Identification of Body Behaviors and Facial Expressions Associated with Induced Orthopedic Pain in Four Equine Pain Scales.
Authors: Ask Katrina, Rhodin Marie, Tamminen Lena-Mari, Hernlund Elin, Haubro Andersen Pia
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Researchers induced orthopedic pain in eight horses using intra-articular lipopolysaccharide (LPS) injection, then systematically evaluated pain-related behaviours and facial expressions at rest using four established equine pain scales, whilst objectively measuring movement asymmetry before and after induction. Postural indicators—including head position, location within the box stall, and interactive behaviour—emerged as the most reliable predictors of induced pain and correlated strongly with measurable gait asymmetry, whereas facial expressions, though strongly associated with pain when present, showed greater variability between individual horses and lower inter-observer reliability. The findings suggest that mild to moderate orthopedic pain can be more accurately detected at rest by focusing on five key behavioural markers (posture, head position, stall location, focus, and interactive behaviour) rather than relying on facial expressions alone, though incorporating facial cues as supplementary indicators may enhance detection in some individuals. For practitioners managing subtle lameness or early-stage orthopedic conditions, this research supports prioritising systematic assessment of static postural changes and behavioural shifts during box rest as sensitive indicators before relying on gait analysis, whilst remaining alert to individual variation in pain expression.
Read the full abstract on PubMed
Practical Takeaways
- •Observe posture and head carriage at rest in your box—these are more reliable indicators of mild orthopedic pain than facial expressions alone
- •Watch for changes in where horses stand in the stall, their attentiveness, and willingness to interact; these five behaviors combined offer better pain detection than existing scales for early lameness
- •Facial expressions can support pain assessment when visible, but don't rely on them as your primary indicator since different horses show them differently and they're harder to assess consistently
Key Findings
- •Five body behaviors (posture, head position, box location, focus, interactive behavior) were the strongest predictors of movement asymmetry in mild orthopedic pain
- •Posture-related scale items showed the strongest association with objectively measured movement asymmetry
- •Facial expressions at rest were strongly associated with movement asymmetry when present, but showed lower inter-observer reliability than behavioral items
- •Behaviors and facial expressions commonly co-occurred in horses with induced orthopedic pain