Understanding High-Low Syndrome in Horses

Photo Credit: Okanagan School of Natural Hoofcare

Uneven feet, also known as mismatched feet or hoof asymmetry, are a common condition found across horse breeds. Most frequently seen in the front hooves, one foot typically appears more upright with higher heels and a shorter toe, while the other has lower heels, a lower angle, and a longer toe. Whether this condition poses a problem depends on the degree of asymmetry and the horse’s intended use.

The Hoof at Birth

Dr. Simon Curtis, PhD in Equine Physiology and Biomechanics, explains that foals are born with perfectly symmetrical hooves, a state maintained during gestation because the developing foal is suspended in utero and not subjected to external forces. In this weightless environment, there is no pressure to distort or influence the hoof's shape. However, once the foal is born and begins to bear weight, the symmetry begins to change. As the foal stands, walks, grazes, and moves, its hooves are subjected to varying forces and weight distribution. These forces—shaped by the foal's conformation, muscular development, habitual postures, and movement preferences—begin to influence hoof growth and form. Over time, this results in the development of hoof asymmetries, which are a natural consequence of how mechanical stress is applied to each limb and foot as the horse matures.

Common Causes of Mismatched Feet

1. Injury During Development

One well-understood cause is early-life injury. When a developing horse suffers an injury in one leg or foot, they often shift weight to the opposite limb. This leads to:

• The injured foot becoming smaller and more upright due to reduced weight bearing.

• The healthy foot bearing more weight, which crushes the heels and allows the toe to grow forward.

This compensation can cause a lifelong disparity in hoof shape and size.

2. Laterality: The Equine “Handedness”

Much like humans are right- or left-handed, horses show a preference for using one side of their body more than the other—referred to as laterality. As a foal grows:

• They may bear more weight on one leg, causing that side to develop differently.

• This preference leads to changes in muscle tone, bone length, and joint development.

Notably, in a foal’s first year of life, 100% of their bone tissue is replaced—a critical time where laterality can significantly shape hoof asymmetry. In comparison, adult horses only regenerate 10% of bone tissue per year.

3. Grazing Stance Theory

Some experts suggest that grazing habits may influence hoof development:

• Young horses often graze with one foot back and one forward.

• The rear foot in this stance may become more upright over time.

However, this theory is countered by another view, the tendon shortening theory.

4. Tendon Shortening Theory

Opponents of the grazing stance theory argue that some foals may naturally have a shortened muscle-tendon unit in the deep digital flexor tendon of one limb:

• This anatomical difference encourages the horse to place the more upright foot in the rear.

• This behavior might create the illusion that the grazing stance is the cause, when it may actually be a result.

  
  

5. Limb Length Disparity

Another theory posits a more structural reason—limb length difference:

• One limb may be shorter, causing the horse to grow more heel on that side.

• This growth allows the short limb to function more like the longer one, but results in a more upright hoof.

  
  

Biomechanical Implications

Uneven feet can affect the horse’s gait and posture. The asymmetry alters:

• How each hoof absorbs impact.

• The rhythm of footfall and breakover, resulting in a gait that feels “uneven” to the rider or handler.

  
  

Management and Therapeutic Strategies

1. Corrective Trimming and Shoeing

A tailored approach to hoof care is essential. The goal is to gradually balance the hooves without causing discomfort. This may involve:

• Reducing the heel height of the "high" hoof

• Encouraging heel growth on the "low" hoof

• Using pads or wedges to support proper alignment

It's crucial to address each hoof individually, considering the horse's overall conformation and movement patterns.

2. Physical Therapy and Bodywork

Incorporating physiotherapy can help alleviate muscle tension and improve symmetry. Techniques may include:

• Massage therapy

• Stretching exercises

• Chiropractic adjustments

• Targeted strengthening

These interventions aim to correct postural imbalances and enhance overall mobility.

3. Saddle Fit and Rider Influence

An ill-fitting saddle or an unbalanced rider can exacerbate asymmetries. Ensuring proper saddle fit and rider alignment is vital to prevent additional strain on the horse's musculoskeletal system.

Read our article Saddle Fitting: A Beginner's Guide to learn more.

Prognosis and Long-Term Considerations

With early detection and a comprehensive management plan, many horses with high-low syndrome can achieve improved balance and comfort. However, chronic cases may require ongoing intervention to maintain hoof symmetry and prevent secondary complications. Regular monitoring and adjustments to the care regimen are essential to accommodate changes in the horse's condition and workload.

Continue Learning

1. Club Foot in the Adult Horse

• This article explores the condition of clubfoot, characterized by a deformity in the deep digital flexor tendon and its associated structures. It explains how this condition can lead to significant differences in hoof angles and discusses its impact on a horse's gait and comfort.

2. The Deep Digital Flexor Tendon

• Understanding the role of the deep digital flexor tendon is crucial when examining hoof asymmetry. This resource offers insights into the function of this tendon, common injuries associated with it, and its impact on hoof conformation.

3. What is “Breakover”? A Deep Dive

• Breakover refers to the phase in a horse's stride when the heel lifts, and the toe pushes off the ground. This article explores how variations in hoof shape, such as those seen in mismatched feet, can affect breakover and, consequently, a horse's movement and performance.

4. Equine Conformation Certification

• For a comprehensive understanding of how conformation affects hoof structure and function, this certification course offers in-depth knowledge. It covers the evaluation of limb conformation and its impact on gait, soundness, and performance, which is essential when addressing hoof asymmetry.

Frequently Asked Questions (FAQ)

What is high-low syndrome in horses?

High-low syndrome refers to a condition where a horse’s front hooves are noticeably different in shape and angle. One hoof is typically more upright with a steeper angle and higher heel, while the other has a flatter profile, lower heel, and longer toe. It’s a common form of hoof asymmetry and may affect a horse’s movement and balance depending on the severity.

Are asymmetrical hooves in horses normal?

Yes, to a degree. Many horses have mild asymmetries in their hooves due to laterality, grazing stance habits, or uneven weight distribution. While not always problematic, significant mismatches can lead to biomechanical stress, uneven gaits, or long-term soundness issues if left unmanaged.

What causes high-low feet in horses?

Common causes of high-low or mismatched feet include:

• Injury during development (leading to compensatory limb use)

• Laterality (natural side preference, similar to handedness in humans)

• Grazing stance behavior in foals

• Limb length discrepancies

• Tendon shortening, particularly involving the deep digital flexor tendon

These factors can influence how weight and pressure are applied to each hoof, leading to asymmetrical growth.

Is high-low syndrome the same as club foot?

No, they are not the same. While both conditions involve an upright hoof, club foot is typically caused by a contracture of the deep digital flexor tendon, resulting in a steep dorsal hoof wall, often accompanied by lameness. In contrast, high-low syndrome is a comparative mismatch between hooves, and while one may appear clubby, it usually stems from functional or postural habits, not structural tendon deformity.

Can you fix high-low hooves in horses?

You can manage high-low feet through careful farrier work, but they often cannot be completely "fixed." The goal is to:

• Improve balance

• Minimize gait disruption

• Prevent long-term lameness or joint strain

Corrective trimming, therapeutic shoeing, and sometimes bodywork can help rebalance limb loading and support healthier hoof development.

How do you treat high-low syndrome in horses?

Treatment depends on the cause and severity but often includes:

• Regular, balanced farriery

• Therapeutic shoeing to redistribute pressure

• Physical therapy or chiropractic care for associated muscular imbalances

• Veterinary consultation if deeper issues (like tendon involvement or limb length disparity) are suspected

Early diagnosis and consistent hoof care are key to managing this condition effectively.

Can high-low syndrome cause lameness in horses?

Yes, especially in severe cases. Uneven hoof loading can lead to:

• Altered gaits and “off” movement

• Joint and tendon strain

• Back and pelvic misalignment

• Chronic lameness if left unaddressed

Horses with pronounced asymmetry should be regularly evaluated by a knowledgeable farrier and veterinarian.

Are horses born with asymmetrical hooves?

No. According to Dr. Simon Curtis, foals are born with symmetrical hooves, as they are suspended in the womb and not subjected to external forces. Asymmetry develops post-birth as the foal begins to bear weight, move, and interact with its environment. Factors like conformation, movement habits, and limb usage all influence hoof development over time.

Can limb length disparity cause mismatched feet in horses?

Yes. If one limb is slightly shorter, the horse may compensate by growing more heel on that side to balance itself, resulting in one upright hoof. This is one of the leading biomechanical theories explaining hoof asymmetry in adult horses.

Should I be concerned if my horse has uneven front feet?

Mild asymmetry is common and often manageable, but noticeable mismatches—especially those affecting performance, comfort, or soundness—should be assessed by a qualified farrier and veterinarian. Early and proactive management can prevent future complications.

Self-Assessment Quiz: High-Low Syndrome & Asymmetrical Hooves

Multiple Choice Questions

1. What is the most common presentation of high-low syndrome in horses?

A. Hind feet of different sizes

B. Front hooves where both have crushed heels

C. One front hoof is upright with a short toe, the other is lower with a long toe

D. All hooves have identical heel and toe proportions

2. According to Dr. Simon Curtis, why are foals born with symmetrical hooves?

A. Because of selective breeding

B. Because they develop equally under saddle

C. Because they are suspended in utero and experience no external forces

D. Because they walk evenly from birth

3. Which of the following is a proposed cause of hoof asymmetry related to behavior?

A. Tendon damage from shoeing

B. Laterality or preference for one side

C. Exposure to cold temperatures

D. Overfeeding during development

4. Which tendon is most often implicated in club foot and some hoof asymmetries?

A. Superficial digital flexor tendon

B. Suspensory ligament

C. Deep digital flexor tendon

D. Extensor tendon

5. What hoof management technique is recommended for high-low syndrome?

A. Trimming all hooves flat and even

B. Allowing hooves to self-balance in turnout

C. Corrective trimming and shoeing tailored to each hoof

D. Applying the same shoe to all feet regardless of shape

True or False

6. High-low syndrome and club foot are the same condition.

7. Asymmetrical hoof development often begins after birth due to weight-bearing and movement.

8. Limb length disparity can result in one hoof growing more heel than the other.

9. A horse with high-low syndrome will always be lame.

10. Grazing stance theory suggests that hoof shape can be influenced by how a foal stands while eating.

Short Answer

11. Briefly explain the difference between high-low syndrome and club foot.

12. Name two therapeutic strategies besides trimming and shoeing that can help address asymmetrical hoof development.

13. How does laterality influence hoof asymmetry in young horses?

14. Why is the first year of a foal’s life considered critical for hoof development?

15. What are two biomechanical consequences of mismatched feet on a horse’s gait?

Answer Key

Multiple Choice

1. C

2. C

3. B

4. C

5. C

   
   

True or False

6. False

7. True

8. True

9. False

10. True

    
    

Short Answer (Suggested Responses)

11. High-low syndrome is a comparative asymmetry between two front hooves, typically due to functional or behavioral factors. Club foot is a deformity involving a contracted deep digital flexor tendon, often causing a steep, upright hoof and potential lameness.

12. Physical therapy (e.g., massage, stretching), chiropractic adjustments, and saddle fit assessment.

13. Laterality causes a foal to favor one side of the body, which influences how weight is distributed across the hooves and can lead to asymmetrical development.

14. During the first year, 100% of the bone tissue is replaced, making it a crucial time when external forces can strongly influence musculoskeletal and hoof development.

15. Uneven concussion absorption and altered breakover timing, leading to an “off” gait or compensation in movement.