Underestimated in the management of horses, the negative palmar angle is a phenomenon that can cause significant pain in our equine companions.
Often referred to as a 'flat-footed horse,' this issue can have significant repercussions on both long-term locomotor health and the horse's athletic performance.
The negative palmar angle: a source of excessive strain on the deep flexor tendon
A palmar angle is considered negative when the angle between the base of the third phalanx (P3) and the ground dips below zero. This condition places increased tension on the deep flexor tendon. While some horses may tolerate this excessive strain, it often leads to serious injuries, as demonstrated by the clinical example below.
In this horse, P3 exhibits an angle of -0.97 degrees. Ultrasound imaging confirms an injury to the deep flexor tendon at the level of the fetlock joint, which, according to the veterinary team, is attributed to this retroversion of the third phalanx measured using the Metron software.
This case clearly illustrates the impact a negative palmar angle can have on the health of the locomotor system and the risk of severe injuries it can cause. The horse presented with significant lameness.
Farriery management: a factor for improvement or aggravation
Dr. Robrecht Vanhoutte, director of the Orthopedic Centre for Horses Buitenzorg in the Netherlands, is well-acquainted with this issue.
Working closely with farriers to manage the negative palmar angle, he draws from his experience to highlight several common farriery mistakes that exacerbate this condition:
• Using toe clips at the front of the hoof can encourage toe elongation. If the foot is not clipped correctly, to good balance, the toe clip prevents the correct placement of the shoe under the coffin bone, always to far forward. This will, over time, cause heel collaps and elongation of the toe.
• Shortening the branches of the horseshoes contributes to increasing the imbalance of the hoof structure. If the branches are shortened or undersized shoes are used (as often happens), the coffin bone is inadequately supported. This results in excessive toe support, shifting the center of load too far back on the shoe.
• Poor correction through trimming, resulting in long toe hooves.
These mistakes can worsen the negative palmar angle, making the horse vulnerable to injuries, lameness, and poor athletic performance.
© OCH Buitenzorg. Before/after examples of negative palmar angle cases managed by the Buitenzorg Equine Clinic.
Fighting against the negative palmar angle: In search of hoof balance
To combat this issue, Dr. Vanhoutte, in collaboration with the farrier he works with, Jan-Willem Gerritsen, has developed an innovative horseshoe designed to optimize balance and force distribution on the hoof: a hybrid "Banana shoe" combined with wedge sole.
Indeed, one of the key challenges for professionals in managing the negative palmar angle is imperatively bringing back balance in the foot and caring for the back part of the hoof, as evidenced by Jan-Willem, the farrier at the clinic:
«Underdeveloped heels usually result from insufficient bearing surface at the back of the foot. The heels collapse under excessive pressure, causing the bearing surface of the foot to shift too far forward in relation to the coffin bone.
I start by trimming the toe as much as possible, shifting the weight bearing surface forward and decreasing toe support, afterwards I bring the heels as much as possible back to the widest part of the frog starting from the most palmar side of the coffin bone.
By extending the bearing surface in this way, the coffin bone will not tip backward, or will do so only minimally.
I add the curvature to the branches of the shoe to support the frog as much as possible by using a wedge sole. Also, the foot must be filled with the appropriate hardness two-component material, otherwise, the wedge will cause more damage than benefit. The placement of the shoe is also extremely important.»
The hybrid methodology used by Jan-Willem: the advantages for the management of negative palmar angle
Jan-Willem developed this shoe because the use of a Banana-shoe is widely accepted as a good practice to tackle NPA, but in his opinion it is not a function shoe (not suited to use in horses that are ridden).
By combining the flat surface under the toe and COR and adding the curvature of the branches he combines best of both worlds.
By that, Jan-Willem means, the SAPAS (or Banana-shoe),is to unstable during work, the same goes for a normal shoe after trimming only the heels, which is illustrated by the Hoofbeat-readings below.
On the left the reading with a normal shoe, on the right the same horse with the hybrid Triple-B.
Wedge soles are shaped with a gradual incline from the heel to the toe, creating a wedge-like structure.
The primary purpose of wedge soles is to help adjust the angle of the hoof, often to address issues like a negative palmar angle, flat feet, or other structural imbalances.
The key benefits of wedge soles are :
• Improving the hoof angle : Wedge soles can help raise the heel and tilt the coffin bone into a more natural or desired position.
• Reducing pressure on tendons : By redistributing forces and pressure, they can reduce strain on structures like the deep flexor tendon.
• Support for hoof healing : Wedge soles may be used in therapeutic contexts to alleviate pain or discomfort caused by hoof imbalances or injuries.
“Keep in mind that wedge soles are only ‘a bandage’!
They help alleviating the symptoms of a bigger problem. As long as we (veterinarians and farriers) keep looking at the foot only, and keep ignoring the coffin bone, we are fighting windmills! The coffin bone is the foundation of the foot, the leg and the horse.
As long as the coffin bone is not supported correctly by the foot, and the shoeing, the horn capsula will, in time, start reshaping, and most of the time not in a good way!” Robrecht recalls.
The method developed by Dr. Vanhoutte and Jan Willem Gerritsen allows for adjusting the palmar angle to relieve the deep flexor tendon, restore hoof function, hoof form, and comfort.
In parallel, for cases that require it, such as the one presented at the beginning of this article, stem cell treatment may be administered to promote rapid and effective regeneration of injured tendon tissues.
Negative palmar angle, a poorly understood issue?
According to Dr. Robrecht Vanhoutte, the observation is clear: « Our biggest challenge is a lack of knowledge within the profession, both vets and farriers. The biggest challenge is to know which NPA needs fixing and which don’t »
It is alongside his clinic’s farrier, Jan Willem Gerritsen (Gerritsen Orthopedisch Hoefbeslag), that Robrecht studies new, more effective approaches to manage the negative palmar angle. He is convinced that veterinarians and farriers are often not sufficiently informed about the consequences and the available solutions for managing this hoof angle issue. This problem is common, as evidenced by the regular number of horses he receives for this reason at his clinic. This condition is often underestimated in the equine world, while the consequences on the health of the affected horses can be serious.
Example of a case managed by the clinic showing the evolution of the hoof after 6 weeks of shoeing with their new approach.
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