Effect of heel elevation on breakover phase in horses with laminitis

Abstract

Background In a laminitic horse, the maximal loading of the toe region occurs during the breakover phase. To date, no kinetic data demonstrates the effect of supportive orthopaedic therapy in horses with laminitis on breakover phase. Thus, the purpose of this study was to examine the effect of heel elevation on the breakover phase. Eight horses with acute laminitis treated medically as well as with application of a hoof cast with heel wedge (HCHW) were included in this study. Immediately following cessation of clinical signs of acute laminitis, two measurements using the Hoof™ System were taken: the first with HCHW and the second immediately following removal of the HCHW, i.e. in barefoot condition (BFC). The hoof print was divided into three regions: toe, middle hoof, and heel. Kinetic parameters included vertical force (VF), stance duration, contact area (CA) for all hoof regions during stance phase, duration of breakover, VF in the toe region at onset of breakover and location of centre of force. Results The VF and CA were higher in the heel region (63 and 61%, respectively) and decreased significantly after removal of the HCHW (43 and 28% after removal, respectively). The breakover phase in horses with HCHW lasted 2% of stance phase and was significantly shorter than that in BFC, which lasted 6% of stance phase. The VF at onset of breakover for the toe region in horses with HCHW was significantly lower than that in BFC. The centre of the force was located at the heel region in all horses with the HCHW, and at the middle the hoof region in BFC. Conclusions Heel elevation in horses with laminitis as examined on a concrete surface significantly shortens breakover phase and decreases the vertical force in the toe region during breakover. HCHW provides adequate support to the palmar hoof structures by increasing the contact area in the heel region and incorporating the palmar part of frog and sole into weight bearing, thus decreasing the stress on the lamellae. Hoof cast with heel elevation could be a beneficial orthopaedic supportive therapy for horses suffering from acute laminitis.

Bilateral Change in Vertical Hoof Force Distribution in Horses with Unilateral Forelimb Lameness before and after Successful Diagnostic Anaesthesia

“…Our final hypothesis stating that the maximum effect of diagnostic anaesthesia occurs during midstance has to be rejected, as we observed the maximum increase in vertical force on the anaesthetised limb during breakover. This result emphasises the meaning of this phase for equine locomotion and compensation mechanisms of painful processes in the limb [ 12 , 20 , 34 ] so that the loss of sensory feedback after diagnostic anaesthesia [ 35 ] might become more obvious during this part of the stance phase.…”

“…In a former study, it was reported that the Hoof™ System is not reliable compared to a force platform when being fixed with an equine hoof boot [ 22 ]. The reliability of mounting the sensor foils with adhesive tape was not evaluated in the current or former studies [ 18 , 19 , 21 , 34 ], which may have had an influence on the results. Another study could show reliability within but not between sessions when the sensor foils were attached with a glue-on shoe [ 38 ].…”