Reproduction

Is that mare in pain?

By Adam Marcus

A simple preliminary 8-point assessment can accurately identify mares in pain in the days after foaling, potentially improving post-partum care, new research shows.

The study, published in the journal Animals by a group in Poland, found the rating instrument agreed with levels of cortisol in saliva, which increase with pain, stress and discomfort. The tool, which was created from existing validated instruments of equine health, covers visual assessments of behavior such as posture, movement, facial expressions and response to food, as well as clinical markers like respiratory rate, body temperature, gastrointestinal function, and whether the horse is off its feed.

“In the immediate postpartum period, pain, stress and physiologic fatigue overlap, so the scale is not designed to cleanly separate ‘tired’ from ‘painful.’ Its purpose is to structure observation and draw attention back to the mare, who can be overlooked once the foal is the focus,” said Anna Rapacz-Leonard, PhD, a faculty member of Veterinary Medicine at the University of Warmia and Mazury, in Olsztyn, Poland, who helped conduct the study.

Dr. Rapacz-Leonard and her colleagues administered the assessment in 10 draft mares that had experienced a pregnancy with dystocia in which the fetus had died. Researchers used the tool to record pain scores twice daily for 1 to 4 days after foaling. They also collected saliva samples to measure cortisol levels.

“We included salivary cortisol because, in addition to behavioral scoring, we needed at least 1 biological measure to check that higher scores on our scale go along with a measurable physiological stress/pain response,” Dr. Rapacz-Leonard said. “Cortisol isn’t a perfect pain marker, but it is a well-established, practical indicator of activation of the stress system and is widely used in horses and other species as a noninvasive reference measure.” Saliva is also easy to collect, and doing so is less stressful on horses than drawing blood, she noted.

Administering the assessment requires observers to stand outside or inside the stall box, depending on what they are measuring. For the last step, mares are led outside to walk. The full test takes less than 30 minutes to perform.

Scores on the scale were highest in the 24 hours after foaling, then fell throughout the recovery period. However, in animals that suffered a clinical setback, the scores spiked. In 1 case involving a mare that developed colon torsion, the horse’s pain score rose from 12% to 15% of the maximum possible during the first postpartum day to 47% of maximum the next morning. The animal was euthanized because the owner could not afford treatment, according to the researchers.

Mares with pain scores exceeding 40% of the maximum were deemed to require analgesia.

Given the small sample size and the nature of the cases—all involving problematic deliveries—the researchers are cautious about recommending a particular cutoff for normal births. The 40% threshold “reflects a pragmatic clinical trigger we established after reviewing the mares’ clinical data, not a statistically derived cutoff that has been validated across normal foalings or across other breeds and/or settings,” Dr. Rapacz-Leonard said. “Applying 40% to routine foalings should be done with caution and ideally within a veterinarian-guided protocol.”

What’s more, she said, a single low score on the scale “should not be used to reassure owners that nothing is wrong. The scale is intended for serial monitoring—we recommend twice daily—because trajectories, such as persistent or rising scores, are more informative than a single measurement, especially when complications develop over time.”
The scale is also not designed to rule out pain or major complications, such as uterine tears or internal bleeding.

“The pain scale is best viewed as a decision-support and monitoring tool, not a standalone diagnostic screen,” Dr. Rapacz-Leonard said. “A pain score should never be used in isolation: a veterinary professional should perform a targeted physical exam,” including an assessment of mucous membranes, heart rate, pulse quality, and other factors. MeV

FOR MORE INFORMATION
Bolesławska-Szubartowska J, Kucharczuk M, Skrabska A, et al. Introducing an innovative pain scale for assessing postpartum pain in mares: preliminary clinical evaluation. Animals. 2025;15(23):3454.
https://www.mdpi.com/2076-2615/15/23/3454