Page 200 - Adams and Stashak's Lameness in Horses, 7th Edition

166 Chapter 2

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Figure 2.159. Image illustrating the locations to block the tibial
and peroneal nerves. The site for injection of the tibial nerve is
approximately 4 inches (10 cm) above the point of the hock on the
medial aspect of the limb between the Achilles tendon and the deep
digital flexor muscle. The location to block the peroneal nerves is
approximately 4 inches (10 cm) above the point of the hock on the
lateral aspect of the limb in the groove formed by the muscle bellies
of the lateral and long digital extensor muscles.

by either standing on the lateral side of the limb to be
blocked or by reaching across from the opposite limb to
access the medial aspect of the limb. A small amount of
anesthetic placed in the skin and subcutaneous tissues
may minimize the horse’s reaction to the block. A 20‐ to
22‐gauge, 1.5‐inch (3.8‐cm) needle is used to deposit
15–20 mL of anesthetic in several tissue planes in the
fascia that overlies the deep digital flexor muscle.
Blocking the tibial nerve provides anesthesia to the plan­
tar tarsus, metatarsus, distal Achilles tendon, calcaneus,
suspensory ligament, and most of the foot. 9,75
To completely desensitize the hock and limb distal to
the hock, the deep and superficial peroneal (fibular)
nerves must be anesthetized. 48,75 The deep peroneal
nerve lies near the lateral edge of the cranial tibial mus­
cle close to the tibia. The superficial peroneal nerve lies
slightly caudal to the septum of the two extensor mus­
cles and more superficial. The location of injection is
approximately 4 inches (10 cm) above the point of the
hock on the lateral aspect of the limb in the groove
Figure 2.158. (a) Blocking the DBLPN by inserting the needle formed by the muscle bellies of the lateral and long digi­
15 mm distal to the head of the lateral splint bone perpendicular to the tal extensor muscle (Figure 2.159). To block the deep
limb. Some clinicians cradle the limb and pull the tendons medially peroneal nerve, a 1.5‐ to 2‐inch (3.8‐ to 5‐cm), 20‐gauge
(b) to facilitate the injection (see Figure 2.156 for needle location).
needle is inserted in a slightly caudal direction until the
needle contacts the caudal edge of the tibia. Ten to 15 mL
The nerve (6 mm in diameter) can be palpated caudal to of anesthetic is injected on the lateral border of the cra­
the deep flexor muscle by unweighting the limb and nial tibial muscle close to the tibia. The needle is then
grasping firmly cranial to the Achilles tendon with the retracted and another 10–15 mL of local anesthetic is
thumb and forefinger. 3,75 The block may be performed injected more superficially in several planes to be sure