|Insane in the membrane. Insane in the brain.|
But still, some dogs just aren’t right. From reactivity to anxiety to aggression, there are dogs who just don’t function well despite training classes and socialization and good intentions. Sometimes this is because the dog’s brain just isn’t wired right. Now, I’m no neuroscientist, but I do play one on the internet. And today, I want to share how stress can affect a developing brain, and why doing everything right may not matter if your dog came from a less-than-ideal background.
Science is pretty clear that stress in young mammals influences both brain development and physical growth. Stress can come in many forms. In children, there’s the obvious abuse and neglect, but then there’s the less obvious: poverty, housing instability, witnessing violence, growing up in bad neighborhoods, malnutrition, and so on. These chronic adverse events that the child and/or his caretakers have no control over changes the way the brain grows.
For dogs, such toxic stress during the early developmental period can happen in a number of ways. Puppy mills – and other deprived environments – are an obvious example of a stressful environment, but growing up in a shelter or a rescue can disrupt the growing brain, too. Sudden separations from human or canine caretakers, frequent change, environments characterized by sensory overload, and long periods of confinement are stressful. And even dogs from good breeders can be subjected to stress in the wrong circumstances: too much handling by a child, being harassed by another resident animal, or chronic medical problems on the part of the pup or the mother.
This does not mean that every dog from a puppy mill or rescue is going to have behavior problems. Indeed, if that were the case, people would stop getting dogs from these places. Some dogs have genes that are “turned on” by stressful events more readily than other dogs, making them more susceptible to the effects of stress. We see this in human children too; for some, stress creates a resilient brain, while in others, it creates a brain vulnerable to a host of behavioral problems.
So, just how does stress affect the developing brain?
First, it’s important to understand that stress is a normal part of functioning, and that overcoming a challenge creates a stronger brain and a sense of mastery. It is therefore important that children and dogs experience occasional frustration in doses they can overcome so that they develop the neuronal connections needed for a healthy brain. Not only is it impossible to shield your young mammal from stress, it’s inadvisable.
When a mammal experiences stress, the brain releases chemicals like cortisol and adrenaline. These prime the brain to be able to respond to potential danger. Once the stressful event is over, the chemicals dissipate, and the brain returns to its normal state of functioning. However, when stress is either prolonged or recurrent, the brain never fully gets rid of the stress hormones. This changes the way the brain develops.
Recent research has shown that there are notable differences in the amounts of gray matter vs. white matter in the brains of overly stressed children as opposed to those who experience normal amounts of stress. Basically, gray matter is responsible for higher functions like thinking and decision-making, while white matter is what connects the various brain structures. Chronic stress seems to create more white matter, which naturally results in less gray matter. In turn, this reduces the volume of brain structures that allow for rational thought in the face of potentially threatening events. At the same time, that increased white matter basically creates a short circuit in the brain. Even when there isn’t a stressor present, the brain may continue to respond as if there is. This tends to cause overreactions to things that aren’t actually dangerous.
Not only are the connections stronger between the lower brain structures that control emotional responses, but some brain structures become overdeveloped. The amygdala and other associated limbic system structures – which are associated with stress responses – are often enlarged, while the hippocampus and other higher brain structures – responsible for problem solving and rational thought – are smaller.
The end result is a brain that idles on high. It is more easily hijacked by stress, and will respond with more frequency and intensity to smaller stressors. The circuitry activates longer, and the recovery time takes longer.
In other words: your reactive dog’s brain? Is not like your normal dog’s brain. And as a result, his ability to process things that happen to him and respond to the world around him is going to be impaired. It’s not only unfair to expect him deal with the world without additional support, it’s probably impossible.
That’s not to say that your dog can’t improve. Science has shown that the brain is incredibly plastic – it can rewire itself and become more functional – but this takes a lot of time and effort. And even with the best interventions, we don’t know yet if all the scars left on the brain by stress can be erased. Sometimes adjusting the expectations we have for our reactive dogs is the kindest thing we can do.