Animal Health
A black and white dog looking sideways
Title Image : The Physiology of Stress & it's effects on boarding Pets
By Professional Pet Boarding Certification Council

We have all felt stress at some point in our lives, and we’ve seen dogs and cats exhibit signs of being stressed—especially those in our boarding facilities. Dealing with a change in routine and environment can cause pets to experience stress and a change in behavior.

What is Stress?
Stress is really just a perception that something is about to change. It is a part of life for all creatures, and there is good stress and bad stress. It may occur as a result of hunger, fear, noise, change of environment, pain or any number of factors. Good stress (also called eustress) causes a change in behavior or a change of environment to eliminate the precipitating factor. Bad stress (or distress) is stress that occurs long-term, when no changes are instituted to help manage or eliminate it.

Biology classes often teach the “fight or flight” theory. In this postulate, an animal that senses danger makes a decision to flee to get away from the stress, or to fight to stay alive. This stress reaction, in either case, changes the body status significantly to enable the animal to either get away safely or to fight hard enough to survive.

What Happens to the Body?

When a perception that something is about to happen reaches the brain, a number of chemical reactions are set off. Remember that stress is based on what we think is going to happen so, therefore, stress can result even though in reality the situation may be perfectly acceptable. This is why pets in a new environment can become upset—the environment is perfectly safe, but they are not sure what may happen next.

Once the brain perceives a stressful situation, the pituitary gland releases ACTH (adrenocorticotrophic hormone) into the bloodstream, which circulates through the body to the adrenal glands. All mammals have two adrenal glands, one on each side of the body, located near the kidneys. The adrenal glands secrete hormones and cortisone. Collectively, these chemicals are called steroids. Steroids go out to all the cells of the body with the message, “Get ready! Something’s about to happen!”

Steroids released by the adrenal glands influence every system of the body. Many of these actions make sense from a “fight or flight” perspective (giving the body extra short-term energy). Here are some things that happen to the body when steroids are released:

  • Glucose (sugar) is released from the liver for energy.
  • Amino acids are released to be used for tissue repair.
  • Cell membranes are stabilized to help resist damage and tearing.
  • The kidneys slow down urine production and retain more water to increase the blood pressure.
  • The heart beats faster.
  • The breathing rate becomes more rapid.
  • The immune system activity is decreased.

Over the short term, these changes do not negatively affect the body. Once the stressful situation has passed, the body goes back to its original state and the excess hormones and steroids are eliminated by the kidneys. A state of homeostasis is resumed. However, long-term stress can have negative effects on the body

Long-Term Stress

Hormones enable the body to deal with short-term stress, but at a cost to the various organs and body tissues. Long-term stress and chronically high levels of steroids prevent the body from maintaining its daily routine of tissue repair and fighting off disease.

When the process of stress goes on long term, functions of body systems such as muscle cells, connective tissue (skin, ligaments and tendons) and the immune system become suppressed. When the immune system is compromised, pets can be more susceptible to infections. This is why older dogs with arthritis or hip dysplasia may not walk well for a few days after lodging. Once the immune system fails, environmental bacteria that wouldn’t normally cause illness, may make a pet sick. This may be why some dogs get bronchitis or urinary infections, or why cats develop respiratory illnesses. It’s also a common cause of diarrhea.

Any pet that has an underlying physical illness, like cardiac or kidney disease, will most likely have progression of the disease. Some diseases that are hidden and haven’t shown symptoms may become apparent when a pet is under stress. These pets come into the facility “healthy” but may become ill during their stay.

There are various stages of stress, and with each stage, the negative effects it has on the body increase. The stages include:

  1. Alarm Reaction. The body reacts to the causative agent (the stressor). This is for a short time.
  2. Resistance. Steroid levels increase, and the body is ready to flee or fight.
  3. Exhaustion. The long–term stress results of the steroids begin to negatively affect the body tissues. The immune system is completely shut down.
  4. Death. All body functions start to fail, and death is the ultimate result.

Just like people, all animals are different. What may cause stress for one person or pet may not for another. Knowing the physiology of stress will allow you to better understand what the pets in your care may be experiencing and put you on the right track to take steps to prevent, or help manage, stress in the pet care facility.

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