Evidence Based Horse Shoeing in Healthy Feet

Understanding the biomechanical principles that govern hoof loading, impact forces, and breakover mechanics is essential for making informed decisions in evidence-based shoeing. Even in healthy horses, subtle variations in hoof shape, limb alignment, and ground interaction can significantly influence how forces are distributed throughout the distal limb. These forces affect not only the hoof capsule but also deeper structures such as joints, ligaments, and tendons. By examining how the hoof interacts with the ground during different phases of the stride and how various farriery interventions alter these dynamics, practitioners can better support limb function, reduce the risk of overload injuries, and maintain long-term soundness. The following report outlines key biomechanical considerations relevant to trimming, shoeing, and managing hoof balance in clinically normal equine feet.

Biomechanical Considerations

Weishaupt, Imboden, Dumoulin, OosterlinckEquine Department, Vetsuisse Faculty University of Zurich, Zurich, SwitzerlandDepartment of Surgery and Anaesthesiology of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Ghent, BelgiumProceedings of the European College of Veterinary Surgeons — 13–15 July, 2017 — Edinburgh, Scotland

1. Introduction: Foot Impact and the Cranial Phase

The impact of the foot on the ground is directly related to the cranial phase of the stride. When the foot strikes the ground, the limb must decelerate to zero—this deceleration is called breaking.

The arc of flight (the movement of the foot in the air) can be influenced by several factors:

• Weight

• Shoes

• Boots

• Pads and packing

• Hoof length

Excessive hoof length or added weight increases the speed at which the foot hits the ground. This leads to higher braking forces on the limb.

2. Forces at Foot Strike

When the horse’s foot meets the ground, two main forces occur:

Vertical Force

• Represents the direct impact downward.

  
  

Horizontal Force (Slide Phase)

• Represents the forward-moving slide during initial contact.

• This is the phase where breaking occurs.

Breaking is influenced by:

• Type of horseshoe (traction level)

• Weight of the hoof and additional appliances

• Ground surface

• Gait

A certain amount of horizontal slide helps dissipate impact energy.Too little slide causes the foot to stick, increasing strain on structures.

3. Lateral vs. Medial Loading During Impact

Pressure-measurement studies show:

• Front limbs: ~60% land on the lateral heel and load the lateral wall first.

• Hind limbs: almost all land on the lateral heel and load the lateral wall first.

• Even horses with good conformation and visually level feet tend to load laterally first.

  
  

Consequences of Uneven Hoof Capsule Loading

Such uneven loading produces distortions including:

• Uneven-angled quarter walls

• Distal one-third flares

• White line separation

• Wry feet

• Sheared heels

• Quarter cracks

  
  

4. Farrier Considerations for Correcting Imbalances

Key considerations include:

• The length of the hoof walls

• Relationship between the hoof’s ground surface and limb axis

• The way the horse lands

• Hoof position at landing

• Hoof position at breakover

Studies show that hooves with uneven walls shift the center of pressure (COP) toward the longer wall. This alters loading in the:

• Coffin joint

• Pastern joint

• Fetlock

  
  

Shifts in Center of Pressure

• A foot out of medial–lateral balance shifts COP to the longer side, increasing load and bone stress.

• The shorter side receives less load and “opens” at the joint, increasing soft tissue strain, especially on collateral ligaments.

  
  

5. Influence of Wedges, Extensions, and Support Devices

Wedges

• Wedging both heels shifts COP toward the heels, especially on hard surfaces.

• Wedging one heel shifts COP toward that specific heel, increasing load.

Extensions (e.g., egg bar shoes)

• Shift load toward the palmar aspect of the foot.

Weak or Collapsed Heels

Horses with:

• Weak walls

• Crushed heels

• Collapsed heels

…typically do not benefit from wedges or extensions alone because the walls cannot support the added pressure.

Additional options include:

• Straight bars

• Heart bars with packing

• Frog-support pads

These help distribute load more evenly across a larger area. The choice of application must be based upon the horse's intended workload, type, and work surface, as these factors may render certain shoeing packages contraindicated.

The weak or collapsed heels should be addressed by removing the deformed horn until healthy tubules are reached. Polyurethane or acrylic material can be used to rebuild the portion of the heel that has been removed.

6. Duty Factor and Weight Distribution

Duty factor is the amount of time the foot remains on the ground (stance phase).

• Highest at mid-stance, when one limb stands opposite the other.

• Duty factor decreases:

  • Walk: ~75%

  • Gallop: ~25%

Because two-thirds of a horse’s weight is carried on the front limbs, forces are greater in the front.

At a gallop/canter, vertical forces can reach 2.5× the horse’s body weight on a single limb.

7. Ground Reaction Forces (GRFs)

All forces between the hoof and ground combine into a Ground Reaction Force (GRF) vector—a straight line representing direction and magnitude.

What Is a GRF?

• According to Newton's Third Law, the ground exerts a force back against any body in contact with it.

• When the horse is standing, GRF equals the horse’s weight.

  

  
  

• During movement, GRF increases due to acceleration forces.

A galloping horse experiences two and a half times its body weight on a single limb.

8. Breakover Phase and Center of Rotation

The starting point of the GRF vector corresponds to breakover, from heel-strike to toe-off.The center of pressure begins at first contact and moves forward toward the toe.

Breakover occurs during the last 15% of the stance phase.

Influence of Shoeing Cycle

Changes in hoof conformation over an 8-week cycle:

• Increase coffin joint extension

• Increase deep digital flexor tendon (DDFT) loading

• Add strain to the podotrochlear apparatus

• Delay breakover

The DDFT may experience up to a 15% increase in load near the end of the cycle.

9. Final Consideration: Hoof Balance

A properly balanced foot—both cranial/palmar and medial/lateral—is essential for stability under maximum weight bearing.

Balanced trimming and shoeing reduce distortion, improve loading patterns, and support long-term hoof and limb health.

FAQ: Horse Shoeing in Healthy Feet

What do hoof biomechanics and ground reaction forces actually mean?

Hoof biomechanics looks at how the hoof and limb land, support weight, and push off with every stride. Ground reaction force is simply the force the ground sends back into the limb when the hoof hits and pushes off. At faster gaits, that force can reach several times body weight on a single limb, which is why small balance changes matter.

How do hoof length, shoe weight, and traction affect impact and breakover?

A longer, heavier foot usually hits the ground faster and harder, increasing braking forces at impact. Shoe design and traction change how much the hoof slides on landing. A bit of slide helps absorb shock, while too much “grab” can make the hoof stick and increase strain higher up.

Why do most horses land on the lateral heel first, and is that always a problem?

Most front and hind feet land on the lateral heel first, even in well-conformed horses. A mild lateral first contact can be normal. It becomes an issue when uneven loading drives persistent distortion, flares, collapsed heels, or recurring cracks.

What visible signs suggest a medial–lateral hoof imbalance that affects biomechanics?

Red flags include one wall consistently longer, flares in the distal third of the wall, white line stretching on one side, uneven heel heights, sheared heels, and repeat quarter cracks. These changes usually reflect a shifted center of pressure and uneven joint loading.

How do wedges, egg bar shoes, and other extensions change hoof loading?

Wedges shift weight toward the heels, and wedging one heel concentrates load on that side. Extensions and bar shoes move load toward the palmar or plantar part of the foot and can add support behind the widest point of the hoof. In weak or collapsed heels, they must be paired with good trimming and sometimes frog support to avoid overloading compromised walls.

When are frog support and heel reconstruction materials appropriate?

They are helpful when heels are crushed or collapsed and trimming alone leaves too little wall to carry load. After removing distorted horn and re-establishing healthier heel alignment, polyurethane or acrylic materials and frog-support pads can help share load over a wider area. These packages should be tailored to the horse’s workload and footing and re-checked over several cycles.

How does the shoeing interval affect breakover, tendon load, and joint angles?

As the hoof grows between visits, the toe runs forward, the coffin joint often extends more, and the deep digital flexor tendon works harder to lift the heel. Near the end of a long cycle, breakover is delayed and strain on the DDFT and podotrochlear region can rise. Many horses, especially performance horses, do better on a consistent, slightly shorter schedule.

How can owners and farriers work together to make evidence-based shoeing decisions?

Owners can watch how their horse lands and breaks over on the actual working surface, take regular photos or video, and share any changes in comfort or performance at each visit. Farriers can combine that information with gait assessment and clinical findings to adjust trims, breakover, and support. The goal is to use biomechanics as a guide, not just tradition, when choosing a shoeing plan.