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PALMAR foot pain represents an important condition in horses, frequently requiring a broad therapeutic approach, as summarised in a paper by Manfredi and others (2012) on p 643 of this issue of Veterinary Record . Management options range from supportive treatments, in the form of corrective trimming and remedial shoeing, to systemic and local administration of anti-inflammatories, tiludronate, extracorporeal shock wave therapy or, in the most refractory cases, palmar digital neurectomies ( Rijkenhuizen 2006 ). The key to successful long-term management is knowledge of the exact nature of the condition; palmar foot pain is a clinical sign and not a diagnosis. Often defined by the response of the palmar digital nerves (PDN) to analgesia, many different conditions may fall into this category such that this blocking pattern would more aptly be regarded as an indicator of foot pain instead (Schumacher and others 2004, Dyson and others 2005, Murray and others 2006). To name only a few conditions, horses with lameness due to solar bruises, osteoarthritis/synovitis of the distal interphalangeal (DIP) joint, deep digital flexor (DDF) tendinopathy, navicular bone disease or navicular bursitis typically improve greatly when this nerve block is applied, while a partial response might be achieved in horses with collateral ligament desmitis of the DIP joint and more extensive DDF tendon injuries. Advanced diagnostics (with the gold standard being MRI) are certainly necessary to accurately identify the structures involved (Dyson and others 2005, Murray and others 2006, Sampson and others 2009) but local analgesic techniques, such as DIP joint and navicular bursa analgesia, help further localise the pain and precisely implicate the palmar foot as the source of lameness (Schumacher and others 2004). The importance of hoof testers can also not be underestimated; while the use of hoof testers does not provide conclusive evidence for navicular pain, it allows exclusion of potential differential diagnoses.
Considering the technical difficulty of injecting the navicular bursa in primary veterinary care, one might shy away from injecting this structure. Given this latest report (Manfredi and others 2012), it could be further argued that injecting the navicular bursa for diagnostic and subsequent therapeutic purposes has become obsolete, since medication of the only other structure, the DIP joint, will also result in bursal concentrations deemed therapeutic. While Manfredi and...