Many dogs can become reactive because their needs are not being met. Some dogs may have lasting effects if needs are not met for long periods of time, this is evident in rescue dogs with known histories of abuse or neglect.
When needs are not being met, dogs are often incapable of quality learning because they are busy seeking their needs. This will prevent us from teaching the dog any skills to assist in reducing reactivity.
It's important that you seriously evaluate your dog and their current lifestyle. Are needs being met? Is there anything missing? Does it seem as though your dog is constantly seeking or looking for something? This can look like a dog who is constantly "getting into trouble" by chewing on furniture, snatching items off tables, or constantly scavenging items from the ground or low-lying shelving in the home. This can also look like a dog who is directing most of their energy to barking at or reacting to passersby. Or a dog who obsessively looks for lizards, cats, other animals, vehicles, or other moving objects to chase.
Many people read this and skip over the first "survival needs" column, but pay attention to the mention of "safety/security" here. Does your dog feel safe most of the time? Is your dog hypervigilant, constantly looking out for danger, or always looking for a hiding space? A dog whose needs are not being met can look very different and present in a variety of ways, so it's good to really sit down and think about this. Observing your dog's behavior throughout the day through a new lens can also be beneficial to this process.
Check Out this Helpful Infographic: Conditions for Dogs Living in a Human Society