Start with direction, not volume
Barking and lunging describe what the dog does. They don’t explain why. Notice whether the dog repeatedly pulls toward the other dog, curves away, hides behind the handler, freezes, or tries to retreat. Direction gives better information than how loud the reaction sounds.
Frustration may show as a forward lean and active body before the leash blocks access. A worried dog may shift weight back, lower the body, close the mouth, pin the ears, or scan for an exit. None of these details should be read alone.
Recovery adds another clue
Watch what happens after the other dog is gone. Quick recovery and renewed attempts to approach can fit frustration. Continued scanning, shaking, avoidance, or refusal to continue can fit fear. A dog can also begin frustrated and become worried when the encounter gets too close.
Don’t test the theory by allowing a greeting. A close meeting can place both dogs in a difficult position, and friendly behavior off leash doesn’t guarantee comfort during a tight on leash encounter.
Use the same safe first step
Create distance early, keep the leash as loose as safety allows, and use a practiced turn before the reaction begins. Distance protects a fearful dog and gives a frustrated dog a chance to practice a different response.
Find a place where the dog can notice the trigger and still eat, turn, or sniff. The threshold distance guide explains how to record that workable starting point.
The training plan may differ
Fear work usually centers on safety, choice, and changing the association with the trigger. Frustration work often adds practice around delayed access, disengagement, and calm movement. Reward based training fits both, but the exact setup should match the dog in front of you.
For reactions aimed at other dogs, continue with the dog directed leash reactivity guide. That page owns the broader training plan. This comparison helps you describe the pattern more accurately.
Get help when risk is unclear
Snapping, nipping, biting, redirected contact, or a reaction too strong for the handler to control calls for qualified help. Avoid close practice while waiting. A veterinarian can check for pain and refer you to a veterinary behaviorist or a credentialed reward based professional.
Write down trigger distance, body position, recovery time, and what happened just before the episode. A short video recorded safely from a distance can help a professional, but nobody should move closer or hold a phone when control is uncertain.
Either type of dog benefits from a leash that's loose before the trigger appears. The basics are in how to stop a dog from pulling on the leash.