Physiological (heart rate and cortisol concentration in saliva) and behavioural responses in horses to four reactivity tests compared to the trainer's opinion about the horses’ temperament

Sammanfattning: When performing studies that test the reactions of horses in different situations, important information may be available about the horse’s reactivity level. With information from these tests, accidents and dangerous situations may be prevented. When the behaviours from tests are compared with race performance it may be possible to evaluate if some behaviours are more desirable at the race track than others. The aim of this study was to see if behavioural responses correlated with physiological parameters (heart rate, cortisol), the trainer’s opinions and actual race performance. Furthermore, it was investigated whether there were any significant differences in physiological and behavioural responses of horses between the first and the second day of testing. The reactions of 16, two-year old Swedish Standardbred trotters were tested in four different behaviour tests. The tests included: 1) novel objects (blue rubber ball and bridge), 2) novel smell, 3) sudden sound and 4) isolation from other horses. The horses experienced all four tests during one day before and once after a 3-day confinement in boxes using the same experimental procedures. Behavioural reactions to the different stimuli and to social isolation were recorded (e.g. move feet, touch object or defecate) and heart rate was measured throughout testing. Three samples of saliva were taken each day (control sample before the tests, after the reactivity test and after isolation) to measure the concentration of cortisol. Furthermore, the horses’ trainer filled in a form where he graded different temperamental traits of the horses. The results indicated that the behaviours were not affected by the 3-day stall confinement or repetition of tests since there were no significant differences between days. The heart rate was lower day two compared with day one, which may be due to that the horses were habituated to the tests on day two. The cortisol level was higher on day two, indicating that the horses were more stressed compared to day one. Some behaviours from the tests had a strong correlation with the trainer’s opinion of the horses’ temperament. This included the behaviour ‘alert’ recorded during the tests that had a strong correlation with the trainer’s opinion of the horse being ‘afraid’ and ‘spooky’. The latter behaviours also correlated with higher winning percentage or place percentage, indicating that these behaviours could be more favorable on the race track than during daily handling and training.