Mechanical nociceptive thresholds of dorsal laminae in horses after local anaesthesia of the palmar digital nerves or dorsal branches of the digital nerve.
Authors: Paz C F R, Magalhães J F, Mendes H M F, Rocha Junior SdS, Belknap J K, Alves G E S, Faleiros R R
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Understanding which nerves transmit pain signals from the equine foot's sensitive structures is fundamental to effective diagnostic analgesia and pain management, yet the precise innervation of the dorsal laminae has remained incompletely characterised. Paz and colleagues used a crossover design in six mares, applying controlled mechanical pressure via dynamometer to various foot structures before and after selective perineural anaesthesia of either the palmar digital nerves (PDNs) or the dorsal branches (DBs) of the digital nerves, comparing anaesthetic and saline control injections. Blocking the PDNs significantly elevated mechanical nociceptive thresholds across the dorsal laminae, sole and heel bulbs (P<0.001), whilst blocking the DBs produced threshold increases only at the coronary band region (P<0.01), demonstrating that PDNs—not DBs—carry the majority of nociceptive signals from the pressure-sensitive dorsal laminae. For practitioners performing diagnostic nerve blocks or managing conditions such as laminitis, these findings confirm that PDN anaesthesia is the critical technique for assessing dorsal lamellar pain, whilst sole and heel sensitivity must also be considered when interpreting PDN block responses in clinical cases.
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Practical Takeaways
- •When diagnosing dorsal laminae pain, blocking the palmar digital nerves distal to the coronary band is more effective than blocking dorsal branches
- •Understanding nerve distribution helps farriers and vets target pain relief more accurately and interpret diagnostic anaesthetic blocks
- •This anatomical knowledge supports more precise diagnostic lameness examinations and may improve treatment planning for foot pain conditions
Key Findings
- •Palmar digital nerve (PDN) anaesthesia increased mechanical nociceptive thresholds in dorsal laminae, sole, and heel bulbs (P<0.001) compared to baseline
- •Dorsal branch (DB) anaesthesia increased thresholds only at the coronary band (P<0.01), not in dorsal laminae
- •PDNs, not dorsal branches, are the primary nerves responsible for pain signal transmission in the dorsal laminae of clinically normal horses
- •Selective nerve blocks can be used to localize the anatomical source of foot pain in horses