Assessment of the interrelationship between personality traits, emotional states and abnormal behaviour in horses

Abstract

Personality traits may be linked to the development of abnormal behaviours in horses. However, abnormal behaviour could represent an attempt to adapt to the environment to improve the horses' emotional state. This study aimed to investigate whether personality traits can predict the expression of acute abnormal behaviours in horses stabled for a short period and whether the emotional state is influenced by the occurrence of these abnormal behavioural responses or by personality traits. To this end, fifteen mixed breed adult mares, housed outdoors, underwent three validated equine personality tests (open field test, novel object test, and startle test) and a new behavioural test aimed to assess neuroticism in horses. Subsequently, the mares were housed in individual stalls for three consecutive days and were filmed using continuous focal sampling to monitor acute abnormal behavioural responses. At the end of the third day, three additional tests were conducted to assess the emotional state of the mares in the stalls: memory bias test, judgement bias test, and attention test. The results showed that the mares exhibited box walking behaviour but no other abnormal behaviour when housed for three days in an individual box stall. Box walking events were counted and ranked according to the frequency observed in each mare. The median of these values was used to separate the mares into two groups categorized as with and without abnormal behaviour. Principal component analyses were performed to extract the main personality traits from each test; however, there was no association between the extract traits and the groups with and without abnormal behaviour. Additionally, no association was found between box walking frequency and the responses in the memory, judgement, and attention tests. When testing the association of personality traits with cognitive tests, neuroticism showed an association with the memory test, the insecurity trait (novel object test) was negatively associated with the judgement bias test, and the duration of the first alert event (startle test) and neuroticism were associated with the attention test. This study identified box walking within the first three days of housing; however, it was not possible to associate this behaviour with personality traits or cognitive test responses. Nevertheless, certain personality traits, including neuroticism, may be associated with horses' cognitive responses over a short period of individual housing.