Association of plasma concentrations of oxytocin, vasopressin, and serotonin with docility and friendliness of horses.

The study explores the relationship between blood levels of oxytocin, vasopressin, and serotonin – neurotransmitters associated with social interaction and behaviour – and the docility and friendliness of horses of various breeds, ages, and sexes. The findings suggest a possible correlation between oxytocin levels and the docility of Thoroughbred horses.

Study Design and Procedures

• The research was performed at Sangju International Equestrian Center. Blood samples from 23 horses of different breeds, sexes, and ages were taken including 6 Thoroughbreds, 6 Warmbloods, 6 ponies, and 5 Quarter Horses.
• Each horse’s plasma oxytocin and vasopressin concentrations were measured using an enzyme-linked immunosorbent assay while serum serotonin concentration was measured via high-performance liquid chromatography.
• The behaviours of each horse were assessed by three horse trainers to evaluate their level of docility and friendliness.

Analysis and Results

• A three-way ANOVA was performed to evaluate the effects of breed, sex, and age on each neurotransmitter level. Linear regression was used to determine the relationship between neurotransmitter levels and horse behaviours.
• The results showed that oxytocin and vasopressin levels did not vary based on the horse’s breed, sex, or age. However, serotonin concentration did vary depending on the breed and age of the horses.
• A correlation between docility and oxytocin concentration was noticed in Thoroughbred horses. No such correlations were established between vasopressin or serotonin levels and docility or friendliness in horses.

Conclusions

• The study concluded that a horse’s docility and friendliness, particularly in Thoroughbreds, may be related to their blood oxytocin concentration.
• The lack of correlation with vasopressin and serotonin suggests these neurotransmitters may not significantly influence horses’ social behaviour.
• The findings provide a potential avenue for further investigation into how oxytocin might be used to enhance the social behaviours of horses, particularly those that are less docile.