Rankins, E. M., Wickens, C. L. 2020. A systematic review of equine personality. Applied Animal Behaviour Science 231, 105076.
Examining the literature suggests equine personality is of interest to behavior and welfare scientists and those involved in the equine industry. Study and assessment of personality is critical because of the profound implications certain traits have with respect to injury risk, the horse-human relationship, training processes, learning in horses, and management or breeding practices. The review summarizes the evidence for a genetic basis of personality, the evidence for modification of personality by environment and experience, the measures and tools used in assessing personality, and the traits comprising personality. The review also highlights key considerations for the researcher and areas warranting further study. A literature search was conducted using Google Scholar and Web of Science with the search terms equine and horse in combination with personality and temperament. One hundred thirteen articles were included in the review after exclusion of non-peer-reviewed articles, abstracts, theses, and dissertations. Differences in personality between breeds, estimates of heritability, and identification of specific genes and genetic markers relating to personality illustrate the genetic basis of personality. Further work in identifying specific genes and genetic markers of other personality traits would enable more targeted breeding programs. Experience with their dam, environmental factors such as housing conditions, and training or handling modify a horse’s expression of personality. These factors also present potential confounding variables for the researcher. The effects of the in vivo environment on personality in horses remains unexplored as does the importance of timing over the lifespan for modification and the duration of these effects. Personality is assessed via direct observation and measurement of behavioral, endocrine, cardiac response, or temperature correlates during structured tests or routine management procedures, questionnaires, or a combination thereof. Careful consideration should be given to selection of the most appropriate assessment method given the aims of the study, resources available, and previous validation of the method or methods. Reactivity, gregariousness, reactivity to humans, sensory sensitivity, and locomotor activity are some of the most assessed traits, but no unifying structure of personality is consistently identified across studies. Researchers should give attention to addressing and acknowledging potential confounding variables and selecting an appropriate trait to assess with validated measures.