Dissimilar feet: associated lameness and remedial solutions
Nine years after he first treated a lame Appaloosa mare with mismatched feet, Andrew Poynton was called in again to repeat the remedial farriery that had previously restored her to soundness. In this case report, he describes the approach he used, which included the application of thermoplastic Imprint shoes.
Many horses have less-than-ideal hoof/limb conformation yet perform well for years with little or no attention paid to these discrepancies. This is not a reason to justify this approach as it could be argued that performance might have been better, and longevity of athletic function prolonged, if an effort had been made to correct the conformational deficiencies. The Appaloosa mare in this case study to some degree bears this view out.
Materials and equipment required
- Imprint Hoof Repair (lowtemperature thermoplastic @65 shore D)
- Imprint Ultrafast Adhesive (fast-curing, moisture-tolerant methyl methacrylate)
- Imprint Sport Shoes (composite, synthetic, shockabsorbing, mould-on shoes)
- Imprint Shoe Freezer (refrigerant aerosol)
- Surgical spirit
- Keratex Hoof Putty (medicated wax)
- Pin nails
- Modified 10 mm twist drill bit
- Cordless drill
- Regular farrier’s tools (rasp, nippers and knives)
- Small butane torch
When presented to me in 2021, the mare was 24 years old, with dissimilar feet that had caused her poblems over time (Fig 1). I had first treated her in 2012, when she presented with broken, poor-quality hooves.
She was 3/10 lame on her left fore (LF), which was a club foot and had led to a broken-forward hoof-pastern axis (HPA) in the left forelimb. The sole was prominent (Fig 2) and the dorsal hoof wall deviated, with laminal stretching across the toe. Heel growth was accelerated compared to the toe. The foot was tight, approximately 10 mm narrower than the right. Growth in the medial aspect was stunted in comparison to the lateral hoof wall and so the mediolateral balance was also poor. Shoe wear was heavy in the lateral toe quarter.
In contrast, the right fore (RF) (1/10 lame) had a brokenback HPA, a flat, thin sole and a prominent, fleshy frog. The heels were close to non-existent. The white line had lesions in the heel quarters.
Although the forelimbs will be the focus of this article, as horses have four feet, it is relevant to briefly describe the mare’s hindlimbs. The issues were similar to the RF but of lesser magnitude and it was possible to maintain soundness in the hindlimbs by careful conventional shoeing.
Approach to treatment
The method of treatment described here is the one I used when I first worked on the mare back in 2012. This led to soundness and then conventional steel shoeing (7/8 x 3/8 concave). An initial total of five shoeings were carried out, of which four were funded by insurance. The mare then returned to her regular farrier until early 2021 when, due to the recurring issues, it was deemed sensible to revert to the remedial farriery treatment even without insurance funding.
Farriers and vets frequently want to discuss what style of shoe and pads should be applied to a patient to procure a sound horse. While this is right and proper, before any shoes and pads are even considered, think back a step – what if the hoof is deformed, cracked, asymmetrical or depleted in some way? The old adage, ‘No foot, no horse’, is a true but negative statement. Try turning it on its head and beginning
with the solution – ‘Optimise hoof structure and function: give the horse the hoof it wants’ – and you’ll be well on the way to reinstating soundness before any shoe or pads are applied. The trim, therefore, is all-important.
Because the LF was the most problematic, this was the foot to start with. If this limb/foot is made more comfortable then the patient will be more relaxed and amenable when asked to bear weight on it for some time. When treating a lame horse’s feet, it is often my preference to adopt this mode of working, leaving the contralateral foot shod or padded while working on the first foot. (The preferred stance of the horse can reveal more valuable information, which is not discussed here.)
The foot was filed clean and some keying points (Fig 3) were made into the lower hoof wall using a 10 mm diameter drill bit with a depth gauge. Adhesive was applied to the lower hoof wall from heel to heel and then some heated Imprint Hoof Repair was modelled to the hoof, reinstating a complete hoof (see www.imprintshoes.com/resources/procedures/ hoof-reconstruction/ for more guidance). This was allowed to cool and harden while weight bearing. Hoof balance on all planes was addressed at this stage and corrected using the hoof repair material to compensate for the discrepancies. This simplifies the next stage – shoe fitting – and means a balanced, sweet shoe can be fitted.
Once the patient had been observed moving, it was possible to see the range of movement afforded to each limb. It is important to remember that walking the horse on a bare, prominent and painful sole will likely give a false representation of the normal range of movement – only when the sole is protected or local anaesthesia is used can a fair assessment be made.
At the first shoeing treatment the heels were the only part on the solar plane that needed trimming; the horn was broken through the nailing area and at the toe there was little horn to sit a shoe on. In time the nailing damage grew out, while the deviated dorsal wall improved more slowly.
Once the adhesive was hardened (about five minutes), an Imprint Sport Shoe, oval in shape and of the size of the hoof was fitted (see www.imprintshoes.com/resources/fitting-instructions/sport-shoe-fitting/), but with a twist. As the lower hoof wall was now plastic and securely attached to the hoof, the surface could be reheated to above 65°C using a butane torch to make it sticky so that it would then weld perfectly with the rim of the Imprint Sport Shoe. The rim was then rapidly cooled using an aerosol refrigerant, making the hoof and shoe one entity, strong, light and flexible (Fig 4). The frog plate on the shoe maintained frog support, similar to the unshod hoof but with more sole protection. Care was taken to keep seating clearance around the sole at the toe.
The result was an intact foot protected by a lightweight, elastic and shock-absorbing shoe, the shoe functioning more like the hoof. The HPA was improved, although it was still steeper than the RF and the mediolateral balance was corrected via the hoof build. It is worth noting that attaining phalangeal axial alignment is the primary aim of this process and if there is dorsal hoof wall deviation, then the HPA will appear correct before phalangeal alignment is achieved unless the hoof wall has been rasped into line with the face of the third phalanx. Any internal bruising and soft tissue damage will take time to heal. In this case, and in the majority of cases, this approach often delivers pain relief that is visible in the patient’s demeanour and freer gait. Ideally, once shod, the patient should stand with a vertical limb and appear generally relaxed; this was achieved with this case.
Just to recap, the mare was 1/10 lame on the RF, which had a broken-back HPA, a flat, thin sole and a prominent, fleshy frog (Fig 5). The heels were close to non-existent. The white line had lesions in the heel quarters. This is not an uncommon scenario, so having an effective method of treatment available is all to the good.
Standard trimming of the hoof and excess horn at the toe was carried out (Fig 6), keeping the wall straight and then bevelling it back to the white line across the toe. The lesions in the white line were pared clean (Fig 7).
Drilled keying points were added on the lower hoof wall (Fig 8). A quick spray of surgical spirit was applied to the hoof and allowed to evaporate, otherwise it will dilute and slow adhesive cure. As the saying goes, ‘A picture is worth a thousand words’, and Figs 9–14 illustrate this well. Keratex putty was applied to the lesions (Fig 9), forming a clean, soft layer where adhesive was not wanted. Adhesive was then applied to the lower hoof wall and onto the sole, from the toe quarters to the heels.
Some Hoof Repair was immediately sculpted to the hoof, creating a shallow graduation from nothing to approximately 10–12 mm at the heels, being level with the frog, now no longer prominent (Figs 10, 11).
The Hoof Repair lapped up the wall a little in the heel quarters. The inner edge of this build was graded towards the sole, leaving the outer edge slightly proud for weight bearing. This was then rapidly cooled with refrigerant and allowed to stand, by which time the adhesive was well on the way to curing. Some rasping to fine-tune the final shape and graduation was in order before the shoe was fitted (Figs 12, 13).
A shoe a size larger than that for the LF was fitted to this wider and longer hoof, ensuring shoe bearing to the length of the foot (Figs 14, 15). As the balancing and graduation were already complete the shoe was fitted in the normal way via hoof keying and adhesive, as much of the lower hoof wall was still exposed and only the heel quarters had some plastic covering.
The shoe was placed with the toe under the bevelled wall, the point of break over below the point of the third phalanx. At final finishing of the fitting, the shoe rim was filed to blend to the hoof wall. Sole clearance around the toe of the shoe was checked on both feet. (If any adhesive or plastic is found to be filling this area, then a heated metal spatula or similar can be used to create clearance to allow the sole and shoe room to flex.)
With the RF, the broken-back HPA and negative palmar angle of the third phalanx were rectified. The completed procedure gave the visual impression of a much closer pair of feet (Fig 16), although this had not been the main objective. The goal was to reinstate comfort and sound movement (Fig 17). The mare was taken for a walk to loosen up and then trotted in a straight line and turned to the left and right. All looked good!
Following her most recent remedial treatments, the mare continues to do all her rider wishes from her with a spring in her stride. As well as the improved angles and hoof integrity, the removal of steel from the fore feet and replacing with shock-absorbing composite shoes markedly reduced the high-frequency shock of impact on the tarmac road. At 24 years old, her joints welcome a little respite! The mare has now been successfully shod in this manner 12 times in total, five times in 2012 and seven times in 2021.
From a case report which first appeared in the Forge Magazine supplement, Forge Knowledge, March 2022. © Andrew Poynton FWCF