II-REGIONAL ANALGESIA
A- Regional analgesia of the head: -
The Horse
1-Infra-Orbital Nerve Block 2-Mental Nerve Block 3-Mandibualr Nerve Block 4-Supra-Orbital Block 5-Retrobulbar Block 6-Auriculopalpebral Nerve Block
The Ox
1-Cornual Nerve Block 2-Auriculopalpebral Nerve Block
The Goat
1-Nerve Block For Dehorning
The Dog
1-Infra-Orbital Nerve 2-Mandibular Nerve 3-Auriculpalpebral Nerve Block
B-Regional analgesia of the limbs: -
The Horse
1-Planter Or Volar Nerve Block 2-Median Nerve Block
3-Complete Desensitization Of The Limb Below The Carpus
4-Posterior Tibial And Anterior Tibial (Deep Peroneal) Nerves Block
The Ox
1-Nerve Block In The Forelimb 2-Nerve Block Of The Hind Limb Method I
Method II
The Dog
1-Brachial plexus block 2-Infiltration of digital nerves
C-Regional analgesia about the trunk
The Horse
1-Analgesia For Castration
The Ox
1-Paravertibral 2-Pudic Or Internal Pudendal 3-Local Analgesia For Castration
The Small Ruminants
1-Paravertibral 2-Pudendal Nerve Block 3-Local Analgesia For Castration
The Dog
1-Paravertibral
2-SPINAL OR EPIDURAL ANALGESIA
A-Caudal epidural analgesia
The Ox The Buffaloes The Horse The Sheep The Dog
B-Lumbar epidural analgesia
The Ox The Sheep The Dog
II-REGIONAL ANALGESIA
Advantages: -1-The amount of used drug is relatively lesser than local infiltration
2-The technique requires no expensive equipments
3-The analgesic area is large enough and there is no need to increase the size of analgesic field during surgery like with local analgesia.
4-Anatomical features of the surgical field don't change as the drug is injected far from surgical field.
5-Healing is not delayed, as the drug is not injected to surgical line.
6-It can be used with or without sedation for surgery on standing animals
Disadvantages: -
1-It is more complicated than local analgesia
2-It has risk of toxicity especially when the nerve is associated with blood vessels
3-General complications of epidural including fracture, infection of neural canal, etc....
1-PERINEURAL ANALGESIA
A- Regional Analgesia Of The Head: -
The Horse
1-Infra-Orbital Nerve Block: -
Anatomy:
It is the continuation of the maxillary division of the 5th cranial nerve. It passes through the infra-orbital canal (innervates the upper molar teeth, canine, and incisors; and their alveoli and gum), and then it emerges through the infra-orbital foramen (innervates skin of upper lip, cheek, and nostril). After it emerges from the infra orbital foramen, it is partially covered with levator nasolabialis muscle.
Sites of perineural injection:
a-After the nerve emerges from the canal:
The desensitized area will be the skin of the lip, nostril, and face up to the level of the foramen.
b-Within the canal:
This will desensitize the upper molar teeth up to the 3rd, the canine, and the incisors, and their alveoli and gum, and the skin up to the level of the medial canthus of the eye.
c-Within the pterygopalatine fossa:
This will desensitize the molar teeth up to the 6th in addition to the previously mentioned regions.
Indications:
1-Suturing of a wound at the lip or nostril
2-Trephining the facial sinus.
Dose: 5 ml
Technique
a- After the nerve emerges from the canal
The lip of the infra orbital foramen can be felt as bony ridge lying beneath the edge of the flat levator nasolabialis muscle, at a point 5 cm forwards and downwards from the anterior end of facial crest. The needle is introduced until its point can be felt beneath the bony lip of the foramen.
b- Within the canal
The same as mentioned but the needle should pass 2.5 cm up the canal.
c- Within the pterygopalatine fossa
The needle is inserted at a point on the side of the face opposite to the lateral canthus, inferior to the facial crest, and above transverse facial vessels. The needle is advanced medially, slightly anteriorly to pass ventral to the border of zygomatic process and drop into the pterygopalatine fossa just posterior to maxillary tuberosity. The needle should be pushed until it strikes the perpendicular portion of palatine bone in the region of maxillary foramen at a depth of 7 cm. Generally it is a dangerous procedure.
2-Mental Nerve Block: -
Anatomy:
The alveolar branch of the mandibular division of the 5th cranial nerve enters the mandibular foramen on the medial aspect of the vertical ramus of the mandible under the medial pterygoid muscle. It traverses the mandibular canal and giving off dental and alveolar branches then it emerges from the mental foramen and called mental nerve. The innervation of the incisors and canines arises from the trunk nerve 3-5 cm before it emerges from the mental foramen.
Technique:
The mental foramen, through which the mental nerve emerges, lies on the lateral aspect of the ramus in the middle of the inter-dental space and covered with the tendon of depressor labii inferioris muscle. Injection of the nerve at this point desensitizes the lower lip only, while advancing the needle 3-5 cm into the canal will desensitize the incisors and canine too.
Indication:
Suturing of wounds of the lower lip
3-Mandibualr Nerve Block: -
Technique:
The mandibular nerve is injected at its point of entry into the mandibular canal at the mandibular foramen. The mandibular foramen lies opposite to the point of intersection of a line passes vertically downwards from the lateral canthus and a line extending backwards from tables of mandibular molar teeth. This nerve can be blocked by two methods.
1-The needle is inserted into a point 3 cm below the temporomandibular joint between the wing of the atlas and base of ear. Then the needle is advanced towards the point of intersection of the mentioned lines, medial to the medial surface of the mandible.
2-The needle is inserted directly in front of the angle of the mandible, medial to the medial surface of the mandible, towards the mentioned point. The needle should be inserted 12 cm forwards at least.
Dose:
5 ml lidocaine HCl 2%
4-Supra-Orbital Block: -
Anatomy:
Supra-orbital or frontal nerve is a branch of ophthalmic division of 5th cranial nerve, emerges from the orbit through the supra-orbital foramen in the supra-orbital process. It innervates the upper eyelid and skin of the fore head.
Technique:
The upper and lower borders of the supra-orbital process, close to its junction to the frontal bone, are palpated, and the foramen is detected midway between the two borders, then the needle is inserted into the foramen and the nerve is blocked.
Dose:
5 ml lidocaine HCl 2%
Indication:
Operations of the upper eyelid or suturing of wounds
5-Retrobulbar Block: -
It is a technique used for blocking of nerves behind the eye ball.
Technique:
1-The needle is inserted 1.5 cm behind the middle of the supra-orbital process and pushed towards the upper molar teeth of the opposite side.
2-The needle is inserted in the angle between the temporal process of zygomatic bone and the supra-orbital process and is advanced towards the base of the orbit (modified Peterson technique).
3-The needle is inserted into 4 sites at 3, 6, 9, and 12 O'clock.
Dose:
20-30 ml lidocaine HCl 2%
Indications:
Analgesia and akinesia of periocular muscles for enucleation of the eyeball. The large amount of injected drugs creates state of exophthalmos to facilitate enucleation.
6-Auriculopalpebral Nerve Block: -
As ox
The Ox
1-Cornual Nerve Block: -
Anatomy:
It is a branch of the superior maxillary division of 5th cranial nerve that innervates the corium and the skin of the horn. It emerges from the orbit and ascends behind the lateral ridge of the frontal bone.
Technique:
The nerve is injected at the upper 3rd of the frontal ridge, just behind the ridge, 2.5 cm below the base of the horn, as it is superficial at this region and covered with thin layer of frontalis muscle. The needle shouldn't be inserted so deep to avoid injection under the aponeurosis of temporal muscle. Another injection 1 cm behind the original site can be done to ensure blocking of the posterior division.
Dose:
*5 ml Lidocaine HCl 2%
Indication:
Dehorning, or surgical intervention of either fractured horn or horn separation
2-Auriculopalpebral Nerve Block: -
Anatomy:
It is a motor nerve of orbicularis oculi muscle, runs from the base of the ear along the facial crest.
Technique:
The needle is inserted rostoral to the base of the ear at the summit of zygomatic arch or its dorsal border.
Dose:
*5-10 ml Lidocaine HCl 2%.
Indication:
Induction of paralysis (akinesia) of the eyelids for eye examination, surgical interferences of the eyeball, or removal of foreign bodies from the cornea or conjunctive (in conjunction with topical analgesia of the cornea)
The Goat
1-Nerve Block For Dehorning: -
Anatomy:
The cornual branch of the lacrimal nerve emerges from the orbit behind the root of the supra-orbital process covered by thin layer of frontalis muscle and innervates the caudolateral aspect of the horn, while infra-trochlear nerve emerges from the orbit dorsomedially and divided into dorsal corneal branch that innervates the dorsomedial aspect of the horn, and medial frontal branch that innervates the caudomedial aspect of the horn, and both nerves are covered with orbicularis muscle at the lower part and with frontalis muscle at the dorsal part.
Technique:
The corneal branch of lacrimal nerve is injected close to caudal ridge of the root of the supra-orbital process.
The corneal branch of the infra-trochlear nerve is injected at the dorsomedial margin of the orbit, 0.5 cm deep.
Dose:
*3 ml lidocaine HCl 2%
Indication:
Dehorning, or surgical intervention for treatment of fractured horn or horn separation
The Dog
This technique of dental nerve block is no longer be used in dogs as a result of the development of technique of general anesthesia in this species, and when it is used, it is combined with sedatives.
1-Infra-Orbital Nerve: -
Anatomy:
The maxillary nerve derived from the 5th cranial nerve, that emerges from the cranium through foramen rotundum, passes forwards in the pterygopalatine fossa, and continued in the infra-orbital canal as infra-orbital nerve.
-The 1st and 2nd molar teeth are innervated by small branches derived from the main trunk before it inters the canal.
-The 4 premolars and their alveoli and gum are innervated by filaments derived from the nerve as it passes through the canal.
-The nerve supply to canines and incisors is given off in the canal and passes forwards in the maxillary and premaxillary bones.
Technique:
a-In the pterygopalatine fossa at its point of entry to desensitize the whole teeth in the upper jaw in that side. A point 4 cm below the lateral canthus in the space between the posterior border of malar bone and anterior border of coronoid process of the mandible is detected. The needle is inserted in this area and advanced in the soft tissue until its point passes the egde of malar bone. Then it is redirected forwards towards the maxillary foramen 3 cm from the point of insertion. The technique is difficult and may have risk.
b-In the lower part of the infra-orbital canal through infra-orbital foramen for desensitization of incisors, canines, and first two premolars. This technique is made through the gum over the 3rd premolar tooth at line of reflection of mucous membrane of cheek under which the lip of the infra-orbital foramen can be detected. The needle should be advanced 1 cm in the canal. The technique is easy but the area of desensitization is small.
Dose:
*Procaine HCl 2% 2 ml for point (a) and 1 ml for point (b).
2-Mandibular Nerve: -
It is derived from 5th cranial nerve, passes downwards deep to the medial pterygoid muscle and inters the mandibular canal at the mandibular foramen on the medial aspect of the ramus.
-Molar and premolar teeth are innervated by fibers derived from the main trunk while it stills inside the canal.
-The canines and incisors are innervated by branch derived from the main trunk and passes forwards within the ramus.
Technique:
a-On the medial aspect of the ramus at the mandibular foramen, that will desensitize all teeth of the lower jaw on that side. The needle is inserted at the middle of the depression on the posterior part of the ventral border of the ramus, in a right angle to the ventral border of the jaw, close to the medial aspect of the bone, and advanced for 2 cm to reach the mandibular foramen. The technique is difficult to be performed.
b-In the anterior part of the mandibular canal through the mental foramen, that will desensitize lower incisors, canines, and first two premolars on that side. The mental foramen is injected through the gum immediately beneath the anterior root of the 2nd premolar tooth, and the needle should be advanced 0.7 cm in the canal. The technique is easy but the area of desensitization is small.
Dose:
*Procaine HCl 2% 2 ml for (a) and 1 ml for (b).
3-Auriculpalpebral Nerve Block: -
Anatomy:
The nerve runs caudal to mandibular joint at the base of the ear, gives the anterior auricular nerve and then proceeds as temporal branch along the upper border of zygomatic arch towards the orbit, and finally near the orbit it divides into medial and lateral branches to innervate the orbicularis oculi muscle.
Technique:
Point of needle insertion is the midpoint of posterior 3rd of zygomatic arch.
Dose:
*Procaine HCl 2% 1 ml
Indication:
The nerve is motor nerve and its blocking has clinical value for facilitating eye examination, eye operations, and prevention of blinking and squeezing of the eye after intra-ocular surgery.
B-Regional Analgesia Of The Limbs: -
The Horse
1-Planter Or Volar Nerve Block: -
Anatomy:
-In the forelimb, the medial high volar nerve passes with the artery and vein (VAN) in the groove between the suspensory ligament and digital flexor tendons. At the middle of the cannon bone, the medial nerve sends branch to the lateral high volar, that passes behind the flexor tendons and join the lateral branch at the level of the button of splint bone. At the fetlock region, every volar nerve divides into three branches named low volar nerves and pass in the same relation to the artery and vein (VAN) but the artery sinks slightly. The anterior branch innervates coronary cushion; the middle branch innervates coronary cushion and sensitive laminae, and the posterior digital branch innervates sensitive laminae and os pedis.
-In the hind limb, planter nerves are the continuation of posterior tibial nerve. They have the same anatomical position like the forelimb, but their clinical significance is lower than that of the forelimb, because the digit is innervated by branches from the anterior tibial nerve (deep peroneal).
Technique for high volar block:
The site of injection is 7 cm above fetlock, in the groove between suspensory ligament and flexor tendons. The needle is inserted with an angle of 15° with the vertical line and directed downward and inward.
Dose:
*5 ml lidocaine HCl 2%
Indication:
Desensitization of the limb from the fetlock and downward, including pastern and coffen joints for;
1-Diagnosis of lameness of affected limb and opposite one 2-Relieve of pain
3-Operative procedures
a-Neurectomy
b-Operative procedures at the foot, coronet, or heel, like exposure of corn, or removal of nail, partial operation of quitter or sandcrack
Technique for low volar block (posterior digital):
The needle is inserted at the midway between fetlock and coronet in the groove between the 1st phalanx and the flexor tendon with an angle of 15° with the vertical line and directed downward and inward.
Dose:
*2-4 ml Lidocaine HCl 2%
Indication:
Sensation remains in the anterior and lateral parts of the foot, so it is used mainly for diagnosis of navicualr disease.
2-Median Nerve Block: -
Anatomy:
The nerve lies 5 cm below the elbow joint in the groove between the posterior border of the radius and the flexor carpi radialis, deep to the posterior superficial pectoral muscle, hand fist above the chest nut.
Technique:
The needle is inserted in the mentioned site and advanced inward and upward with an angle 20° with the vertical line
Dose:
*10 ml Lidocaine HCl 2%
Indication:
Median nerve neurectomy, as the desensitized area is little more than that obtained by medial high volar block.
3-Complete Desensitization Of The Limb Below The Carpus: -
Anatomy:
For complete desensitization of the limb below the carpus, three nerves should be blocked. Theses three nerves are the median, ulnar, and musculocutaneous nerves. Ulnar nerve can be located 7 cm above the carpus in the groove between the ulnaris lateralis and flexor carpi ulnaris, while musculocutaneous nerve lies at the medial aspect of the limb on the surface of the radius half way between the elbow and the carpus in front of cephalic vein.
Technique:
The needle is inserted in the mentioned sites
Dose:
*10 ml Lidocaine HCl 2% for each nerve
Indication:
Any surgical interference below the carpus
4-Posterior Tibial And Anterior Tibial (Deep Peroneal) Nerves Block: -
Anatomy:
The posterior tibial nerve lies 15 cm above the point of the hock in the space between Achilles tendon and long digital flexor. The nerve becomes closer to the Achilles tendon as the limb is flexed. While the anterior tibial nerve lies in the groove between tendons of long and lateral extensors above the lateral malleolus.
Technique:
The needle is inserted in the mentioned sites
Dose:
20 ml lidocaine HCl 2% for posterior tibial and 10 ml for anterior tibial nerve
Indication:
Desensitization of the posterior aspect of metatarsus, the medial and lateral aspects of the fetlock, and the whole digit. For complete desensitization down the hock, the saphenous, superficial peroneal, and posterior cutaneous nerves should be blocked.
The Ox
1-Nerve Block In The Forelimb: -
Nerve supply of the digits of the ox is much more complex than the horse. For complete analgesia of the digits, five points (1, 2, 3, 4 & 5) should be blocked. For analgesia of the medial digit, points (1, 4 & 5) should be injected with analgesic. While for complete analgesia of the lateral digit points (1, 2, 3 & 4) should be blocked.
1-Dorsal metacarpal nerve (Radial) at the middle of metacarpal medial to extensor tendon.
2-The dorsal branch of ulnar nerve about 5 cm above the fetlock on the lateral aspect in the groove between suspensory ligament and metacarpal bone.
3-The volar branch of ulnar nerve about 5 cm above the fetlock, and caudal to the suspensory ligament at the same level of dorsal ulnar nerve.
4-The lateral branch of the median nerve and small branch of the ulnar nerve can be injected at the midline just above the fetlock on the caudal aspect of the limb.
5-The medial branch of the median nerve can be injected in the grove between suspensory ligament and flexor tendon on the medial aspect.
However the technique is not easy and missing of one nerve block requires re-blocking of all the sites again, so it is preferred to make ring block rather than perineural injection for surgical interference at the digits.
2-Nerve Block In The Hind Limb: -
Method I: -
The tibial and external popliteal (common peroneal) are blocked above the hock and they produce complete loss of sensation down the fetlock.
Advantages:
1-Only two injections are necessary.
2-Injection to soft tissue and at convenient level permits easy application with thin needle, during standing with minimal restraint.
3-The nerves can be located by clear landmarks.
4-There is moderate interference with the motor function of the limb.
5-Most of the lower limb rendered analgesic.
6-It avoids complications of injection at the diseased tissue of the digit.
Technique:
1-The common peroneal nerve (external popliteal) can be blocked behind the posterior edge of the lateral condoyle of the tibia, over the fibula and before it dips down between the extensor pedis and flexor metatarsi muscles, for giving off superficial and deep peroneal nerves.
2-The tibial nerve can be blocked 10 cm above the summit of os calcis on the medial aspect of the limb anterior to Achilles tendon.
Dose:
1-The common peroneal nerve is blocked with 20 ml Lidocaine HCl 2%
2-The tibial nerve is blocked with 20 ml Lidocaine HCl 2%
Method II: -
Technique:
1-The superficial peroneal is blocked in the upper 3rd of metatarsus subcutaneously over the dorsal aspect of the metatarsus.
2-The deep peroneal nerve can be located halfway down the metatarsus in a groove on the dorsal aspect and covered with extensor tendons.
3-The planter metatarsus nerves can be blocked on both sides like high volar in horse.
Dose:
*5 ml Lidocaine HCl 2% for each nerve of the mentioned 4 nerves
The Dog
1-Brachial plexus block: -
It is a simple method for induction of analgesia of the forelimb, and it causes analgesia and relaxation from the elbow joint and downwards.
Technique:
With the animal standing, the depression at the center of the triangular area (bounded by the anterior border of supraspinatus muscle, the chest wall, and the dorsal border of brachiocephalicus muscle) is detected. The head is held away, and the 7.5 cm long needle is inserted into of that depression after locating the 1st rib. The needle is guided backwards lateral to the chest wall and medial to subscapularis muscle until its point is judged to be at the level of scapular spine.
Dose:
Lidocaine HCl 2% 2 ml
Complications:
1-Hematoma. 2-Acedintal intravenous injection of the drug
3-Damage and neuritis of the plexus 4-Penetration of the thorax 5-Infection of the axilla
2-Infiltration of digital nerves: -
These nerves are injected subcutaneously, medial and lateral to the 1st phalanx of each digit, with 2 ml lidocaine HCl 2%.
C-Regional Analgesia About The Trunk: -
The Horse
1-Analgesia For Castration: -
Local infiltration of the scrotum and direct injection of up to 20 ml lidocaine HCl 2% into the testicle itself
The Ox
1-Paravertibral Block: -
It is a perineural injection of spinal nerves as they emerge from the vertebral canal through the inter-vertebral foramina. It can be used for induction of laparotomy (rumenotomy or caesarian). The last thoracic and the 1st and 2nd lumbar nerves can be blocked for induction of rumentomy, while the 1st three lumbar nerves should be blocked for caesarian section in the flank region.
Advantages:
1-Complete and uniform desensitization of the abdominal wall and peritoneum
2-Relaxation of the abdominal muscles with reduction of intra-abdominal pressure
3-Short post-surgical convalescence period 4-Lower amount of local analgesia can be used.
5-It over comes the disadvantages of inverted-L block and linear infiltration
Technique:
1-The last thoracic can be blocked 5 cm from the midline caudal to the head of the last rib and 5 cm deep.
2-The lumbar nerves can be blocked by insertion of the needle 5 cm far from the midline on a level with a line drawn just behind the spinous process of particular vertebra.
Dose:
*20 ml Lidocaine HCl 2% for each nerve (15 ml below the inter-transverse ligament and 5 ml above it)
2-Pudic Or Internal Pudendal Block: -
This nerve is blocked for induction of protrusion of the penis by a method other than epidural analgesia to avoid the disadvantages of epidural in large or heavy bulls.
Technique:
1-After location of the nerve per rectum, in the sacrosciatic foramen, the needle is introduced via the ischiorectal fossa medial to the sacroisciatic ligament, and is directed forwards and downwards for 7 cm.
Dose:
*30-40 ml Lidocaine HCl 2% (20-25 at the mentioned site and 10-15 slightly behind)
Disadvantages:
1-The success rate of this technique is 66%.
2-The onset can be delayed as late as 30-45 minutes.
3-Some bulls may show protrusion of the penis as long as 24 hours post injection.
3-Local Analgesia For Castration: -
1-The site of the proposed incision in the scrotum may be rendered analgesic by local or subcutaneous infiltration, however this will not block the nerve fibers in the spermatic cord. Accordingly, these fibers can be rendered analgesic by;
2-Direct injection of 10 ml Lidocaine HCl 2% into each cord at the neck of the scrotum.
3-Direct injection of 5-25 ml Lidocaine HCl 2% into the testicle itself. Accordingly the drug will pass through the lymph, diffuses, and blocks the fibers in the spermatic cord.
For bloodless castration, both local infiltration at the scrotal neck and direct injection into the spermatic cord should be used.
The Small Ruminants
1-Paravertibral Block: -
It can be performed as with cattle, and each nerve is blocked by 7 ml lidocaine HCl 1% (5 ml below the inter-transverse ligament and 2 ml above it).
2-Pudendal Nerve Block: -
Anatomy:
The anterior tuberosity of tuber ischii is used as fixed point, and the length of sacro-tuberous ligament is sued as a radius. This distance is used to establish a site on a line parallel to the midline in front of the fixed point. A finger is introduced through the rectum for detection of the lesser sciatic foramen, and the needle is inserted at the previously mentioned point. The penis will protrude 5 minutes post injection.
Dose:
7 ml lidocaine HCl 2%
3-Local Analgesia For Castration: -
1-Direct injection of 2-10 ml lidocaine HCl 1% into the testicle itself, followed by local subcutaneous infiltration at the line of incision.
2-Other methods mentioned in cattle.
The Dog
1-Paravertibral Block: -
The last three thoracic and the 1st four lumbar nerves should be blocked to produce analgesia and relaxation of abdominal muscles; accordingly it can be sued with light general anesthesia. This technique can be used bilaterally to induce complete relaxation of abdominal muscles, however, disadvantage of this technique is time consuming, and its advantage is there is no need for muscle relaxant and artificial ventilation.
Dose:
Lignocaine HCl 1 % 2 ml
2-SPINAL OR EPIDURAL ANALGESIA
A-Caudal Epidural: -
The Ox
It is a process through which the analgesic solution is injected between the two layers of dura matter and affects the terminal nerves or cauda equina thus producing analgesia of the posterior half of the animal. The term anterior and posterior epidural analgesia is related to the dose of injected analgesic solution and not to the site of injection.
1-Posterior epidural characterized by no affection of the motor function of the hind limbs, but analgesia or loss of sensation can be observed over the tail, croup as far as the mid-sacral region, the anus, vulva, perineum, and posterior aspect of the thighs. Paralysis of motor fibers predisposes to relaxation of anal sphincter and ballooning of posterior part of the rectum. Defecation will be suspended and stretching of the vulva provokes no response. The vagina will dilate and straining, during parturition, ceases without affecting uterine contraction.
2-Anterior epidural shows some degree of interference with motor function of the hind limbs. This will vary from partial paralysis of stifle flexors, and flexors and extensors of hocks and digital joints, to complete paralysis. In coordination may predispose to injury to the animal or the workers. Loss of sensation spreads forwards, according to the dose; over the croup; between hind limbs till the inguinal region, scrotum, and prepuce; over the hind limbs; mammary gland; and finally flanks and abdominal wall till the umbilicus. As the drug blocks the sympathetic outflow of the thoracic and lumbar segments, hypotension will occur and the normal compensatory mechanism (tachycardia) will be affected as the cardiac accelerator nerves will be blocked so the heart rate will not be increased to compensate the hypotension. This hypotension has the advantage of lowering the chance of bleeding during surgery but on the other hand, minimal loss of blood threatens the animal life.
Seat of injection:
The first intercoccygeal space between the 1st and 2nd coccygeal vertebra. Its dimensions are 2 cm transversely, 2.5 cm anterior-posteriorly, and 0.5 cm deep. The canal is 2-4 cm deep from the skin surface.
Technique:
The needle is inserted with 15° degrees with the vertical. When the needle reaches the accurate site, there will be no resistance for injection, and suction of the drug from the hub of the needle can be seen.
1-The tail is gripped 15 cm from its base and raised in pump-handle fashion. Seat of injection is the 1st obvious articulation behind the sacrum.
2-Stand beside the animal and detect the 1st prominence after the croup (prominence of the sacrum), seat of injection is the depression directly behind this prominence.
3-A line has drawn directly over the back connecting two points (one on each side) 10 cm anterior to posterior prominence of the ischeal tuberosity. Seat of injection is the point of intersection between this line and midline.
Dose:
1-Caudal block:
| a-Procaine HCl *15-20 ml 1%. *10-15 ml 2%. *5-10 ml 3-5%. | b-Lignocaine HCl or lidocaine HCl 5-10 ml 2% |
| a-Procaine HCl *40 ml 3% (mastectomy) *170 ml 1% or 120 ml 1.5% (amputation of the digit) *45 ml 2% (caesarean) | b-Tutocaine 1% *60-100 ml (difficult obstetrical interferences) *120 ml (caesarean) |
a-Caudal block:
Paralysis of the tail can be observed after 1-2 minutes, the maximal effect appears after 10-20 minutes, and lasts for 60 minutes, and the animal becomes normal again by the end of 120 minutes.
b-Anterior block:
Paralysis of the tail can be observed after 1-2 minutes, the maximal effect appears after 10-20 minutes, and the animal will be unable to rise for 120 minutes, and in coordination may persist for 3-4 hours
Indications:
1-Caudal block:
a-Obstetrics:
1-To overcome straining for correction of malpresentation, or for simpler embryotomy
2-Operative treatment of parturient injuries 3-Reduction of prolapsed uterus or vagina
b-General:
1-Surgical operations of the tail 2-Surgical correction of tears of vulva or perineum
3-Examination of the vagina or external cervical os 4-Protrusion of the penis
2-Anterior block:
a-Obstetrics:
1-To overcome straining during extensive embryotomy
2-Amputation of gangrenous prolapsed uterus 3-Caesarian section
b-General:
1-Surgery of penis 2-Cutting operations about the prepuce or inguinal region
3-Amputation of the udder 4-Castration 5-Surgery of hind limb like amputation of digit
Disadvantages:
1-Infection of the nervous system
2-Fracture of the animal pelvis, and injury to workers, or veterinarian (anterior block)
3-Hypovolumic shock due to involvement of vasomotor nerve fibers and pooling of blood in the venous side with absence of compensatory tachycardia (anterior block)
4-Asphyxia due to paralysis of phrenic nerve
5-Twisting of the tail few days or even permanent paralysis after injection due to injury of nerve fibers innervate the tail
The Buffaloes
The needle is inserted downwards and forwards in the sacrococcygeal with an angle 45º with the vertical.
The Horse
The technique is not common in equine as in bovine because the indications for such technique in equine are not frequent and the detection of site of injection is more difficult.
Seat of injection:
1st intercoccygeal space in horse and 2nd intercoccygeal space in donkey. The depth of the canal is 4-8 cm.
Technique:
The needle is inserted forwards and downwards with an angle of 30° degrees with the horizontal (60° with the vertical).
1-A line drawn connecting the hip joints and intersects the midline at the level of the sacrococcygeal joint caudal to which the dorsal spine of the 1st coccygeal bone can be felt. The needle inserted into the depression directly caudal to this point.
2-The space is opposite the caudal fold formed on each side of the tail when raised.
Indications:
1-Caudal block:
a-Obstetrics:
1-To overcome straining during manipulative correction of simpler forms of malpresentation 2-Partial embryotomy
b-General:
1-Amputation of the tail 2-Operations about the anus, perineum, or vulva
3-Operation for rectal prolapse 4-Caslick operation for windsucking
2-Anterior block:
a-Obstetrics:
Obstetrical difficult manipulative repositions and extensive embryotomy
b-General:
Scrotal hernia and cryptorchidism
Dose:
1-Caudal block:
| a-Procaine HCl 2% *5-15 ml (amputation of the tail) *10-25 ml (perineal and vulvar operation) *15-30 ml (obstetric manipulation) | b-Lignocaine HCl or lidocaine HCl *10 ml 2% |
| a-Procaine HCl *50-120 ml 1% (severe obstetrical interferences) *30-80 ml 2% (cutting operation) | b-Lignocaine HCl or lidocaine HCl *100-150 ml 2% (analgesia of hind limbs to the costal arch) |
Seat of injection:
Sacrococcygeal space
Dose:
*3-4 ml 2% lignocaine HCl (intravaginal obstetrical procedures)
*1 ml 5% procaine HCl (docking of lambs)
Indications:
1-Intravaginal obstetrical procedures
2-Relief of painful conditions of vagina and rectum that provoke severe straining
The Dog
Seat of injection:
Sacrococcygeal or 1st intercoccygeal space
Dose:
*1 ml 2% lignocaine HCl
Indications:
1-Docking of tail
B-Lumbar Epidural Analgesia: -
Injection of analgesic solution into the epidural space in the caudal region (caudal epidural) affords very save method of inducing epidural analgesia, but sometimes it is not easy to produce satisfactory anterior block via this site. The lumbar epidural analgesia through the anterior lumbar region or lumbosacral spaces, affords a belt of analgesia around the trunk of the animal without affecting the motor function of the hind limbs.
The Ox
Seat of injection:
Seat of injection is just to the right of the lumbar spinous process of the 2nd lumbar vertebra, 1.5 cm caudal to the anterior edge of the second lumbar transverse process.
Dose:
* 10-15 ml Tutocaine 2%
* 10 ml Procaine HCL 4% (15 ml weakens the hind limbs- 20 ml the animal lie down)
*8 ml Lignocaine 3%
*10 ml Lignocaine 2%
Indications:
This technique is used for induction of flank analgesia for rumenotomy or caesarian.
The Sheep
Seat of injection:
Lumbosacral space to avoid puncturing of meninges. It is located just behind the spinous process of last lumbar vertebra that lies at a point of intersection between line drawn to connect the anterior borders of the two illiums and midline.
Technique:
The needle is inserted in the mentioned space with an angle 10° anterior and 15° lateral with the vertical.
Dose:
8-15 ml Lignocaine 3%
Indication:
Intra-abdominal, pelvic, or hind limb surgery
The Dog
Seat and technique:
Lumbosacral space as sheep
Dose:
0.5 ml/Kg
Indications:
1-Posterior abdominal (hysterectomy, or cystotomy) or inguinal surgery
2-Treatment of hind limb fracture
