What A Horse’s Posture May Say About His Health

 
New research explores what a horses posture says about his health. Horses may adopt different stances to compensate for discomfort.
When it comes to evaluating horses their movement has always been a primary focus. Now research suggests that more consideration should be given to what a horses posture says about his health.
Standing is the horses most prevalent activity says Karen Gellman DVM PhD. Horses stand nearly all day but we usually only assess their locomotion. Gellman a veterinarian with a doctorate in animal locomotion biomechanics became interested in equine posture while doing an acupuncture internship with Judith M. Shoemaker DVM more than 20 years ago.

A simplified model created using principles of mathematics and physics depicts the postural stability of different equine stances. The model consists of three elements a trunk representing the back head and neck as a horizontal line and a single front leg and single back leg rendered as vertical lines connecting to each end of the trunk and to the ground.  The modeljust two legs hinged at the trunkis inherently unstable in that the hinges can rock the legs to any angle explains Karen Gellman DVM PhD. In the living horse the legtrunk connection is stabilized by muscles tendons and ligaments. Our question was How much neuromuscular effort would the model horse need to stabilize its stance at different leg angles postures?  
Dr. Shoemaker had observed that certain common problems were closely associated with horses using an abnormal compensatory posture explains Gellman. Specifically horses who stand with their legs cantedin under their body are more likely to have chronic or recurrent lameness issues including navicular syndrome suspensory strains hock arthritis and back pain. This becomes a chickenandegg question Gellman adds. Do these things make a horse stand this way or does standing this way cause the pathology?
With a grant from the American Holistic Veterinary Medical Foundation Gellman was able to begin investigating this question in a research setting. As part of this work she teamed up with Andy Ruina PhD a professor of mechanical engineering at Cornell University.
Using principles of physics and mathematics Ruina created a simplified model of a standing horse to explore postural stability. Human postural stability is modeled in a similar way Gellman says. The equine model simplified to 2D consists of three elements a trunk representing the back head and neck as a horizontal line and a single front leg and single back leg rendered as vertical lines connecting to each end of the trunk and to the ground.
The modeljust two legs hinged at the trunkis inherently unstable in that the hinges can rock the legs to any angle says Gellman. In the living horse the legtrunk connection is stabilized by muscles tendons