In practice, anaesthesia of cattle under field conditions involves the application of local anaesthetic techniques such as flank anaesthesia, regional limb perfusion and caudal epidural anaesthesia in order to obtain suitable operating conditions without having to perform general anaesthesia. Caudal epidural anaesthesia can be divided into 2 different categories: High dose and low dose. High epidural anaesthesia involves administration of a relatively large volume of local anaesthetic to provide analgesia to more cranial body regions and is therefore used for surgeries on the hind limb and flank. The more common method is low epidural analgesia which differs only in the volume of the local anaesthetic injected. This technique is inexpensive, effective and practical and requires no sophisticated equipment. It is therefore relatively easy to perform under field conditions.Author has checked copyrightAMS. No abstract or keywords

Beltman, Marijke Eileen

Duane, M.

Self, I.

Research Repository UCD

Title The use of epidurals in cattleAuthors(s) Beltman, Marijke Eileen, Self, I., Duane, M.Publication date 2010-01Publication information Beltman, Marijke Eileen, I. Self, and M. Duane. “The Use of Epidurals in Cattle” 63, no. 1 (January, 2010).Publisher BioMed CentralItem record/more informationhttp://hdl.handle.net/10197/4664Downloaded 2023-11-01T04:02:15ZThe UCD community has made this article openly available. Please share how this accessbenefits you. Your story matters! (@ucd_oa)© Some rights reserved. For more information Practical Approach to Caudal Epidural Anaesthesia and sedation for flank and other 1 surgeries in Ruminants 2  3 Beltman M.E.1, Self I.2 and Duane M.1 4  5 1. Section of Herd and Veterinary Public Health, UCD School of Agriculture, Food Science 6 and Veterinary Medicine, University College Dublin, Belfield, Dublin 4. 7  8 2. University of Edinburgh, Easter Bush Veterinary Centre, Easter Bush, Roslin, Midlothian, 9 EH25 9RG, Scotland 10  11 Introduction 12 In practice, anaesthesia of cattle under field conditions involves the application of local 13 anaesthetic techniques such as flank anaesthesia, regional limb perfusion and caudal epidural 14 anaesthesia in order to obtain suitable operating conditions without having to perform general 15 anaesthesia. Caudal epidural anaesthesia can be divided into 2 different categories: High dose 16 and low dose. High epidural anaesthesia involves administration of a relatively large volume 17 of local anaesthetic to provide analgesia to more cranial body regions and is therefore used for 18 surgeries on the hind limb and flank. The more common method is low epidural analgesia 19 which differs only in the volume of the local anaesthetic injected. This technique is 20 inexpensive, effective and practical and requires no sophisticated equipment. It is therefore 21 relatively easy to perform under field conditions. 22  23 Technique for epidural anaesthesia. 24 In ruminants, the end of the spinal cord extends from the lumbar region into the midsacral 25 region and entrance into the spinal canal is achieved at the first coccygeal interspace (Co1-26 Co2). The other interspace that can be used is the sacrococcegeal space (S5-Co1), but this 27 space calcifies in older cattle. To identify the correct location, the tail is moved up and down 28 in a ‘pump-like’ fashion. The most proximal moving space palpable is the preferred location 29 for injection. After identification of the space, the skin is clipped and disinfected and an 18 30 gauge needle is used to penetrate the interspace directly in the dorsal midline in the adult cow. 31 The needle is directed in a slightly cranial direction and advanced until a ‘popping’ sensation 32 is felt. This pop indicates entrance into the epidural space. If the needle is advanced too far it 33 may contact the ventral floor of the spinal canal. If this occurs the needle should be 34 withdrawn slightly to ensure correct placement in the epidural space. Correct positioning of 35 the needle can be checked by placing a few drops of sterile water or lidocaine into the needle 36 hub during insertion and observing aspiration of the drop into the epidural space, which has 37 negative pressure (‘hanging drop technique’). Prior to injection it is important to apply 38 negative pressure to the syringe to ensure blood is not aspirated. If this occurs, the needle 39 should be withdrawn slightly and the syringe re-aspirated. Injection into the epidural space 40 should encounter no resistance. 41  42 Low dose epidural anaesthesia 43 Low dose epidural anaesthesia aims to desensitize the last three pairs of sacral nerves within 44 the spinal canal without impairment of motor function to the pelvic limbs. The anaesthesia 45 obtained by this low dose technique involves the tail and caudal reproductive tract and can 46 therefore be used in surgery of the vagina, vulva, anus, rectum, caudal prepuce, scrotum and 47 to perform urethrostomies. It can also be useful to control tenesmus and uterine contractions 48 during repair of a prolapsed rectum or vulva, repositioning of a prolapsed uterus, dystocia 49 with repositioning. 50  51 High dose epidural anaesthesia 52 High dose epidural anaesthesia aims to desensitise nerves further cranially and can lead to 53 anaesthesia as far cranial as the diaphragm, depending on the amount of local anaesthetic 54 used. This type of anaesthesia will lead to the animal becoming recumbent and it can, be used 55 for surgery of the hind legs. It has also been used for umbilical surgery in calves. The 56 technique and injection site are the same as for the low dose epidural, but the volumes are 57 higher than with the low dose. The positioning after the administration of the epidural will 58 determine the response of the animal as well as the distribution of the anaesthesia. Elevation 59 of the front of the animal will mean that the local anaesthetic will not distribute further than 60 the caudal end of the epidural space and elevation of the hind quarters will lead to the 61 anaesthetic solution being distributed more cranially. With most local anaesthetic solutions, 62 when the animal is positioned in lateral recumbency the anaesthetic will distribute better to 63 the side the animal is positioned on (the lower side), whereas dorsal recumbency will lead to 64 bilateral distribution of the anaesthetic solution. The major risk for this type of epidural is that 65 incorrect positioning or a volume that is too high can lead to the anaesthetic travelling too far 66 cranially with a chance of respiratory paralysis and death. Due to residual paralysis and 67 muscle weakness, it is also advisable to hobble the hind legs of animals recovering from this 68 type of anaesthesia as this will prevent abduction of the hind legs and as such unwanted 69 damage or paralysis of the obturator nerve. 70  71 Drugs 72 The most commonly used drug for low dose epidural anaesthesia is 2% lidocaine at a dose 73 rate of 0.2mg/kg (1ml/100 kg). Depending on the size of the animal cow the total volume that 74 is injected should be greater than 6 mls. There is a risk of paralysing the spinal nerves to the 75 hind limbs when the dose is too large leading to unwanted recumbency. Anaesthesia using 76 this technique usually occurs within 5 minutes and will last between 30 and 150 minutes 77 depending on the dose. Mild ataxia can occur. No anaesthetic effect after 10 minutes usually 78 indicates that the injection was not made into the epidural space. For high dose epidurals the 79 drug of choice is 2% lidocaine on its own in a maximum dosage rate of 2mg/kg bodyweight 80 (1ml/10kg). 81  82 Xylazine alone or added to lidocaine provides a longer duration of anaesthesia using the low 83 dose epidural technique. The dose used for xylazine anaesthesia on its own is 0.05 mg/kg (2% 84 xylazine) diluted into 5 ml sterile water. Onset of anaesthesia will be within 10 minutes and 85 the anaesthesia will last between 3-4 hours.  Xylazine in combination with lidocaine gives a 86 longer lasting anaesthetic effect. The dose of the xylazine in this mixture is 0.03-0.05mg/kg 87 made up to 5 ml with2% lidocaine. Onset of anaesthesia will be within 5 minutes and the 88 duration of anaesthesia up to 6 hours. The use of xylazine in an epidural not only gives longer 89 anaesthesia, but also gives mild to moderate sedation of the animal as well as mild ataxia with 90 an increased risk of recumbency, decreased ruminal motility and bradycardia. 91  92 The effectiveness of all epidurals can vary between animals due to minor differences in 93 distribution of the drugs in the epidural space. These differences in distribution are due to the 94 degree of negative pressure in the epidural space as well as variations in epidural fat content 95 between different animals; these factors can affect both the spread and pharmacokinetics of 96 the drugs used.  97  98 Applications 99 Low dose epidural anaesthesia gives regional analgesia of the tail, anus, vulva, perineum, 100 thighs and mid sacral region as well as relaxation of the anal sphincter and vagina and 101 cessation of straining. The aim of the anaesthesia is to leave the motor function of the hind 102 legs unaffected so that the animal remains standing. Applications for low dose epidural 103 analgesia are shown in table 1. The choice of drug depends on the desired effect. In 104 castrations analgesia is required, not only during the procedure but also during recovery. A 105 combination of xylazine and lidocaine is therefore the best option. For caesarean sections and 106 fetotomies it is necessary that the animal stops straining during the procedure. Lidocaine on 107 its own can be sufficient in these cases depending on the length of the procedure. However, it 108 is essential to ensure flank anaesthesia in addition to the epidural anaesthesia – epidurals do 109 not fully anaesthetise the flank skin, muscles or peritoneum. 110  111 Sedation via epidural injection 112 As described above, the epidural use of xylazine on its own or with lidocaine gives mild to 113 moderate sedation in animals. This knowledge was used by the authors to develop a method 114 in which the animal is sedated by epidural injection. Most procedures, such as flank 115 laparotomies and caesarean sections that are performed in the standing animal require the 116 animal to stand quietly with appropriate restraint. Sedation of the animal by intramuscular 117 injection can be helpful in this situation, but can be unpredictable also may have  the 118 undesired effect of the animal  becoming recumbent  and  in the case of a caesarean section  119 will sedate the calf. The use of xylazine administered into the epidural space for sedation 120 purposes only requires a small dose of xylazine and results in an animal that is 121 moderately sedated which will remain standing . Epidural xylazine also provides a 122 degree of flank analgesia which makes injection of regional lignocaine less painful 123 and therefore less difficult.  The dose of xylazine that was used was 0.016-0.018 124 mg/kg (0.4-0.5 ml of 2% xylazine made up to 5 ml with 0.9% saline for a 600 kg animal). 125 Compared with the intramuscular dose of 0.05 - 0.3 mg/kg this is a much lower dose. The 126 authors have used this method effectively in caesarean sections, in combination with flank 127 anaesthesia.  All cows remained standing in all cases and were effectively sedated. The calf 128 remained unaffected by the low doses of sedative used. This sedation method has also been 129 used in castrations and - flank surgery - in fractious animals. 130  131 Table 1: Applications of low dose epidural anaesthesia in cattle and the most common drugs 132 used for the different applications. 133  134  Lidocaine Lidocaine/Xylazine Castration Common Most common Vaginal prolapse Common Common Uterine prolapse Common Common Foetotomy Most common  Caesarian Most common   135  136 Epidurals in sheep and goats 137 Caudal epidural anaesthesia also has many applications in sheep and goats, but the main 138 practical use for an epidural in these animals would be correction of dystocia and 139 replacement/retention of a vaginal and/or rectal prolapse. However, since caesarean section in 140 these animals is usually performed in lateral recumbency and it is not necessary for the animal 141 to remain standing, a higher dose epidural could also be used for this procedure as well as for 142 surgery on the hind limbs. The epidural technique used is much the same as the one used in 143 cattle, but as it is sometimes harder to find the first intercoccygeal space (Co1-Co2), the most 144 common place used is the sacrococcegeal space (S5-Co1). Both these sites can be identified 145 in standing animals as well as animals in lateral recumbency. After identifying the space by 146 movement of the tail and palpation the area should be clipped and surgically prepared. With 147 the tail held horizontally, a 20 gauge needle should then be inserted at an angle of 148 approximately 20-30° towards the tail. The insertion should be done very gently as the ‘pop’ 149 sensation that is felt in cattle is not as clear in small ruminants which could lead to penetration 150 of the nerves in the epidural space. This has the effect of making the animal jump with 151 movement of the needle and possible unwanted bleeding as a consequence. Anaesthetic 152 solution should be injected slowly as in small ruminants the total volume of spinal fluid is a 153 lot less than in cows and fast addition of extra fluid can lead to a dangerous increase of 154 intracranial pressure followed by CNS and cardiovascular collapse. Again, the position of the 155 animal after injection is important when dealing with the higher dose type of anaesthesia. 156 Higher dose anaesthesia involves the administration of 1ml/7kg bodyweight of 2% lidocaine 157 with or without adrenaline which will give flank analgesia for a maximum of 2 hours.  With 158 these high doses it will take at least 3.5 hours of recovery time before the animal has regained 159 total control of its legs and is standing again.  160 For the correction of dystocia and retention of prolapses, the volume of the local anaesthetic is 161 reduced but care should still be taken during injection and recovery. Drugs used for these 162 procedures are again 2% lidocaine alone or a combination of 2% lidocaine with 2% xylazine. 163 Dosage for the lidocaine alone is 0.5mg/kg with a maximum volume of 2 mls/animal. Dosage 164 for the combination is 0.07mg/kg of  2% xylazine and dose of 0.5mg/kg of 2%  lidocaine.  165  166  167 Additional reading 168 Skarda, R.T. 1996. Local and regional anesthesia in ruminants and swine. Veterinary Clinics 169 of North America: Food Animal Practice. Volume 12, no. 3 170  171 Hall, L.W., Clarke, K.W, Trim, C.M. 2001. Veterinary Anaesthesia 10th edition. WB 172 Saunders 173  174 Muir, W.W., Hubbel, J.A.E and Skarda, R.Y. et al (eds). 1995. Handbook of Veterinary 175 Anesthesia. St. Louis, Mosby Year Book. 176 

Practical Approach to Caudal Epidural Anaesthesia and sedation for flank and other surgeries in Ruminants

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