Heel Pain in the Performance Horse
In the past “navicular disease” was the term more commonly used to describe all pain associated with the heel in the performance horse.
Navicular disease is now reserved for proven clinical heel pain with moderate to severe navicular bone remodelling. It is useful to review the anatomy of all the associated soft tissue structures in the heel region to better understand “heel pain”, as often there is no clinical or radiographic bone remodelling at the time of diagnosis.
Early recognition of heel pain in the horse is the most critical factor in successful long term management. Often the horse will have a 18-24 month history of intermittent stumbling/ poor performance/behavioural change and reluctance to work, often linked with the end of the shoeing cycle or immediately after shoeing. This has been called the “prenavicular syndrome” and early recognition of symptoms will ensure permanent damage is not done to the navicular bone and associated soft tissue structures. If heel pain is recognised within the first 12 months there is a better chance of preventing chronic changes and improving longevity of performance.
Poor foot conformation and inadequate mechanical support are the most common predisposing cause of heel pain. Broken back foot pastern axis with or without medial-lateral foot balance are the most common presentations. This conformational fault places constant stress on the heel region especially during the long break-over phase in the long toe low heel horse. Upright pasterns and a contracted heel conformation increase the concussive forces on the navicular bone and associated soft tissues. Irregular shoeing intervals and training schedules will also increase the chance of heel pain for tendon, ligament and joint disease in the performance horse.
DIAGNOSIS of heel pain involves accurate history and a complete examination of the horse’s conformation, action on different surfaces, hoof testing and response to regional anaesthesia (nerve blocks).
Heel pain is usually bilateral, unless there is an acute injury to either the DDFT or bone. Once the source of lameness is confirmed in the heel, X-rays of the foot are used to assess mechanical balance as well as whether there is degeneration of the navicular bone or coffin and pastern joint.
The past decade has seen an increase in ultrasound quality and technical expertise. However, adequate foot preparation is needed for good imaging of the DDFT, navicular bursa and suspensory apparatus of the navicular bone all which can be done in a clinical setting. Advanced diagnostics such as CT and MRI are the gold standard for diagnosis of soft tissue injury in the foot, and these are only available in large referral centres.
The cause of pain in heel pain and navicular disease is linked to strain/inflammation in the supporting ligaments, reduced blood flow and increased hoof and navicular bone pressure, increased pressure/inflammation within the navicular bursa, cartilage erosion, fibre disruption/tear in the DDFT/Impar/ Suspensory ligament of the navicular. Often chronic cases will have solar margin bruising and laminar inflammation secondary to a change in foot placement in an effort to unload the heel. In many cases the heel pain may be just bruising in the corn area and heel bulbs of the foot, with no significant or sinister bone and soft tissue injury. However, accurate assessment and management of foot mechanics will prevent further progression of lameness.
TREATMENT of heel pain ALWAYS involves accurate assessment of foot mechanics and appropriate therapeutic farriery. Once good foot mechanics have been achieved, other treatments may include coffin or navicular bursa medication, shockwave therapy, systemic Tildren and many other medications have been recommended and tried over the last decade. There is no single treatment recommended for all cases as each case has different predisposing factors and no single cause. The environment, facilities and expectation of each owner/trainer also needs consideration when formulating a management plan for each case. There are many ways to manage and shoe the horse with heel/navicular pain, and it is vital to create a good working relationship with both vet and farrier to ensure performance longevity. At the Equine Podiatry & Lameness Centre our goal is to foster good working relationships between client/vet and farrier.