Hoof Biomechanics Kwantlen Polytechnic University Farrier Training

The Hoof A spring A shock absorber A plastic cone An airbag The toe – rigid Heel area - distorts Change of shape = reduction of shock

Pressure Pressure = force/unit of area. Pressure increases as the force increases or the area that the force is acting on decreases. Example: If the horse gets fatter or the hooves get smaller then the pressure becomes greater.

Levers A lever is a device to facilitate moving an object by creating a torque or turning force The hoof wall is a lever

Impact When two bodies collide they are in contact for a short period of time During that time each body exerts a force on the other Each time the hoof contacts the ground it constitutes an impact The forces associated cause a shock wave to be transmitted through the hoof and leg

Initial Ground Contact Ground Contact may be Heel first Flat footed Toe first Lateral side then medial Medial then lateral

Impact sequence of events Initial impact Rapid deceleration – speed zero Centre of pressure moves from the heels to the tip of frog area then to the point of breakover

Factors that affect hoof function Wall length Wall angle Sole thickness Frog size White line thickness Bar size, length and connection to frog Moisture content Health of horse Shoes Terrain Speed Weight

The Normal Hoof P.3. P.3 descends and rotates slightly Pulls the dorsal proximal wall backwards and down The wings of P.3 push the Collateral Cartilage outwards, spreading the wall at the quarters P. 2. and P. 1 rotate backwards around the distal interphalangeal joint (coffin joint)

Insert animation of bone sinking in hoof.

The Collateral Cartilage Carried back, down and outwards against the hoof wall. Tension in the ligaments to the surrounding tissue Expel blood up the leg

Digital Cushion Descending bones drive the cushion downwards against the frog. Frog stay forces the d. cushion sideways Fatty tissue allows distortion Fibrous tissue resists distortion

Vascular System Blood is squeezed out of the Plexus of the foot Blood in trapped below the plexus in the palmer area of the foot

The Hoof The Wall The distal border at the toe is driven outwards Coronary border at the toe is pulled back and down The quarters are pushed outwards The heels are pushed back/out

The Bars Act as compression springs Resist forwards and backwards movement

The White Line The white line is compressed by the sole

The Sole The sole flattens Pushes the distal border of the wall out

The Frog Spreads sideways and backwards Acts as a soft arch support for the descending bones

Moisture

Review The hoof behaves like a ………..? If the pressure increases on the hoof, the force on the hoof is increasing or the area of the hoof is decreasing. T/F? The hoof wall is a lever. T/F? Initial ground contact of the hoof may be, heel first, toe first, flat footed, m/l or l/m. T/F? Which of these does not affect hoof function? Moisture, weight, hoof colour, speed, terrain. The dorsal wall at the coronary band descends under load. T/F? P.1 and P.2 rotate backwards around the coffin joint. T/F? The collateral cartilage keep the quarters from spreading.T/F? The frog stay plays no part in shock absorbtion. T/F? The blood being driven up the leg acts like a hydraulic damper. T/F? Most of the movement of the hoof is in the toe area. T/F? In a healthy foot the sole should flatten under load. T/F?