Dexmedetomidine and Bupivacaine Association in Caudal Epidural Injection in Mares

The objective of the study was to compare the effects of caudal epidural bupivacaine and dexmedetomidine (DEX) combination, with bupivacaine or DEX plain for perineal analgesia in mares. Six healthy saddle mares weighing 330–370 kg and aged 10–15 years were used in this study. Each mare was assigned to receive three treatments: 0.04 mg/kg 0.25% bupivacaine (BP), 2 μg/kg DEX (DX), or 0.02 mg/kg bupivacaine and 1 μg/kg DEX (BPDX). The order of treatments was randomized. All drugs were injected into the caudal epidural space (Co1-Co2) through a 16-G Tuohy epidural needle. After the epidural injections, heart rate, respiratory rate, arterial blood pressures (systolic, diastolic, and mean), and rectal temperature were measured at 5, 10, 15, 30, 60, 90, and 120 minutes, and after this time, every 60 minutes until the end of the experiments. A subjective score system was used to assess analgesia, behavioral and motor blockade at the same time points. The BPDX treatment produced analgesic action with twice the duration (200 minutes) of the BP treatment (97 minutes), but with an analgesic duration shorter than the DX treatment (240 minutes) in the regions of the tail, perineum, and upper hind limbs in mares. All treatments showed mild motor blockade. No behavioral changes were observed in any of the animals. There was hemodynamic stability without significant changes in respiratory rate for all treatments. Epidural analgesia using DEX alone or the combination of DEX and bupivacaine may be an option for painful obstetric and gynecological procedures in mares.     

Thoracic epidural analgesia via the lumbosacral approach using multiport catheters with a low concentration of bupivacaine and morphine in sheep

ObjectiveTo determine the analgesic and systemic effects of thoracic epidural administration of bupivacaine (BP) and morphine (MP) in conscious sheep.Study designRandomized, crossover, experimental study.AnimalsSix healthy castrated sheep weighing between 40 and 50 kg.MethodsEach sheep received, via the lumbosacral approach, BP (0.5 mg kg^?1), MP (0.1 mg kg^?1), and BP plus MP (BPMP; 0.25 mg kg^?1 + 0.05 mg kg^?1) in a randomized order. Heart rate, blood pressure, respiratory rate, blood gas analysis, skin temperature, rectal temperature, analgesia, sedation, and motor blockade were determined before treatment and at predetermined intervals until analgesia had disappeared.ResultsThe main areas of complete analgesia for the BP and BPMP treatments were the thorax and forelimb bilaterally. The median duration of analgesia was shorter with MP treatment (45 minutes; score 2) than with BP treatment (70 minutes) and BPMP treatment (140 minutes; p < 0.05). The BP and BPMP treatments caused motor block, and MP and BPMP treatments showed mild sedation. Significant decreases in systolic and diastolic arterial blood pressures were observed only with the BP treatment (p < 0.05). Epidural MP combined with the BP local anesthetic depressed ventilation but within acceptable limits in these clinically healthy sheep.ConclusionsThoracic epidural administration of BPMP to sheep resulted in longer duration of analgesia of the thorax and forelimbs bilaterally in conscious sheep than the administration of MP or BP alone. The incidence of complications was low, but side-effects such as depressed ventilation and muscle paralysis occurred and require appropriate management.Clinical relevanceThis technique should be considered as another method for the relief of postoperative pain after thoracic surgery in sheep.     

Perineal analgesia and hemodynamic effects of the epidural administration of meperidine or hyperbaric bupivacaine in conscious horses

Epidural administration of bupivacaine and meperidine produces analgesia in several animal species and in humans. A prospective randomized study was conducted in 18 healthy horses to compare the effect of these 2 drugs administered by the epidural route. Animals were divided into 3 treatment groups of 6 animals each. All drugs were injected by the epidural route in all animals between the 1st and 2nd coccygeal vertebrae. Treatment 1 (BUP)--0.06 mg/kg of body weight of 0.5% hyperbaric bupivacaine; treatment 2 (MEP)--0.6 mg/kg of body weight of 5% meperidine; treatment 3 (SS)--0.9% saline solution (control group). Heart rate, arterial pressure, respiratory rate, rectal temperature, analgesia, sedation, and motor-blocking were determined before drug administration (baseline values); at 5, 10, 15, and 30 minutes after drug administration, and then at 30-minute intervals thereafter. Both hyperbaric bupivacaine and meperidine administered epidurally produced complete bilateral perineal analgesia in all horses. The onset of analgesia was 6, s = 2.6 minutes after injection of bupivacaine, as opposed to 9, s = 2 minutes after meperidine. The duration of analgesia was 240, s = 57 minutes for meperidine and 320, s = 30 minutes for bupivacaine. Heart and respiratory rates, arterial pressure, and rectal temperature did not change (P < 0.05) significantly from basal values after the epidural administration of bupivacaine, meperidine, or saline solution. To conclude, both bupivacaine and meperidine induced long-lasting perineal analgesia, with minimal cardiovascular effects. Analgesia was induced faster and lasted longer with bupivacaine.     

Analgesic, hemodynamic, and respiratory effects induced by caudal epidural administration of meperidine hydrochloride in mares.

OBJECTIVE: To determine the analgesic, hemodynamic, and respiratory effects induced by caudal epidural administration of meperidine hydrochloride in mares. ANIMALS: 7 healthy mares. Procedure: Each mare received meperidine (5%; 0.8 mg/kg of body weight) or saline (0.9% NaCl) solution via caudal epidural injection on 2 occasions. At least 2 weeks elapsed between treatments. Degree of analgesia in response to noxious electrical, thermal, and skin and muscle prick stimuli was determined before and for 5 hours after treatment. In addition, cardiovascular and respiratory variables were measured and degree of sedation (head position) and ataxia (pelvic limb position) evaluated. RESULTS: Caudal epidural administration of meperidine induced bilateral analgesia extending from the. coccygeal to S1 dermatomes in standing mares; degree of sedation and ataxia was minimal. Mean (+/- SD) onset of analgesia was 12 +/- 4 minutes after meperidine administration, and duration of analgesia ranged from 240 minutes to the entire 300-minute testing period. Heart and respiratory rates, rectal temperature, arterial blood pressures, Hct, PaO2, PaCO2, pHa, total solids and bicarbonate concentrations, and base excess were not significantly different from baseline values after caudal epidural administration of either meperidine or saline solution. CONCLUSIONS AND CLINICAL RELEVANCE: Caudal epidural administration of meperidine induced prolonged perineal analgesia in healthy mares. Degree of sedation and ataxia was minimal, and adverse cardiorespiratory effects were not detected. Meperidine may be a useful agent for induction of caudal epidural analgesia in mares undergoing prolonged diagnostic, obstetric, or surgical procedures in the anal and perineal regions.     

Epidural administration of tiletamine/zolazepam in horses

Objectives To evaluate the analgesic, physiologic, and behavioral effects of the epidural administration of tiletamine/zolazepam in horses. Study design Prospective, double‐blind, randomized experimental study. Animals Five adult, healthy horses aged 10–16 years and weighing (mean ± SD) 400 ± 98 kg. Methods The horses were sedated with 1.0 mg kg^?1 intravenous (IV) xylazine, and an epidural catheter was placed into the first intercoccygeal intervertebral space. After a 48‐hour resting period, epidural tiletamine/zolazepam, 0.5 mg kg^?1 (treatment I) or 1.0 mg kg^?1 (treatment II), diluted up to 5 mL in sterile water, was administered with a 1‐week interval between the treatments. Heart rate, respiratory rate, arterial blood pressure, and sedation were evaluated. In order to evaluate the respiratory effects, blood from the carotid artery was withdrawn at time 0 (baseline), and then after 60 and 240 minutes. Analgesia was evaluated by applying a noxious stimulus with blunt‐tipped forceps on the perineal region, and graded as complete, moderate, or absent. Data were collected before tiletamine/zolazepam administration and at 15‐minute intervals for 120 minutes, and 4 hours after tiletamine/zolazepam administration. Data were analyzed with anova and Bonferroni's test with p < 0.05. Results The results showed no significant difference between treatments in cardiovascular and respiratory measurements. Sedation was observed with both doses, and it was significantly different from baseline at 60, 75, and 90 minutes in treatment II. Moderate analgesia and locomotor ataxia were observed with both the treatments. Conclusions and clinical relevance The results suggest that caudal epidural 0.5 and 1.0 mg kg^?1 tiletamine/zolazepam increases the threshold to pressure stimulation in the perineal region in horses. The use of epidural tiletamine/zolazepam could be indicated for short‐term moderate epidural analgesia. There are no studies examining spinal toxicity of Telazol, and further studies are necessary before recommending clinical use of this technique.     

Sedation and Pain Management with Intravenous Romifidine−Butorphanol in Standing Horses

The objective of this study was to determine the sedation, analgesia, and clinical reactions induced by an intravenous combination of romifidine and butorphanol in horses. The study was conducted on six saddle horses weighing 382 to 513 kg (mean ± SD; 449 ± 54 kg) and aged 6 to 14 years. The horses each underwent three treatments: intravenous romifidine 0.1 mg/kg body weight (RM; mean dose, 4.5 mL); intravenous butorphanol 0.05 mg/kg body weight (BT; mean dose, 2.4 mL); and intravenous romifidine 0.1 mg/kg body weight plus butorphanol 0.05 mg/kg body weight (RMBT; mean dose, 7.0 mL). The order of treatments was randomized. Heart rate, arterial pressure, respiratory rate, rectal temperature, sedation, and analgesia were measured at two times before treatments, 15 minutes apart (times –15 and 0) and at 5, 10, 15, 30, 45, 60, 75, 90, 120, 150, and 180 minutes after drug administration. The onset of sedation was approximately 5 minutes after intravenous injection of RM and RMBT, whereas BT did not present this effect. The duration of complete sedation was approximately 60 minutes for RMBT and approximately 35 minutes for RM. The RMBT treatment provided 30 minutes and the RM treatment 20 minutes of complete analgesia. Heart rate decreased significantly (P < .05) from basal values in the RM and RMBT treatments. Only RM caused significant decreases (P < .05) in the respiratory rate. Arterial pressure did not change significantly (P > .05) in any treatment. Intravenous administration of a romifidine−butorphanol combination to horses resulted in longer duration of sedation and analgesia than administration of romifidine or butorphanol alone. These effects probably resulted from a synergistic effect of the two drugs.     

Epidural Injection of Ketamine for Perineal Analgesia in the Horse

Objective—To determine the analgesic, sedative, and cardiopulmonary effects of epidural ketamine in the horse. Animal Population—Six healthy horses (three males and three females) weighing between 350 and 450 kg. Methods—Three doses of ketamine were selected (0.5, 1, and 2 mg/kg). Two months before the beginning of experiments, the carotid artery was exteriorized, and 1 week before experiments began, an epidural catheter was placed percutaneously in all animals with the tip located 12 cm cranially in the midsacrum. One week later, either saline (control) or one of three doses of ketamine was injected epidurally. Each animal received each ketamine dose and saline in random order at 1-week intervals. Ketamine was diluted in saline 0.9% before the experiment, and the volume used was adjusted to horse size and correlated to clinically used volumes. All the animals received a standard noxious stimulus consisting of needle insertion into the skin and deep muscle using a 3-point scale for scoring the response. A second scale was used to score the degree of sedation. The response to a noxious stimulus, the degree of sedation, and arterial blood pressure were assessed at previously determined intervals: before drug and 2, 5, 10, and 15 minutes and every 15 minutes to 210 minutes after ketamine or saline administration. Arterial blood samples were drawn for blood gas analysis before drug and at 15, 30, 60, and 90 minutes. Results—All the tested doses of ketamine were effective in producing analgesia of the tail, perineum, and upper hindlimb. Total tail and perineal analgesia times were similar depending on dosage (30 minutes for 0.5 and 1.0 mg/kg and 75 minutes for 2.0 mg/kg). A sedative effect of ketamine was also observed in a dose-response manner with a peak effect between 15 and 30 minutes postadministration. No cardiopulmonary effects were observed with any dose of ketamine. Conclusions—Results indicate that epidurally administered ketamine in the horse produces local spinal and central nervous system effects with analgesia and sedation but minimal cardiopulmonary effects. Clinical Relevance—Further studies are required to determine whether the analgesia is sufficient for surgery.     

L-Bupivacaine 0.5% vs. racemic 0.5% bupivacaine for caudal epidural analgesia in horses

Bupivacaine is available as a racemic mixture of its enantiomers, d -bupivacaine and l -bupivacaine (LB). The aim of this randomized, double-blind study was to investigate the clinical efficacy and safety of S(−)-bupivacaine compared with standard racemic bupivacaine (RB) in horses under caudal epidural analgesia. Two treatments were administered to each horse, with a 2-week interval between subsequent treatments. Treatment 1 consisted of 0.5% LB at a dose of 0.06 mg/kg of body weight, and treatment 2 consisted of 0.5% RB at a dose of 0.06 mg/kg of body weight. Epidural injections were given in all animals between the first and second coccygeal vertebra. Heart rate (HR), arterial pressures, respiratory rate (RR), rectal temperature (RT), analgesia, and motor blocking were determined before drug administration (basal) and 5, 10, 15 and 30 min after drug administration, and at 30 min intervals thereafter. There were no significant differences between the two treatments in the quality of sensory and motor block. The duration of analgesia was 320 ± 30 min (mean ± SD) for RB and 360 ± 42 min for LB. HRs and RRs, arterial pressures and RT did not change ( P  < 0.05) significantly from basal values after epidural administration of LB or RB. This study supports that 0.5% LB is an effective alternative to RB in caudal epidural analgesia in conscious, standing horses. The use of LB vs. RB warrants further investigation, particularly for long-lasting surgery in the perineal region.     

Clinical use of epidural xylazine in the horse

Xylazine was administered into the epidural space of nine horses to facilitate various perineal manipulations (ie rectovaginal laceration repair, replacement of prolapsed rectum and urethral extension). The resulting caudal analgesia was sufficient for all procedures. The duration of analgesia from a single injection of epidural xylazine (0.17 to 0.22 mg/kg bodyweight) was at least 3.5 h. No horses were ataxic during or after the treatment. This trial demonstrates that xylazine given into the epidural space of horses provides prolonged regional analgesia which is sufficient for clinical use.     

Caudal epidural co-administration of methadone and morphine in horses: An evaluation of analgesic properties and effects on locomotor function,mentation and physical examination parameters

Caudal epidural analgesia is a well-established therapeutic modality for pain alleviation in horses. Additionally, epidural analgesia could potentially be a complementary diagnostic tool for confirmation of pain-related conditions in horses presenting with nonspecific signs of poor performance or rideability issues. To use the epidural as a diagnostic tool, the administered medications should provide efficient analgesia without accompanying adverse effects. Therefore, the objectives of the current study were to evaluate the analgesic properties and effects on locomotor function, mentation and physical examination parameters of caudal epidural co-administration of methadone and morphine in horses. Five mares received a caudal epidural injection of 0.1 mg/kg bwt methadone and 0.1 mg/kg bwt morphine diluted to a total volume of 4.4 mL/100 kg. Before and several times thereafter, horses were subjected to mechanical nociceptive threshold evaluation, physical examination, assessment of mentation and locomotor function examination. Horses were assigned ataxia scores (0–4) by a group of inexperienced raters (three senior-year veterinary students) and a group of experienced raters (two board-certified internal medicine specialists) that assessed the locomotor examinations either live or video-based. The epidural co-administration of methadone and morphine resulted in clinically relevant and statistically significant increases of horses’ tolerance to mechanical noxious stimuli at the coccygeal, perineal, sacral, lumbar and thoracic regions. Analgesia was evident after 4.4 h and lasted at least 5 h. Regional differences in the onset of analgesia reflected a cranial spread of the analgesic solution. No horses showed signs of gait disturbances; the overall median ataxia score was 0 at all times; and the average difference in scores between two randomly selected raters for a random horse at a random time point was 0.377 indicating high inter-rater agreement. There were no adverse changes of mentation and physical examination parameters. Observed side effects included signs of decreased frequency of defaecation, generalised sweating, and pruritus.     

Efficacy of concurrent epidural administration of neostigmine and lidocaine for perineal analgesia in geldings

Objective-To evaluate perineal analgesic effects of 3 doses of neostigmine coadministered epidurally with lidocaine to geldings. Animals-6 healthy geldings. Procedures-A few days before each treatment, a catheter was inserted between the first and second coccygeal vertebrae via the caudal approach in each gelding; the catheter tip was threaded approximately 10 cm cranial into the midsacral region. Each horse received 4 epidural treatments: 2% lidocaine (0.2 mg/kg) alone and 3 doses of neostigmine (0.5, 1, or 2 μg/kg) coadministered with that same dose of lidocaine. Horses were restrained in stocks in a standing position. Heart rate, blood pressure, respiratory rate, rectal temperature, intestinal motility, analgesia, behavior, and ataxia were determined before treatment (time 0; baseline); at 5, 10, 15, 30, 45, 60, 75, and 90 minutes; and every 30 minutes thereafter until the cessation of analgesia. Results-All doses of neostigmine coadministered with lidocaine improved and extended the duration of analgesia in the perineal region of the geldings. Total duration of analgesia was not a dose-dependent effect (120, 150, and 150 minutes for 0.5, 1, and 2 μg/kg, respectively). All treatments induced mild or moderate ataxia. Cardiovascular changes were within acceptable limits. Conclusions and Clinical Relevance-Administration of neostigmine (1 μg/kg) combined with lidocaine (0.2 mg/kg) in the caudal epidural space induced analgesia for 2.5 hours with a low prevalence of adverse effects in standing conscious geldings. Epidural doses of neostigmine greater than these should be avoided because they may cause undesirable effects in geldings.     

A comparison of the analgesic effects of caudal epidural methadone and lidocaine in the horse

Objective To evaluate and compare the effects of caudal epidural administration of methadone (METH) and lidocaine (LIDO) on tolerance to thermal stimulation over the dermatomes of the perineal, sacral, lumbar and thoracic regions in the horse. Study design A blinded, randomized, prospective, experimental cross‐over study. Animals Seven healthy horses, 15.7 ± 4.9 years (mean ± SD) of age, weighing 536 ± 37 kg. Methods The horses were randomly assigned to receive two treatments (group M: METH, 0.1 mg kg^?1 or group L: LIDO, 0.35 mg kg^?1) at intervals of at least 28 days. An 18‐gauge 80‐mm Tuohy epidural needle was placed in the first intercoccygeal space (Co1–Co2) in awake standing horses restrained in stocks. Analgesia was assessed by use of a probe maintained at a constant 62 °C by circulating hot water. The maximum stimulation time was 30 seconds. Bilateral stimulation was performed at five defined points. Before drug administration, baseline values of response time to thermal stimuli were obtained. Time to response was then measured 15 and 60 minutes after METH or LIDO administration and then hourly until the response returned to baseline at all stimulation points on two further assessments. Development of any ataxia and/or sedation was recorded. Positive pain responses were defined as purposeful avoidance movements of the head, neck, trunk, limbs and tail. Absence of attempts to kick, bite and turning of the head toward the stimulation site were used to indicate analgesia. Results Caudal epidural administration of METH and LIDO significantly increased reaction time to thermal stimulation (one‐sample t‐test; p = 0.05). Analgesia in the perineal region was present 15 minutes after both METH and LIDO administration and progressed from caudal to cranial dermatones with time. The duration of a significant increase in reaction time was 5 hours after METH injection compared to 3 hours following LIDO. All horses defaecated and urinated normally, and no excitement, sedation or ataxia were observed after METH administration. The horses were unable to defaecate normally and were moderately to severely ataxic with hindlimb weakness after LIDO. Conclusions Caudal epidural administration of methadone has considerable potential in the management of perineal, lumbo‐sacral and thoracic pain in horses. Regional differences exist in the onset, duration and intensity of the pain relief. Clinical relevance Epidural methadone administration provides analgesia with no measured side effects in these healthy adult horses.     

Bovine Chlamydophila spp. infection: Do we underestimate the impact on fertility?

The efficacy of ketamine and bupivacaine in enhancing the epidural analgesia induced by medetomidine was evaluated in 10 buffalo calves utilized repeatedly after a gap of 10 days so that each drug combination was tested in 4 randomly selected animals. In group A, medetomidine (15 microg/kg), in group B ketamine (2.0 mg/kg), in group C bupivacaine (0.125 mg/kg), in group D medetomidine and ketamine (15 microg/kg and 2.0 mg/kg), and in group E medetomidine and bupivacaine (15 microg/kg and 0.125 mg/kg) was administered epidurally. Onset of analgesia was significantly earlier in animals of groups B and D compared to the animals of groups A, C and E. Medetomidine alone or in combination with ketamine/bupivacaine produced complete analgesia of the tail, perineum, inguinal region and upper parts of hind limbs. Ketamine produced a very short duration of complete analgesia at the tail and perineum. Bupivacaine alone produced only mild to moderate analgesia. Both ketamine and bupivacaine prolonged the duration of analgesia. Motor incoordination was mild to moderate in animals of all the groups, but animals remained standing throughout the period of observation. Animals of groups A, D and E showed mild to moderate sedation during the observation period. Ruminal movements decreased nonsignificantly in animals of groups A and E. Mild salivation was observed in animals of all the groups except group C. Significant decrease in heart rate (HR) was recorded after epidural administration of medetomidine or bupivacaine; however, ketamine caused short duration of tachycardia. The administration of ketamine with medetomidine caused lesser decrease in HR compared to medetomidine alone or in combination with bupivacaine. Significant fall in respiratory rate (RR) was recorded after epidural administration of medetomidine or bupivacaine alone, but an increase in RR was recorded after ketamine administration. The fall in RR was less pronounced in animals in which medetomidine was used with ketamine compared to the animals in which medetomidine was used alone or in combination with bupivacaine. Mean arterial pressure (MAP) decreased and central venous pressure (CVP) increased significantly after epidural administration of medetomidine in combination with ketamine or bupivacaine. The ECG changes included tall T wave, QS pattern, RS pattern and ST elevation and heart blocks at different intervals, which were more frequent and pronounced in animals given bupivacaine with medetomidine. It can be concluded that epidural administration of medetomidine can produce complete analgesia of the tail, perineum, inguinal region and upper hind limbs in buffaloes. However, significant depression of cardiovascular parameters was recorded. Administration of ketamine along with medetomidine resulted in significantly early onset and slightly longer duration of analgesia with lesser cardiopulmonary side-effects compared to medetomidine alone or medetomidine with bupivacaine. Addition of ketamine to medetomidine thus seems to be useful for producing epidural analgesia; however, addition of bupivacaine failed to provide any advantage over medetomidine alone.     

Meperidine prolongs lidocaine caudal epidural anaesthesia in the horse

The aim of the study was to evaluate and compare the effects of caudal epidural administration of meperidine (MP), lidocaine (LD), and a combination of the two (MPLD) in six mature saddle horses. Horses were randomly assigned to receive three treatments (MP 0.3 mg/kg; LD 0.2 mg/kg; and MPLD: MP 0.3 mg/kg and LD 0.2 mg/kg), with at least 1 week between treatments. Drugs were injected into the epidural space between the first and second coccygeal areas in conscious standing horses. Analgesia, ataxia, sedation, cardiovascular and respiratory effects, and rectal temperature were recorded at different intervals before (baseline) and after administration. Epidural administration of MPLD resulted in a longer duration of analgesia of the tail, perineum, and upper hind limb regions than did administration of MP or LD alone.     

Epidural anesthesia and analgesia in horses.

Intercoccygeal, or caudal, epidural injection of local anesthetics is a convenient method of producing analgesia and local anesthesia of the tail and perineal structures in conscious standing horses. This technique has been further developed to provide long duration analgesia and anesthesia by placement of catheters into the epidural space of horses. More recently, opioid, alpha-2 adrenergic agonists, ketamine and other analgesic agents have been administered by caudal epidural injection, providing pain relief in both conscious, standing and anesthetized, recumbent horses. This chapter describes the development of different anesthetic and analgesic epidural techniques in horses, methods for epidural injection and catheterization, and reviews the current literature related to epidural analgesia and pain control in horses.     

Pharmacokinetics of Tramadol after Epidural Administration in Horses

Tramadol is a centrally acting analgesic structurally related to codeine and morphine. The aim of the present study was to evaluate the pharmacokinetic of tramadol and its major metabolites after caudal epidural administration in the horse. Six gelding male adult horses were assigned to receive epidural administration of tramadol at 2 mg/kg. Plasma substances detection was achieved using a HPLC-FL method. Tramadol was detectable after 5 minutes up to 8 hours after epidural administration. Metabolites plasma concentrations were found under the limit of quantification of the method; however negligible amounts of M2 was detected from 30 min up to 1 hour in three subjects. In conclusion, this study shows that tramadol administered by caudal route in horses produces plasma concentrations within the extrapolated therapeutic range from humans for sufficient time to provide analgesia. Further study of the drug's safety and efficacy for the treatment of pain in horses is warranted.     

Epidural injection of xylazine for perineal analgesia in horses

Local anesthetics given in the epidural space of a horse may cause hind limb weakness in addition to analgesia. Because alpha 2 agonists given by epidural injection cause sensory blockade without motor effects in human beings and other species, their use in veterinary anesthesia is appealing. This study was designed to examine the effectiveness of xylazine HCl, an alpha 2 agonist commonly used in horses. Xylazine, 0.9% NaCl, and lidocaine were given by epidural injection to horses subjected to perineal electrical stimulation. Administration of xylazine (0.17 mg/kg of body weight, diluted to a 10-ml volume, using 0.9% NaCl) induced approximately 2.5 hours of local analgesia without apparent side effects. Higher doses of xylazine caused mild hind limb ataxia. Administration of lidocaine induced a similar duration of analgesia, with severe hind limb ataxia (100% incidence). We concluded that xylazine given by epidural injection results in safe, effective perineal analgesia in horses.     

RESEARCH PAPER: Segmental dorsolumbar epidural analgesia via the caudal approach using multiple port catheters with ketamine or lidocaine or in combination in cattle

ObjectiveTo determine the analgesic and systemic effects of epidural administration of ketamine, lidocaine or a combination of ketamine/lidocaine in standing cattle.Study designProspective, randomized, experimental trial.AnimalsSix healthy male cattle weighing between 335 and 373 kg.MethodsThe animals received 0.5 mg kg^?1 of ketamine (K), 0.2 mg kg^?1 of 2% lidocaine (L) or 0.25 mg kg^?1 ketamine plus 0.1 mg kg^?1 lidocaine (KL). All the drugs were injected into the dorsolumbar epidural space via a caudal approach through a non‐styletted multiple‐port catheter. Each animal received each treatment at random. Evaluations of analgesia, sedation, ataxia, heart rate, arterial pressure, respiratory rate, skin temperature and rectal temperature were obtained at 0 (basal), 5, 10, 15, 30, 45, 60, 75, 90 minutes after epidural injection, and then at 30‐minute intervals until loss of analgesia occurred. Skin temperature was taken at these intervals up to 60 minutes. All the animals received a standard noxious stimulus; a 4‐point scale was used to score the response. A second scale was used to score ataxia and a third for sedation.ResultsThe duration of analgesia in the upper and lower flanks in cattle was 140 ± 15, 50 ± 14 and 80 ± 22 minutes (mean ± SD) after dorsolumbar epidural KL, K or L, respectively. The cardiovascular changes were within acceptable limits in these clinically healthy cattle.ConclusionsDorsolumbar epidural administration of KL to cattle resulted in longer duration of analgesia of the upper and lower flanks in standing conscious cattle, than the administration of K or L alone.Clinical relevanceFurther research is necessary to determine whether this combination using this technique provides sufficient analgesia for flank surgery in standing cattle.     

Clinical assessment of epidural analgesia induced by xylazine-lidocaine combination accompanied by xylazine sedation in calves

: The aim of the present study was to investigate whether epidural administration of a xylazine-lidocaine combination accompanied by xylazine sedation would provide satisfactory analgesia for some surgical procedures on 10 calves admitted to the Department of Veterinary Surgery, University of Kafkas with perineal urolithiasis (n:2), rectovaginal fistula (n:1), atresia ani (n:2), omphalophlebitis (n:2), omphaloarteritis (n:1) and umbilical hernia (n:2).Following intramuscular injection of xylazine at a dose of 0.05 mg/kg for sedation, xylazine-lidocaine combination (0.2 mg/kg lidocaine + 0.02 mg/kg xylazine + 5 ml 0.9% NaCl) was administrated into the lumbosacral (L6-S1), sacrococcygeal (S5-Co1) or intercoccygeal (Co1-Co2) space. Heart rate, respiratory rate and rectal temperature were recorded prior to and during analgesia at 5, 10, 15, 30 and 60 minutes. Furthermore, depth and duration of analgesia were evaluated during surgical intervention.The study revealed that the combination of epidural xylazine-lidocaine with xylazine sedation was highly satisfactory for surgery of the lower urinary tract and the perineal region, but it was less so for surgery of the umbilical area.     

Caudal epidural analgesia in cattle using xylazine.

Each of 25 mature Holstein cows were given a single 5 mL epidural injection of one of four different concentrations of xylazine or saline. The onset, magnitude and duration of caudal epidural analgesia was quantitated with the use of a low voltage DC current applied to the perineal area. The dose that produced the longest duration of analgesia and produced the least ataxia or sedation was approximately 0.05 mg/kg (25 mg in 5 mL diluent). The analgesia produced by this xylazine dose was compared to a standard dose of epidural lidocaine (100 mg/5 mL) by the same method. To investigate the role of systemic absorption in the production of epidural analgesia, the previously utilized epidural xylazine dosage was given intramuscularly to four adult cows. Analgesia was quantitated as before and the results compared with epidural xylazine. Epidural xylazine produced a significantly greater duration of analgesia, as measured by this model, than did epidural lidocaine. Xylazine, given epidurally, produced greater perineal analgesia than did xylazine given intramuscularly.