As with any living creature, stress can have a massive impact on a dog’s emotional and physical well-being. The effects of stress can be observed through a dog’s behaviour and physiological functions.
While the impact of stress can be monumental in a dog’s body, we as humans don’t always recognize the symptoms. This can happen for several reasons. One is that dogs can be incredibly stoic. It is not often biologically beneficial to them to advertise their vulnerability, susceptibility, and weakness due to stress or illness, and as a result, we may not always pick up on their earlier indications and symptoms of stress until it has had a massive impact on their physiological state. Another reason is that humans are not always as aware of their dog’s commuincation and body language as they probably should be. In my practice, we focus on owner education before anything else. The best education we can provide dog owners is to help them to improve their observation skills and properly interpret their dog’s behaviour.
Stress impacts dogs on a cellular level, meaning it can have an impact on the entire body and all of it's systems.
At the onset of a stressful occurrence, the dog’s nervous system jumps to action. The nervous system is designed to protect the body from danger and ensure survival. The central nervous system sends signals along the spinal cord from receiving nerves to responding nerves. The reflex arc ensures an immediate, unconscious response to pain by removing the body from harm. This is the reason why you pull your hand away immediately without thinking if it gets burnt on the stove. The central nervous system also stores important information regarding previous threats to protect against future occurances.
The peripheral nervous system is made of two different parts, the autonomic nervous system and the somatic nervous system. The autonomic nervous system can be further divided into two divisions, the parasympathetic and the sympathetic nervous systems. The sympathetic nervous system is the dog’s front-line response to fear and is critical for survival, it responds rapidly to either escape or defend, also known as fight, or flight. During these moments, there are a plethora of body language indicators that can be observed, and some body responses that cannot be directly observed.
When activated, the sympathetic nervous system has physiological responses from the liver, heart, lungs, eyes, blood flow, adrenal glands, digestive and elimination systems as well as the body’s internal thermometer. The body's main goal here is to allocate its resources to the systems that may be required to survive. All other non-essential systems are put on hold. If a dog is stuck in this state for long periods of time, there can be a physiological breakdown of the dogs vital organs and systems.
Immediately following a stressful event, the body’s parasympathetic nervous system hits central stage. Its job is to try and regulate the body and reverse the effects of the sympathetic nervous system. It is commonly referred to as the ‘rest and digest’ system. This is the restoration and recovery process. Again, many body language signals can be observed which indicate that the parasympathetic nervous system is engaged, and some cannot. If the dog's parasympathetic nervous system is not provided enough time and support to fully recover from stressful events it can have a long-term negative impact on their entire system (physical and mental health and well-being).
Should recovery not occur, we may begin to see what is referred to as 'trigger stacking' where numerous small stress events begin to build up within a period of time. As a result, the dog may exhibits what appears to be an 'overreaction' to something small, when in fact it is a reaction from an accumulation of stress events the dog has not fully recovered from.
By simply taking vitals and observing, much can be learned about the immediate effects of stress on the body. However, it is the long-term effects of stress which are often misunderstood or underestimated.
The most notable body system affected by long-term stress is the immune system. Without a fully functional immune system, the body is at great risk of illness and infection. Since the immune system is connected to all other systems throughout the body, it is not hard to understand that stress can have a wide impact on the entire physiological being and overall health and wellness.
This is by no means a comprehensive explaination of the full affect of stress on a dog's body or the actions of the nervous system. Please feel free to learn more through the resources below.