There are 3 different types of reactivity: fear-based, frustration-based, and defensive. This is true regardless of the trigger (dogs, new people, etc). Despite what you may have heard, not every reactive dog is afraid or frustrated.

FEAR-BASED REACTIVITY

Fear-based reactivity is basically what it sounds like - the dog is afraid of dogs and reacts offensively in an attempt to scare off that dog or person. They’ll get you before you can get them. These dogs don’t want conflict, and seemingly counterintuitively use an aggressive-looking display to back other dogs or people off. They would prefer to simply be left alone, but when they feel threatened they will respond with a big, barky/growly outburst in an attempt to get the scary thing to back off.

This type of reactivity is most often caused by lack of socialization before 12 weeks. The young puppy, during his critical socialization period (3-12 weeks), did not get to meet enough dogs or new people and now finds them scary and intimidating. These dogs usually have fairly poor social skills and low confidence. They typically come from substandard breeders who don’t socialize and then go to owners who don’t socialize until it’s too late. Often the parents of these fearful puppies are also fearful - anxiety is partly genetic, and this is why anxious, fearful dogs should not be bred.

It can also be caused by a bad experience, such as a dog being attacked or injured by another dog. One of my dogs, at the age of 7 years, was attacked by an off-leash dog and gradually became dog-reactive after that. He was not going to take the chance of being attacked out of nowhere again and decided to preemptively warn every dog he saw away.

AS PUPPIES

As puppies, these guys were likely very fearful and avoided other dogs or people. In puppy class during play time, these puppies hid under the chairs and cowered or growled when approached by other puppies and never approached new people for an interaction. When someone reached to pet them, they would duck or back up to avoid contact.

This type of reactivity can generally be completely prevented with proper early socialization.

Owners of these dogs may believe that their fearful dog just needs socialization and might try taking their reactive dog to a dog park to help them “get over it.” This can backfire tremendously and is not recommended. Socialization is not a training tool, and it is meant to prevent problems, not fix them. Once you have a reactive dog, socialization isn’t the answer. It WAS the answer, but now it’s too late. Now we need training.

FRUSTRATION-BASED REACTIVITY

These dogs are usually playful and friendly off leash, but when on a leash are quite frustrated at their inability to go play or greet the way they want to. It’s essentially a giant temper tantrum at not getting their way.

This type of reactivity is often seen in dogs who are naturally very social, such as labs or golden retrievers, and it’s made worse when well-meaning owners constantly allow their dog to greet other dogs. This usually starts in puppyhood under the guise of socialization and can quickly lead to problems when the puppy begins to expect greetings every time they see a dog.

AS PUPPIES

As puppies, these dogs had lots of puppy play, daycare, playdates, etc, that led them to feel entitled to regular dog-dog interactions or dog-person interactions. During puppy class playtime, these puppies often were screaming and lunging on leash, frantic to be let loose and go play. They generally play very roughly and intensely and pursue other puppies relentlessly. They often have a hard time focusing in class because their only concern is playing with the other puppies.

These dogs often have fairly poor frustration tolerance and impulse control in other areas of life as well, having a hard time not getting what they want immediately. They struggle being told no, and this is often paired with a well-meaning but overly accommodating owner who allows the dog to do whatever they want.

People often wrongly say the cause of frustrated reactivity is “over-socialization,” but this simply demonstrates a fundamental lack of understanding of what socialization is. Puppy owners tend to think allowing puppies to run up to everyone and everything is socializing. It’s not. Socialization is exposure that should build neutrality, not excitement. For dogs who are intrinsically very social and outgoing, a lot of focus should be on NOT greeting and simply watching other dogs or being in the presence of other dogs without an interaction. A focus on training manners and teaching boundaries should be a priority along with socialization.

DEFENSIVE OR GENETIC REACTIVITY

This is the least talked about type of reactivity and one that’s more common than people realize. These are dogs who are neither frustrated nor afraid - they rather enjoy the conflict. They enjoy the rush of kicking off at other dogs or strangers. It’s an extremely rewarding behavior for them, and that can make it more difficult to train away.

These dogs are often German shepherds, malinois, or livestock guardian dogs who are bred to enjoy that type of behavior. If you think about a working line Great Pyrenees guarding their flock, they are hardwired to react aggressively and chase off intruding animals. That’s normal. Put that same dog on a leash and walk through the neighborhood, and suddenly barking at unfamiliar animals is “reactivity” and a “problem behavior” - even though it’s what the dog is bred to do. This is a very innate, genetically driven behavior that these dogs find inherently fun, as they’re fulfilling their breed roles quite well.

These dogs are often very pushy, bold, and confident, fearless in their desire to respond to a dog or person who doesn’t belong. After a reactive outburst, they may proudly strut or parade, seemingly quite pleased with themselves for a job well done. These are dogs who are very watchful and alert when out in the environment - they’re watching for who doesn’t belong so they can get to work getting rid of them.

They are dogs who often don’t mind a good squabble with another dog or even conflict with a person (like bite work or protection sports). A bit of physical combat is great fun! If they were humans they would enjoy MMA or boxing and would love an adrenaline-filled job full of conflict, like law enforcement or being a bouncer at a rowdy bar.

Even though it’s not fear-based, socializing these breeds early and often is a significant help in teaching them that random dogs or people they encounter in daily life are not their concern. They should be heavily socialized in urban settings around lots of other dogs and strange humans milling randomly about to help them understand that this is normal and not their business.