It is often assumed that giving birth is both stressful and painful for the mother. This might be the case for humans, but does it also apply to horses or are we transferring human experiences to the animals?
Scientists at the Vetmeduni Vienna have investigated the stress associated with birth in horses and other domestic animals, and the findings show that, contrary to expectations, mares appear to be completely relaxed when foaling.
Foaling in horses is extremely fast. Labor and the active part of foaling (those that result in the foal's delivery), take 10 to 20 minutes and are considerably shorter than giving birth in humans or in cows. Is this brief period stressful for the mares or are horses more relaxed than humans when giving birth? Researchers recently set out to find out.
Christina Nagel, MSc, PhD, and colleagues, closely observed 17 foalings at the Brandenburg State Stud in Neustadt, Germany, and recorded electrocardiograms before, during, and after foaling. The researchers also took samples of saliva and blood and analyzed the levels of stress hormones such as cortisol and epinephrine.
“Normal foaling appears to cause just the opposite of a stress response,” Nagal said.
The team found that mares' heart rates did not increase during labor. The mares even missed some individual heart beats due to delayed stimulus conduction in the heart, the team said. In humans, such second-degree atriventricular (AV) blocks often require medical treatment, but many healthy horses show AV blocks at rest. The fact that foaling mares exhibited AV blocks suggests that mares are strongly influenced by the parasympathetic nervou