📝 STANDARD DESCRIPTION:
PUDENDAL (PUDIC) NERVE (S2-S4):
- Runs through pelvic cavity along sacrosciatic ligament.
- Supplies: perineum, scrotum, prepuce, vulva, penis, clitoris.
- BLOCK SITE (Pudic / Pudendal block): Per-rectal — needle inserted via the rectum, palpate the lesser sciatic notch on lateral pelvic wall, deposit anaesthetic there. Used for EXTRUSION OF THE PENIS in bulls (for examination, surgery).
EPIDURAL ANAESTHESIA:
1. Caudal (Low) Epidural:
- Site: between Sacrum-Cy1 OR Cy1-Cy2 (first movable joint felt when wagging tail).
- Small dose (5-10 ml in cow).
- Blocks: tail, anus, vulva, perineum.
- Cow remains STANDING.
- Used for: vaginal/rectal/uterine procedures, prolapse correction.
2. Cranial (High) Epidural:
- Site: same point or L6-S1; LARGE dose (~50-100 ml in cow).
- Blocks: hindlimbs + perineum.
- Animal must be cast (RECUMBENT).
- Used for: major hindlimb surgery, caesarean section.
📚 DETAILED DESCRIPTION:
PUDENDAL (PUDIC) NERVE & EPIDURAL ANAESTHESIA
PUDENDAL NERVE — supplies the perineum and external genitalia:
Origin: Sacral nerves S2-S4.
Course: Runs caudo-ventrally on the medial face of the sacrosciatic ligament inside the pelvis.
Branches & supply:
• Perineal nerves — to skin of perineum and anal area.
• Caudal rectal nerve — to anal sphincter.
• Dorsal nerve of penis (or clitoris) — sensory to penis/clitoris.
• Branches to scrotum, prepuce, vulva, udder.
PUDIC (PUDENDAL) NERVE BLOCK in BULL:
Indication: To extrude (relax) the penis for examination, semen collection, breeding soundness exam, or penile surgery (e.g. preputial prolapse repair).
Technique: With sterile sleeve, the operator inserts a hand into the rectum and palpates the lesser sciatic notch on the lateral pelvic wall. A long needle is then directed through the ischio-rectal fossa onto the nerve at that point and ~20 ml local anaesthetic deposited bilaterally.
Effect: Penis relaxes and protrudes from sheath within 5-10 minutes; lasts ~1 hour.
EPIDURAL ANAESTHESIA — KEY UG TOPIC:
'Epidural' = local anaesthetic placed in the EPIDURAL space (around dura mater of spinal cord, between dura and bony canal). Blocks spinal nerves as they leave the cord.
(A) CAUDAL ('LOW') EPIDURAL:
• Site: Sacro-coccygeal space (S5-Cy1) OR first inter-coccygeal space (Cy1-Cy2). Identify by lifting the tail up & down — first 'pumping' joint felt is the spot.
• Volume: SMALL — 5-10 ml of 2% lidocaine in cow.
• Block: tail, anus, vulva, perineum, caudal vagina.
• Cow remains standing.
• Indications: Repair of prolapsed vagina/uterus/rectum, dystocia manipulation, perineal surgery, embryotomy.
(B) CRANIAL ('HIGH') EPIDURAL:
• Site: SAME injection point (S5-Cy1) but LARGE volume (~80-100 ml in cow, ~10 ml in dog).
• OR direct injection at lumbosacral (L6-S1) space.
• Block: hindlimbs + perineum + lower abdomen.
• Animal becomes recumbent — must be CAST first.
• Indications: Major hindlimb surgery, caesarean section, foot amputation in cattle.
PARAVERTEBRAL block (for flank surgery in cow) — last thoracic + first 2 lumbar spinal nerves blocked at vertebral level. Used for caesarean/rumenotomy via flank approach.
// COMPARATIVE ANALYSIS
| BULL |
Pudic nerve block is the standard way to relax penis for examination/surgery. |
| MARE |
Caudal epidural common for obstetric work; takes 50-100 ml. |
| DOG |
|
CLINICAL RELEVANCE
UG SYLLABUS — Hindlimb/Pelvic Surgical Sites:
• Pudic Block: Per-rectal at lesser sciatic notch — extrudes penis in bull.
• Caudal Epidural: S5-Cy1 small dose — cow stands; for obstetric work.
• Cranial Epidural: S5-Cy1 large dose OR L6-S1 — cow recumbent; for major surgery.
• Patellar Desmotomy: Cut medial patellar ligament for upward fixation of patella in horse.
• Urethrotomy: Open the urethra surgically to remove uroliths (calculi) — usually at sigmoid flexure in male cattle (where stones lodge).
• Castration / Vasectomy: Performed via scrotal/inguinal approach.
