Study: 'Nanny' Horses Reduce Weaning Stress for Foals

Are you expecting new foals on the ground next spring? Then consider finding a "nanny" horse for them at weaning time.

According to a new study by Austrian researchers, foals cope with the stress of weaning better when they're accompanied by mares other than their dams before and after weaning. These "nanny" horses shouldn't have foals of their own, the researchers noted, and should be in the same herd as the weanling from the time that baby is born.

"If you reduce the stress in the first days after weaning, you also reduce the risk that foals injure themselves," said Christine Aurich, DVM, PhD, professor at the Graf Lehndorff Institute at the University of Veterinary Sciences in Vienna and senior author on the study.

In the experiment the research team divided 17 Warmblood foals into three weaning groups. They were either weaned abruptly into an all-foal group, weaned consecutively as dams were removed from the group over a period of several days, or weaned into a group with other foals and two unrelated mares that had been with the foals since birth--the "nanny" group. The researchers measured foal behavior, locomotion, weight, and specific indicators of stress (salivary cortisol [a stress hormone] concentration, beat-to-beat interval, heart rate variability) to determine the foals' response to weaning.

The "nanny" group of foals showed the least amount of stress from weaning. Over the first few days of weaning, these foals whinnied and paced less and ate and slept more, compared to the foals in other groups. They also produced less cortisol in their saliva, which indicated lower stress levels.

The nanny group foals also lost less weight compared to the other foals and were back to their pre-weaning weight sooner--in less than two weeks.

The abruptly weaned foals from the first group showed the most signs of stress, lost a significant amount of weight, and were on average barely above pre-weaning weight a full month after weaning.

The consecutively weaned foals of the second group probably benefited somewhat from the presence of the other dams, but not as much as the "nanny group" foals, according to Aurich.

"A mare with her own foal might defend her own foal," she said, "But a mare without a foal could behave more positively towards an unrelated foal."

The study, "Behavioral and physiological responses of young horses to different weaning protocols: A pilot study," will be published in an upcoming issue of the international journal Stress. The abstract is available online.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.