18/12/2025
🙌 What is a broken back hoof pastern axis (BBHPA)?🙌
🌟Identifying a healthy hoof series Christmas 2025 special - with Beccy Smith Equine🌟
Bite size news you can use! Last week I defined “long toe”, “under run heel” and “low (and high) toe” and illustrated how to identify it using a quality lateral photo and HoofmApp parameters, which are considered important objective assessment tools in a evidence based, welfare focused integrative approach.
This is the same hoof, and I have used a radiograph taken several months earlier, a lateral hoof photo pre trim and a illustration depicting healthy/ideal hoof morphology and physiological welfare parameters to highlight how to identify a broken back hoof pastern axis (BBHPA) from lateral photos of horses standing as close to neutral as possible, and what this means in terms of lack of ideal phalangeal alignment on the same view of a radiograph.
In a healthy/ideal non-distorted hoof, where there is evidence of ideal welfare parameters associated with soundness, a straight or ideal hoof pastern axis (HPA) is identified as the same dorsal hoof wall angle as pastern angle, from a lateral view, with the horse standing in neutral posture.
On a radiograph this can be confirmed as phalangeal alignment, identified as similar or same angle between P1 and P2 and the same angle P2 and P3. There will also be healthy palmar(PA - front hoof) or plantar (PLA - hind hoof) P3 angle (the angle at which the underside of P3 sits in relation to the level ground) of typically between 5 and 8 degrees (with some exceptions outside this range).
There is also an association between healthy/ideal hoof morphology and posture, with horses more able to stand in neutral posture when the hoof parameter lie with healthy ranges.
Typically, HPA is assessed from the angle of the pastern - identified from the centre of rotation of the fetlock joint or line bisecting the middle of the pastern to the centre of rotation of the coffin joint, (approximated by the centre of the green circle on the HoofmApp coronet line). The dorsal hoof wall is the angle of the top third of the hoof wall from the coronet or hair line. A line of the same angle is then placed at the centre of rotation of the coffin joint to help identify disparity in orientation and angles.
In this example (bottom left) the pastern is 52 degrees and the wall angle is 45.
This is objective evidence of a broken back hoof pastern axis or BBHPA.
In the radiographic of the same hoof several months earlier, there is evidence of disparity of angles between the phalanges (P1 = 72, P2 = 62 and P3 (dorsal wall angle) = 44. The dorsal wall angle is very similar to the photo bottom left, so we can also assume (as this isnt a foundered laminitic hoof) the palmar P3 angle is also very similar.
This is objective evidence of phalangeal misalignment and low palmar (PA) P3 angle, which typically accompany BBHPA.
BBHPA/phalangeal misalignment with low PA or PLA is significant because it is associated with evidence of with compensatory pathological posture and greater incidence of injury, lameness and pathology (see the comments for resources). An unhealthy palmar angle is an unbalanced hoof with a loss of ideal equilibrium around the coffin joint. This creates unhealthy load and forces on the hoof, altering ideal circulation, growth, and also biomechanics, wear, posture and development of the whole horse.
Nearly every horse we meet in the UK and during consults and travel abroad has evidence of distorted hooves which include BBHPA and identifiable hoof distortions as previously discussed in posts in this series.
To summarise, a broken back HPA (BBHPA) is identified from external lateral hoof and pastern angles, in horses standing as close to neutral as possible, and where the pastern angle is lower than the hoof angle.
BBHPA can be confirmed on lateral digits radiographs where phalangeal misalignment is identified as disparity between the angle of the phalanges.
The next post in this series will provide examples of a broken forward hoof pastern axis (BFHPA) and how to identify this on lateral photos and radiographs!
Resources and background science in the comments.
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