The animal may be standing or in lateral recumbency. (B205.13.w13)

• Locate the lumbosacral junction. (B205.13.w13)
  • The lumbosacral site is 1 to 3 cm caudal to an imaginary line drawn between the cranial borders of the ileum and forms a palpable depression. (J296.42.w1)
  • The lumbosacral junction is easily palpated in thin individuals. (B205.13.w13)
  • In animals which are well muscled or fat it is necessary to use recognition of landmarks:
    • Draw an imaginary line between the cranial borders of the ileum crossing between the spinous processes of the last lumbar vertebrae. (B205.13.w13)
    • The caudal borders of the ileum, where the angle bends, are level with the cranial edge of the sacrum. (B205.13.w13)
    • If the spinous process of the last lumbar vertebra is palpable then the depression caudal to this is the lumbosacral space. (B205.13.w13)
    • The needle will be inserted on the midline halfway between the spinous processes of the seventh lumbar vertebra and the sacrum. (B205.13.w13)
• Clip the area for injection and prepare the skin with surgical scrub. (B205.13.w13, J296.42.w1)
• Using a fine needle, inject 1 to 3 mL of 2% lidocaine subcutaneously (not required if the procedure is carried out in an anaesthetised animal). (B205.13.w13)
• Warm the local anaesthetic solution if the injection is to be made in a conscious animal. (B205.13.w13)
• If the skin is thick, puncture with a large, sharp hypodermic needle. (B205.13.w13)
• Insert a spinal needle over the lumbosacral junction, on the midline, perpendicular to both the curvature of the hindquarters and the sagittal plane of the animal.  (B205.13.w13)
  • This will not necessarily be perpendicular to the floor/table top. (B205.13.w13)
  • A notch on the hub of the spinal needle indicates the direction of the bevel of the needle; use this to ensure that the local anaesthetic solution will be injected cranially. (B205.13.w13)
  • An ordinary hypodermic needle (e.g. 19 gauge, two inch/5cm) can also be used. (J296.42.w1)
• Once through the skin, slowly advance the needle until first the resistance of the interarcuate ligament over the epidural space is felt, then the "pop" as this is penetrated. Immediately stop the needle so that it is in the epidural space and does not advance further to penetrate the spinal cord. (B205.13.w13)
  • If the spinal cord is penetrated in a conscious animal it will jump and the needle may be dislodged from its position. (B205.13.w13)
  • It the needle strikes bone before it is deep enough to reach the epidural space, withdraw the needle until the tip is just under the skin then redirect cranially. If this is still unsuccessful, withdraw again and advance with the needle directed caudally to the original position. (B205.13.w13)
• Once the needle is in position remove the stilette (place on a sterile surface) and attach a 3mL syringe containing 0.5mL air.  (B205.13.w13)
• Withdraw the plunger. If the needle is in the epidural space there should be only a vacuum. (B205.13.w13)
  • Aspiration of blood or cerebrospinal fluid indicates incorrect placement. (B205.13.w13)
  • Aspiration of air indicates the syringe is not tightly attached to the needle. (B205.13.w13)
• Test inject a small amount of air (if no blood or cerebrospinal fluid was aspirated); this should inject easily if the needle is in the epidural space. (B205.13.w13)
• Attach the syringe containing the local anaesthetic solution and inject SLOWLY, over at least 30 seconds. (B205.13.w13)
  • If the injection is carried out too rapidly intracranial pressure is increased which is seen in the conscious animal as opisthotonus, nystagmus and collapse. (B205.13.w13)
• Withdraw the needle once the injection is completed. (B205.13.w13)
• For bilateral analgesia position the animal prone or supine so that the spinal canal is horizontal. (B205.13.w13)
  • Do NOT allow the animal to "dog sit" as this will prevent analgesia developing cranially. (B205.13.w13)
• For unilateral analgesia place the animal in lateral recumbency with the side on which analgesia is required downwards. (B205.13.w13)
• During recovery allow to recover quietly; it should be able to maintain sternal recumbency but if it makes uncoordinated efforts to rise then injury to the hindlimbs may result. (B205.13.w13)
• An indwelling catheter can be inserted at the lumbosacral junction if prolonged analgesia is required.:
  • The catheter is placed into the epidural space using a Tuohy needle; the needle has a curved end which directs the catheter. (B205.13.w13)
  • The catheter is advanced 6-8 cm into the epidural space. (B205.13.w13)
  • The needle is withdrawn. (B205.13.w13)
  • The catheter must be secured in position. (B205.13.w13) 
  • The free catheter end must be protected to ensure that injections into the catheter will be sterile; for example the catheter may be capped and then wrapped in sterile gauze. (B205.13.w13)
  • Local analgesic solution is injected whenever the animal shows signs that sensation to the blocked region is returning. (B205.13.w13) 

• In sheep and goats: 1 mL 2% lidocaine with adrenaline per 5 kg bodyweight, or 1 mL 0.5% or 0.75 % bupivacaine per 4 kg bodyweight, for flank laparotomy. (B205.13.w13)
  • Note: reduce the dose in individuals which are old, obese, or pregnant. (B205.13.w13)
• In sheep and goats: 1 mL of 2% lidocaine with adrenaline per 7 kg bodyweight, for analgesia of the hind limbs or for perineal surgery or for caesarian section. (B205.13.w13)
  • lidocaine with adrenaline is preferred to bupivacaine for caesarian section as the long duration of hindlimb paralysis with bupivacaine interferes with sucking of the newborn. (B205.13.w13)
• In sheep and goats: 1 mL of 2% lidocaine per 5 kg bodyweight for analgesia and elimination of muscular resistance to penile extension for examination (e.g. in diagnosis of urolithiasis.). (B351.32.w32)

Doses of other drugs:

• In sheep and goats:  
  • Morphine, 0.1 mg/kg as a 1 mg/mL preservative-free solution or 15 mg/mL diluted in saline to give 0.15-0.20 mL/kg provides analgesia without paralysis and may be used to decrease the requirement for general anaesthetic agents and to provide postoperative analgesia. Provides relief from pain following either orthopaedic or (for six hours) abdominal surgery. (B205.13.w13)
  • Xylazine, 0.05 mg/kg. Dilute with saline to give 0.1 mL/kg. As an adjunct to general anaesthesia for surgery. There may be systemic effects of sedation and decreased gastrointestinal mobility. Zylazine at 0.4 mg/kg has been used to provide analgesia for surgery involving the penis, providing analgesia extending to T5-6 within 10 minutes and lasting for 120 to 140 minutes. (B205.13.w13)
• In sheep:
  • Xylazine, 0.07 mg/kg made up to a volume of 2.5 mL in sterile water has been used to provide analgesia for caesarean section in sheep. A period of 40 to 50 minutes was allowed between injection and incision. (J35.154.w3)

Can be used for provision of analgesia in various field situations (J296.42.w1)

• Provides superior analgesia for vasectomy of rams (superior to analgesia provided by local infiltration of t he spermatic cord). (J296.42.w1)
• Indicated in Caesarean section associated with severe vaginal prolapse or delivery of a fetal monster. (J296.42.w1)
• Avoids struggling and prolapse of the rumen through the laparotomy site as may occur following use of local infiltration. (J296.42.w1)
• Has been used successfully (xylazine, 0.07 mg/kg made up to a volume of 2.5 mL in sterile water) in Caesarean section of ewes associated with vaginal prolapse, vaginal and rectal prolapse, incomplete cervical dilatation, fetal malposition, absolute fetal oversize, ovine pregnancy toxaemia and presence of emphysematous lambs. (J35.154.w3)

• Sensory block may extend several dermatomes cranial to the level at which motor block develops therefore limb movement may be possible even though analgesia is sufficient for surgery. (B205.13.w13)
• During recovery the ability to move the hindlimbs may develop before analgesia is lost, however ability to stand may not develop until some time after analgesia is lost. (B205.13.w13)
• It is recommended that a venous catheter is placed when epidural analgesia is to be used for surgery

Notes on use in the field:

• Lumbosacral analgesia using 2 mg/kg 2% lidocaine injected epidurally at the lumbosacral site provided excellent analgesia for vasectomy in 28 of 28 rams. (J296.42.w1)
• Lumbosacral analgesia using 4 mg/kg 2% lidocaine injected epidurally at the lumbosacral site provided excellent analgesia for caesarian section in 33 of 38 (87%) ewes. Anaesthesia was not achieved in four sheep, associated with poor positioning and subsequent incorrect identification of the epidural space. One individual died. This was considered to be associated with lidocaine overdose (5 mg/kg) and probable pooling of blood in the splanchnic vasculature. Ewes treated with 4 mg/kg of 2% lidocaine showed paresis of the pelvic limbs for two to four hours and dragged the pelvic limbs during this time. (J296.42.w1)
• Lumbosacral analgesia using xylazine, 0.07 mg/kg made up to a volume of 2.5 mL in sterile water has been used to provide analgesia for caesarean section in sheep. A period of 40-50 minutes was allowed between injection and testing by skin-prick followed by incision. Analgesia was considered good in five ewes and adequate in three ewes, while one ewe required additional local anaesthetic line block; this failure was considered likely to be due to incorrect injection. No sedation was noted in any of the ewes. Hind limb ataxia persisted for up to eight hours. This may cause practical problems with husbandry, including inability of lambs to suck colostrum from the udder while the ewe is recumbent. (J35.154.w3)

• Requires detailed anatomical knowledge, strict attention to detail and aseptic preparation. (J296.42.w1)
• This procedure results in loss of the use of the hind limbs for the duration of the anaesthetic. (B359.App8.w30)
• Pelvic limb paresis may interfere with nursing of lambs and development of the ewe-lamb bond. (J296.42.w1)
• Affected by poor positioning and restraint. (J296.42.w1)
• Affected by inexperience with the technique. (J296.42.w1)
• If cold anaesthetic solution is injected in a conscious individual the animal will jump, due to stimulation of receptors in the spinal cord, and the needle may be dislodged. (B205.13.w13)
• More difficult to perform correctly than caudal epidural analgesia; penetration into the subarachnoid space may occur easily. (B359.App8.w30)
• If the spinal cord is penetrated in a conscious animal it will jump and the needle may be dislodged from its position. (B205.13.w13)
• If the dura is penetrated then CSF will be aspirated when the plunger is withdrawn. Injecting the same amount of local anaesthetic solution into the subarachnoid space as is suitable for use in the epidural space will result in the block extending further cranially and therefore cause respiratory arrest. The dose for subarachnoid injection is usually half that required for epidural injection. (B205.13.w13)
  • If the spinal needle, having penetrated the dura, is partially withdrawn and redirected into the epidural space a few mm from the original insertion point, some local anaesthetic solution may enter the CSF through the original puncture hole. (B205.13.w13)
• If the needle had entered a venous sinus and this has not been detected by aspiration of blood then intravenous injection of local anaesthetic solution may result in cardiovascular depression. (B205.13.w13)
• If local anaesthetic solution moves cranially to the cervical (neck) region, for example if calculations are inaccurate and the dose injected is too large, then respiratory paralysis can occur. In such a case, general anaesthesia must be induced quickly, the animal intubated, and IPPV (intermittent positive pressure ventilation) applied until spontaneous breathing is possible once more. (B205.13.w13)

• Local anaesthetic solution e.g. 2% lidocaine hydrochloride.
• Needle.
• A spinal needle is preferable since this contains a stylet, which prevents a core of subcutaneous tissue from being injected into the epidural space.  (B205.13.w13)
  • For lambs, kids and pygmy goats a 22 gauge 3.7 cm long needle.  (B205.13.w13)
  • For adult sheep and goats an 18 gauge 6.25 cm long needle is recommended.  (B205.13.w13)
• Syringe.