Evidence-based shoeing in healthy feet: biomechanical considerations

The way a horse’s hooves are trimmed and shod can have a significant influence on limb movement and loading. Medio-lateral and dorso-palmar/-plantar balancing in particular, as well as mechanical features of the horseshoe are crucial in maintaining a healthy hoof. Evidence based farriery can also be used to correct individual conformational shortcomings of the limb or to address certain pathologies of the hoof and distal limb (see the subsequent abstract text by Oosterlinck et al.). Over the last decades, biomechanical tools such as kinetic and kinematic analysis have shed light on the basic mechanics of trimming and shoeing.

Limb protraction

How the hoof impacts the ground and is loaded depends directly on the protraction phase of the limb. The flight arc of the foot is influenced by the conformation of the limb as well as by the angle of the dorsal hoof wall¹ and weight of the hoof. Hooves that are artificially weighted by attaching weighted boots, using heavy horseshoes, pads and packing material or by letting them grow unnaturally long lead to a higher limb action^2,3 , higher limb impulse and increased difference between horizontal hoof velocity at impact and the ground which results in higher braking forces⁴ .

Limb impact

The hoof’s impact with the ground can be divided into two phases; the primary impact phase representing the initial ground contact, characterised by rapid vertical deceleration and resulting in high-frequency oscillations; and the secondary impact phase, during which the vertical force gradually increases while the hoof is braking in a horizontal direction to become firmly placed on the track. The primary impact phase lasts around 30ms, which is less than proprioceptive reactivity and therefore makes neuromuscular adaptive corrections impossible. Peak vertical impact deceleration can amount to 400g and horizontal deceleration to 200g depending on the horseshoe and ground surface properties⁵. [...]