The whole barn gets caught up in the drama, with other mares whinnying concern. The mare is the foal's lifeline and as she's brought back we see an increase in maternal care. The reunions are emotional - and analyzed. Changes in heart rate are measured and saliva samples collected. Blood samples from the foals measure levels of cortisol - a hormone from the adrenal gland present in the blood during stress.
Early observations indicate that short separations spur more intense maternal care.
The expectation is that the initial increase in maternal care will be sustained throughout the period that mares and foals are kept together. But if you separate them for too long too early, there seem to be real problems. What it means Zanella and Moons hope to shed light on behaviors horse trainers have observed for years. The orphans are really brats. Anticipating a foal's ability to cope with stress, and having insight into the impact of stress - such as on a foal's immune system, is a potential benefit of the research.