When looking at any “unexpected” behavior from a dog, the first thing I think about is how stress affected the situation. Stress, and how a dog naturally learns to manage and cope with stress, is a major contributing factor in how a dog is able to react in almost any situation.

How Stress Works

To understand the subject of stress, it is often easier to think about it in human terms, and how we cope with it on a daily basis. I have experience in a variety of professions. I have worked as a web producer at a of couple high-end design firms, worked in construction, and as an emergency medical technician. I am currently a veterinary technician student and small business owner. Through all of these careers, I have learned that stress is very contextual and individual to the moment. If the corporate conditions are right, that office deadline has the potential to feel like a genuine life-threatening emergency.

Going through any typical day, we encounter the good and bad experiences in life, called Stressors. The good is called Eustress, this can be: a good cup of coffee, seeing a long lost friend, getting a promotion, or getting recognition for a job well done. The bad is called Distress or traumatic stress, this can be: sitting in 3 hours of traffic, getting in a traffic accident, or just showing up to a job that you hate.

Each of these stressors can further be categorized into acute or chronic stress. Acute stress is a single incident, such as getting reprimanded by a boss. Chronic stress can stretch out over weeks or years. This can be repetitive small stressors, stacking upon themselves, or a single, long-drawn-out stressor.

If distress, whether acute of chronic, is severe enough, this can result in posttraumatic stress disorder. (PTSD) There are documented cases in both humans and animals. Severe or repeated distress often results in ongoing fears and/ or phobias. Phobias and other severe mental and fear disorders exist in both humans and dogs, but that is outside of the scope of this article, so I won’t be going into great detail about them here.

Physiology of Stress and Fear

Stress and fear are associated with the autonomic nervous system, (ANS) which controls involuntary vital functions of the body. The ANS is controlled by a primitive area of the brain called the Amygdala, also known as the “stress center.” There is a strong corelation with this area of the brain and long-term emotional memories and responses. The ANS is divided into two subsystems, namely the Sympathetic and Parasympathetic systems.

Sympathetic (Fight or Flight)

When the body senses danger it is flooded with stress hormones, mainly Adrenaline and Cortisol. There is an immediate response, including:

  • Increased heart rate
  • Increased blood pressure
  • Rapid, shallow breathing, panting
  • Surface blood vessels contract
  • Muscle tension, muscles contract, body braces for action
  • Pupils dilate
  • Digestive system both tenses and slows down, salivation inhibited
  • Relaxes bladder and constricts rectum
  • Suppressed immune system
Parasympathetic (Rest and Restore)

The body cannot maintain health in a hyper-aroused state indefinitely. The parasympathetic system is responsible for returning the body to a normal state, and reverses the effect of the sympathetic nervous system. Unlike the sympathetic response, this is a gradual process. With severe trauma recovery, this can take days, weeks or months. Also, anxious or fearful animals, or animals that live in an unstable environment, can potentially live in a constant state of arousal, not allowing time for the following parasympathetic effects to occur:

  • Slowed heart rate
  • Decreased blood pressure
  • Slower, deeper breathing
  • Surface blood flow returns to normal
  • Relaxed muscles, no longer braced for action
  • Pupils return to a normal size
  • Digestive system returns to normal, salivation is stimulated
  • Bladder and rectum return to normal
  • Restores immune system