Horses discriminate conspecific odours

Horses (Equus caballus) discriminate body odour cues from conspecifics – Peron et al. 2014

• Individuals within a social setting benefit from the recognition of kin in order to modify behaviour towards non-group mates
• Horses have been shown to recognize kin as well as competitors based on a variety of sensory information including visual and auditory. They are also capable of discriminating olfactory cues, as done by pregnant mares, however there were multiple responses thus a solid conclusion could not be made, hence the reason for this study.
• Aim: was to see whether the horses were able to discriminate between conspecifics based on body odour by using both males and females (w/o pregnant mares), n=16
• Method: subjects were presented with samples from the same sex and 1 year age gap. Rubbed fabric for 30s on various parts of the horse then placed into airtight bag. Used on the same day? Placed the fabric over an apparatus and held for a 2min period in front of the horse, with 2 habituation trials and a final third trial with a simultaneous exposure of both familiar and novel horse. Inter-trial interval of 15min.
• Results: Horses spent significantly more time investigating the scent during the first presentation compared to the second. They also spent significantly more time investigating the novel scent compared to the familiar. There was no significant difference between performance of males and females.  
• Discussion: Aligns with previous findings, can now add olfactory discrimination to the list of cues horses can use to discriminate conspecifics. This finding can aid in refining husbandry and management techniques to improve welfare. Integrating horses with one another safely is required and olfactory cues may be a method of doing this safely. Future work should investigate how the retention interval as well as the quality of the sample may influence the recognition process. Also should investigate whether the familiarity of odour cues increases the resilience of social memory, since other studies have shown that elements of common husbandry like handling can affect social recognition (I think its in rats).