Lameness and Pelvic Height

The results of a recent study published in the American Journal of Veterinary Research suggest that hind limb lameness in the horse can be evaluated most effectively and objectively by measuring changes in pelvic height during trotting.

Accurate assessment of lameness in horses is essential for making the correct diagnosis and deciding on the proper treatment. Detecting and evaluating hind limb lameness can be difficult, especially when the condition is mild or intermittent. Although several methods have been developed to assess forelimb lameness, few objective techniques exist for evaluating lameness of the hind limbs.

The lead investigator in the hind limb lameness study, Joanne Kramer, DVM, clinical assistant professor of equine surgery at the University of Missouri College of Veterinary Medicine, explained, "In the trotting horse, the pelvis normally rises and falls twice during each stride--once when the horse lands on the right hind limb and pushes off, and once when the horse lands on the left hind limb and pushes off."

To measure changes in pelvic height in sound and lame horses, 17 adult horses were filmed while trotting on a treadmill. The hind feet of each horse were shod with custom-made, adjustable heart-bar shoes designed to induce temporary lameness by applying reversible pressure to the frog.

Using a computer-assisted video motion analysis system called signal decomposition, Kramer's team measured changes in pelvic height at the trot in sound horses and in horses with varying degrees of hind limb lameness.

The researchers found that in sound horses, the pelvis drops to an equal degree when the right hind leg is the weight-bearing limb as when the left hind leg is the weight-bearing limb. Similarly, the pelvis rises to the same height after the right hind limb pushes off as when the left hind limb pushes off.

In lame horses, the pelvis drops less when the lame leg is weight-bearing, and rises less following push-off from the lame limb. Kramer noted, "The horse with hind limb lameness is reluctant to bear full weight on the lame limb, and typically doesn't push off as powerfully with the lame limb compared to the sound limb."

According to Kramer, hind limb lameness can be visually assessed best by watching the pelvis move up and down twice during each stride. She said, "If the movement of the pelvis is symmetrical, the horse is sound in the hind limbs. If the movement is asymmetrical, the limb that is weight-bearing when the pelvis is at its lowest point is the sound limb."

About the Author

Rallie McAllister, MD

Rallie McAllister, MD, grew up on a horse farm in Tennessee, and has raised and trained horses all of her life. She now lives in Lexington, Ky., on a horse farm with her husband and three sons. In addition to her practice of emergency and corporate medicine, she is a syndicated columnist (Your Health by Dr. Rallie McAllister), and the author of four health-realted books, including Riding For Life, published by Eclipse Press and available at www.ExclusivelyEquine.com or by calling 800/582-5604.

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