Leash reactivity: why your dog explodes on the canal path

A bike bell, a dog on the other side of the bridge, and suddenly your sweet dog is barking and lunging at the end of the leash. People stare. You feel embarrassed. Your dog is not being bad. Your dog is overwhelmed.

What reactivity really is

Reactivity is a big emotional response to something the dog finds hard: another dog, a bike, a stranger. Underneath it is usually fear, frustration or both. The leash makes it worse: the dog cannot move away, and it cannot go and greet. So it shouts.

Thresholds and trigger stacking

Every dog has a threshold: a distance at which it can see the trigger and still think. Closer than that, the thinking brain switches off.

Stress also adds up. A noisy tram, a bad night, a dog behind a fence and then a bike: each one pushes your dog closer to the edge. This is called trigger stacking, and it explains why the same dog is fine on Monday and explodes on Thursday.

First steps that help

1. Distance first. Cross the street, step behind a parked car, turn around. Distance is not avoiding the problem. It is where learning can happen.
2. Make the trigger predict good things. When your dog sees another dog from a safe distance, food arrives. Over time, the sight of a dog starts to feel like good news. This is classical conditioning, the same principle Pavlov described.
3. Play "look at that". Your dog looks at the trigger, you mark it and reward. Developed by trainer Leslie McDevitt, it turns watching into a calm, rewarded behaviour.
4. Choose quieter routes and times. Fewer surprises means fewer explosions, and every explosion you prevent is one your dog does not practise.
5. Add decompression walks. Long-line sniffing in a quiet park lowers overall stress.

What not to do

Corrections, leash pops and prong collars can make a dog go quiet for a moment. But they add more stress to a dog that is already overwhelmed, and the research links them to poorer welfare (Vieira de Castro et al., 2020). The dog learns that other dogs predict pain. That is the opposite of what we want.