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The effect of bilateral palmar digital nerve analgesia on the compressive force experienced by the navicular bone in horses with navicular disease
Author(s) -
McGUIGAN M. P.,
WILSON A. M.
Publication year - 2001
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.2746/042516401778643363
Subject(s) - navicular bone , heel , medicine , sesamoid bone , lameness , horse , digital nerve , anatomy , surgery , radiography , geology , paleontology
Summary Horses with navicular disease have an increased load on the navicular bone in early stance. This has been suggested to be a response to pain in the heel region. Seven horses with clinical, radiographic and scintigraphic signs of navicular disease underwent forceplate and kinematic analysis before and after desensitisation of the heel region with a bilateral palmar digital nerve block. The compressive force exerted on the navicular bone during stance, and stride kinematics, were determined in each state. After regional analgesia of the palmar digital nerves (PDNB) the compressive force on the navicular bone was lower throughout stance. The mean ± s.d. peak force at the beginning of stance was 7.05 ± 1.10 N/kg before, and 6.46 ± 1.15 N/kg after PDNB (P = 0.01) and at the end of stance the mean peak values were 5.00 ± 2.05 N/kg before, and 4.39 ± 1.65 N/kg after PDNB (P = 0.05). We explained this finding as indicating that the horse responds to heel pain (including pain in the navicular region) by contracting the deep digital flexor muscle to unload the heels. This increases the compressive load on the navicular bone, which may cause remodelling and, in some horses, damage to the overlying flexor cartilage, which is then painful and identified as navicular disease. This mechanism identifies navicular disease as a possible end point for a variety of heel related conditions.