Field Trials with Twin™ Shoes

Summary

Theory: 5 factors contribute to Healthy Hooves, (1) Hoof Mechanism, (2) Blood Circulation, (3) Shock Absorption, (4) Biomechanics and (5) Hoof Growth, Quality and Shape.

​Research: (University of Ghent, Belgium): Twin™ Shoes allow heel expansion as in barefoot (-> improved circulation and shock absorption) and as such are beneficial for the maintenance of soundness and prevention of injury in horses.

Field Trials: detailed follow-up of 31 horses in California shod with Twin™ Shoes since June 2020 with detailed measurements and analyses focusing on Biomechanics and Hoof Growth, Quality and Shape.

Findings: we found that Twin™ Shoes:

  • ​allow for increased hoof growth.
  • result in more balanced/symmetrical hooves.
  • reduce and eliminate flares.
  • improve the Frog Ratio
  • improve the body size to hoof ratio (by increasing the coronet band circumference while shod & in training!).
  • result in a more stable hoof capsule/coffin bone position between shoeing intervals.
  • show balanced shoe wear indicating more balanced landing, loading and breakover patterns.
  • have significantly improved lameness in horses with front pastern osteoarthritis.

Remark: There are some subtle differences in applying Twin™ Shoes versus traditional shoes, during the tests we found that these differences are essential for a good stability and functioning of the Twin™ Shoes.

Conclusion: Twin™ Shoes have a positive effect on the 5 factors contributing to Healthy Hooves and as such are Health Enhancing (Therapeutic and Preventive), setting up the horse for optimal performance.

Analyses & Findings

Biomechanics:

  • Coronet Band Circumference & Body Weight to Hoof area
  • Dorsal Hoof Wall Angle
  • Palmar Angle
  • Toe Length & Support
  • Shoe Wear
  • Lameness
 Hoof Growth, Quality & Shape:

  • Frog Ratio
  • Hoof Growth
  • Hoof Quality, Shape & Balance:
    • Horn Lammellar Zone
    • Hoof Wall Deviation

Coronet Band Circumference and Body Weight to Hoof Area

We observed a coronet band circumference (proximal hoof circumference) increase in all horses and all feet shod with Twin™ Shoes contrary to the typical effect of traditional shoeing where the Coronet Band Circumference reduces. All horses were in training/working. The coronet band circumference reaches a peak (maximum average increase of 3.5% or 12.8 mm) around 6-7 months after which the coronet band circumference stabilizes.

This is the only equine study so far that provides a shoeing/trimming method to reverse a decrease in coronet band circumference over time that is seen in horses due to traditional shoeing and/or training. With Twin™ Shoes, we were able to improve the body size to hoof area below its critical upper limit of 78 lb/in2 (5,5 kg/cm2) and as such reduce the risk of unsoundness in the future or mitigate current unsoundness issues. Body size to hoof ratio decreases over time to reach a stable plateau around 6-7 months.

Dorsal Hoof Wall Angle (DHWA)

We observed a clear trend in the DHWA of horses shod consistently with Twin™ Shoes: The DHWA of the feet that are within the normal range (50°-55°) stay within the normal range. The DHWA of the steeper feet (high hoof angle >55°) seems to reduce back into the normal (50°-55°) range. In feet with a low DHWA (<52°), the DHWA increases into the normal range.

The change in Dorsal Hoof Wall Angle within the shoeing cycle is minimized by more equal wear of toe and heel. The average decrease in Dorsal Hoof Wall Angle within a cycle with Twin™ Shoes is only 0.43° per 2 weeks which is significantly lower than with traditionally shod horses (with one piece/closed shoes) where the average decrease is 0.79° per 2 weeks.

Palmar Angle

We observed a clear trend (similar to the DHWA) in the Palmar Angle of horses shod consistently with Twin™ Shoes: The Palmar Angle of the feet that are within the normal range (3-5 degrees) stay within the normal range. The Palmar Angle of the steeper feet (>5 degrees) seems to slowly reduce towards normal over time. The Palmar Angle of the lower feet (<3 or <2 degrees) increases into normal range (3-5 degrees) within 6-7 months.

The change in Palmar Angle within the shoeing cycle is minimized by more equal wear of toe and heel. The average decrease in Palmar Angle within a cycle with Twin™ Shoes is only 0.15 per 2 weeks which is significantly lower than with traditionally shod horses (with one piece/closed shoes) where the average decrease is 0.40 per 2 weeks.

When we stay within a 6-week shoeing interval we are able to maintain our palmar angle during the shoeing cycle. As the position of the internal structure (rather than the DHWA) is the most important factor in determining the load on the internal structures, this is a very important finding which makes the Twin™ Shoe stand apart from traditional (closed toe) shoes.

Toe Length and Support

We could see a slow reduction of toe length with Twin™ Shoes over time with a stabilization around 7 months into the clinical trials. Use of toe clips is not affecting the toe length in a negative way. Less toe length means less lever arm and as such less stress on the caudal structures of the foot.

​We notice an improvement in the Toe Support Ratio to the more ideal 60:40 ratio within 7 months. Improvement in toe/support % correlates with a shorter toe and better heel structure and as such reduces the stresses on the internal structures in the back of the foot.

Shoe Wear

We could observe a more balanced wear, as well as landing, loading and breakover patterns with a Twin™ Shoe (the wear from breakover is more pronounced with traditional shoes and the wear into the heels is much deeper due to the excessive friction of the hoof on the shoe at the level of the heels). A Twin™ Shoe wears more evenly across the entire shoe surface compared to a traditional shoe (which wears more at the heel).

Lameness

Lameness is a major health problem in horses, with up to 60% of the lameness estimated being related to osteoarthritis.

Currently, we are following 5 cases with pastern OA:

  • All severe cases unresponsive to medical treatment
  • 3/5 have significantly improved. None got worse
  • Improvement most likely related to improved biomechanics on the turns reducing stress on the joints

We are following one horse with collateral ligament foot lameness for which we have a seen significant short and long-term reduction in lameness from grade 3/5 RF to grade 1-2/5 RF with just the change in shoeing (from traditional shoes to Twin™ Shoes)!

We are following one horse with moderate-severe bilateral suspensory disease for which we have seen a significant improvement in RH lameness from grade 3/5 to mild RH irregularity after a combination treatment of PRP/Pro-stride and Twin™ Shoes. Positive response still present after 7 months and ongoing.

Frog Ratio

We noticed a clear improvement in frog shape (wider, stronger) and opening of the heels. If no underlying health or lameness issues, this response is initially rapid (within 1-2 shoeing cycles) followed by a continuous gradual improvement.

9/30 feet (30%) had a frog ratio ≤ 50%. Within one shoeing interval (6 weeks) the frog ratio increased above the critical minimum limit of 50% and continued to improve more slowly over time towards the ideal ratio (67%).

Hoof Growth

Hoof growth in horses with Twin™ Shoes was increased with 11.6% on average during the first year compared to traditional shoes.

​Hoof growth in horses with Twin™ Shoes seems to have a continuous positive trend year over year.

​Increase in hoof growth rate is likely secondary to increased circulation/perfusion of the hoof and increased mechanical stimulation as the Twin™ Shoe allows heel movement to take place. The continuous long-term positive trend in hoof growth rate can best be explained by positive hoof adaptations to mechanical stimulation (improvement of the hoof mechanism by a better quality hoof) allowed by the Twin™ Shoe.

Hoof Quality, Shape and Balance

Horn Lamellar Zone

With Twin™ Shoes, we see a slow progressive increase in the proximal HL zone, which would indicate a stronger dorsal hoof wall. In horses with thin hoof walls (<16mm) we see a slow progressive increase in hoof wall thickness into the normal range (16-18mm).

Hoof Wall Deviation

The Twin™ Shoe reduces Hoof Wall deviations and does not create (dorsal nor medial nor lateral) hoof wall flares.

Horses which started with Dorsal Hoof Wall flares slowly improved towards below-flare level. Horses which started with Medial or Lateral Hoof Wall flares saw a significant deviation reduction. We observed a slight increase in Dorsal, Medial and Lateral Hoof Wall Deviation during a brief transition period (during first 3 shoeing cycles) when healthier hoof wall is growing in and old unhealthy hoof wall is growing out.