Loneliness and Social Isolation Linked to Serious Health Conditions^¹

Restrictions on social gatherings due to COVID-19 over the past year have led to a surge of news headlines warning about the harmful psychological effects of social isolation in humans, which include impaired health, sleep, and immune function. The spotlight on social isolation raises questions about the effect it might have on horses as well.

Social Isolation Is Stressful

Much of what we know about the harmful effects of social isolation comes from biomedical research with animals. Social isolation is an animal model for human neuropsychiatric disorders such as anxiety, depression, attention-deficit disorder, PTSD, and schizophrenia. Stress is induced in laboratory animals through physical restraint, mild pain, impoverished environment, and social isolation, all of which have striking parallels to some equine management practices.

Horses might experience acute distress when they are separated from other horses for routine health care, training, or transportation. Many horse owners have witnessed frantic calling, agitation, and pacing when pasture companions are separated. Horses might also experience long-term isolation stress when they are transported long distances, moved to a new stable, quarantined, or confined to a stall because of an injury or illness. Management practices might also contribute to chronic social isolation distress when horses are housed and exercised in ways that limit their opportunities to interact with other horses.

Social animals have a basic need to connect with others, and it is essential to their well-being and survival. There is safety in numbers. The survival benefits of living in groups include detecting and avoiding predators, finding food and water, and learning from others. Being alone is risky and can trigger an urgency to reunite (flight/fight) or to shut down (freeze/fawn) for self-preservation. Horses form strong attachments with one another, and breaking up socially bonded individuals generally causes greater distress than isolation alone.

Responses To Isolation

Social isolation affects behavior, physiology, and brain activity similarly across a wide range of animal species. Behaviorally, socially isolated animals vocalize more and show ‘locomotor syndrome,’ with increased agitation, vigilance, and movement. Physiologically, socially isolated animals have increased heart rate, respiration, and sweating. Cognitively, socially isolated animals tend to show impulsive decision-making, abnormal fear memory, and impaired mental flexibility.

Social isolation is a significant stressor in horses. Responses to separation can overshadow responses to pain, potentially resulting in an inaccurate assessment of pain severity, according to a 2017 study by Reid et al.^² In this research study, pain was induced by a neck skin pinch. If horses experienced pain while another horse was nearby, they moved less and showed less contact-seeking behavior. In contrast, if horses experienced pain while socially isolated, they showed increased locomotion, vocalization, and contact seeking, similar to the way they responded to social isolation without pain.

Prevent and Reduce Social Isolation Stress

Here are a few strategies that can help prevent and mitigate the stress associated with social isolation:

Prepare your horses to be alone. 

Research on the harmful effects of social isolation often focuses on young animals soon after they are weaned, which corresponds to a critical period for social development. Progressive exposure to mild stressors early in life can build resilience to those stressors. For example, gradual introduction to weaning, trailer loading, health care and handling procedures, and separation from other horses can reduce future stress responses to these experiences.

Provide an emotional support animal.

In both young and older horses, introducing an equine companion can immediately eliminate the behavioral and physiological effects of social isolation distress. Horses are particularly sensitive to and will mirror the emotional state of other horses, so having a calm horse nearby is ideal. Other species, including humans, might also serve this purpose. In a recent study, when horses were separated from the person and alone, they became anxious and their heart rate increased. When the horses were reunited with the person, they calmed down and their heart rate decreased. Any human served as a “safe haven,” as horses showed the same response with their owners and strangers.^³

Introduce enrichment.

Adding enrichment opportunities might help reduce stress by providing sensory and mental stimulation and creating a more complex environment during periods of social isolation and for horses housed alone. For example, sensory enrichment might include providing odors, sounds, and tactile experiences, and cognitive enrichment might include introducing problem-solving tasks such as food puzzles. Mirrors might function as a proxy for an equine companion and have been shown to reduce isolation distress during transport.4 

Consider medication.

Consult a veterinarian to determine if a horse who is distressed due to social isolation would benefit from anti-anxiety medication. A recent study in pigs found that fluoxetine (Prozac) reversed many of the physiological effects of chronic stress induced by social isolation.5 The potential benefits of anti-anxiety medication to reduce isolation stress in horses is not known.

Take-Home Message

Some common equine management practices can cause social isolation distress in horses. Taking steps to reduce the harmful effects of acute and chronic social isolation can improve equine health and well-being.

References

1. CDC. April 29, 2021. https://www.cdc.gov/aging/publications/features/lonely-older-adults.html 
2. Reid, K., Rogers, C. W., Gronqvist, G., Gee, E. K., & Bolwell, C. F. (2017). Anxiety and pain in horses measured by heart rate variability and behavior. Journal of Veterinary Behavior, 22, 1–6. https://doi.org/10.1016/j.jveb.2017.09.002
3. Lundberg, P., Hartmann, E., & Roth, L. S. V. (2020). Does training style affect the human-horse relationship? Asking the horse in a separation–reunion experiment with the owner and a stranger. Applied Animal Behaviour Science, 233, 105144. https://doi.org/10.1016/j.applanim.2020.105144
4. Kay, R., & Hall, C. (2009). The use of a mirror reduces isolation stress in horses being transported by trailer. Applied Animal Behaviour Science, 116(2–4), 237–243. https://doi.org/10.1016/j.applanim.2008.08.013
5. Menneson, S., Ménicot, S., Ferret-Bernard, S., Guérin, S., Romé, V., Le Normand, L., Randuineau, G., Gambarota, G., Noirot, V., Etienne, P., Coquery, N., & Val-Laillet, D. (2019). Validation of a psychosocial chronic stress model in the pig using a multidisciplinary approach at the gut-brain and behavior levels. Frontiers in Behavioral Neuroscience, 13, 161. https://doi.org/10.3389/fnbeh.2019.00161