The most common dog behavior problem that I deal with is "dog leash reactivity".  That is dogs acting badly while on leash when they come  into contact with other dogs or critters. Such as lunging, barking, crying and spinning out of control on the leash. This behavior is often mistaken for dog aggression. The elevated excitement when these dogs see another dog can quickly turn into aggression if the dogs come into contact. In many cases these same dogs who act like Cujo when on leash may do fine with other dogs when off-leash. 

This common scenario gets played out daily in almost every neighborhood in America. It leaves dog owners frustrated and uncertain as to what to do other than walking their dogs at times when they are not likely to meet other dogs. Often times the owners just stop walking these dogs and the problem gets worse. 

By the time I get called in to help, owners have mostly given up. Often times they will report that their dog is not reactive to all dogs they meet and the behavior is unpredictable making walks nerve raking and unenjoyable. 

The majority of dogs that I work with who have this behavioral problem are rescue dogs but I also see it in dogs who have been raised as puppies in one home. With rescue dogs we often have no past history and only know what we have and observe. The causes of leash reactivity can be caused by many factors. The most common causes are: 1. lack of proper exposure to dogs at an early age. 2. Lack of leash training and general obedience. 3. Too much exposure to dog parks and doggie day care without proper obedience training.  

4. A traumatic experience such as being attacked by a dog while on leash. 5. Generalized fearfulness either based on lack of socialization or genetics. 6. Over protectiveness of the owner.

What are the steps that are necessary to work through this behavior problem? A dog will first need the following skill set to be able to deal with dogs calmly while on leash. 1. Loose leash walking (heel command).  

2. Sit/Stay command. 3. Watch-me command. and 4. Leave-it command.  

When the dog can execute these commands reliably in a distraction free environment then you should add distractions.

Once the dog is more reliable with the commands then you can start desensitization exercises. That is presenting the triggering object (dogs) at a distance and slowly decreasing the distance while the dog is under control. This process can take weeks or even months to complete depending on the dog and the severity of the problem. Some behavior problems are so ingrained that the help of a professional dog trainer might be needed.