Subjective and quantitative scintigraphic assessment of the equine foot and its relationship with foot pain.
Authors: Dyson S J
Journal: Equine veterinary journal
Summary
# Editorial Summary Dyson's 2002 investigation used nuclear scintigraphy to establish baseline parameters for normal equine forefeet and determine whether quantitative image analysis could reliably identify the source of foot pain in lame horses. Fifteen sound Grand Prix showjumpers underwent dorsal, lateral and solar phase imaging, with results compared against three separate populations: 53 horses with primary foot pain, 21 with concurrent foot pain and other lameness, and 49 with non-foot-related lameness. Quantitative assessment of radiopharmaceutical uptake in regions of interest around the navicular bone, DDFT insertion, and distal phalanx periphery revealed that 97% of normal feet showed less than 10% variance between these sites—establishing a reliable normal reference—whilst horses with foot pain demonstrated significantly elevated uptake at the navicular bone region, with good correlation between positive scintigraphic findings and diagnostic analgesia response. However, the DDFT insertion region generated substantial false-positive results, particularly in horses with low heel conformation, although lateral pool phase images proved more diagnostically sensitive for genuine DDFT pathology. For practitioners, this work demonstrates that quantitative scintigraphy combined with regional analgesia blocks offers a useful diagnostic framework for localising foot pain, but interpretation requires caution: navicular bone uptake changes correlate well with clinical findings, whilst DDFT insertion changes must be interpreted conservatively and contextualised against conformation and clinical response to treatment.
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Practical Takeaways
- •Quantitative scintigraphic assessment combined with local analgesia blocks can help pinpoint the source of foot pain in lame horses, but should not be interpreted in isolation—correlation with clinical response is essential
- •Be cautious interpreting DDFT insertion region findings as these frequently produce false positives, particularly in horses with low heel conformation; lateral pool phase imaging is more reliable for DDFT pathology
- •Normal navicular bone uptake should show <10% variance compared to peripheral distal phalanx regions; significant increases suggest navicular pain even without radiological changes
Key Findings
- •97% of clinically normal showjumpers had <10% variance in radiopharmaceutical uptake between navicular bone and peripheral distal phalanx regions, supporting this as a normal reference threshold
- •Horses with primary foot pain showed significantly increased radiopharmaceutical uptake in the navicular bone region compared to normal horses
- •High incidence of false positive results occurred with DDFT insertion region assessment, though lateral pool phase images were more sensitive for identifying potential DDFT lesions
- •Good correlation existed between positive response to intra-articular distal interphalangeal joint and intrathecal navicular bursa analgesia and increased navicular bone uptake on scintigraphy in horses with primary foot pain