BARKS from the Guild January 2021

Page 22

c a n i n e

Itchy Dog or Stressed Dog? Dr. Naomi D. Harvey discusses the role of stress in skin allergies and the corresponding potential impact on behavior

© Can Stock Photo / Colecanstock

T

he relationship between stress, behavior and animal health is com­ plex and varied. Chronic, long­term stress interacts in various ways with personality type, behavior and immune health in both people and nonhuman animals. It’s not often straightforward to decipher which causes which when we evaluate chronic stress and health, however.

Links between Stress, Behavior and Health An animal’s behavior can impact aspects of its physiology, such as its im­ mune system, and conversely, the animal’s physiology and immune sys­ tem can affect its behavior. According to Lopes (2017) the links between immune health and behavior can be grouped into three categories: 1)

Behavioral traits affecting immune traits: An example of this would be increased exploratory behavior leading to increased exposure to immune antigens or access to a wider variety of food, impacting nutrition and the gut microbiome.

2)

Immune traits affect behavior: For example, by triggering ex­ pression of sickness behavior.

3)

Something else that affects one can simultaneously affect the other: This is when another event causes changes to both the immune response and behavior.

Stress (physical and psychological) is one of those things that falls into the third category. Stress disrupts homeostasis (the complex functions through which the body self­regulates to maintain a stable state suitable for survival), and this disruption can affect both the immune system and

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BARKS from the Guild/January 2021

The results of the study by author Dr. Harvey and colleagues support acceptance of their hypothesis that dogs with skin allergies would exhibit more problem behaviors, lower scores for trainability and no differences for generic fearful or environmentally anxious behavior

behavior. Normally, this disruption is short­lived and adaptive, as the changes to homeostasis and alterations to behavior may help an animal to escape or deal with a stressor (such as a predator or environmental challenge). This form of adaptive stress is known as eustress. However, when stress becomes long­term, homeostasis is altered for longer than is adaptive and leads to distress. Chronic stress (distress) is implicated as a risk factor in a number of health conditions from cancer to heart disease (Maddock & Pariante, 2001) and in people, chronic stress is also a factor in the development of various psychopathologies such as clinical depression and post­trau­ matic stress disorder (Marin et al., 2011).

Stress and the Skin Skin conditions have long been considered to be indicators of psycho­ logical distress although only recently has evidence for this begun to ac­ crue. A growing number of research studies now provide evidence that emotional stress is linked to skin conditions such as atopic dermatitis. Some of this research suggests that emotional stress can cause im­ pairments to the skin barrier. Research conducted with mouse models has shown that emotional stress from social isolation can disrupt skin barrier function, and that this disruption can be reversed with anxiolyt­ ics (Denda et al., 1998, 2000). In people, undergraduate students have been shown to exhibit impaired skin barrier function during times of heightened psychological stress, and improved skin barrier function dur­ ing times of reduced psychological stress (Garg et al., 2001). The impli­ cations of these findings suggest that emotional stress could be an inducer of impaired skin barrier function, which for animals that suffer from inflammatory skin conditions suggests that emotional stress could