This week is International Stress Awareness Week. An annual event run by the International Stress Management Association (ISMA), the theme in 2020 is ‘Managing Stress and Mental Health Issues in the Age of Covid-19’, so perhaps it is a pertinent time to explore the link between stress and global pandemics.
I’m not just referring to the stress on ourselves that another lockdown 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 animals, with stressed handlers actually being detrimental to an animal’s own welfare¹. Whilst being around animals can be beneficial for humans suffering from stress or depression, this might be at a cost to the animals with their innate ability to sense our negative emotions potentially causing them discomfort².
Stress is defined as any internal or external stimuli or threat that disrupts homeostasis (our body’s optimum place to be)³. 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. 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 viral load and shedding⁵, 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, with appropriate handling and husbandry aiding disease monitoring and reducing fear and stress.
This is an issue affecting all of us and as equestrians and animal owners we have an important role to play by keeping our own animals healthy and happy. In horses, stress can be particularly catastrophic for gut health, with horses suffering from chronic stress more likely to develop gastric ulcers⁹ and a healthy gut microbiota integral not only to productivity but also to cognitive and emotional development¹º a worrying thought when a high proportion of horses are thought to suffer from gastric ulcers from foal age¹¹. This is due to compromised gut microbiome neonatal development as a result of suboptimal management due to limited forage, social isolation and restricted movement¹².
Increased consideration of the way we handle, feed and manage our horses, including providing them with choice, control and predictability in their environment, can help to reduce stress and negative affective states. The ISMA might be focusing on helping humans to manage stress and mental health in the age of Covid-19 but 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 life for animals can therefore promote a good life for humans and so, beyond International Stress Awareness Week, 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 Hemsworth, P. (2010). Human-Livestock Interactions: The Stockperson and the Productivity and Welfare of Intensively Farmed Animals. CABI, ISBN: 9781845936730.
¹º Wiley, N. C., Dinan, T. G., Ross, R. P., Stanton, C., Clarke, G. and Cryan, J. F. (2017). The microbiota-gut-brain axis as a key regulator of neural function and the stress response: Implications for human and animal health, Journal of Animal Science, 95 (7), 3225-3246, DOI:10.2527/jas.2016.1256.
¹¹ Haggett, E. (2020). Equine gastric ulcer syndrome in foals. UK-Vet Equine, 4 (4), DOI: 10.12968/ukve.2020.4.4.98.
¹² Tavenner, M. McDonnell, S.M. and Biddle, A.S. Development of the Equine Hindgut Microbiome in Semi-feral and Domestic Conventionally-Managed Foals, Research Square, DOI: 10.21203/rs.3.rs-53473/v2.