The leash is loose for most of the walk. Then another dog appears, and your dog leans into the harness with their full weight, both your arms straight, heels dug into the pavement.
This is different from a dog who tows you everywhere, and different from the dog who lunges and barks. Yours goes quiet, focused, and pulls like a sled dog toward one thing.
What is being rewarded
For most dogs who pull only toward other dogs, the pull has been working. Reaching the other dog, or getting close enough to greet, has paid off often enough to be worth the effort.
If your dog seems frightened rather than keen, use the distance method in the related article on dogs who only pull when another dog appears. This page is about the friendly, forward version.
Stop paying the pull
Decide now that on-leash greetings happen rarely, if ever. If reaching the other dog is what pulling has always earned, the pulling is being paid every time you allow it.
The instant the leash tightens toward a dog, stop moving forward. Do not reel your dog in, and do not keep walking while braced against the pull.
Turn and walk the other way for 10 steps, calmly, saying nothing. A pull that ends in the opposite direction stops being useful to your dog.
Teach the pattern that replaces it
This is sometimes called an engage-disengage game. Your dog looks at the other dog, then looks back at you, and the look back is what earns the reward.
At a distance where your dog notices a dog but the leash stays loose, say your dog's name once as they look.
The moment they glance back toward you, even briefly, feed 3 treats quickly at your knee. You are paying for the glance back, not for ignoring the other dog entirely.
Repeat for 4 or 5 passing dogs, then end the session. That is a full practice, and it takes under 10 minutes.
The body mechanics that help meanwhile
Hold the leash with both hands, one near the clip, so a sudden lean does not travel straight to your shoulder.
Turn your whole body sideways to the other dog rather than facing it directly. A sideways body is easier to walk away with.
Keep 4 to 6 feet of slack rather than a short, tight hold. A short leash gives your dog less room to think and you less time to react.
Safety note
Get a veterinary examination if the pulling arrived suddenly, or if your dog shows stiff, frozen body language rather than a bouncy, forward one. The same applies if your dog has growled or snapped.
Why not a corrective collar
A tightening or shock collar punishes the pull, but it also punishes your dog for noticing another dog at all. A review of aversive methods found them associated with worse welfare outcomes and no training advantage.
Reward-based methods are what the veterinary behaviour guidance recommends. They teach your dog a different pattern, rather than adding pain to the old one.
Today's version, in one line: no more leash greetings, and pay every glance back at you instead.