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?