Page 169 - The Veterinary Care of the Horse

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VetBooks.ir DIAGNOSTIC PROCEDURES AND

IMAGING TECHNIQUES

NERVE BLOCKS

Injection of a small amount of local anaesthetic around a sensory nerve causes the area it

supplies to become numb (in the same way that we may have a nerve block when we visit the
dentist). Nerve blocks are useful for:

• minor surgical procedures

• assisting examination of sensitive areas, e.g. the eye
• localizing or confirming the site of pain contributing to a lameness.

Diagnosis of lameness

When the cause of lameness is not obvious from the clinical examination, nerve blocks may

help the vet to reach a diagnosis. Since a horse cannot tell you exactly where it hurts,
reducing or abolishing the pain with a nerve block can provide useful information as to the

site and cause of the lameness. The horse must be sufficiently lame for a difference in gait to
be readily appreciable following the nerve block.

There are 3 types of nerve block.

1 Perineural The local anaesthetic is injected around a specific nerve. If the block is
successful, all structures supplied by that nerve are desensitized.

2 Intrasynovial The local anaesthetic is injected into a joint space, tendon sheath or bursa
that is thought to be a site of pain.

3 Local infiltration The anaesthetic is injected around or into a region of suspicion, e.g. a

splint, the origin or insertion of a particular ligament, or between the dorsal spinal
processes of the thoracic or lumbar vertebrae

The procedure