Egg-Bar Horseshoes: An Advanced Review of Biomechanics and Recent Research
Caudal support, tendon strain, navicular loading, and hoof stability, including findings from studies published in 2023 and 2025.
The egg-bar horseshoe is a familiar option in farriery, particularly when a horse needs additional support in the caudal portion of the hoof. It is used in the management of certain painful or structurally compromised feet and may also be considered when the way a hoof interacts with soft ground needs to change.
An egg-bar can influence the ground-bearing platform, hoof deformation, and loading within the foot and limb. Whether those changes are useful depends on diagnosis, hoof preparation, shoe fit, and footing. The goal when utilizing an egg-bar is to produce a specific mechanical change that benefits the individual horse.
For an introduction to egg-bar design, common uses, and fitting considerations, start with our basic guide: Horseshoes: The Egg Bar.
What Is an Egg-Bar Horseshoe?
An egg-bar is a horseshoe whose branches curve together behind the heels, forming a continuous, oval-like extension beyond the back of the hoof. It belongs to the broader family of bar shoes, which connect the branches rather than leaving the heels open.
The word caudal means toward the rear. In this context, caudal support describes the additional bearing platform behind and beneath the heel region.
Compared with a conventional straight-bar shoe, an egg-bar generally provides a more rounded rear extension. However, the actual dimensions and fit determine how much bearing surface either design offers.
For a comparison of related patterns, see Bar Shoes: Common Designs and Uses.
Historical Development: From Bar Shoes to the Modern Egg-Bar
The egg-bar developed from a much older tradition of closed-heel shoeing. George Fleming’s Horse-Shoes and Horse-Shoeing: Their Origin, History, Uses, and Abuses (available in our free online library) reproduced a bar-shoe illustration from Cesare Fiaschi’s sixteenth-century work, demonstrating that farriers were connecting the branches of horseshoes centuries before the modern egg-bar became familiar. These early designs were predecessors of today’s bar shoes, rather than necessarily the same extended oval pattern.
Historical applications focused on protecting weak or painful heels, redistributing bearing away from damaged hoof wall, and, in some designs, allowing the frog to carry additional load. Nineteenth- and early twentieth-century texts described bar shoes for corns, hoof cracks, and compromised feet. Lungwitz and Adams also discussed increasing bearing surface and incorporating leather soles and packing, while William J. Moore noted the structural advantage of joining the branches to help prevent lightweight shoes from spreading or distorting.
The modern egg-bar’s distinguishing feature is its rounded extension behind the heels. Historical sources do not establish a single inventor or reliable introduction date for this specific design.
Its association with navicular disease was documented in a 1984 clinical study by Ostblom, Lund, and Melsen, which reported resolution of clinical signs in more than half of the treated cases. That finding did not establish reversal of the underlying disease or identify the precise mechanism responsible.
This history helps separate the shoe’s longstanding purposes from later biomechanical explanations. Hoof protection, expanded bearing area, and clinical improvement are distinct from proof of reduced tendon strain or navicular compression. Those proposed effects must be evaluated against the experimental evidence discussed below.
Materials and Variations
Egg-bars can be manufactured or handmade, and their mechanical properties vary with their construction.
Material | Practical considerations |
Steel | Commonly selected for durability and the ability to shape or modify the shoe. Weight depends on the section and dimensions used. |
Aluminum | Provides a lighter option for comparable dimensions, although wear resistance and rigidity differ from steel. |
Synthetic or composite materials | Offer different combinations of flexibility, weight, attachment methods, and wear characteristics. Properties vary substantially between products. |
Material alone does not determine ground contact, cushioning, or suitability.
An egg-bar may also incorporate a rolled toe, wedge, pad, or frog-supporting component. Each addition changes the complete application.
Did you know? An egg-bar does not automatically provide direct frog support. A standard egg-bar closes behind the heels. A heart-bar includes a component intended to engage the frog. Combining these features creates a different shoeing arrangement.
How Does an Egg-Bar Work?
The main mechanical objective is to extend the caudal ground-bearing platform and influence how the foot accepts and distributes load.
When the horse bears weight, force passes through the hoof and shoe into the ground. The ground applies force back through the areas in contact with it. Extending the shoe behind the heels changes the available contact platform.
Bearing Area and Pressure
Pressure is force distributed over an area. In a simplified model, spreading the same force over a larger area lowers average pressure.
The living foot is more complicated. Contact changes throughout the stride, the surface may deform, and pressure is not evenly distributed. A larger shoe therefore does not prove that pressure has decreased beneath every part of the hoof.
Two interfaces matter:
Hoof-to-shoe contact: Where the hoof transfers load into the shoe.
Shoe-to-ground contact: Where the shoe transfers load into the surface.
A broad ground-bearing platform can still be associated with unwanted focal pressure if the fit beneath the hoof is inappropriate.
Likewise, it is inaccurate to say that open-heel shoes allow weight-bearing only through the wall while egg-bars automatically distribute weight through the frog and heel bulbs. Contact depends on hoof preparation, surface penetration, and any additional support materials.
Support and Leverage
Ground forces also produce turning effects around joints. These depend on the magnitude and direction of the force and its distance from the joint’s axis.
An egg-bar may change these relationships, but its shape alone cannot tell us exactly what happens inside the limb. Toe position, heel height, hoof orientation, posture, and movement also contribute.
These principles are explored further in What Is Hoof Balance? A Scientific, Peer-Reviewed Guide.
Footing and the Heel “Floating” Effect
The term heel flotation is sometimes used to describe the effect of a larger rear bearing platform on deformable ground.
The mechanical reasoning is straightforward: additional bearing area may resist penetration into a yielding surface. If the rear platform changes how deeply the heels sink relative to the toe, it may also change the foot’s orientation under load.
However, “flotation” should not be interpreted as a guarantee that the heels cannot sink or that tendon loading will always decrease.
The result depends on:
Surface depth, firmness, and moisture.
How the shoe engages the footing.
The shoe’s dimensions and rigidity.
The horse’s speed, movement, and loading pattern.
Researchers have specifically studied egg-bar effects on three-dimensional joint movement in horses walking on sand. This highlights why surface conditions belong in the mechanical assessment. Findings from one surface or gait should not automatically be applied to another. beva.onlinelibrary.wiley.com
On firm ground, the assessment changes. The important questions include where contact occurs, whether loading is balanced for that foot, and whether the rear extension introduces an unwanted interaction during landing or turning. An egg-bar does not inevitably strike the ground first simply because it extends behind the heels.
Which Anatomical Structures May Be Affected?
The shoe attaches to the hoof, but changes at ground level may influence several structures.
Heel wall and quarters: Their bearing contact determines how load transfers into the shoe.
Third phalanx, or P3: Also called the coffin bone, this lies within the hoof capsule. Its movement is particularly important when lamellar support is compromised.
Coffin joint: Its position and mechanical demands are influenced by hoof orientation and ground forces.
Deep digital flexor tendon, or DDFT: This tendon passes over the navicular region and attaches to P3.
Navicular apparatus: Forces in this region depend partly on DDFT tension and the tendon’s path.
Suspensory apparatus: Changes in foot mechanics may also alter demands on structures supporting the fetlock.
The Hoof Anatomy Flashcards provide a useful way to review the sensitive and insensitive structures of the foot.
What Does the Research Show?
Research on egg-bars has measured several different outcomes. These findings help explain possible effects, but they should not be combined into one general claim that the shoe “reduces stress.”
Tendon and Suspensory Strain
Riemersma and colleagues studied five ponies walking with different shoeing arrangements. Compared with normal flat shoes, egg-bars reduced mean peak DDFT strain by 0.13 percentage points and increased mean peak suspensory ligament strain by 0.22 percentage points.
Strain describes relative elongation. These measurements are not percentages of pain relief or injury prevention.
The study used P < 0.1, a less stringent significance threshold than the commonly used P < 0.05. The small sample and experimental conditions also limit generalization.
The finding illustrates a possible tradeoff: reducing strain in one structure can coincide with increased strain in another. It does not establish that egg-bars routinely unload the inferior check ligament. beva.onlinelibrary.wiley.com
Navicular Compression
Willemen and colleagues evaluated 12 sound Dutch Warmblood horses using gait analysis and force measurements.
Egg-bar shoes did not significantly reduce the calculated compressive force exerted by the DDFT on the navicular bone compared with flat shoes.
A horse with palmar foot pain may still benefit from an individualized shoeing change.
However, improvement does not prove that navicular compression decreased, and routine claims that egg-bars “take pressure off the navicular bone” are not supported by this experiment. pubmed.ncbi.nlm.nih.gov
Coffin-Bone Movement in Laminitic Feet
Aoun and colleagues’ 2023 study examined eight unaffected and eight laminitic distal forelimb specimens under controlled compression.
Egg-bars reduced overall three-dimensional P3 displacement in laminitic hooves compared with open-heel shoes, with significant differences at particular stages of the loading cycle.
However, movement relative to individual hoof landmarks varied.
This laboratory finding supports a possible stabilizing effect under the tested conditions. It does not demonstrate pain relief, healing, or prevention of further displacement in living horses. Reduced overall movement also does not mean that every direction of movement improved. journals.plos.org
Ground Reaction Forces During Walking
Aoun and colleagues’ 2025 study compared unshod feet, open-heel shoes, egg-bars, heart-bars, and wooden clogs in six non-lame horses.
The researchers measured ground reaction forces and their timing during walking. Peak propulsive force occurred slightly earlier within stance with egg-bars than with open-heel shoes.
These results describe interactions between the limb and ground. They do not directly measure tendon strain, navicular compression, or treatment success in lame horses. pmc.ncbi.nlm.nih.gov
Did you know? Less bone movement, less tendon strain, and less navicular compression are three different findings. A study demonstrating one cannot automatically be used as evidence for the others.
When Might an Egg-Bar Be Considered?
Selection should begin with a diagnosis and a mechanical objective. The question is: What needs to change in this foot, and how will the application achieve it?
Palmar Foot Pain and Podotrochlear Disease
Egg-bars are used in some management plans for pain originating from the back of the foot. However, palmar foot pain can involve different structures, and the general location of "palmar pain" alone does not identify the appropriate shoe.
The veterinarian and farrier may consider the bearing platform, heel penetration, breakover, and other aspects of the application. A shoe should be selected for those specific objectives rather than because it carries a reputation as a “navicular shoe.”
Read Navicular: The Current Consensus and the Guide to Equine Lameness Diagnosis and Assessment for additional context.
Deep Digital Flexor Tendon Injuries
An egg-bar may be considered within a veterinary plan for a DDFT injury when its expected mechanical effects match the needs of the case.
The location and severity of the lesion, associated injuries, hoof configuration, and rehabilitation surface all matter. An egg-bar, heel elevation, and a toe modification are separate interventions. Their effects should not be treated as interchangeable.
The presence of a tendon injury also makes exercise management important. A shoeing change does not replace a prescribed rehabilitation plan.
Quarter Cracks and Damaged Hoof Walls
A closed shoe may form part of a support strategy when the hoof wall is compromised. The objective may include redistributing bearing away from a damaged region and supporting the remaining hoof.
However, a quarter crack requires attention to its cause, associated distortion, and movement of the affected wall. A shoe alone does not repair the crack or guarantee that it will grow out normally. Clinical farriery guidance emphasizes correcting the underlying loading problem alongside any stabilization or repair.
White Line Disease and Hoof-Wall Resection
Removing diseased or detached wall can reduce the hoof’s available bearing strength. Depending on the extent of the defect, additional support may be required.
An egg-bar may be one component of that arrangement, but extensive defects can require frog support or other modifications beyond a standard egg-bar. The support must be matched to the remaining structures, and the underlying disease still requires management. IVIS
Related reading includes Seedy Toe in Horses and A Deeper Dive Into White Line Disease Management.
Horses Working on Yielding Surfaces
An egg-bar may be considered when altering heel penetration is a defined objective. Working in sand does not, by itself, establish a need for one.
The application should be assessed on the horse’s actual working surface. Additional rear bearing area does not make excessively deep, inconsistent, or poorly maintained footing harmless.
Application Considerations
Hoof Preparation Comes First
Sole depth, heel integrity, hoof-wall condition, and internal alignment determine the available options. Adding a larger shoe cannot compensate for unsuitable preparation or contact beneath the foot.
Radiographs may help relate external landmarks to internal structures in complicated cases.
For horses with mismatched feet, each foot needs individual assessment. The aim should not be to force both feet into an identical external shape. See Understanding High-Low Syndrome in Horses.
Match the Extension to the Purpose
There is no universal rear-extension measurement suitable for every horse.
The extension should serve its intended function while accounting for terrain, interference, and retention. Increasing its length without a clear reason can create additional opportunities for catching or being stepped on.
Evaluate Breakover Separately
The rear extension does not define the shoe’s toe mechanics.
An egg-bar can incorporate a rolled or rockered toe, but these features need their own rationale. Learn more in What Is Breakover? and The Rolled Toe Horseshoe.
Consider Shoe Retention
The projecting rear section can be caught by another foot or an external object. Mud, uneven terrain, overreaching, and changing fit during the shoeing interval may complicate retention.
Appropriately fitted bell boots may help protect against overreach contact when recommended for the horse. They do not correct poor fit or eliminate shoe-loss risk.
Contraindications and Cautions
An egg-bar deserves reconsideration when its expected effects conflict with the needs of the foot or limb.
Important cautions include:
Concurrent tendon or ligament injury: The entire limb must be considered when redistributing load.
Unwanted pressure: The shoe or added materials may load a region that needs protection.
Repeated catching or interference: The extension may be unsuitable for the horse’s movement or environment.
Inadequate surface engagement: The intended support may not function as expected.
Deteriorating comfort: Increased pain requires reassessment.
A suspensory, superficial digital flexor tendon, or check-ligament injury should prompt case-specific evaluation. The evidence does not justify treating every such injury as an automatic prohibition.
Similarly, trail riding is not a blanket contraindication. Terrain and catching risks must be weighed against the horse’s support needs. A rolled toe also does not automatically replace an egg-bar, because the two features address different aspects of foot mechanics.
Monitoring the Response
Before changing the shoeing, document the horse’s comfort, movement, hoof condition, and working surfaces. Reassess these observations after application and throughout the shoeing interval.
Useful records include:
Comparable hoof photographs.
Videos on the same surface, when movement is permitted.
Changes in comfort standing, walking, or turning.
Interference marks, loose shoes, or repeated shoe loss.
Changes in heel contact as the hoof grows.
The veterinarian and farrier should agree on the intended outcome and review schedule. Worsening lameness should not be dismissed as a routine adjustment period.
For structured learning, explore the Equine Lameness Study Kit, Equine Anatomy Study Kit, and Farrier and Hoof-Care Study Resources. The Hoof Triage Toolkit can also help owners organize observations and communicate hoof concerns.
Frequently Asked Questions About Egg-Bar Horseshoes
1. What is the main purpose of an egg-bar horseshoe?
Its primary purpose is to extend the bearing platform behind the heels. This may influence caudal support, pressure distribution, and heel penetration, depending on the hoof, fit, and surface.
2. Can egg-bars help horses with navicular syndrome?
They may be included in an individualized management plan. However, they should not be described as reliably reducing navicular compression. The diagnosis, intended mechanical change, and horse’s response should guide their use.
3. Does an egg-bar support the frog?
A standard egg-bar does not automatically contact or support the frog. Direct frog support requires suitable contact through the design, additional materials, or the ground. An egg-bar incorporating a heart-bar component is a different arrangement.
4. Can egg-bars help quarter cracks or white line disease?
They may form part of a support plan for a compromised hoof capsule. The underlying cause, damaged tissue, and available bearing structures still need attention. A standard egg-bar is not sufficient for every defect.
5. Do egg-bars prevent heels from sinking into sand?
They may resist heel penetration by increasing the effective rear bearing area. They do not prevent sinking under all conditions, and results depend on the surface, shoe dimensions, and loading pattern.
6. Are egg-bars appropriate for suspensory injuries?
That requires individual assessment. Changes intended to help structures within the foot can alter demands elsewhere in the limb, so the specific injury and complete shoeing arrangement must be considered.
7. Can a trail horse wear egg-bars?
Possibly. Rough terrain, catching hazards, and interference may affect suitability, but trail use alone does not rule them out. The farrier and veterinarian should balance those risks against the horse’s needs.
8. Should a horse wearing egg-bars use bell boots?
Bell boots may be useful when overreach contact threatens the heel area or shoe. Their fit and use should be discussed with the farrier. Repeated shoe loss requires assessment of the underlying cause.
9. Are egg-bars only for lame horses?
No. They may be selected for a defined mechanical objective in a sound horse. However, using them in a sound horse does not establish that they prevent future lameness.
10. How can I tell whether the shoe is helping?
Compare the horse’s response with the original treatment objective. Comfort, movement, hoof condition, and shoe retention are useful observations. Professional reassessment is needed to determine whether the application remains appropriate.
References
Willemen MA, Savelberg HHCM, Barneveld A. The effect of orthopaedic shoeing on the force exerted by the deep digital flexor tendon on the navicular bone in horses. Equine Veterinary Journal. 1999;31:25–30. DOI
Riemersma DJ, van den Bogert AJ, Jansen MO, Schamhardt HC. Influence of shoeing on ground reaction forces and tendon strains in the forelimbs of ponies. Equine Veterinary Journal. 1996;28:126–132. DOI
Aoun R, Charles I, DeRouen A, Takawira C, Lopez MJ. Shoe configuration effects on third phalanx and capsule motion of unaffected and laminitic equine hooves in-situ. PLOS ONE. 2023;18:e0285475. DOI
Aoun R, Ogunmola Z, Musso A, Taguchi T, Takawira C, Lopez MJ. Shoe configuration effects on equine forelimb gait kinetics at a walk. PeerJ. 2025;13:e18940. DOI
Chateau H, Degueurce C, Denoix JM. Effects of egg-bar shoes on the 3-dimensional kinematics of the distal forelimb in horses walking on a sand track. Equine Veterinary Journal Supplement. 2006;(36):377–382. DOI
Additional clinical guidance
O’Grady SE. How to Manage a Quarter Crack. AAEP Convention Proceedings. 2010. Read the proceedings article
How to Manage White Line Disease. AAEP Annual Convention. 2006. Read the proceedings article
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