The learning ability of horses may be enhanced by moderate exercise beforehand, the findings of fresh Australian research suggest.
Cathrynne Henshall and her fellow researchers, writing in the journal Scientific Reports, noted that domestic horses are widely used for physically demanding activities, but the effect of exercise on their learning abilities has not been explored.
Exercise leads to increased oxygen consumption and a higher metabolic load. As a consequence, there is an increase in cardiac output as well as a range of other physiological processes to support increased demands on the body.
The exercise physiology of horses has been well characterised and, in other species, exercise has been shown to benefit learning, memory and cognitive functioning, the authors noted.
Exposure to stress may also affect the learning ability of horses. “There is growing evidence,” they said, “that exposure to different forms of stress can affect equine learning, depending on the stressor, type of learning task and in some studies, the temperament of the horse.”
Collectively, findings from previous studies suggest that equine cognition may be sensitive to uncontrollable stress. However, most learning tasks employed in these studies do not reflect the cognitive tasks horses undertake in industry settings, where apparent failures to learn can lead to risks to both human safety and horse welfare.
“Consequently, there is a need for more research into the effects of stress and exercise on equine learning in industry type settings,” they said.
Researchers in the Charles Sturt University study used 41 horses, all of whom could be ridden at a walk, trot and canter on a loose rein.
The horses were randomly assigned into three groups: 14 into the inactive group, 13 into the exercise group, and 14 into the stress group.
There were three phases to the experiment. In all cases, the first phase involved tying each horse to a railing and leaving it undisturbed for 15 minutes, after which blood and saliva samples were taken for analysis.
In the next phase, those in the exercise group were subjected to a moderate exercise routine, which lasted a little over 20 minutes, involving walking trotting and cantering
Those in the stress group were released into a round yard for 20 minutes and exposed to stress by way of a large rubber ball that was repeatedly tapped, bounced or pushed. A plastic tarpaulin, moved in an unpredictable way, was also employed in some cases.
The horses in the inactive group were tethered to a rail and left undisturbed for 22 minutes in the company of a companion horse.
All horses were then subjected to the learning phase, using the same trainer.
The trainer stood on the right side of the horse with the reins or lead rope in their right hand, with a dressage whip in their left hand. The horses were taught to move away from the whip. The whip was firstly raised to the tap position, level with the right hip joint.
If the horse did not move its hindquarters away within 2 seconds, gentle rhythmic tapping was applied. It was maintained until the horse made an attempt to move the hindquarters towards the left.
Tapping stopped as soon as the horse lifted a hind leg towards the midline.
The response of each horse was graded in a predetermined scoring system. The trainer called the performance score to a helper, who recorded the scores in a notebook.
Blood and saliva samples were taken after the learning phase.
The exercised horses achieved the best results, achieving the learning target in the fewest number of trials compared to the stressed and inactive horses, whose learning performance were the same.
The exercised horses’ salivary concentrations of the stress-related hormone cortisol decreased during learning whereas concentrations in the other groups increased.
Horses with the highest cortisol concentrations required the most trials to reach the learning target.
The findings, they said, indicated that a short session of ridden exercise prior to learning may enhance the learning ability of horses.
“Findings from other species suggest that the cognitive benefits of the exercise in this study were likely to be mediated by beneficial increases in cortisol and noradrenaline interacting with dopamine, brain-derived neurotrophic factor and other neurotransmitters that collectively enhance synaptic plasticity and excitability in regions associated with learning.”
They continued: “Training activities conducted while the horse is under the influence of high cortisol concentrations, whether from extrinsic or training related stressors, appear to impair aversive instrumental learning acquisition compared to lower cortisol concentrations.”
The researchers said their study supports industry advice that a short period of physical warm-up of low cognitive demand, with the horse moving freely and calmly, may set the horse up for enhanced learning during a training session, particularly when compared to commencing training without any prior physical activity.
“In contrast, exposure to uncontrollable stress prior to a training session should be avoided as learning may be impaired.”
The study team comprised Henshall, Hayley Randle, Nidhish Francis and Rafael Freire, all with the School of Agricultural, Environmental and Veterinary Sciences at Charles Sturt University in Wagga Wagga, Australia.
Henshall, C., Randle, H., Francis, N. et al. The effect of stress and exercise on the learning performance of horses. Sci Rep 12, 1918 (2022). https://doi.org/10.1038/s41598-021-03582-4