Leash reactivity is when a dog exhibits fearful behaviors that may become aggressive when the dog is restrained by a leash, confined to a small space, or otherwise feels trapped. It is characterized by barking, lunging, growling, air snapping, or even biting. Leash reactivity is caused by a variety of factors, including fear, anxiety, lack of socialization, and past negative experiences. Dogs that have not been properly socialized with other dogs and humans are more likely to develop confinement/leash reactivity, as they may feel threatened, nervous, or uncomfortable when they encounter people or other dogs. This feeling increases when the stimulus or trigger moves closer into your dog’s comfort zone. There are certain risk factors that can lead to this type of reactivity, including being physically or mentally punished during training, having negative experiences while being on leash, such as being attacked by another dog, or exhibiting fearful behaviors while outside due to a lack of socialization. In some cases, leash reactivity may be due to an underlying medical condition such as pain, discomfort, or illness.