What A Horse’s Posture May Say About His Health

and ligaments. Our question was How much neuromuscular effort would the model horse need to stabilize its stance at different leg angles postures?  Ruina added theoretical springs to the models shoulders and hips The stiffer the springs needed to stabilize the model the more effort required to maintain the corresponding posture.
Using these calculations Ruina tracked how much spring energy would be necessary to stabilize a horses stance across a wide range of leg positions from cantedin with fore hooves and rear hooves closer together to standing square with the hind and forelegs vertical under the body  to splayedout with the fore and rear hooves relatively far apart.
The researchers found that a horse must expend twice the amount of neuromuscular effort to stabilize his body in a cantedin stance versus a square stance. We found it takes twice the amount of neuromuscular effort to stabilize a horse who is standing cantedin than one who is standing square says Gellman. Even a small difference in cost of standing can add up since most horses are standing for long periods every day. 
A cantedin stance abnormal compensatory posture doesnt just consume more energy continues Gellman. Its maladaptive to the way the equine musculoskeletal system is designed. Standing cantedin puts abnormal stresses on the limb joints muscles the structures of the hooves as well as the back.
The model also showed that horses who stand splayed out or parked use even less stabilization effort than horses standing square. We see horses assume a splayedout posture naturally when challenged with a heavier load says Gellman like mares in late pregnancy or horses pulling a laden cart. And you have probably experienced something similar yourselfyou instinctively take a wider stance when lifting something heavy. However most feral and healthy domestic horses usually stand with verticalnot splayedoutlimbs. While splayedout posture is slightly less costly vertical posture can be more versatile for daily activitiesallowing rapid mobilization for escape from predators and strengthening leg structures in the vertical orientation for peak loading during fast locomotion.
This study didnt address why a horse might adopt a stance that requires more energy to maintain but ongoing research by Gellman Shoemaker and colleague Elizabeth Reese is designed to tease out the causes of abnormal compensatory posture.
Our clinical experience has shown that cantedin posture in horses is closely associated with dental malocclusion and distorted morphology of hoof capsules says Gellman. We believe these abnormalities along with pollmuscle dysfunctions are sending distorted proprioceptive signals to the postural control centers of the brain. Clinically when we fix the structural and functional problems in the upper cervical region hooves and teeth the horses posture reverts to vertical neutral. This theoretical study was our first pass at showing
the physical basis for this phenomenon.
While many questions remain Gellman says the study does support the desirability of the square stance.
In a dressage test they require horses to stand square for the salute. Show dogs are expected to stack which is a vertical stance. Clearly a square vertical limb stance is a sign of a healthy quadruped. If you have to force or hold a horse into a square stance I think its worth exploring why.