What About The Hinds? - Shoeing the Powerhouse
Updated: Sep 25, 2019
Farriery care can often be guilty of being fore limb focused, most of the research on horses’ feet has been fore limb dominant, there are set parameters for the ideal fore hoof conformation but not hinds and the majority of diagrammatical writing uses the fore hoof for illustration purposes. The rationale for this is usually put down to the fact that the fore limbs carry 60% of the horses weight, other factors may be that lameness is more easily recognised in the fore limbs with studies showing that the observer agreement on lameness even from experienced vets vastly reduces when assessing hind limbs. I have certainly been guilty in the past of sayings such as “lets sort out the fronts, the hinds will sort themselves.” And seeing hind feet like these (Fig1) while the owner insists it only needs fronts on!
Fig 1. bare foot hind showing imbalances and possible indications of higher pathologies.
Meanwhile the equine performance world is experiencing more and more hind limb and spinal pathologies, Sacro-Illiac disorders, kissing spines and proximal suspensory desmopathy/desmitis being prevalent, so should we be paying much more attention to how we are shoeing (or not) the hinds!? We must remember that the hinds have a different job to do and therefore work differently, for instance the hind limbs are “picked up” my muscular effort compared to the fronts which breakover, the hinds need toe to drive off as they are the power house, responsible for providing propulsion and even being responsible in some cases for compensating for fore limb disorders (see my article on high-low hoof conformation) and are therefore vitally important in longevity of working careers and maybe have even more effect on the musculoskeletal system than the fronts when considering their direct bony attachment to the axial skeleton compared to the muscular attachment of the fore limbs.
Dr Stephen O’Grady presented on applying farriery principles to hind feet (https://www.facebook.com/farriers/videos/1467883573375546/) where he spoke about the prevalence of low heel “bull nosed” hinds, but what was interesting to the author was the radiographs used to represent good hind hoof conformation (Fig 2).
Fig2. Expressing O’Grady (2019), an ideal front radiograph showing a straight phalangeal alignment and the “common” conformation in hind radiographs showing a distally plantarly displaced middle phalanx. Note that the angle of the distal phalanx is not dissimilar. Radiographs courtesy of Progressive Equine.
O’Grady found that in the majority of hind radiographs the middle phalanx presented as mildly displaced distally and plantarly, although this is not a peer-reviewed study it perhaps points at the ideal hind conformation being different from the fore, many farriers not armed with this information may be forgiven for thinking these hinds presented as having a broken back phalangeal alignment as it would be described as that would it of been a fore foot, however you can see that the angle of the distal phalanx is not dissimilar to the fore (Fig.2). ). Having said that common must not be confused with ideal and farriers should be careful to change practice on this evidence. O’Grady did highlight however that a negative plantar angle (NPA) was abnormal and needed to be addressed. Dyson (2007) and Mannsman et al (2010) amongst other studies have linked the “prevalent” low heel hind with higher pathologies and then expressed the remedial effect farriery can have, Mannsman et al (2010) linked it with gluteal pain and highlighted the stance adopted by the horses with the conformation which can be seen in both of the case studies further on in this article. Mannsman described these hooves as “long toed” however often long toes are actually a case of low heels as trigonometry dictates that reduction of the angle of the hypotenuse increases the base length, conversely this same formula can be used to work out the extra length needed to compensate for the elevation when graduating in any form in addressing a NPA, HL / cosine AE = LH the horizontal length you want on the flat divided by the cosine of the angle of elevation gives you the new length of the hypotenuse you need, ill use this in an example in one of the case studies.
O’Grady also discussed the differences in the solar proportions attributed to the different role it plays (Fig.3)
Fig.3 The shape of the hind is designed to provide traction and enable efficient propulsion primarily. The widest point of the foot is located more palmerly in the hind.
So we have established that the parameters for ideal fore and hind limb hoof conformations may not be the same, therefore comparing the hinds to the fronts to establish what is correct is probably not advisable especially considering their different roles in locomotion, however when it comes to dorso-palmer balance a NPA does predispose to higher pathologies as it would in the front and shoeing to address this conformation will have a remedial effect. An established external reference marker for assessing hind hoof conformation is the coronet trajectory which should fall around the knee of the fore limb, hinds with NPA will often have a trajectory much higher than this, again an example will be shown in one of the following case studies.
Fig.4 Typical hoof conformation and stance of NPA, low crushed heels and a stood under stance. This horse had SI pathology and kissing spine, as well as proximal suspensory desmitis, expressing the link mentioned by the above studies but which caused which?
Fig.5 radiography clearly showed a NPA
Fig.6 Duo ellipse hind (Advocated and principles of which taught to the author by Mark Caldwell and available from the shoeing lab.) fitted to provide elevation while channelling the point of force trajectory away from the compromised structures.
Fig.7 The external geometrics looked improved.
Fig.8 HL / cosine AE = LH
Fig.9 The change in stance from the shoeing application.
This case exhibited the stance highlighted in Mannsman et al (2010), the horse preferred to stand far under himself to relieve the higher pathologies, but in doing so he was crushing his heels, the author sought veterinary intervention to establish related pathologies and the horse was treated for SI and kissing spine at the same time as the shoeing was changed, as its important to appreciate that there is still a chicken and egg situation when it comes to whether the higher pathologies cause the conformation or vice versa, (read my article on disordered physiology and hoof morphology). Fig.9 clearly shows the change in stance achieved by addressing the geometric proportions of the hoof, the author hopes to see continued improvement as we have in Fig.11-13, the second shoeing, in the coronet trajectory over time (shown with the yellow line).
Fig.10 Shows the radiographic improvement of the pedal angle from -9 degrees to neutral after the first shoeing, the second shoeing will look to further improve this.