Morphological and Behavioural Predictors of Motor Laterality in Domestic Horses: A Cross-Sectional Field Study.

Overview

• This study investigated whether visible physical traits and behaviors in domestic horses can predict motor laterality, which influences their performance and welfare.
• The key finding was that the orientation of a horse’s mane strongly correlates with the horse’s preferred side for movement, providing a simple way to identify laterality without special equipment.

Introduction

• Motor laterality refers to the preference for using one side of the body more than the other during movement, similar to handedness in humans.
• Understanding motor laterality in horses is important since asymmetries in movement can affect training effectiveness, riding performance, and animal welfare.
• Currently, identifying laterality often requires specialized kinematic tools, which may not be easily accessible.
• The researchers aimed to find straightforward, observable markers—like mane direction or other physical/behavioral traits—that predict motor laterality.

Methods

• A cross-sectional field study was conducted involving 100 horses regularly ridden in the Blida and Algiers regions of Algeria.
• Data collected included:
  • Mane orientation (left or right).
  • Facial whorl characteristics (patterns in hair growth on the forehead).
  • Standing body curvature.
  • Masticatory laterality (preferred chewing side).
  • Mouth hardness side (side where the horse shows more resistance in the mouth when bridled).
  • Spontaneous body bending and preferred limb use (e.g., which leg initiates movement).
• Experienced riders assessed two specific motor laterality traits:
  • Preferred forelimb at walk departure (dep1).
  • Ease of canter departure from a particular side (dep2).
• Statistical analyses were performed to find associations between the physical/behavioral traits and motor laterality:
  • Univariable analysis to test each trait independently.
  • Multivariable (combined) analysis to see which traits independently predict laterality.

Results

• The orientation of the mane was the strongest and only independent predictor of motor laterality:
  • Right-maned horses most often showed right-side motor preference.
  • Left-maned horses were predominantly left-side preferred.
  • Statistical significance was very strong (p < 0.001).
  • Odds ratios indicated a very high likelihood linking mane orientation to side preference.
• Other factors like masticatory laterality and mouth hardness side showed some correlation in simple analyses but were not independent predictors when combined with mane orientation.
• No significant association was found with facial whorl patterns, age, breed, training discipline, or sex.
• The model predicting laterality from mane orientation had excellent accuracy (AUC = 0.91).

Discussion

• The study suggests that mane orientation is a robust, easy-to-observe, non-invasive morphological marker that can help anticipate laterality in horses.
• This has practical implications:
  • Riders and trainers can use mane direction to gauge locomotor asymmetries without expensive or complex equipment.
  • Veterinarians can apply this knowledge in early detection and management related to horse performance and welfare.
• Limitations of the study include:
  • Cross-sectional design cannot confirm causality, only association.
  • Laterality assessments depended on rider perception, introducing potential observer bias compared to objective motion capture methods.
  • Further longitudinal and biomechanical studies are needed to validate these findings and establish causal links.

Conclusions

• Mane orientation stands out as a strong, practical predictor of motor laterality in domestic horses.
• It offers a valuable tool for equine professionals to anticipate motor preferences and asymmetries, enhancing training, performance, and welfare strategies.
• Future research should focus on longitudinal tracking and kinematic validation to confirm and build upon these results.