Horse Anatomy: Pastern

Approximately 60% of the weight of a horse is carried on his forward limbs. During locomotion, the forelimbs must be able to take a significant amount of pounding and some rocking side to side. The rear limbs also take a considerable beating during exercise. The pastern joint is part of the shock absorbing conformation of the lower leg, front and rear.

extended pasternThe pastern consists of the long pastern bone and the short pastern bone. The long bone sits just under the fetlock joint and above the short pastern bone. The tendons surrounding the joints allow the pastern and fetlock to flex up and down to cushion the impact of the hoof hitting the ground. Ideally there is only vertical movement at the pastern joint – no lateral movement to interfere with forward motion.

The short pastern bone attaches under the long pastern bone and moves in concert with the coffin bone below it. It allows for some flexibility side to side to keep the foot evenly on the ground.

The joint where the two pastern bones meet is the pastern joint. While the pastern joint only has a small amount of flexibility, combined with the fetlock joint, it increases the total flexibility of the limb during concussion to absorb the shock of hoof meeting ground. This protects the bones and joints from damage caused by hard pounding up the leg.

extended pastern

The visible angle of a standing pastern can tell you a lot about the horse’s way of going and his soundness. The correct angle is important not only for the horse’s comfort and ability to function, but also (depending on the work the horse will do) his ability to hold up.

A nicely-sloped pastern is the best for a riding horse (approximately 45 degrees to the ground). It is sloped adequately to absorb the concussion of the horse’s gait, but not so sloped that it will break down (hyper-extend), ending his riding career.

A longer, more sloping pastern increases the comfortable ride due to its ability to flex more deeply to absorb shock. However, it is inherently weaker than a moderately upright pastern, and increases the risk of break-down and lameness. When the pasterns are too long or sloping, the flexor tendons may hyper-extend, possibly to the point of dropping the fetlock all the way to the ground. This stresses the soft tissues that run under the fetlock, causing lameness.

A short upright pastern will increase the concussion transmitting up the leg via bones instead of engaging the tendons. This type of horse will have a much rougher, jarring gait. Additionally it decreases his stride length: Short strides are uncomfortable to ride. They also decrease the efficiency of a horse’s movement, calling for more strides (more energy) in a given distance. It also increases the likelihood of arthritis and other concussion bone problems caused by lack of elasticity at impact.

Draft horses, who are not selected for smooth riding but for pulling, have more upright pasterns (approximately 65 degrees to the ground). However, because they work at slower speeds, there is less chance of damage from the upright position of the pastern. Care should be taken that draft breeds bred for pulling but now used as performance horses don’t suffer concussion damage because of the new stress put on bones from an upright pastern used in uncharacteristic gaits.

Ponies often have upright pasterns. When training a child to ride, it would be much easier to use a Caspian Horse (small like ponies but built like horses) because they have a conformation similar to a horse, including an adequately slanted pastern for a smoother ride.

caspian horse with child rider

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