IN THE BOVINE F. D. Horney*

ATARACTIC DRUGS (TRANQUILIZERS) REGIONAL ANESTHESIA THESE PREPARATIONS, usually phenothia- Techniques for regional anesthesia have zine derivatives, are effective in reducing been devised for most areas of the bovine apprehension in nervous animals and pro- body. The most useful are the epidural, vide a means of producing a state of paravertebral, cornual, regional eye blocks, indifference in the animal during which and regional limb blocks. non-painful, thorough examinations and manipulations can be conducted. The seda- Epidural Anesthesia tive effect of these agents usually is con- This regional block is the one most sistent. Side effects, such as antipyretic, frequently used. The agents most com- hypothermic and hypotensive action will monly used are procaine hydrochloride vary with the specific agent. and lignocaine hydrochloride. The strength Tranquilizers are useful for producing of anesthetic solution used is 2% (1.5- prior to performing under 2.5%). The volume has more bearing on local or regional anesthesia. They may the effect produced than does the strength also be used for premedication in general of solution, although complications have anesthesia, but in some cases they prolong been observed with higher concentrations recovery time. (16, 22). The size of the neural canal and The dosage used depends on the pre- the patency of the intervertebral foramina paration and its route of administration. will influence the effect produced by a In nervous cattle the intramuscular route given amount of anesthetic solution. In is preferred and should precede the ad- rare cases, where repeated epidural injec- ministration of the by 30 tions have been made, there may be diffi- to 60 minutes. The excitation caused by culty in obtaining satisfactory anesthesia. an intravenous injection may nullify the The effect which is produced is used sedative effect of the tranquilizer. to classify the type of anesthesia, and These drugs should be administered within limits consistent results can be according to the prescribed dosage, but achieved with a predetermined amount of the following "thumb rules" may be useful: anesthetic solution. Where motor control promazine and chlorpromazine are usually of the hind limbs is not affected, the block given at the rate of 30 mg. per 100 lb. is referred to as a posterior epidural. (45.5 kg.) of body weight, and acepro- Where there is loss of motor control to the mazine at 7.5 mg. per 100 lb. (45.5 kg.) hind limbs, the anesthetic is called an of body weight. An increase of 100% in anterior epidural. dosage with acepromazine does not cause As variations in response occur, it is untoward effects; however, increased advisable to leave the needle in the epi- dosages may cause the animal to lie down. dural space and to give the anesthetic to This is undesirable for operations which effect over a period of five to ten minutes. are performed better when the animal Posterior epidural anesthesia would be remains standing. even more valuable if it could be main- Tranquilization is most beneficial prior tained for extended periods (20). To to restraint; by using an ataractic, opera- achieve prolonged analgesia a continuous tions such as laparotomy, claw amputa- infusion technique (3) or preparations tion, urethrotomy, and extirpation of containing alcohol may be used (7, 26). interdigital fibromata may be carried out These may, however, cause complications. if the surgical site is aiesthetized. The use of anterior epidural anesthesia is restricted to major surgical procedures, 'Ontario Veterinary College, University of and the possibility of damage resulting Guelph, Guelph, Ontario. during the period of motor incoordination ,24 CAN. VET. JOUR., vol. 7, no. 10, October, 1966 BOVINE ANESTHESIA

must be considered. Although it is unusual, excellent analgesia in dairy cows because marked hypotension and respiratory de- of the ease with which landmarks for the pression may occur. Large amounts of sites of injection can be located. In beef anesthetic administered rapidly may cause cattle more difficulty may arise because convulsions. This is usually transient, and of fat deposits obscuring these landmarks. it is thought to be the result of excessive The extremities of four of the lumbar pressure on the dura. The size of the transverse processes usually can be readily animal will govern the effect produced identified (L2,3,4 and 5). In thin cows the and dosages of 20 to 150 ml. may be re- transverse process of L1 can also be felt, quired to produce the desired plane of but L6 in all animals is obscured by the analgesia. Various obstetrical and surgical ilium. Perpendicular lines from the an- procedures may be carried out under an- terior aspect of the extremities of L3, L2, terior epidural anesthesia. The repair of and L1 (Figures 1 and 2) will cross over an umbilical hernia is an example of the the nerve trunks L2, L1 and T13 about 2" kind of procedure which can be performed from the midline. Since most operations in with anterior epidural and local infiltra- the flank region involve incisions in the tion anesthesia. mid paralumbar fossa these three nerves must be anesthetized. If more anterior or Paravertebral Anesthesia posterior incisions are required T12 and In regional anesthesia of the flank, L3nerves may have to be anesthetized. paravertebral nerve blocks are of value in providing anesthesia of the sensory Technique nerves. The use of a regional block, as A small amount of anesthetic solution opposed to local infiltration of the pro- is injected beneath the skin with a 25- posed site of incision or a field block in gauge, one-quarter-inch needle. The skin the form of an inverted "L", eliminates is punctured through the bleb thus formed the necessitv of subsequent injections into with a 16-gauge, two-inch needle. This the muscles as they are exposed. The needle is withdrawn, taking care to de- peritoneum is also anesthetized by the press the skin on either side to prevent air paravertebral block. accumulating under the skin. A four-inch, No difficulty is encountered in obtaining 18-gauge needle is passed through the

FIGURE 1. Last thoracic and lumbar distribution to the flank. (Photograph courtesy of Dr. 0. W. Sack.) 225 CANADIAN VETERINARY JOURNAL

gesia. A rapid acting anesthetic to decrease this interval has been suggested (15). Peterson Eye Block (23) The incidence of traumatic injuries and neoplastic lesions of the eye and associated structures is relatively low. When they do occur, however, economy usually dictates that the treatment of choice in severe cases will be removal of the eye. Complete analgesia is, unfortunately, not always obtained. The technique requires a curved needle to by-pass the coronoid process of FIGURE 2. External palpable landmarks for the mandible. The hypodermic needle paravertebral anesthesia. (four and one-half inches), is inserted in the angle formed by the zygomatic and skin puncture and the lumbodorsal fascia. supraorbital processes, which is just below The anesthetic solution should be injected and slightly posterior to the lateral canthus as the needle progresses in order to block of the eye (Figure 3). The concavity of the dorsal branches and to eliminate the the needle should face posteriorly (Figure tendency of the animal to arch its back, 4), and the direction of insertion is slightly as this may shear the shaft of the needle. downward from a horizontal plane. The Most of the anesthetic solution (10 ml.) curve of the needle directs it around the is deposited just below the level of the transverse process by "walking" the needle off the posterior edge and penetrating the intertransverse ligament. The udder and teats may also be anesthetized by blocking the appropriate lumbar nerves (L2, 3 and 4) and the perineal nerve (18); however, this is usually not required since most surgery in this region is confined to the teats which are best blocked by local infiltration at the base of the teat. Other approaches to obtain comparable analgesia have been suggested. These include injec- tions at the extremities of the 1st, 2nd and 4th transverse processes (4), or the FIGURE 3. Arrow pointing to the angle use of a lumbar epidural (1). The lumbar formed by the zygomatic and supraorbital epidural technique is difficult and poten- processes. tially more dangerous than the other techniques. Cornual Nerve Block The site of this regional block is mid- way between the eye and the horn. As the nerve approaches the horn, however, it becomes more superficial and the block may be easier to perform by injecting closer to the horn. The anesthetic solution should be deposited just under the margin of the frontal crest. Analgesia is good in most cases, although in excessively fat animals the nerve may be displaced and more anesthetic will be required. As with other regional blocks, it is necessary to FIGURE 4. Insertion of needle with the wait for at least ten minutes for full anal- concavity of curve facing posteriorly. 226 BOVINE ANESTHESIA

anterior edge of the coronoid process and duce fewer side effects, and reduce the the needle is advanced until it strikes the danger of local damage (19). The use of perpendicular part of the palatine bone in tranquilizers, in most cases, will relax the the vicinity of the orbito-rotundum fora- penis so that exposure may be obtained. men (Figure 5). A second injection is Once exposed, local infiltration will pro- required to anesthetize the auriculo- vide sufficient analgesia for the removal palpebral branch of the facial nerve. This of fibromata or severing fibrous bands. is made over the zygomatic arch at the base of the ear. These injections should Regional Anesthesia of the Limbs paralyze all sensory and motor nerves to This type of block is commonly em- the eye and associated structures. Unless ployed in horses but, with some modifica- the eye and eyelids are immobilized and tion, may be used in cattle. For surgery of insensitive, the block is not complete. the hind limb anterior epidural anesthesia may be used but it is risky. The foot may be anesthetized by perineural injection at |1_'~~~~~~~^ ^ ^'^~~~~~'''...... the junction of the proximal and middle thirds of the metatarsus, or by specific digital nerve block of the peroneal and tibial nerves (6, 10). The former involves four injections but the latter involves only two injections. Five injections will provide comparable anesthesia of the fore limb (Figure 6). For veterinarians who do not perform surgery routinely, the ring block will produce adequate analgesia for such operations as claw amputation.

FIGURE 5. Skull showing point of needle close to the orbito-rotundum foramen. When ablation is not required, the eye- ball may be anesthetized by injecting 20 to 25 ml. of 2% procaine into the retractor oculi muscle by entering through the lower lid midway between the medial and lateral canthi, or by local infiltration of the eye- lids and orbit (5, 11). A small amount of FIGURE 6. Front leg sites for blocking the 2% butyn ointment may also be instilled nerves to the digits. The site for blocking the into the eye (2). As difficulty is frequently cutaneous branch of the radial is not visible. encountered in obtaining a complete block, intravenous anaesthesia should be con- sidered for surgical conditions of the eye. GENERAL ANESTHESIA General anesthesia is not employed fre- Anesthesia of the Penis quently in cattle because of the advantages Thorough examination of the penis by of exploring the viscera while the animal observation during natural service or fol- is standing. There are occasions, however, lowing exposure using an electro ejaculator when intravenous anesthesia is the pre- is difficult. Epidural anesthesia may be ferred method. The hazards of bloat and used, but it is difficult to obtain relaxation of regurgitation of ingesta must be fore- of the penis without causing some degree most in the mind of the surgeon when of impairment to motor control of the hind general anesthetic techniques are em- limbs. The pudendal (pudic) block is ideal, ployed. but results may be disappointing unless proficiency is maintained in exercising the Intravenous Anesthesia technique (17). A lateral approach to this The agents most frequently used in this block is reported to be quicker, to pro- type of anesthesia are chloral hydrate and 227 CANADIAN VETERINARY JOURNAL the barbiturates, or a combination of these agents. A qualified person should be on hand to monitor and reinforce the anes- thesia. A technique for chloral hydrate anes- thesia which has been advocated for calves is carried out as follows: food and all but a little water are withheld for 18 hours prior to operation, and 6.5 mg. of atropine are given 20 to 40 minutes prior to the administration of the anesthetic. A 40% chloral hydrate solution is injected intra- venously at a dosage level of .44 ml. per kg. of body weight (8 Gm./100 lb.). FIGURE 7. Chloral hydrate sedation and Approximately one-half this amount is in- rope restraint~~~~~~~~~~~~~~~~~~~~...--...with the incision.... and field block jected over a period of two minutes and outlined. the calf is lowered to the floor before continuing the slow and intermittent ad- B-methylethylglutarimide2. Intravenous ad- ministration until the palpebral reflex has ministration of a tranquilizer followed disappeared. The duration of anesthesia is immediately by Thiamylal3 has been re- from 16 to 52 minutes (27). ported to produce anesthesia for seven to Chloral hydrate has been used to pro- ten minutes (24). The anesthesia may be duce narcosis which is then potentiated by maintained by the periodic infusion of the administration of chlorpromazine. Pro- Thiamylal. longed recovery accompanied by rumen A newer oxybarbiturate, tympany may be encountered when using sodium4 is also a satisfactory ultra short- this technique although various combina- acting anesthetic agent. Both methohexital tions have been tried in an effort to shorten and Thiopental5 are useful for the induc- the period of recovery. Twenty grams of tion of anesthesia. Muscle tremors may be chloral hydrate followed by Methitural1 observed following induction with the (15 mg./Kg. of body weight I.V.) will former and either may cause transient produce narcosis with almost complete apnoea occasionally (21, 25). absence of reflex for 30 to 45 minutes (8). Chloral hydrate narcosis combined with Inhalation Anesthesia rope restraint and field blocks provides Economic aspects of cattle practice pre- many advantages to the surgeon. Several clude extensive use of the newer inhalation hundred operations involving paramedian agents in bovine anesthesia. Both halo- incisions have been performed following thane6 and methoxyflurane7 have been intravenous chloral hydrate (7% solution) used in circle absorber and to-and-fro with magnesium sulphate at dosages of systems (9, 12, 14). Premedication with 3 Gm./100 lb. of body weight and field atropine is not usually required. Induction block (Figure 7). The advantages of this is usually carried out with ultra short- method are that the animal usually lies acting barbiturates, although this adds to down without the exertion of force, and arises immediately after removal of the 2Megimide. Abbott Laboratories Limited, rope restraint. The main disadvantage is Montreal, Quebec. that there may be some feeble attempts 3Surital. Parke, Davis and Company, De- to move during surgery, and these move- troit, Michigan. ments may interfere with surgical tech- 4Brevane. Corn States Laboratories, Inc., nique in operations of longer than 30 to Omaha, Nebraska. 45 minutes' duration. 5Sodium Pentothal. Abbott Laboratories, Barbiturate Montreal, Quebec. anesthesia is not recom- 6Fluothane. Ayerst McKenna and Harrison, mended for calves because of the long Montreal, Quebec. recovery period although this may be Halothane B.P. Hoechst Pharmaceuticals, overcome by the administration of B, Montreal, Quebec, 7Penthrane. Abbott Laboratories, Montreal, IThiogenal. Merck, Darmstadt, Germany. Quebec. 228 BOVINE ANESTHESIA the expense and risk. Intubation with SUMMARY cuffed endotracheal tubes is advisable and may be performed under chloral narcosis A review of anesthetic preparations and (Figure 8). Maintenance of anesthesia is techniques used in the bovine is given. easily Various ways of producing analgesia are controlled and relaxation is excellent. evaluated. RE'SUMiE ...... Revue des preparations et techniques anesthesiques utilisees chez les bovins. Evaluation de differentes formes d'anal- gesie. REFERENCES 1. ARTHUR, G. H. Some notes on a pre- liminary trial of segmental epidural anesthesia of cattle. Vet. Rec. 68: 254. 1956. 2. BELLING, THEO. H. Surgery for corneal and eyelid lesions. Mod. vet. Pract. 45: 48. 1964. 3. BIERSCHWAL, C. J. A technic for con- tinuous epidural anesthesia in the bovine. Vet. Med. 55: 44. 1960. 4. CAXALA, S. A technic for the para- vertebral lumbar block. Cornell Vet. 51: 64. 1961. 5. CHRISTIAN, PAUL. Anesthesia of the bovine eye. Veterinarian. 20: 79. 1960. 6. COLLIN, C. W. Hindlimb digital nerve block. Vet. Rec. 75: 833. 1963. 7. DESEo, L. Epidural anesthesia with novacain and alcohol. Magy Allatorv. Lap. 18: 323. 1963. FIGuRE 8. Inhalation anesthesia. jennings- 8. DIETZ, 0. Modern narcosis in cattle. Fischer anesthetic circle absorber. J.S. Afr. vet. med. Ass. 31: 321. 1960. 9. DOUGLAS, T. A., S. JENNINGS, J. LONG- STREETH, and A. D. WEAVER. Methoxy- Balanced Anesthesia flurane anesthesia in horses and cattle. Clinical use of balanced anesthesia is Vet. Rec. 76: 615. 1964. possible and has been used to some extent 10. GABEL, A. A. Local and regional anes- in Europe. This involves superficial anes- thesia. Mod. vet. Pract. 45: 39. 1964. thesia with nitrous oxide, muscle relaxation 11. GIBBONS, W. J. Technic for prolapsing with a short-acting neuromuscular blocking eyeball. Mod. vet. Pract. 43: 79. 1962. agent (succinylcholine) and controlled 12. HALL, L. W. Bromochlorotrifluoroethane (Fluothane) a new volatile anesthetic respiration (13). Other combinations in- agent. Vet. Rec. 69: 615. 1957. clude the use of inhalation agents, muscle 13. HANSSON, C. H., and D. JOHANNISSON. relaxants and assisted ventilation. All of Inhalation anesthesia with automatic arti- these require close supervision by a quali- ficial respiration during succinylcholine fied person. relaxation in large animals. Nord. Vet. Med. 10: 469. 1958. Electroanesthesia 14. JENNINGS, S. The use of volatile anes- This form of immobilization and anal- thetic agents in horses and farm animals. gesia has been attempted for many years. Can. vet. J. 4: 486. 1963. 15. JOHNSON, B. L. A rapid-acting anes- Experimentally there would appear to be thetic for comual nerve block. Mod. vet. some evidence of greater success with Pract. 45: 65. 1964. modem instrumentation but there are still 16. KOHLER, H. Spinal cord histopathology many factors to be studied before this can following epidural anesthesia. Berl. become a routine clinical procedure. Munch. tierarztl Wschr. 76: 46. 1963. 229 CANADIAN VETERINARY JOURNAL

17. LARSON, L. L. The internal pudendal 22. MUSSILL, J. Decubitus following epi- (pudic) nerve block for anesthesia of the dural anesthesia. Berl. Munch. tierarztl penis and relaxation of the retractor penis Wschr. 76: 45. 1963. muscle. J. Am. vet. med. Ass. 123: 18. 23. PETERSON, D. R. Nerve block of the 1953. eye and associated structures. J. Am. vet. 18. LITrTLE, R. B., and W. N. PLASTRIDGE. med. Ass. 118: 145. 1951. Bovine mastitis. First edition. Toronto: 24. RICHARDS, B. Report on a short dura- McGraw Hill Book Co. Inc. 1946. tion bovine anesthetic. Calif. Vet. 14: 22. 19. McFARLANE, I. S. The lateral approach 1961. to pudendal nerve block. J.S. Afr. vet. 25. ROBERTSHAW, D. Methohexital sodium med. Ass. 34: 73. 1963. anesthesia in calves. Vet. Rec. 76: 357. 20. MILNE, F. J. Efocaine-an aid in the 1964. treatment of bovine vaginal prolapse. 26. TOBE, S. B. Prolonged J. Am. vet. med. Ass. 124: 108. 1954. with alcohol. Can. vet. J. 1: 223. 1960. 21. MONAHAN, CAROLYN M. Methohexital 27. WILDE, J. K. H. Chloral hydrate anes- for induction of anesthesia. Vet. Rec. 76: thesia in calves. Br. vet. J. 118: 206. 1333. 1964. 1962.

ABSTRACTS Kolb, E. (1965). Does a large proportion pigs and horses on the farm. Of 477 of silage in the ration cause impairment of cattle, 21 were positive for S. miinster, health and milk yield in cows? Mh. Vet- seven for S. typhimurium and five for S. Med. 20, 50-56 (G.) (Vet. Physiol.-Chem. brandenburg. Of 275 pigs and 281 horses, Inst., Karl-Marx Univ., Leipzig). seven and two respectively were positive for S. miunster. No S. choleraesuis agglu- The ruminant digestive system can well tinins were detected. cope with even large amounts of silage and the considerable amounts of lactic Reprinted from "The Veterinary Bulletin", and acetic acid in silage are well tolerated. Vol. 36, No. 1, January, 1966. Harmful effects are mainly the result of lack of protein (when the diet consists predominantly of maize silage) and phos- phate. Bartley, E. E. (1965). Report on poloxa- lene-a new agent for the prevention of Reprinted from "The Veterinary Bulletin", legume bloat. Feedstuffs, Minneapolis 37, Vol. 36, No. 4, April, 1966. No. 39, p. 22 (Kansas State Univ., Man- hattan). Minev, M. (1965). Investigations into In field trials, 5-20 g. poloxalene, fed salmonellosis in cattle. Vet. Med. Nauki, daily for up to 113 days to cows and steers Sof. 2, 139-145 (B.e.r.) Opitno-diagno- on bloat-producing legumes, was highly stichna vet. Stantsiya, Kolarovgrad, Bul- effective in preventing bloat. Only a few garia. animals fed poloxalene bloated, and these had consumed less than half the poloxa- S. brandenburg and S. choleraesuis were lene offered. Little or no poloxalene was isolated from an aborted calf and its absorbed from the digestive tract, and it placenta, and from the placentae of two had no effect on rumen fermentation. Its other aborted calves. Later in the year on action appears to be due to its lowering the same farm, three other cows with pro- of surface tension, and as it is only slowly fuse diarrhoea aborted; S. miinster was broken down, this effect is maintained for isolated from one cow, while the other at least 12 hours. two gave positiveW serum agglutination tests for S. munster. Serum agglutination Reprinted from "The Veterinary Bulletin", tests were then carried out on all cattle, Vol. 36, No. 4, April, 1966. 230