Variation in frontal plane joint angles in horses

Conformation in horses is often considered an indicator of athletic ability, performance and resistance to orthopaedic disease. Evaluation is performed in the standing horse and repeatability influenced by stance. Ground reaction forces increase in the moving horse as speed increases.

To determine the effect of locomotion on equine carpus, tarsus, metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in the frontal plane.

Valgus/varus angulation will change when moving.

Kinematic data were collected standing, walking and trotting for 2 groups of horses. The change in angle for carpus, tarsus, MCP and MTP joints was calculated standing and midstance for each stride. Comparison of joint angles between left and right limbs, standing, walking and trotting were made. Inter- and intrahorse variations were investigated.

Significant differences were observed between groups of horses and left and right forelimbs. Between walk and trot, the MCP joint changed from valgus to varus, and the tarsus and MTP joints increased in valgus deformity. Between standing and walk the carpus increased in valgus deformity. Interhorse variation was significantly different, intrahorse variation was not. Variation in measurements between gaits was minimal.

This study validates the measurement of joint angles from the front in the walking and trotting horse using kinematic data, interhorse variation in joint angle measurements exceeding intrahorse variation. The increases in joint angles between standing and walking, and walking and trotting warrant further investigation.