explosive because their nervous system hasn’t fully reset. These little moments accumulate if the dog isn’t getting enough opportunities to decompress.

This nuance—intensity levels and stacking—is what most people don’t realize is influencing their dog’s seemingly “random” outbursts.

Tips to Make Walks Manageable (and Less Miserable)

Here’s where you can start helping your dog right away, without needing to memorize a 15-step training protocol.

1. Look at your dog more than you look for triggers

Most people scan the environment like secret service agents. Instead, keep your eyes mostly on your dog. Of course, you’ll still want to be generally aware of your surroundings, but for about 80–90% of my walk, my eyes are softly focused on my dog. Not laser-focused -- just soft, relaxed focus where you can still see with your peripheral vision and stay aware of what’s happening around you.

If you didn’t know that you can control the intensity of your focus, I encourage you to try it. Look at something in your room and keep your eye muscles relaxed while continuing to breathe. Notice how you can still take in what’s happening around that item. Now try staring at it with hard, laser focus. Everything around it becomes blurrier, and most of us instinctively hold our breath when we do that.

Our dog's body language will often give you clues to how they feel about their environment before the outburst happens or before you even see a trigger. You might not even be able to perceive what your dog is activated by, and that could be because their senses are different than yours. They have an entire world of smell we do not have access to. A good rule of thumb, is that if you see their body language shift from soft and relaxed to stiff and alert, there is something in their environment that triggered that change of arousal in them. 

Early red flags include:

• Mouth closes

• Tail goes up

• Body stiffens

• Ears lock forward

• Sudden stillness, sudden speeding up, or sudden slowing down

• Slower response to your voice or no response

• Less interested in food or being touched

• Scanning or hyper-vigilance

When you catch these cues early, you can often intervene before your dog has a reaction. And even when we try our best, there will still be scenarios that I like to call, "the oh sh*t moments" where you didn't catch something fast enough or the environment suddenly changed and was too challenging for you both to navigate. It happens to me too and I do this for a living. Give yourself (and your dog) some grace. 

2. Treat training like (an ethical) science experiment

My next tip is to treat training like a fun science experiment instead of a showcase of how good or bad of a dog mom you are. Approach your dog's behavior with curiosity...trust me, it's way more fun. 

Ask yourself questions like:

• If I do this, how does my dog respond?

• In this environment, what changes in my dog's body language?

• Are they able to hear me when I speak?

• Can they take food?

• How quickly does their arousal rise or fall?

When you approach behavior with curiosity, not judgment, the entire walk becomes lighter.
You can’t be curious and pissed off at the same time. (I’ve tried.)

3. Take the path of least resistance

Some dogs truly hate neighborhood walks. They freeze, bolt, or try to drag you home.

If your dog is terrified, this is not the time for “pushing through.” But if potty walks are unavoidable, you’ll face the environment daily. So:

• Choose less busy times.

• Go out, potty, come home.

• Take nature hikes when possible.

• Skip nature hikes when you don’t have the capacity.

• And remember: real training happens when both of you have the bandwidth.

And if something looks too close or too intense? Don’t tough it out...pivot.

Cross the street.
Turn around.
Hide behind a car.
Use a “ready… get it!” treat toss.

And sometimes, the path of least resistance means finally hiring a trainer because your anxiety and avoidance are taking over. That’s what we’re here for.

You’re not failing. You’re learning.

4. And if your dog reacts? It’s not the end of the world.

One reaction doesn’t mean your training failed. It doesn't mean you suck. It doesn't mean your dog is an a**hole. It just means your dog's nervous system responded to its' environment. That's it. 
It doesn’t mean your dog is regressing necessarily.
It doesn’t mean you’re doing anything wrong necessarily. 

Take a mental note of it or better yet track it in your phone notes. If you start to see a pattern of reactions growing in intensity and frequency, that's information and a sign you should probably call in for more support if you can. Sometimes medical issues can contribute to this or the training plan may just need some tweaks. And sometimes we just need to accept reality and give our dogs a little more grace to be different than what we expected. 

If This Sounds Overwhelming… You Don’t Have to Navigate It Alone

Reactivity is complicated because life is complicated and full of nuance. But it becomes so much easier when you have guidance, a plan, and someone who understands how to blend behavior science with emotional regulation for both ends of the leash.

If you’re ready for calmer walks, more confidence, and to build a stronger relationship with your pup, this is exactly what I help dog parents with.

You bring an open mind, your dog, and your questions.
I’ll bring the training plan, the nuance, and the support system.

If you want help making sense of your dog’s reactivity, I’d love to work with you.