Summary: Researchers report horses tend to snort more when they are in positive emotional situations. The findings suggest snorts are reliable indicators of positive emotions in horses..
New evidence that horses reliably produce more snorts in favorable situations could improve animal welfare practices, according to a study published July 11 in the open-access journal PLOS ONE by Mathilde Stomp of the Université de Rennes, France, and colleagues.
Assessing positive emotions is important for improving animal welfare, but it has been challenging to identify reliable indicators. Physiological markers often give contradictory results, and many behavioural signals are ambiguous. In particular, few studies have examined acoustic indicators of positive emotions.
Anecdotal reports have indicated that horses frequently produce snorts in positive situations. Following up on this evidence, Stomp and colleagues evaluated snort production by 48 horses that lived either in restricted conditions (i.e., riding school horses that spent much of their time in individual stalls) or naturalistic conditions (i.e., stable groups of horses always in pasture).
Snort production was significantly associated with positive situations and with a positive internal state, as indicated by ears positioned forward or sideways. For example, riding school horses produced twice as many snorts in pasture than when they were in stalls. In addition, horses living in naturalistic conditions emitted significantly more snorts than riding school horses in comparable contexts. Taken together, the findings suggest that snorts are reliable indicators of positive emotions in horses.
Dr Stomp notes: “The snort, a non-vocal signal produced by the air expiration through the nostrils, is associated with more positive contexts (in pasture, while feeding) and states (with ears on forward position) in horses. Moreover, it is less frequent in horses showing an altered welfare. These results provide a potential important tool as snorts appear as a possible reliable indicator of positive emotions which could help identify situations appreciated by horses.”
Funding: This study was funded by IFCE (Institut français du cheval et de l’équitation), the Fonds éperons, the University of Rennes, and the CNRS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Source: Mathilde Stomp – PLOS
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Original Research: Open access research for “An unexpected acoustic indicator of positive emotions in horses” by Mathilde Stomp , Maël Leroux, Marjorie Cellier, Séverine Henry, Alban Lemasson, Martine Hausberger in PLOS ONE. Published July 11 2018.
An unexpected acoustic indicator of positive emotions in horses
Indicators of positive emotions are still scarce and many proposed behavioural markers have proven ambiguous. Studies established a link between acoustic signals and emitter’s internal state, but few related to positive emotions and still fewer considered non-vocal sounds. One of them, the snort, is shared by several perrisodactyls and has been associated to positive contexts in these species. We hypothesized that this could be also the case in horses. In this species, there is a clear need for a thorough description of non-vocal acoustic signals (snorts, snores or blows are often used interchangeably) but overall this sound produced by nostrils during expiration has up to now been mostly considered as having a hygienic function. However, observations revealed that snorts were produced more in some individuals than in others, without relationship with air conditions. We observed 48 horses living in two “extreme” conditions: restricted conditions (single stall, low roughage diet) and naturalistic conditions (stable groups in pasture). The immediate place (e.g. stall/pasture) and the behavioural/postural (behaviour performed/ears positions) contexts of snort production were observed. We additionally performed an evaluation of the welfare state, using validated behavioural (e.g. stereotypies) and postural (e.g. overall ears positions) welfare indicators. The results show that 1) snort production was significantly associated with situations known to be positive for horses (e.g. feeding in pasture) and with a positive internal state (ears in forward or sidewards positions), 2) the riding school horses produced twice as many snorts when in pasture than in stall, 3) the naturalistic population emitted significantly more snorts than riding school ones in comparable contexts, 4) the frequency of snorts was negatively correlated with the composite total chronic stress score (TCSS, reflecting compromised welfare based on the horse’s rank on the different indicators): the lower the TCSS, the higher the snort rate. Snorts therefore appear as reliable indicators of positive emotions.