Why does my dog bark and lunge at other dogs on walks?

4 min read Updated on October 8, 2026

In shortMost of the time, because he is afraid, or frustrated that he cannot go say hello. The leash takes away his escape route and his dog manners, like curving around or sniffing, and the barking “works”: the other dog always moves on eventually, so he does it again. This is called leash reactivity. It is not dominance or meanness, and punishment makes it worse. What works: distance and rewards.

What it often means

Fear: he is anxious by nature, met few other dogs as a puppy, or had a bad encounter, and he barks to keep the other dog at a distance.
Frustration: he loves dogs, the leash stops him from greeting them, and the excitement spills over into high-pitched barking, whining and lunging.
Learning: every time he barks, the other dog ends up walking away. To him, barking makes the threat leave, so he keeps doing it.
The leash and the sidewalk: he cannot flee, curve around or sniff freely, his calming signals are hampered, and a head-on meeting is rude in dog language.
More rarely, pain or failing eyesight: a dog who hurts or sees poorly feels more vulnerable, and reacts faster.

Signals to read at the same time

The distance: how many yards away he starts staring at the other dog, then how many yards away he explodes. The gap between the two is your working room.
What comes before the explosion: a hard stare, a body that freezes, a mouth that closes, ears pricked forward. That is the moment to act, not after.
Body weight: leaning back, tail low, ears flat means mostly fear, even if he charges; pulling forward and whining means more frustration. Raised hackles show strong emotion, not intent.
The treat: if he refuses it or snatches it hard, he is too close to learn anything. Back up.
His day: after a bike, a noisy truck and a first dog, the second dog is the last straw. Stress adds up.

What you can do

Create distance as soon as a dog appears: cross the street, turn around, step behind a parked car. He learns where he can see the other dog without exploding.
Play “dog means treat”: the moment he looks at a dog in the distance, give him a piece of chicken; when the dog disappears, the treats stop.
Practice a happy U-turn at home, then on quiet streets: a cue word, a pivot, a treat. The day a dog pops out, the move is ready.
Walk him in a harness on a loose leash, at quiet times and in quiet places, and skip dog parks and narrow sidewalks while he is still reacting.
Do not punish him, jerk the leash or force a greeting: he would link other dogs with pain and fear, and react even harder.

When to see a vet

See your vet first if the reactivity started suddenly in a dog who used to pass others calmly, or if he limps, gets up stiffly, no longer likes being touched, or seems to see or hear less well: pain or a fading sense makes a dog more irritable. Then, if he has ever bitten a dog, the leash or your leg mid-reaction, takes a long time to calm down, or is getting worse, call a veterinary behaviorist or a certified behavior consultant. Meanwhile, a basket muzzle taught with treats keeps everyone safe.

Frequently asked questions

Why does he bark on leash when he is friendly with dogs off leash?

Because the leash changes everything. Off leash, he can approach in a curve, sniff, and leave when he wants. On leash, he is held facing the other dog with no way out, and often frustrated that he cannot reach it. Skip on-leash greetings and practice calm passes at a distance instead.

How can I tell whether he is scared or frustrated?

Look at the whole body, not just the voice. A 2018 review points out that dogs communicate through combined visual, vocal and scent signals, which have to be read together and in context. Fear: weight back, tail low, he retreats right after charging. Frustration: he pulls, whines, and relaxes as soon as he can sniff the other dog. Often it is a mix of both.

Should I let him meet other dogs to socialize him?

No, not while he is reacting. Forcing contact overwhelms him and confirms his fears. Here, socializing means seeing dogs from afar while staying calm, with rewards. Later, side-by-side walks with a calm dog he knows, guided by a professional, can help.

Can a reactive dog get better?

Yes, many improve a lot, but rarely in a few days. Every explosion rehearses the habit, so avoiding them matters as much as the training. A large 2019 owner survey found that the vast majority of dogs show at least one problem behavior, often several linked together: if he also fears noises or strangers, work on the whole picture with a professional.

Sources

The studies this page relies on, with a link to the original publication.

Siniscalchi et al. (2018). Communication in dogs. Animals.Review: dogs communicate through combined visual, vocal and scent signals, which have to be read together and in context.
Dinwoodie et al. (2019). Demographics and comorbidity of behavior problems in dogs. Journal of Veterinary Behavior.In a large owner survey, the vast majority of dogs showed at least one problem behavior, often several linked together.

Mimo reads behavior. It does not replace a vet.