Links between behaviour, discipline and gut health found in sport horses

Scientists have been researching the links between gut bacteria and mental health in humans for many years now. Studies have shown that people with depression have consistently low levels of some gut microbes. This has led to new treatments for mental health disorders based on probiotics that boost the levels of “good” bacteria in the intestines.

Now a team of researchers have looked at the link between gut health and the behaviour, management and discipline of horses. They have found that behaviours indicated in poor welfare – such as stereotypies and aggression – are linked to the composition of their gut bacteria.

The researchers took blood and faecal samples from 185 sport horses that had similar management conditions. They assessed 41 factors – ranging from the horse’s age, sex, diet, behaviour, bedding, housing and ridden discipline to their physiological status including parasite levels and faecal pH.

46% of the horses were trained for dressage, 25% were showjumpers and 25% eventers. 30% of the horses were used for Gala and Cadre Noir displays.

The findings identified that equitation factors (ie. the horse’s ridden discipline or speciality) were associated with differences in gut microbiota, indicating a relationship between gut health and the levels of physical and mental stressors the horse was subject to.

Behaviours related to mental distress, including hypervigilance and oral stereotypies, were also related to the composition of the faecal microbiota in the horses.

The researchers commented, “In our study, the prevalence of stress was believed to be higher in horses that were trained for dressage and jumping, as most of them were elite athletes that travelled to international competitions, trained many hours per day, five days a week, for several weeks without taking time off from intense training.”

I find it extremely concerning that the behaviour assessment showed that ‘the expression of both oral and locomotion-related stereotypies was observed in 17% of the individuals, whilst 99% of the individuals were experiencing unresponsiveness to the environment (the so-called withdrawn posture) at least once within the eight-month period. Hypervigilance was observed in 75% of our individuals, whereas aggressiveness was observed in 43% of our horses.’ These are serious welfare issues! Why on earth are these horses being managed in such a way that they are performing so many stress-related behaviours? Are the caretakers of these horses not seeing these problems? It’s so worrying that basic behavioural science is still not reaching – or influencing – the competition world.

I hope this study will spark an interest in improving welfare for horses via their management and training. However, I fear it may lead to supplement companies producing a wider range of probiotics as a solution to equine stress...

This is a fascinating study and well worth reading in full. You can read it here: Priming for welfare: gut microbiota is associated with equitation conditions and behavior in horse athletes’. Mach, N., Ruet, A., Clark, A. et al. Sci Rep 10, 8311 (2020). https://doi.org/10.1038/s41598-020-65444-9