Updated: Apr 17, 2022
While reactivity can and does happen with any breed, you may have noticed it often happens in working breed dogs. This includes mixed breed does as well. You see many years ago, dogs had a job. Most of them anyway. Yes some were bred to be lap dogs for royalty but the vast majority come from working heritage. What does that mean for today's dogs? Well, more often than not dogs today are expected to be couch potatoes. Many live in apartments and most are not getting the mental stimulus they need to be happy and well rounded dogs. They also lack training. Those who attend training general only do so for basic obedience or puppy classes. This can be problematic for so many dogs and their owners. The result is often a dog who becomes reactive. Leash reactive, dog reactive or human reactive.
How do we fix this? Partially through counter conditioning, partially through meeting your dogs needs. If you have a guarding breed, you need to find productive ways to meet their needs. There are plenty of dog sports that allow for this, however not all dogs have what is needed to participate in these. Pay attention to what your dog naturally enjoys and look for ways to fill those instincts. If you have a herding breed and don't have a working farm, look into things like herding balls to help fulfill their need to herd. For some dogs this isn't enough and you need to train an alternative acceptable behavior. This is doable but will take some patience, time and experience. It's important to remember that many of these breeds where bred to be intolerant of humans and dogs outside of their pack. That doesn't mean they all will be and that doesn't mean they have to be. That can almost always be prevented with the proper steps early in life.
In short, you can not expect a dog who was bred to hunt, to track, to guard, or to herd to just be well rounded couch potatoes. Consider the lifestyle you live before purchasing a pup. Do your research on the needs of that breed and ask yourself if you are able to provide them with that lifestyle. If you are dealing with reactivity, seek out a trainer to help you with this.