Intra-articular lidocaine plus bupivacaine in sheep undergoing stifle arthrotomy

Objective To evaluate the effect of intra‐articular (IA) lidocaine plus bupivacaine on post‐operative pain in sheep undergoing stifle arthrotomy. Study design Randomized controlled experimental trial. Animals Sixteen adult Rambouillet‐cross ewes. Methods Sheep were randomly assigned to one of two treatment groups. The lidocaine/bupivacaine group (L/B, n = 8) received IA lidocaine (40 mg (2 mL)) prior to incision and IA bupivacaine (10 mg (2 mL)) post‐closure, while the control group (n = 8) received no IA injections. IA local anesthetics were an addition to the standard analgesic protocol of phenylbutazone (1 g orally, every 24 hours for 5 days) and transdermal fentanyl (equivalent to 15 mg), initiated 24 hours prior to surgery. A stifle arthrotomy was performed with the purpose of creating a full‐thickness articular cartilage defect. Two observers blinded to treatment assessed sheep for total pain score using a numeric ranking scale that included: comfort, movement, and flock behavior. The first observation (T = 0) was obtained the evening of surgery (3–7 hours post‐operatively); subsequent observations occurred every 12 hours for 72 hours. Nonparametric statistical tests were used to evaluate differences between groups for total pain score. Results L/B sheep had significantly lower total pain scores at T = 0 than control sheep (p < 0.05). No significant differences between treatments were noted at any subsequent time periods. There were no differences attributable to the use of different observers. Conclusions and clinical relevance IA lidocaine plus bupivacaine provided analgesia at 3–7 hours post‐operatively. Use of IA lidocaine and bupivacaine is a simple, effective, yet inexpensive perioperative analgesic protocol for joint surgery in sheep.     

Long-term degeneration and regeneration of the rabbit facial nerve blocked with conventional lidocaine and bupivacaine solutions

The alterations due to the long-term degeneration and regeneration of the rabbit facial nerve were investigated. The facial nerve was blocked with conventional lidocaine and bupivacaine solutions. The rabbits were sacrificed and facial nerves were removed 2, 4, 6 and 8 weeks after the administration of normal saline, lidocaine and bupivacaine. The samples were then processed for electron microscopic observation. Degenerations were seen 2-4 weeks after the injection of normal saline, lidocaine and bupivacaine. In the normal saline group the regeneration process was observed after 6 weeks, whereas in the lidocaine and bupivacaine groups this process was first noticed after 8 weeks. In the lidocaine and bupivacaine groups, regeneration was not completed at the end of 8 weeks; however, it was faster in the bupivacaine group. Bupivacaine is therefore suggested as the drug of choice for neural blockade as it caused less damage and a faster regeneration.     

Assessment of brachial plexus blockade in chickens by an axillary approach

ObjectiveTo assess the brachial plexus block in chickens by an axillary approach and using a peripheral nerve stimulator.Study designProspective, randomized, double-blinded study.AnimalsSix, 84-week old, female chickens.MethodsMidazolam (1 mg kg⁻¹) and butorphanol (1 mg kg⁻¹) were administered into the pectoralis muscle. Fifteen minutes later, the birds were positioned in lateral recumbency and following palpation of the anatomic landmarks, a catheter was inserted using an axillary approach to the brachial plexus. Lidocaine or bupivacaine (1 mL kg⁻¹) was injected after plexus localization by the nerve stimulator. Sensory function was tested before and after blockade (carpus, radius/ulna, humerus and pectoralis muscle) in the blocked and unblocked wings. The latency to onset of motor and sensory block and the duration of sensory block were recorded. A Friedman nonparametric one-way repeated-measures anova was used to compare scores from baseline values over time and to compare the differences between wings at each time point.ResultsA total of 18 blocks were performed with a success rate of 66.6% (12/18). The latency for motor block was 2.8 ± 1.1 and 3.2 ± 0.4 minutes for lidocaine and bupivacaine, respectively. The latencies for and durations of the sensory block were 6.0 ± 2.5 and 64.0 ± 18.0 and 7.8 ± 5.8 and 91.6 ± 61.7 minutes for lidocaine and bupivacaine, respectively. There was no statistical difference between these times for lidocaine or bupivacaine. Sensory function was not abolished in nonblocked wings.Conclusions and clinical relevanceThe brachial plexus block was an easy technique to perform but had a high failure rate. It might be useful for providing anesthesia or postoperative analgesia of the wing in chickens and exotic avian species that have similar wing anatomy.     

利多卡因、布吡卡因行硬膜外阻滞对羊肝、肾功能的影响

为研究利多卡因、布吡卡因硬膜外阻滞对山羊肝、肾功能的影响,将16只成年山羊被随机分成2组(n=8),L3-4之间行硬膜外穿刺、置管后,分别注入2%多利卡因6mg/kg和0.75%布吡卡因2mg/kg。在注药前及注药后的30min、24h、72h和120h采集血样,测定ALT、AST、ALP、γ-GT及LDH的活性和Bilirubin、Grea、UA和Gluc等生化指标。结果表明,利多卡因、布吡卡因行硬膜外阻滞对血清ALT、AST、ALP、γ-GT及LDH活性和Grea、Urea、Gluc和Bilirubin均没有明显影响。     

Epidural analgesia with 0.75% bupivacaine for laparotomy in goats

Epidural nerve block with 0.75% bupivacaine (1 ml/4 kg of body weight) was performed in 17 goats tranquilized by IM administration of acetylpromazine (0.07 mg/kg). For comparison, epidural nerve block with 2% lidocaine containing 1:100,000 epinephrine (1 ml/5 kg) was performed in 7 goats. Transient signs of CNS stimulation were observed during injection of bupivacaine in 5 goats and of lidocaine in 2 goats. Analgesia of the flank was inadequate for laparotomy in 4 goats given bupivacaine (including 1 goat given a two-thirds dose) and in 2 goats given lidocaine. Analgesia for these goats was provided by local infiltration of the operative site with lidocaine. With bupivacaine, the onset of analgesia was up to 40 minutes, and the duration of analgesia was several hours; most goats were unable to stand for at least 11 hours. In comparison, epidural nerve block with lidocaine had a more rapid onset and much shorter duration. For both anesthetic drugs, despite adequate analgesia for laparotomy, response to manipulation of abdominal viscera was observed in 12 goats. Arterial blood pressure and blood gas tensions were measured in 8 goats given bupivacaine; 3 goats had mean arterial blood pressure less than 70 mm of Hg. Seven goats had normal PaCO2 but 2 goats had low PaO2; 1 goat sedated with xylazine had increased PaCO2 and hypoxemia.     

Plasma lidocaine concentrations in conscious horses after cervicothoracic (stellate) ganglion block with 1% lidocaine HCl solution

Arterial and/or central venous plasma concentrations of lidocaine were determined in 12 nonmedicated adult horses (422 +/- 59 kg of body weight, mean +/- SD) after injecting a 1% lidocaine HCl solution into the cervicothoracic ganglion (CTG). A mean dosage of 2.9 +/- 0.5 mg of lidocaine/kg of body weight was used to induce unilateral CTG blockade in 8 horses and 4.8 +/- 0.8 mg was used to induce bilateral CTG blockade in 4 horses. Blood samples were collected before and at 5, 15, 30, 45, 60, 75, 90, 105, and 120 minutes after injection. The plasma lidocaine concentrations were determined by use of gas chromatography (sensitivity less than 0.01 microgram/ml). Cervicothoracic sympathetic blockade was characterized by Horner's syndrome and by profuse sweating over the face, neck, and thoracic limbs. Mean maximal venous concentrations of lidocaine were 0.86 +/- 0.33 microgram/ml at 26.3 +/- 6.9 minutes after unilateral CTG blockade, and 1.14 +/- 0.25 micrograms/ml at 31.2 +/- 18.9 minutes after bilateral CTG blockade. The mean venous and arterial concentrations of lidocaine were not significantly different at 45 and 120 minutes after injection. Venous concentrations of lidocaine were consistently higher than were concentrations in simultaneously collected arterial blood samples in 2 horses in which the right CTG and brachial plexus were temporarily anesthetized after repeated administration of 100 ml of lidocaine into the right CTG.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of the analgesic effect of lidocaine and bupivacaine used to provide a brachial plexus block for forelimb surgery in 10 dogs

Twenty adult dogs weighing between 1.4 and 53.5 kg and aged between six months and nine years were anaesthetised and the brachial plexus was localised with the aid of a nerve stimulator. In 10 of the dogs a brachial plexus block was induced with a mixture of lidocaine and bupivacaine and the other 10 each received 0.25 ml/kg saline as a control. The end-tidal isoflurane concentration was maintained between 1.3 and 1.4 per cent during surgery for carpal arthrodesis or a fracture of the radius or ulna. Acute heart rate or blood pressure increases of 20 per cent or more were treated with 1 microg/kg fentanyl intravenously. Postoperatively, signs of pain were scored by a single blinded observer at hourly intervals until eight hours after the block had been induced, on a scale from 0 to 18. Dogs with pain scores above 5 received 0.1 to 0.2 mg/kg methadone intravenously, repeated as necessary. During surgery the control dogs received significantly more fentanyl (median 0.05 microg/kg/minute, range 0.02 to 0.20 microg/kg/minute) than the group given local anaesthetic (median 0 microg/kg/minute, range 0 to 0.02 microg/kg/minute). Postoperatively, the control group required significantly more methadone (median 0.2 mg/kg, range 0.1 to 1 mg/kg) than the treated group (median 0 mg/kg, range 0 to 0.13 mg/kg).     

Evaluation of lidocaine for brachial plexus blockade in eastern box turtles (Terrapene carolina carolina)

ObjectiveTo evaluate latency and duration of a brachial plexus block technique in eastern box turtles performed with 2% lidocaine at three dose rates.Study designProspective, randomized, blinded crossover study.AnimalsAdult eastern box turtles, two for drug dose evaluation and a group of six (three male, three female) weighing 432 ± 40 g (mean ± standard deviation) for the main study.MethodsAnimals were randomly assigned to four brachial plexus blocks with lidocaine at 5, 10 and 20 mg kg^–1 or 0.9% saline (treatments LID5, LID10, LID20 and CON, respectively), separated by 1 week. Treatment side was randomized and blocks were performed unilaterally. Baseline observations of mentation, heart rate (HR), respiratory rate (f_R), skin temperature and limb response to manipulation or toe pinch were evaluated. Assessments were made every 10 minutes until 1 hour of normal sensory and motor function to the treated thoracic limb, or for a total of 2 hours if no block was evident.ResultsMotor and sensory blockade was achieved in treatments LID10 and LID20 in one turtle, with a latency of 10 minutes and duration of 50 minutes for both doses. Raising of the ipsilateral lower palpebra occurred with both blocks. Turtles administered lidocaine experienced higher HR compared with CON, and HR decreased over time for all individuals. Mentation and f_R were not changed with any lidocaine dose.ConclusionsThe technique was unreliable in producing brachial plexus motor and sensory blockade at the lidocaine doses evaluated in this study. HR was higher in lidocaine-administered turtles but remained within normal limits for the species. No change in mentation or f_R was observed among treatments.Clinical relevanceGeneral anesthesia with systemic analgesia is recommended for surgical procedures involving the chelonian thoracic limb. Further studies are needed to optimize a brachial plexus block in this species.     

Combined paravertebral plexus block and parasacral sciatic block in healthy dogs

ObjectiveTo evaluate the effectiveness of paravertebral lumbar plexus block combined with parasacral sciatic block to anesthetize one hind limb in awake dogs.Study designRandomized, controlled, blinded experimental study.AnimalsEight healthy mongrel dogs weighing 12.4 ± 4.5 kg and aged 7 ± 2.33 years.MethodsAfter sedation with medetomidine, dogs received B1: bupivacaine 0.25%, 0.2 mL kg^?1, B2: bupivacaine 0.5%, 0.2 mL kg^?1, B3: bupivacaine 0.25% 0.4 mL kg^?1, P1: NaCl 0.2 mL kg^?1, P2: NaCl 0.4 mL kg^?1. The lumbosacral plexus was blocked through a paravertebral block of the fourth, fifth and sixth lumbar nerves combined with a parasacral block. The relevant nerves were located using a nerve stimulator and injections of each treatment were administered. Degree and durations of sensory blockade were determined through the response to a Halsted clamp pressure on the skin innervated by the saphenous/femoral and lateral cutaneous femoral nerves (lumbar dermatomes) and by the peroneal and tibial nerves. The degree and duration of motor blockade was assessed evaluating the ability to walk normally and proprioception.ResultsP1 and P2 treatments did not show any grade of sensory or motor blockade. The B2 treatment produced a higher degree of sensory blockade compared to B1 and B3 for both lumbar and sciatic dermatomes. There was no significant difference in the degree of sensory blockade comparing B1 to B3. The B2 treatment had greater motor blockade compared to B1 and B3. The duration of sensory and motor blockade was longer in B2 compared to B1 and B3.Conclusion and clinical relevanceWhen the nerve stimulator is used to perform the lumbosacral plexus block, the concentration of the bupivacaine has a more important role than the volume to produce a more solid and longer block.     

A comparison of four methods of analgesia in cats following ovariohysterectomy

OBJECTIVE: To evaluate the effectiveness of preoperative administration of oral carprofen, subcutaneous ketoprofen, and local nerve block with bupivacaine in preventing postoperative pain-associated behavior in cats after ovariohysterectomy. ANIMALS: Fifty-two female intact cats. Materials and methods Cats received butorphanol (0.44 mg kg(-1) IM), carprofen (2.2 mg kg(-1) PO), ketoprofen (2.2 mg kg(-1) SQ), or bupivacaine infiltration block (1.1 mg kg(-1) SQ) before surgery. Cortisol and drug concentrations and visual analog scale (VAS) and interactive visual analog scale (IVAS) pain-associated behavior scores were measured 2 hours before and 0, 1, 2, 4, 8, 12, and 24 hours after ovariohysterectomy. RESULTS: Cats receiving butorphanol had significantly increased IVAS scores 2 hours after surgery compared with baseline measurements. Cats receiving carprofen, ketoprofen, and bupivacaine had significant increases from baseline in VAS and IVAS scores 1 and 2 hours after surgery. VAS and IVAS scores for cats receiving bupivacaine were significantly greater 1 and 2 hours after surgery than for cats that received butorphanol. Cats receiving carprofen had significant increases in cortisol 1 hour after surgery and significant decreases 24 hours after surgery compared with baseline measurements. CONCLUSIONS AND CLINICAL RELEVANCE: Preoperative carprofen and ketoprofen have effects on pain-associated behavior similar to butorphanol in cats undergoing ovariohysterectomy. Cats receiving bupivacaine blocks may require additional analgesics immediately after surgery.     

Evaluation of a regional nerve block with an experimental formulation of encapsulated lidocaine in sheep

ObjectiveTo compare the duration of nociceptive and proprioceptive blockade from an experimental encapsulated lidocaine preparation with that of conventional lidocaine.Study designProspective, blinded, randomly assigned, crossover study.AnimalsA total of six adult Dorset ewes, American Society of Anesthesiologists physical status I or II, weighing 60.4 ± 18.0 kg (mean ± standard deviation).MethodsUnder general anesthesia and guided by electrolocation, the common peroneal nerve was blocked unilaterally with encapsulated lidocaine (0.1 mL kg^–1, 200 mg mL^–1) or conventional lidocaine hydrochloride (0.1 mL kg^–1, 20 mg mL^–1). Each sheep was administered both treatments with an interval of 2 weeks between treatments. Nociception and proprioception were scored (scales of 0–3) before anesthesia, at 0.5, 1, 2, 4, 8, 12, 16, 20 and 24 hours after completion of local anesthetic injection, and every 12 hours thereafter for 9 days. Nociceptive and proprioceptive blockade ended the first time each score reached ‘0’; maximum blockade duration was considered and recorded to be the time point immediately prior to this end point. Significance of differences between treatments for duration of blockade was tested with the Wilcoxon rank-sum test. Effects of time and treatment on nociceptive and proprioceptive blockade were evaluated with mixed-effect models. Significance was set at p < 0.05.ResultsCompared with conventional lidocaine, nociceptive blockade lasted 88 hours longer with encapsulated lidocaine (p = 0.008), and proprioceptive blockade lasted 6 hours longer (p = 0.03). Significant effects of time (p < 0.0001), treatment (p = 0.0435) and treatment1time (p < 0.0001) were observed for nociception. Significant effects of time (p < 0.0001) and treatment1time (p = 0.0058) were observed for proprioception.ConclusionEncapsulated lidocaine produced nociceptive blockade with a duration substantially longer than conventional lidocaine.Clinical relevanceSustained-release encapsulated lidocaine alleviates pain and may minimize systemic analgesic use.     

Palpation‐ and ultrasound‐guided brachial plexus blockade in Hispaniolan Amazon parrots (Amazona ventralis)

ObjectiveTo compare palpation-guided with ultrasound-guided brachial plexus blockade in Hispaniolan Amazon parrots.Study designProspective randomized experimental trial.AnimalsEighteen adult Hispaniolan Amazon parrots (Amazona ventralis) weighing 252–295 g.MethodsAfter induction of anesthesia with isoflurane, parrots received an injection of lidocaine (2 mg kg^?1) in a total volume of 0.3 mL at the axillary region. The birds were randomly assigned to equal groups using either palpation or ultrasound as a guide for the brachial plexus block. Nerve evoked muscle potentials (NEMP) were used to monitor effectiveness of brachial plexus block. The palpation-guided group received the local anesthetic at the space between the pectoral muscle, triceps, and supracoracoideus aticimus muscle, at the insertion of the tendons of the caudal coracobrachial muscle, and the caudal scapulohumeral muscle. For the ultrasound-guided group, the brachial plexus and the adjacent vessels were located with B-mode ultrasonography using a 7–15 MHz linear probe. After location, an 8-5 MHz convex transducer was used to guide injections. General anesthesia was discontinued 20 minutes after lidocaine injection and the birds recovered in a padded cage.ResultsBoth techniques decreased the amplitude of NEMP. Statistically significant differences in NEMP amplitudes, were observed within the ultrasound-guided group at 5, 10, 15, and 20 minutes after injection and within the palpation-guided group at 10, 15, and 20 minutes after injection. There was no statistically significant difference between the two groups. No effect on motor function, muscle relaxation or wing droop was observed after brachial plexus block.Conclusions and clinical relevanceThe onset of the brachial plexus block tended to be faster when ultrasonography was used. Brachial plexus injection can be performed in Hispaniolan Amazon parrots and nerve evoked muscle potentials were useful to monitor the effects on nerve conduction in this avian species. Neither technique produced an effective block at the doses of lidocaine used and further study is necessary to develop a useful block for surgical analgesia.     

Hypobaric intrathecal anaesthesia for partial hemipelvectomy in a dog.

OBJECTIVE : To report the intrathecal use of a hypobaric anaesthetic solution for partial hemipelvectomy in a nine-year-old, neutered female, Golden Retriever dog, weighing 34 kg. METHODS : Under inhalational anaesthesia, with the dog lying in lateral recumbency and the surgical side uppermost, 1.9 ml of a hypobaric solution containing 3.42 mg of bupivacaine and 0.66 mg of morphine were administered in the subarachnoid space at L5-6 level 30 minutes before surgery. Following the intrathecal injection the dog was maintained for five minutes in a 10 degrees head-down position, then for three minutes in a 10 degrees head-up position. RESULTS : Apart from a transient increase in heart and respiratory rates during resection of the sartorius muscle, which was treated with a plasma Target Controlled Infusion (TCI) of fentanyl, spinal anaesthesia provided cardiovascular stability and excellent relaxation of the surgical site. Neither motor blockade nor proprioceptive deficit were apparent in the contra-lateral hind limb at recovery, 200 minutes after injection. Postoperatively, rescue analgesia was not required in the 48 hours following surgery. CLINICAL SIGNIFICANCE : In dogs, the use of intrathecal hypobaric bupivacaine and morphine as a part of a balanced anaesthetic protocol should be considered during unilateral major orthopaedic surgeries of the pelvis and hind limb, as it allowed a reduction in the dose administered compared to isobaric solutions, providing selective spinal anaesthesia, excellent long-lasting analgesia, and rapid recovery of ambulation.     

Evaluation of corneal anaesthesia after the application of topical 0.5% bupivacaine, 2% lidocaine and 0.4% oxybuprocaine in normal horses

ObjectiveTo compare the corneal anaesthetic effect of 0.5% bupivacaine, 2% lidocaine and 0.4% oxybuprocaine on normal equine eyes.Study designProspective, blinded crossover study.AnimalsA group of 10 clinically healthy horses.MethodsCorneal sensitivity was determined in each eye by measuring corneal touch threshold (CTT). The study had three phases. Each subject was randomly given one of the three treatments followed by a 72 hour washout period. Every horse received all treatments. Baseline CTT was recorded prior to anaesthetic instillation (T0) then CTT was measured 5 and 10 minutes after (T1 and T2, respectively), then 20 to 90 minutes (T3 to T10) at 10 minute intervals. CTT data were compared among treatments at each time point using the Friedman test p < 0.05.ResultsMedian (range) baseline CTT was 51.3 (25.0–60.0) mm for bupivacaine, 50.0 (40.0–55.0) mm for oxybuprocaine and 55.0 (30.0–60.0) mm for lidocaine. All treatments caused a significant decrease in CTT at T1. The lowest CTT was observed at T3 with bupivacaine and oxybuprocaine treatments. Median CTTs at this time point were 18.7 (5.0–25.0) mm and 28.7 (25.0–40.0) mm, respectively. The lowest CTT with lidocaine treatment was 28.7 (20.0–50.0) mm at T6 (50 minutes). At T3, CTT was significantly lower with the bupivacaine treatment compared with oxybuprocaine and lidocaine treatments (p < 0.0074). There was no significant difference in CTT values between T1 and T6 for bupivacaine, between T1 and T7 for lidocaine, and between T1 and T8 for oxybuprocaine. Duration of the maximum effect was 45 minutes for the bupivacaine, 55 minutes for the lidocaine and 65 minutes for the oxybuprocaine treatment.Conclusions and clinical relevanceAdministration of a 0.5% injectable solution of bupivacaine or a 2% lidocaine had similar anaesthetic effect to the commonly used oxybuprocaine. Therefore, they might be used as alternatives for corneal anaesthesia.     

Use of a continuous, local infusion of bupivacaine for postoperative analgesia in dogs undergoing total ear canal ablation

OBJECTIVE: To determine whether addition of a continuous, local infusion of bupivacaine would improve postoperative analgesia in dogs undergoing total ear canal ablation. DESIGN: Randomized controlled trial. ANIMALS: 16 dogs undergoing total ear canal ablation (12 unilaterally and 4 bilaterally with > 1 month between procedures). PROCEDURE: Dogs were randomly allocated to receive morphine (0.25 mg/kg [0.11 mg/lb]) at the end of the procedure (10 procedures) or morphine and a continuous, local infusion of bupivacaine (0.13 to 0.21 mg/kg/h [0.06 to 0.1 mg/lb/h]; 10 procedures). Dogs were observed for 48 hours after surgery. Additional doses of morphine were administered up to every 4 hours in dogs with signs of severe pain. RESULTS: Temperament, sedation, analgesia, and cumulative pain scores were not significantly different between groups any time after surgery. Recovery score was significantly higher for dogs that received bupivacaine than for control dogs 2 hours after extubation but not at any other time. Serum cortisol concentration was not significantly different between groups at any time but, in both groups, was significantly increased at the time of extubation, compared with all other observation times. Total number of additional doses of morphine administered was not significantly different between groups. Bupivacaine was not detected in the plasma of any of the dogs that received the local bupivacaine infusion. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that addition of a continuous, local infusion of bupivacaine did not significantly increase the degree of postoperative analgesia in dogs that underwent total ear canal ablation and were given morphine at the end of surgery.     

Evaluation of intraperitoneal and incisional lidocaine or bupivacaine for analgesia following ovariohysterectomy in the dog

Objective To determine if intraperitoneal (IP) and incisional (SC) lidocaine or bupivacaine provide analgesia following ovariohysterectomy (OHE). Study Design Prospective, randomized, controlled, blinded clinical trial. Animals Thirty dogs presenting to the Veterinary Teaching Hospital for elective OHE. Methods Dogs were pre‐medicated with acepromazine and butorphanol, induced with thiopental and maintained with isoflurane. They were randomly assigned to three groups: 10 received 8.8 mg kg^?1 2% lidocaine with epinephrine IP (LID); 10 received 4.4 mg kg^?1 0.75% bupivacaine IP (BUP); and 10 received 0.9% saline IP (SAL) upon completion of OHE. All IP doses were standardized to 0.88 mL kg^?1 with saline. An additional 2 mL of undiluted solution was placed SC prior to incisional closure. Dogs were scored at 0.5, 1, 2, 3, 6, 8 and 18 hours post‐extubation by one observer. Dogs were evaluated using a visual analogue scale (VAS) for pain and sedation, and a composite pain scale (CPS) that included physiologic and behavioral variables. Dogs were treated with 0.22 mg kg^?1 butorphanol + acepromazine if their VAS (pain) score was >50. Parametric variables were analyzed using Student's t‐test or repeated measures anova as appropriate. Non‐parametric variables were analyzed by χ²‐test. Results There were no significant differences in age, weight, incision length, surgery time, anesthesia time, or total thiopental dose among groups. Peak post‐surgical pain scores for all groups occurred at 0.5 hours and returned to baseline by 18 hours. Dogs in the BUP group had significantly lower VAS‐pain scores overall than dogs in the SAL group. Seven out of 10 dogs in the SAL group, 4/10 in the LID group and 2/10 in the BUP group were treated with supplemental acepromazine and butorphanol. No differences between groups were detected with the CPS. No adverse side‐effects were observed. Conclusions and clinical relevance Our findings support the use of IP and SC bupivacaine for post‐operative analgesia following OHE in the dog.     

Cervicothoracic (stellate) ganglion block in conscious horses

Seven adult horses were used to compare the cardiovascular and respiratory effects of unilateral (right side) and bilateral cervicothoracic ganglion (CTG) blockade. An 18-gauge, 25-cm needle was placed midventrally between articulations of the 1st and 2nd ribs from a cranial and paratracheal site. One gram of lidocaine HCl in aqueous solution (100 ml) was used to infiltrate the CTG. Cervicothoracic sympathetic blockade was characterized by Horner's syndrome, increased skin temperature and profuse sweating over the face, neck, and thoracic limb. Comparison of base-line data with data obtained during unilateral and bilateral CTG blockades indicated a significant (P less than 0.05) decrease in respiratory rate, significant (P less than 0.05) increases in arterial oxygen, and carbon dioxide tensions, and a significant increase in subcutaneous temperature at the neck and shoulder. Systolic, diastolic, and mean aortic blood pressures, pulse pressure, rectal temperature, arterial pH, bicarbonate, PVC, and total solid concentration did not change significantly from base-line values. Arterial O2 tension was significantly (P less than 0.05) less in horses with bilateral CTG blockade than in horses with unilateral CTG blockade. In 4 horses without cervicothoracic sympathetic blockade that were given lidocaine (1 g in 100 ml) in the right cervicothoracic region, cardiovascular and respiratory values did not change significantly from base-line values. The nonsedated healthy horse tolerated unilateral CTG blockade well. Bilateral and unilateral injections of 100 ml of 1% lidocaine into the CTG at intervals of less than 2 hours induced bilateral recurrent nerve paralysis and airway obstruction.     

Hemodynamic effects of interpleural lidocaine and bupivacaine combination in anesthetized dogs with and without an open pericardium

OBJECTIVE: To identify dysrhythmias and hemodynamic changes after lidocaine and bupivacaine infusion into the interpleural space with an open pericardium. STUDY DESIGN: Experimental study. ANIMALS: Six adult dogs. METHODS: Systemic arterial pressure and electrocardiogram were recorded. A 7.5 Fr Swan-Ganz catheter was advanced to the level of the main pulmonary artery to record pulmonary arterial pressure. Cardiac output was measured by a thermodilution technique. A pericardial window (PW) was performed in 3 dogs using thoracoscopy. Hemodynamic variables were recorded before and 15 minutes after injection of lidocaine (1.5 mg/kg) and bupivacaine (1.5 mg/kg) into the pleural space in the control group and in the pericardial space for the PW group. A randomized-block ANOVA for repeated measures was used to evaluate the effect of local anesthetic administration on hemodynamic and electrophysiologic variables in dogs with a pericardectomy. RESULTS: Each dog maintained sinus rhythm. Infusion of local anesthetic induced a significant increase in right ventricular diastolic pressure (P = .002) and a significant decrease in stroke volume (P = .047) in both groups; however, the effects were not significantly different between groups. CONCLUSIONS: Infusion of lidocaine and bupivacaine, either intrapleural or in the pericardial space, had a mild detrimental effect on cardiac output. CLINICAL RELEVANCE: Intrapleural administration of lidocaine and bupivacaine at a therapeutic dose can be used safely in healthy dogs with a pericardectomy.     

Comparison of the cytotoxic effects of bupivacaine, lidocaine, and mepivacaine in equine articular chondrocytes

Objective To compare the chondrotoxicity of bupivacaine, lidocaine, and mepivacaine in equine articular chondrocytes in vitro. Study design Prospective, experimental study. Study material Equine articular chondrocytes. Methods Primary cultured equine chondrocytes were exposed to 0.5% bupivacaine, 2% lidocaine, or 2% mepivacaine for 30 or 60 minutes. After treatment, cell viability was evaluated by trypan blue exclusion and the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) colorimetric assay in a dose dependent manner. Apoptosis and necrosis of chondrocytes were analyzed with the double staining of Hoechst 33258 and propidium iodide using fluorescence microscopy, and the results were confirmed using flow cytometry. Results After 30‐minute exposure, trypan blue exclusion assay revealed that cell viability of 0.5% bupivacaine group was 28.73 ± 8.44%, and those of 2% lidocaine and 2% mepivacaine were 66.85 ± 6.03% and 86.27 ± 2.00%, respectively. The viability of chondrocytes after saline treatment was 95.95 ± 2.75%. The results of MTT assay and fluorescence microscopy had similar tendency with trypan blue assay. Each result showed that bupivacaine was the most toxic of the three local anaesthetics. Mepivacaine was less toxic than lidocaine. The results of the viability test suggest that bupivacaine and lidocaine exhibit a marked chondrotoxicity, and that this is mainly due to necrosis rather than apoptosis. Conclusions and clinical relevance Bupivacaine may induce detrimental chondrotoxicity when administered intra‐articularly, especially in patients with joint disease, and we suggest that it should be used cautiously in equine practice. Mepivacaine may be an alternative to both bupivacaine and lidocaine.     

Clinical evaluation of the anaesthetic sparing effect of brachial plexus block in cats

ObjectiveTo evaluate the isoflurane sparing effect and the post-surgical analgesia provided by a brachial plexus block (BPB) in cats undergoing distal thoracic limb surgery.Study designProspective randomized blinded clinical study.AnimalsTwenty client-owned cats.MethodsCats were assigned to receive either no BPB (group NB) or a nerve stimulator guided BPB (group BPB) using lidocaine (3.6 mg kg^?1) and bupivacaine (1.2 mg kg^?1). Pre-medication consisted of midazolam and ketamine intravenously (IV). Anaesthesia was induced with propofol IV to effect and maintained with isoflurane delivered in oxygen and a continuous rate infusion of fentanyl (2 μg kg^?1 hour^?1). End-tidal isoflurane concentration (Fe′ISO) was adjusted every 3 minutes guided by changes in cardiorespiratory parameters and reflexes present, to maintain a stable depth of anaesthesia. Five time points were chosen to record all parameters and compare values between groups. Recovery and post-operative pain assessment were performed using a visual analogue scale (VAS) at 15 and 45 minutes after extubation and thereafter at hourly intervals until 5 hours after placement of the BPB.ResultsNo clinically significant differences were seen for heart rate, respiratory rate and non-invasive blood pressure between groups. Mean Fe′ISO was significantly lower in group BPB compared with group NB at all time points. In group NB, all intraoperative measurements of Fe′ISO were significantly higher compared with baseline (3 minutes before start of surgery) measurements. During recovery, VAS scores for group BPB were significantly lower than for group NB. Additional analgesics were needed in all cats within the study period.Conclusion and Clinical relevanceIn cats undergoing orthopaedic surgery of the thoracic limb, BPB reduced intra-operative isoflurane requirement and pain during the early post-operative period when compared with procedures without a BPB. BPB is a useful adjunct to anaesthesia in such cases.