By Kate Fletcher (MSc, BA (Hons))
As parts of the world gradually emerge from COVID19-instigated lockdowns, people are understandably feeling a combination of trepidation, stress, and excitement faced with the prospect of being able to socialize once more. It is therefore perhaps a pertinent time to utilize a ‘One Health’ lens to explore the way in which stress affects both humans and other species lens is crucial if we are to prevent a similar tragedy from unfolding in the future.
I’m not just referring to the stress on ourselves that a lockdown situation or exposure to Coronavirus might cause, although it is worth considering that one rarely discussed wider motivation to look after our own mental health is the impact that our own stress levels have upon our immunity and vulnerability to disease (more on that later), but also the impact of stress on other species, with stressed humans actually being detrimental to animal welfare¹.
Many of us with pets have enjoyed being at home with them more, with our furry office companions proven to be beneficial for humans suffering from stress or depression. However, whilst our pets have also undoubtedly relished spending more time with us, our increased stress levels, whether pandemic-related, as a result of job insecurity or otherwise, might be at a cost to animals with their innate ability to sense our negative emotions potentially causing them to experience stress and discomfort themselves².
Stress is defined as any internal or external stimuli or threat that disrupts homeostasis (our body’s optimum place to be)³. For non-human animals, this can be psychological stress, such as handling, restraint, transport, and weaning, or physical stress such as hunger, thirst, fatigue, injury, thermal extremes, and biological factors such as population density (so no surprises that intensive farming is considered a major risk factor for stress¹).
However, it is worth noting that the absence of stress is not necessarily a positive thing as it can lead to boredom and frustration – something we may well have witnessed in our own pets when we are busy with Zoom meetings and they want us to amuse them. Stress is what motivates us to do things, be that engage in physical activity, go to work or escape from danger. The challenge is to identify where stress, or ‘eustress’, as a natural and often unavoidable experience which generally has positive effects, ends and where ‘distress’, which has negative effects begins⁴.
Whether stress is good or bad can also depend on intensity and duration. When we are in a state of chronic stress, this alters physiological levels of hormones and sends information to our Central Nervous System that then suppresses our immune system, making us (human or animal) more susceptible to disease, hence why consideration of stress is important when we are considering disaster preparedness to avoid future pandemics. Arguably, if we had considered the physical and mental health of the animals at the wet markets in Wuhan, where COVID-19 is believed to have stemmed and where hygiene measures are poor and disease risk is great, would the world be in the state it is in right now?
Stress can increase the viral load and shedding in animals⁵, which can lead to higher levels of meat contamination in production animals and reduced yield, metabolism, fertility, and immunity, thereby increasing the risk of disease transmission⁶. Healthy and happy animals reduce the need for antibiotics and equate to increased productivity, healthier and happier owners, and more successful livelihoods for farmers and owners of working animals⁷.
With intensive farming dispensing 131,000 antibiotics to stressed animals to manage sickness⁸ subsequent antimicrobial resistance (AMR) is a growing problem affecting humans and animals worldwide. The focus of tackling AMR needs to be on prevention rather than cure, forcing us to look beyond just meeting an animal’s biological and functional needs, with appropriate handling and husbandry aiding disease monitoring, reducing fear and stress⁹ and improving overall health¹⁰.
This is an issue affecting all of us and animal owners have an extra important role to play by keeping our own animals healthy and happy. Increased consideration of the way we handle, feed and manage our animals, including providing them with choice, control, and predictability in their environment, can help to reduce stress and negative affective states.
With the health of humans, animals, and the environment in which we all live so interlinked², if we don’t take proactive action now to predict, detect and manage threats to the mental health of all living beings we may not even reach a post-pandemic world. Promoting a good, less stressful life for animals can therefore promote a good life for humans and so, even beyond Covid-19, we have a duty to continue being mindful of the impact that stress can have on ourselves and the animals around us.
¹ Abdela, N., Jilo, K., Siraj, S., Adem, J. and Mohammed, A. (2016). Impact of Stress on Health and Productivity of Animal: A Review. Journal of Natural Sciences Research, 6 (9).
² Hediger, K., Meisser, A. and Zinsstag, J. (2019). A One Health research framework for animal-assisted interventions. Int. J. Environ. Res. Public Health 2019, 16(4), 640; DOI:10.3390/ijerph16040640.
³ Tsigos, C., Kyrou, I., Kassi, E., et al (2000). Stress: Endocrine Physiology and Pathophysiology. In: Feingold, K.R., Anawalt, B., Boyce, A., et al., editors. Endotext. South Dartmouth (MA): MDText.com, Inc.; 2000-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK278995/.
⁴ Curtis, S.E. (1985) What constitutes animal well-being? In Animal Stress, G.A. Moberg (Ed). American Psychological Society, ISBN: 978-1-4614-7544-6.
⁵ Gervasi, S.S., Burgan, S.C., Hofmeister, E., Unnasch, T.R. and Martin, L. B. (2017). Stress hormones predict a host superspreader phenotype in the West Nile virus system. Proc. R. Soc. B. 284, 1859, DOI:10.1098/rspb.2017.1090.
⁶ Waiblinger et al., (2006). Assessing the human–animal relationship in farmed species: A critical review. Applied Animal Behaviour Science, 101, 3-4,185-242. DOI: 10.1016/j.applanim.2006.02.0013
⁷ Van Boeckel, T.P., Glennon, E.E., Chen, D., Gilbert, M., Robinson, T.P., Grenfell, B.T., Levin, S.A., Bonhoeffer, S. and Laxminarayan, R. (2017). Reducing antimicrobial use in food animals. Science, 29, 357, 6358, 1350-1352, DOI: 10.1126/science.aao1495.
⁸ Banse, H.E. and Andrews, F. M. (2019). Equine glandular gastric disease: prevalence, impact and management strategies. Vet Med (Auckl), 10: 69–76, DOI: 10.2147/VMRR.S174427.
⁹ Albernaz-Gonçalves, A., Olmos, G., Hötzel, M.J. (2021). My pigs are ok, why change? – animal welfare accounts of pig farmers, Animal, Volume 15, Issue 3, 100154, https://doi.org/10.1016/j.animal.2020.100154.
¹⁰ Hemsworth, P. (2010). Human-Livestock Interactions: The Stockperson and the Productivity and Welfare of Intensively Farmed Animals. CABI, ISBN: 9781845936730.