Nerve Blocking Horses as Part of a Lameness Exam

 

Nerve blocking particular leg structures is a method veterinarians can use to help locate, or confirm, the location of pain associated with lameness. Veterinarians will inject an analgesic to numb the nerves in the area suspected to be the source of pain. Many chronic hoof and leg ailments present as lameness without enough specific characteristics to determine the location of the pain. In this case your veterinarian may begin by numbing the lowest structure on the leg and work their way up the leg.

The numbing affect is seen about 10 minutes after injecting. The veterinarian will then perform a lameness evaluation. The horse will be asked to jog in a straight line away from them, and then towards them. The horse may also be asked to work on the lounge line while the doctor evaluates gait and transitions.

A horse is considered to have “blocked sound” when lameness is no longer exhibited.

Types of Nerve Blocks

Palmar Digital Nerve Block (Heel Block) – The block targets the back of the foot. It is injected over the palmar digital nerve just under the skin. It blocks the heel bulbs, frog, navicular bone, navicular bursa, the coffin joint, and the phalanx.

Abaxial Sesamoid Nerve Block – The block targets the palmar nerve: includes the medial and lateral palmer and the dorsal branch. The nerve runs along the back of the pastern. It blocks the deep digital flexor tendons in the foot, pastern joint and may numb portions of the fetlock joint.

Palmar Nerve Block, or Low 4-point Block – This block will block the palmar nerves below the communicating branch and also the palmar metacarpal nn. at the level of the distal ends of the splint bones.

 

High Palmar Nerve Block, or High 4-point Block – This block is performed above the communicating branch and blocks the same structures as the low palmar at a higher level. In turn, most of the suspensory ligament is blocked also.

(These are the most common lower limb nerve blocks, there are many more higher up in the limb that can be performed also. If you have questions, call or email our office staff )