Mechanical nociceptive assessment of the equine hoof after navicular bursa anesthetic infiltration validated by bursography.
Authors: Cota Letícia de Oliveira, Malacarne Bruno Dondoni, Dias Lucas Antunes, Neto Antônio Catunda Pinho, Kneipp Maria Luiza Arruda, Cavalcante Marina Alcântara, Cunha Marina de Souza Luz da, Paz Cahuê Francisco Rosa, Carvalho Armando de Mattos, Faleiros Rafael Resende, Xavier Andressa Batista da Silveira
Journal: PloS one
Summary
# Editorial Summary Determining whether navicular bursa anaesthesia produces true diagnostic specificity remains clinically important, as non-specific analgesia could confound lameness investigations. Researchers infiltrated the navicular bursa of one forelimb with 2% lidocaine and the contralateral forelimb with saline in six clinically sound horses, then measured mechanical nociceptive thresholds across ten hoof sites (dorsal lamellae, sole, coronary band, and heel bulbs) using a pressure dynamometer before and at multiple timepoints post-infiltration. Whilst no statistically significant difference emerged between lidocaine and control treatments across all measured regions, one of the six lidocaine-treated hooves exhibited complete analgesia (unresponsive to 6 kg pressure) in the dorsal lamellae between 30 and 60 minutes post-injection. These findings suggest that although navicular bursa infiltration is generally specific in clinically normal horses, variable diffusion patterns may occasionally result in unintended analgesic spread—a consideration when interpreting diagnostic blocks in clinical practice, particularly if a horse demonstrates unexpected pain relief patterns. Practitioners should recognise that whilst the technique is usually reliable, occasional anecdotal non-specificity could occur in individual animals, warranting cautious interpretation alongside other diagnostic findings.
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Practical Takeaways
- •Navicular bursa anesthesia may have inconsistent diagnostic and analgesic specificity—some horses show non-specific spreading to dorsal lamellae while others show none, limiting its reliability as a sole diagnostic test.
- •Use navicular bursa blocks as part of a multi-step lameness workup rather than in isolation; combine with other regional anesthesia (e.g., palmar digital nerve blocks) and imaging for clearer diagnosis.
- •Be aware that positive response to navicular bursa anesthesia may not guarantee pathology is confined to the bursa itself; clinical response should always be interpreted alongside radiographic and ultrasonographic findings.
Key Findings
- •Navicular bursa lidocaine infiltration did not produce statistically significant increases in mechanical nociceptive threshold across hoof regions (P>0.05) in clinically healthy horses.
- •One of six hooves (16.7%) showed complete analgesia in dorsal lamellae (maximum 6 kg force) between 30–60 minutes post-infiltration, indicating variable technique specificity.
- •No statistical difference was detected between lidocaine and control (lactated Ringer's) infiltrations in any of the 10 hoof evaluation points.
- •Radiographic bursography confirmed accurate navicular bursa needle placement and absence of NB-DIP joint communication in all horses.