Leash reactivity is a common problem in dogs. It is when a dog becomes anxious or aggressive when they are on a leash.
There are a number of factors that can contribute to leash reactivity, including: Fear or anxiety, Lack of socialization, Past negative experiences, etc.
Desensitization and counterconditioning
Desensitization and counterconditioning is a gradual process of exposing your dog to the trigger in a controlled environment and rewarding them for staying calm.
Positive reinforcement training is a method of training that rewards your dog for good behavior.
If you can, it is best to avoid triggers that your dog reacts to. This may mean walking in different areas or avoiding certain times of day.