Nerve blocks are a common first line of diagnostics when investigating a lameness or poor performance case. The blocks are used to more accurately locate the region of pain allowing targeted further work-up.
Nerve blocks work by injecting local anaesthetic around the nerves which supply sensation to parts of the limb. The local anaesthetic prevents conduction of impulses along the nerves so that the horse is no longer able to feel the source of pain, therefore improving the lameness. The blocks take between 5-10 minutes to have their effect, then once the block is checked to have worked a re-assessment is performed. The overall aim is to continue blocking until the lameness improves substantially (>50%) or ideally, is abolished altogether.
Local anaesthetics can also be injected into joints, tendon sheaths or other synovial structures further localising the source of pain.
Once the region of interest has been located, we can then use diagnostic imaging such as X-ray, ultrasound or MRI to try and identify what is causing the pain. Once the lesion is identified we can then implement appropriate management or treatment plans specific to the horse.
Nerve blocking isn’t just restricted to the limbs and can be utilised in other procedures such as the examination of eyes, tooth removal, suturing of wounds and to facilitate surgical procedures, just to name a few.