Do horses with poor welfare show ‘pessimistic’ cognitive biases?

Abstract

This field study tested the hypothesis that domestic horses living under putatively challenging-to-welfare conditions (for example involving social, spatial, feeding constraints) would present signs of poor welfare and co-occurring pessimistic judgement biases. Our subjects were 34 horses who had been housed for over 3 years in either restricted riding school situations (e.g. kept in single boxes, with limited roughage, ridden by inexperienced riders; N = 25) or under more naturalistic conditions (e.g. access to free-range, kept in stable social groups, leisure riding; N = 9). The horses' welfare was assessed by recording health-related, behavioural and postural indicators. Additionally, after learning a location task to discriminate a bucket containing either edible food ('positive' location) or unpalatable food ('negative' location), the horses were presented with a bucket located near the positive position, near the negative position and halfway between the positive and negative positions to assess their judgement biases. The riding school horses displayed the highest levels of behavioural and health-related problems and a pessimistic judgment bias, whereas the horses living under more naturalistic conditions displayed indications of good welfare and an optimistic bias. Moreover, pessimistic bias data strongly correlated with poor welfare data. This suggests that a lowered mood impacts a non-human species' perception of its environment and highlights cognitive biases as an appropriate tool to assess the impact of chronic living conditions on horse welfare.

Low plasma cortisol and fecal cortisol metabolite measures as indicators of compromised welfare in domestic horses (Equus caballus)

“…In horses, backward ear position is commonly associated with negative emotional states, such as pain or a negative cognitive bias [ 34 , 67 , 68 ]; or during agonistic interactions [ 69 ]. Ear position for each horse was noted at 15 minute intervals and on two different rest days until 10 ear positions were obtained per horse according to the method used by Lesimple et al [ 42 , 43 ].…”

Indicators of Horse Welfare: State-of-the-Art

“…In some cases, chronic health disorders are related to typical postures, such as laminitis with an arched body that takes the weight off the fore feet [20]. Ear positions are good indicators: if ears pointing backwards are associated with negative states, including pain (e.g., [20] for a review) or agonistic social interactions [70], they are also associated with chronically restricted conditions-the time spent with ears backwards in homogenous conditions (i.e., foraging) is related to chronically restricted living conditions (strict social isolation [35]) and chronic welfare impairment (e.g., vertebral disorders, stereotypic behaviours [36,37]), while horses under naturalistic conditions are almost never observed with such ear positions. Although time spent with ears backwards while foraging is not related to one particular context, it is a reliable indication of impaired welfare.…”

“…Finally, a cognitive bias was shown to reflect horses' welfare state. Thus, a recent study [37] showed that horses in a poor welfare state (evaluation based on the expression of SB/ARB, ear position, aggressive reactions to humans and vertebral disorders) were also more pessimistic when in the presence of an ambiguous stimulus, whereas horses in a good welfare state were clearly optimistic.…”

On-Farm Welfare Assessment of Horses: The Risks of Putting the Cart before the Horse

“…Some new or better-defined indicators may be worth investigating: "alertness", "attentional engagement" and "responsiveness" are a strong part of the SEBWAT protocol and have revealed interesting [29,39,43], as well as some acoustic signals (e.g., [75]), and would deserve refining. Ear positions during feeding on roughage or grass correlate with cognitive biases, and hence represent horses' perception of their situation [76] and this criterion is under validation. Burn et al [29] identified positive reactions to human approaches as a sign of good welfare.…”