One of the most common issues myself, and trainers in general see is reactivity. So what exactly is it, how does it start and how do we fix it? Let's begin at the start.
Reactivity has a sliding scale. On one end, you have the dog who is so excited to see people or dogs that they just can not contain themselves. They are wiggling, likely jumping, whining and sometimes even barking. On the other end of that scale is the dog that wants to eat the humans and or dogs. In between these two extremes are a variety of other levels of reactive behaviour. It is very important to note that if your dog is the first type, it absolutely CAN become the latter type if the dog is still maturing. This does not mean it will become the latter, rather that if it is not addressed it can become aggression. It is important to know that if your dog is the latter type (wants to eat the people and or dogs), that does not mean your dog is aggressive. More often than not this type of dog is actually fearful, anxious and lacking confidence.
So how does reactivity start? Well, there is not one answer for that exactly. Dogs go through a variety of developmental periods in their first two years that are referred to as fear periods. During these periods it is not uncommon for a dog to begin to show fearful or reactive behaviour towards things that were previously not scary or if something happens that the dog sees as negative. Remember that the dog decides what is negative, not us. When this happens it is important that we handle it correctly. Do not comfort your dog. Do not force them to approach the trigger. Allow them to stand back far enough that they are not reacting so they can observe. Then, contact a trainer who can help you work through this as how it is addressed is not the same for every dog. Sometimes a dog who was over socialized or incorrectly socialized as a puppy can become reactive. Subsequently, a dog who is under socialized can and often will become reactive during this periods and this is when it usually sticks. There is also a genetic component to reactive behaviour as well. If your dogs parents were reactive, then the puppies are more likely to also be reactive. That's the short version without going into proper breeding, the level of stress the mother may experienced during pregnancy etc. While some breeds are more predisposed to be human or dog aggressive, that doesn't mean this is a breed specific issue. It is absolutely not. As you can see, reactivity is a complicated thing to understand.
How do we fix it? Slowly. This is key. We must find the dog's threshold, start below it in small increments of time and then build from there. We can not rush the process and there is no timeline. Too much too soon and you make things worse. Slow is fast. You must trust the process and let your dog show you when it is time to move forward. Please use an experienced trainer for this.
Not one program for any of the reactive dogs I work looks the same. Sure, they all have the same base elements to the plan but the execution is different for each one. The exercises and timeline are all different. What remains the same across the board is this. The dog sets the timeline. Not me and not the owner. This is not a quick thing to fix especially with one lesson a week. It takes time and patience and dedication from the owner to follow the directions in the homework precisely. Trust your trainer and be patient with your dog and the results will come.