05/11/2025
Negative Plantar Angle (most commonly referenced as โNPAโ) is one of the most frequent hoof-related issue I see when evaluating horses. I see this SO often. Alongside NPA, I usually notice ๐น๐๐บ๐ฏ๐ฎ๐ฟ ๐ฝ๐ฎ๐ถ๐ป (in some instances kissing spine), ๐ฟ๐ฒ๐ฐ๐๐ฟ๐ฟ๐ฒ๐ป๐ ๐ด๐ฎ๐๐๐ฟ๐ถ๐ฐ ๐๐น๐ฐ๐ฒ๐ฟ๐, ๐๐ผ๐ฟ๐ฒ + ๐๐ถ๐ด๐ต๐ ๐ต๐ฎ๐บ๐๐๐ฟ๐ถ๐ป๐ด๐, ๐๐ผ๐ฟ๐ฒ ๐ต๐ผ๐ฐ๐ธ๐, ๐ต๐ถ๐ป๐ฑ ๐ฒ๐ป๐ฑ ๐๐ฒ๐ฎ๐ธ๐ป๐ฒ๐๐ & ๐ฒ๐
๐ฐ๐ฒ๐๐ ๐ฒ๐ณ๐ณ๐๐๐ถ๐ผ๐ป ๐ผ๐ณ ๐๐ต๐ฒ ๐๐๐ถ๐ณ๐น๐ฒ.
As a quick background -
The coffin (P3) bone is located within the hoof capsule below the short pastern (P2) bone. When we trim our horses, the angle of the coffin bone is directly impacted.
When the coffin bone tips upward, the heel shifts down and the toe moves up. This is essentially what is occurring in NPA. Everything shifts backward and down. The heel is negative๐ I cannot emphasize enough how often I see this! On average approximately 8 out of 10 horses I work on are NPA or borderline NPA.
The effect of NPA is a lot like wearing a high heel backwardsโฆ Now your toes are pointing to the sky, while your heel is much lower than your toes.
The solid pink line in the image provides a visual to hypothesize the possible angle of the coffin bone. When drawing this imaginary line, a possible NPA case might reach the upper forearm or above. A lateral x-ray taken by your veterinarian will officially confirm a conclusive diagnosis.
I think itโs really important to take a minute and remember how immensely interconnected the body is through fascia and soft tissue structures. These fascia lines are patterns of spider-web like tissue connecting tissue.
For simplicity, two primary fascial lines are directly connected to the angle of the coffin bone: the dorsal and the ventral lines.
The dorsal line runs from the TMJ along the top line, down the back of the hind leg to the back of the hind foot. This line is represented in the image by the dark dashed line.
The ventral line is the mirror to the dorsal line, running along the underneath of the horse. This is represented by the light blue dashed line.
As one line tightens, the other has to act accordingly to its complimentary line.
If you imagine these lines similar to a rubber band, think about how the tension would change if you pulled one end. In this case, the end would be the bottom of the dorsal line at the heel.
Think back to the backward high heel analogy & try it! Point your toes straight up with your heels planted on the ground. Notice what happens through your hamstrings all the way up to your back and the increased pressure to your knees. You also might have to change your posture to balance.
This is exactly whatโs happening with our horses when their heels are too low, and the coffin bone reaches a negative angle. And again, this is SO common! But, just because itโs common does not mean itโs normal. As this line shortens, thereโs also an increased risk of soft tissue injuries occurring.
That โrubber bandโ pulls down with the heel increasing tension throughout the dorsal line. Now the ventral line has to mirror the behavior of the dorsal line.
Relaxing the tension in these lines by lifting the heel to its appropriate position and restoring an optimal coffin bone angle may resolve the tension and soreness in the back, hamstrings, hocks, stifles, TMJ etc.
I see several horses with the above symptoms who are on a very short injection schedule to control pain of the coffins, hocks, stifles and/or back, possibly even the SI. Of course every case is different; however, a simple fix of addressing hoof angles is sometimes the biggest game changer.
The best thing we can do together is begin training our eye to identify abnormalities in the body. Together we can become the voice for our horses.๐
As always, consult with your veterinarian before making any changes. I am not a veterinarian, therefore I cannot diagnose or make medical claims.
