Exploring non-invasive methods to assess pain in sheep

Area of Science:

• Veterinary Medicine
• Animal Welfare Science
• Pain Research

Background:

• Accurate pain assessment in sheep is crucial for welfare and ethical treatment.
• Non-invasive physiological measures are needed to detect pain in livestock.
• Infrared thermography (IRT) and heart rate variability (HRV) are potential indicators of pain.

Purpose of the Study:

• To evaluate if eye temperature (IRT) and HRV can detect moderate pain in sheep.
• To compare the sensitivity of IRT and HRV as pain indicators in sheep.

Main Methods:

• Six ewes were subjected to three treatments: ischemic stimulus (S), stimulus with flunixin (S+F), and flunixin alone (F).
• Measurements included eye temperature (IRT), heart rate variability (HRV), nociceptive threshold, blood pressure, and behavior.
• Data were collected during baseline, intervention, and post-intervention periods over multiple test days.

Main Results:

• HRV parameters (RMSSD, SDNN) showed a tendency to decrease with pain stimulus (S vs. F) and increased significantly between test days.
• Eye temperature decreased across all treatments, but no significant differences were found between pain and control groups.
• Behavioral indicators like lip licking and vocalization decreased over test days, while ear posture varied.

Conclusions:

• HRV is a sensitive, non-invasive method for assessing mild to moderate pain in sheep.
• IRT is less sensitive than HRV for detecting moderate pain in this ovine model.
• Further research can refine HRV analysis for objective pain monitoring in sheep.