Reactive dogs: what's actually going on
A reactive dog is one who barks, lunges or panics at specific things — other dogs, bikes, loud noises — at a level that looks out of proportion to what happened. Reactivity is not aggression and it is not disobedience; it is a stress response, and stress from separate events accumulates across days rather than resetting between them. That accumulation is the single most common reason a walk goes wrong for no visible reason. CalmDogs is an iPhone app that logs what a dog met on each walk — the trigger, the distance, the reaction, the recovery time — so the accumulation is visible before the next walk rather than after it.
Most of what makes a reactive dog's week hard is invisible from inside a single walk. These pages explain the parts that are hard to see: what reactivity is, what a threshold is and why it moves, how stress stacks across days, and how long recovery actually takes.
Start here
If you have just been told your dog is reactive, read these three in order.
- What is a reactive dog? What the word describes, and how it differs from aggression.
- Why does my dog bark at other dogs on walks? The most common version of the problem, on a lead.
- Your dog was fine yesterday and terrible today Why two days in a row can look like two different dogs.
- When you're the one who's trigger stacked It happens to the person holding the lead as well.
The mechanics
The parts that are hard to see from inside a single walk.
- Trigger stacking in dogs How stress from separate events adds up instead of resetting.
- Thresholds, and why they move The line past which a dog stops being able to respond to you.
- How to tell when your dog is over threshold What owners report seeing, and why your dog's own sign is the one that counts.
- How long does it take a dog to calm down? Recovery time, and why it is the first thing that shifts.
Keeping a record
What to write down, what it costs to get help, and what to bring to the people who can give it.
- What to write down after a reactive dog's walk The four fields that make a walk log worth keeping.
- Tracking a reactive dog in a spreadsheet Why most sheets die in a fortnight, and what makes one survive.
- Apps for reactive dogs Seven apps compared, side by side, checked in August 2026.
- Dog behaviour tracking apps What general tracking apps do and do not record.
- What a reactive dog trainer costs Session prices, and how many sessions it usually takes.
- What to tell your vet about your dog's reactivity Turning months of walks into ten useful minutes.
By trigger
One page per thing your dog reacts to. Same structure each time. None of these is written yet.
- Bikes soon
- Cars and traffic soon
- Men soon
- Children soon
- Fireworks soon
- Thunderstorms soon
- Dogs behind fences soon
- Delivery vans soon
- Joggers soon
- Cats soon
- Skateboards soon
- Umbrellas soon
- Buses and lorries soon
- Wheelchairs and mobility scooters soon
- Hats and hoods soon
- Puppies soon
- Doorbells soon
- Vacuum cleaners soon
Every page here is written by the person who built CalmDogs, an iPhone app that keeps this kind of record for you. There is no free tier, and the pages are free to read either way.
Questions
Is a reactive dog an aggressive dog?
No, though they can look alike from across a street. Reactivity describes an outsized response to a specific trigger. Aggression describes intent to do harm. Most reactive dogs are frightened rather than dangerous — but if your dog has bitten someone, that is a situation for a qualified professional, not an app.
Can reactivity be trained away completely?
That is a question for a qualified behaviourist who has met your dog, and the honest answer is that it varies enormously. What is true for every dog is that you cannot judge whether anything is working without a record of what you have actually been doing.
Why does my dog react to some dogs and not others?
Distance, angle, the other dog's behaviour, what happened earlier that day, and how much sleep your dog got can all move the outcome. It is rarely one variable, which is exactly why single walks are misleading and several weeks of them are not.