Why we must address stress in dogs

Conventional practice assumes that stress is reflected in behavior and virtually every animal-related field (shelters, training, veterinarians) use observational data as the sole welfare metric.  Hennessy (2013) clearly demonstrates that this assumption is flawed. A dog that stops struggling is “cooperative”. A dog that goes quiet is “settled”. A dog that complies is “trained”. Yet all these dogs may be experiencing significant levels of stress that is not shown by their behavior, but can be detected in their hypothalamic-pituitary-adrenal (HPA) system (Hennessy, 2013).

The animal field operates as if stress is event bound. That the dog is stressed during the vet visit, during the thunderstorm, or during intake. Remove the stressor and the stress ends. However Hennessy (2013) shows that cortisol remains elevated for days following shelter admission and  Sapolsky (2017) describes how chronic stress produces lasting negative changes, such as dendritic growth in the amygdala, weakened prefrontal control, facilitated fear learning, impaired extinction. These changes persist and alter the dog’s baseline temperament.

These finding have direct implication for training methodology. Because stress facilitates fear acquisition while impairing fear extinction. This finding clearly undermines punishment-based approaches. Adding aversive stress to an already stressed animal is working against the exact neurobiology needed for lasting change. The glucocorticoids make the amygdala more excitable which strengthens fear memory consolidation and weakens the prefrontal cortex’s inhibition (Sapolsky, 2017).

Individual variation adds another layer of complexity. Koolhaas et al. (1999) demonstrates that animals have different coping styles, with proactive and reactive styles showing distinct neuroendocrine profiles and different vulnerabilities to stress related diseases. This means that standardized protocols may be adequate for some animals and harmful to others simply due to neurobiological differences.

However, the interventions to reduce stress are often surprisingly practical. Hennessy (2013) found that 30 minutes of calm human presence in a quiet room reduced cortisol in 95% of newly admitted shelter dogs. The barrier is not resources but awareness. Bringing the awareness to animal-related fields is both worthwhile and realistic, because current practices may be undermining the goal and the solutions based on science are accessible.

Hennessy, M. B. (2013). Using hypothalamic–pituitary–adrenal measures for assessing and reducing the stress of dogs in shelters: A review. Applied Animal Behaviour Science, 149(1–4), 1–12. https://doi.org/10.1016/j.applanim.2013.09.004

Koolhaas, J. M., Korte, S. M., De Boer, S. F., Van Der Vegt, B. J., Van Reenen, C. G., Hopster, H., De Jong, I. C., Ruis, M. A. W., & Blokhuis, H. J. (1999). Coping styles in animals: Current status in behavior and stress-physiology. Neuroscience & Biobehavioral Reviews, 23(7), 925–935. https://doi.org/10.1016/S0149-7634(99)00026-3

Sapolsky, R. (2017). Behave: The biology of humans at our best and worst. Penguin Press.