Diagnostic nerve blocks are essential tools in equine lameness investigation, but their welfare implications require careful consideration in clinical and competition contexts.
Diagnostic nerve blocks are welfare-positive when used to identify the source of pain so it can be treated. The temporary discomfort of needle placement is outweighed by the diagnostic benefit. However, welfare concerns arise when horses are worked on desensitized limbs - removing pain sensation removes the protective reflex that prevents further injury. The prohibition on competition nerve blocks exists partly for this reason. The welfare principle is clear: nerve blocks should be used to diagnose and ultimately treat pain, not to enable continued performance despite pain.