Oxytocin, vasopressin (AVP) and serotonin are hormones and neurotransmitters that play a role in shaping social behaviours, such as aggression and social recognition.
In a study performed at Sangju International Equestrian Center, Geumhui Lee and Minjung Yoon measured the levels of the three hormones in the blood of a varied group of adult horses.
They assessed the influence of breed, sex, and age on the concentration of each hormone. They also looked to see if there was any relationship between their concentration and docility and friendliness of the horses. A report of the work is published in the journal Domestic Animal Endocrinology.
The authors report that oxytocin and vasopressin concentrations did not vary with the breed, sex, or age of the horse. But they did find that serotonin concentration varied with the breed and age of the horse.
There was no correlation between docility and friendliness of the horses and either AVP or serotonin concentrations. However, the researchers did find a trend towards a correlation between docility and oxytocin in Thoroughbred horses.
They conclude that oxytocin concentration may be related to docility and friendship in Thoroughbred horses.
For more details, see:
Association of plasma concentrations of oxytocin, vasopressin, and serotonin with docility and friendliness of horses
Geumhui Lee, Minjung Yoon
Domest Anim Endocrinol (2021) 74:106482.