Analgesic efficacy of a bilateral erector spinae plane block versus a fentanyl constant rate infusion in dogs undergoing hemilaminectomy: a retrospective cohort study.

BACKGROUND: Erector spinae plane block (ESPB) is an ultrasound-guided interfascial plane block used to provide analgesia in dogs undergoing hemilaminectomy. The aim of this study is to compare the analgesic efficacy of a bilateral ESPB with a fentanyl constant rate infusion (CRI) in dogs undergoing hemilaminectomy. METHODS: This is a retrospective cohort study. Anaesthetic records of client-owned dogs undergoing hemilaminectomy (June 2019-August 2020), and in which a bilateral ESPB was performed (group ESPB), were retrieved and compared to a cohort of 39 dogs that underwent hemilaminectomy (September 2014 - June 2017) and in which a fentanyl CRI (2 µg/kg bolus followed by 5 µg/kg/hour) was used as a primary intraoperative analgesia (group CRI). The prevalence of dogs in which intraoperative rescue fentanyl boluses were administered, the total dose of rescue fentanyl boluses administered, the postoperative methadone requirement and anaesthetic complications during the first 24 postoperative hours were evaluated. Univariate statistical analysis was used. RESULTS: Group ESPB comprised of 93 dogs. The bilateral ESPB was performed using a median (range) levobupivacaine volume of 1 (0.5-1.7) mL/kg per side, at a concentration of 0.125% (0.12-0.25). At least one rescue fentanyl bolus was administered in 54.8% and in 56.4% of dogs in group ESPB and CRI, respectively (p > 0.99). The number of rescue fentanyl boluses was higher in group CRI (p = 0.006), especially during lumbar hemilaminectomy. Rescue fentanyl boluses were more frequently administered from skin incision to end of vertebral lamina drilling in group CRI (p = 0.001), and from end of vertebral lamina drilling to end of surgery in group ESPB (p = 0.0002). During the first 6 (p = 0.0035) and 6-12 (p = 0.0005) postoperative hours, the number of dogs that required at least one dose of methadone was higher in group CRI. In group ESPB, dogs were more likely to become hypothermic (p = 0.04). One dog, not included in the study, developed sinus arrest after performing a caudal thoracic ESPB. CONCLUSIONS: Under the conditions of this study, a bilateral ESPB was associated with a lower number of rescue fentanyl boluses administered in dogs undergoing hemilaminectomy, especially between skin incision to end of vertebral lamina drilling. Despite ESPB being associated with a reduced opioid consumption during the first 12 hours postoperatively, differences in the postoperative management precluded any firm conclusion regarding its postoperative effect.

Ultrasound-guided bilateral erector spinae plane block in dogs undergoing sternotomies anaesthetised with propofol-dexmedetomidine continuous infusion.

BACKGROUND: To describe the use of a bilateral thoracic (T5 - T9) ultrasound-guided erector spinae plane block (UG-ESPB) in dogs undergoing sternotomy anaesthetised with propofol and dexmedetomidine continuous infusions. METHODS: Demographic information, perioperative anaesthetic and analgesic drugs, the prevalence of hypotension and nociceptive events, and their treatment, were recorded and analysed. Local anaesthetic injection point, volume and concentration were reported for each dog. In attempt to differentiate somatic nociception from visceral nociception, the surgery was divided into three timeframes: from the skin incision to the thoracic cavity opening; from the latter to the beginning of its closure; from thoracic cavity closure to the end of surgery. RESULTS: Overall, 10 dogs were included and four experienced nociception: somatic nociception was recorded in one dog, whereas visceral nociception was recorded in four dogs. The overall fentanyl consumption to control nociception was 0.3 µg/kg/h. No adverse events associated with the UG-ESPB were reported. CONCLUSION: The bilateral UG-ESPB could be used as a part of a multimodal analgesic technique in dogs undergoing sternotomies. However, more clinical studies are warranted to assess its safety and effects.

Evaluation of bilateral maxillary nerve block in dogs undergoing surgery for brachycephalic obstructive airway syndrome.

This retrospective study assessed the effect of an intraoral bilateral maxillary nerve block in dogs undergoing surgery for brachycephalic obstructive airway syndrome (BOAS). Records of dogs that underwent BOAS surgery were retrieved. Cases were assigned to Group B or C if a preoperative bilateral maxillary nerve block was performed or not. Type and dose of local anesthetic, inhalant anesthetic minimum alveolar concentration multiples, intraoperative fentanyl and injectable anesthetic use, prevalence of intraoperative hypotension or bradycardia, and postoperative opioids administration, were compared between groups. Sixty-seven cases met the inclusion criteria: 33 were assigned to Group B and 34 to Group C. In Group C, 18 dogs required intraoperative fentanyl (P = 0.005), and 12 needed injectable anesthetic top-ups (P = 0.006). Hypotension, or bradycardia, were not different between groups. Bilateral maxillary nerve block reduces intraoperative fentanyl and injectable anesthetic requirement in dogs undergoing BOAS surgery.

Évaluation du bloc nerveux maxillaire bilatéral chez les chiens brachycéphales opérés pour un syndrome obstructif des voies respiratoires. Cette étude rétrospective a évalué l'effet d'un bloc nerveux maxillaire intra-oral bilatéral chez des chiens brachycéphales subissant une intervention chirurgicale pour le syndrome obstructif des voies respiratoires (BOAS). Les dossiers des chiens qui ont subi une chirurgie BOAS ont été récupérés. Les cas ont été classés dans le groupe B ou C si un bloc du nerf maxillaire bilatéral préopératoire était réalisé ou non. Le type et la dose d'anesthésique local, les multiples de concentration alvéolaire minimale d'anesthésique par inhalation, l'utilisation peropératoire de fentanyl et d'anesthésiques injectables, la prévalence de l'hypotension ou de la bradycardie peropératoire et l'administration postopératoire d'opioïdes ont été comparés entre les groupes. Soixante-sept cas répondaient aux critères d'inclusion : 33 ont été affectés au groupe B et 34 au groupe C. Dans le groupe C, 18 chiens ont eu besoin de fentanyl peropératoire (P = 0,005) et 12 ont eu besoin de compléments anesthésiques injectables (P = 0,006). L'hypotension ou la bradycardie n'étaient pas différentes entre les groupes. Le bloc nerveux maxillaire bilatéral réduit les besoins peropératoires en fentanyl et en anesthésique injectable chez les chiens subissant une chirurgie BOAS.(Traduit par Dr Serge Messier).

Success Rate and Perioperative Complications of Lumbosacral Extradural Anaesthesia in Dogs Undergoing Total Hip Replacement: A Double-Centre Retrospective Study.

OBJECTIVE: The aim of this study was to retrospectively evaluate the success rate and perioperative complications of lumbosacral extradural anaesthesia in dogs undergoing total hip replacement. STUDY DESIGN: Records of dogs undergoing total hip replacement in which lumbosacral extradural anaesthesia with 0.5% levo- or bupivacaine combined with either morphine or buprenorphine were retrieved. Success rate was defined as intraoperative fentanyl consumption <1 µg/kg/h with no intravenous infusion of other analgesic drugs and no additional morphine/methadone within the first 3 hours from premedication. Prevalence of intraoperative anaesthetic and postoperative surgical complications was calculated. RESULTS: Overall, 206 dogs were included in the study. Success rate was 88.7%. Hypercapnia (75.2%), hypotension (46.1%), hypothermia (27.7%) and regurgitation (6.3%) were recorded during anaesthesia. Within 24 hours post-surgery, urinary retention (17.8%), vomiting/regurgitation/diarrhea (8.2%) and sciatic neurapraxia of the operated limb (5.8%) were recorded. Luxation of the operated hip occurred at 48 and 72 hours after surgery in two dogs and one dog respectively. One dog had cardiopulmonary arrest at 52 hours after surgery. CONCLUSION: While hypercapnia, hypotension and hypothermia might develop intraoperatively, the high success rate and the relatively low prevalence of postoperative surgical complications directly associated with lumbosacral extradural anaesthesia justify its use in dogs undergoing total hip replacement.

Serum C-reactive protein in dogs with paraplegia secondary to acute intervertebral disc extrusion.

BACKGROUND: Apart from the absence of nociception, there is no readily available prognostic test for dogs presenting with paraplegia secondary to acute intervertebral disc extrusion (IVDE). OBJECTIVE: To assess if serum C-reactive protein (CRP) can predict the postoperative outcome in paraplegic dogs undergoing surgery for IVDE and to assess the association between serum CRP and presence/absence of nociception on admission, and serum CRP and presence/absence of intramedullary changes seen on magnetic resonance imaging (MRI). ANIMALS: One hundred dogs that underwent surgery at our hospital between 2018 and 2020 because of acute paraplegia secondary to IVDE and in which serum CRP was measured. METHODS: Retrospective observational cohort study. Dogs were classified as 4 or 5 according to the modified Frankel score (MFS) depending on presence/absence of nociception, respectively. MRI images were reviewed and the T2-weighted hyperintensity: L2 vertebral body length was measured. Postoperative outcome was defined as positive if nociception, ambulation or both returned after decompressive surgery. RESULTS: The median (95% CI) serum CRP was 4 (4-5) and 6 (4-7) mg/L in MSF4 and MSF5, respectively (P = .03). A weak linear relationship (R2  = 0.049, P = .03) was found between CRP and the T2-weighted hyperintensity: L2 vertebral length. Outcome data was available for 85 dogs: CRP was 4 (4-5) and 5 (4-10) mg/L in positive and negative outcome dogs, respectively (P = .32). CONCLUSION AND CLINICAL IMPORTANCE: Serum CRP did not predict outcome after surgery in dogs with paraplegia secondary to IVDE.

Sevoflurane with opioid or dexmedetomidine infusions in dogs undergoing intracranial surgery: a retrospective observational study.

This study reports the clinical use of two sevoflurane-based anesthetic techniques in dogs undergoing craniectomy. Twenty-one animals undergoing elective rostrotentorial or transfrontal craniectomy for brain tumor excision, anesthetized with sevoflurane, were enrolled in this retrospective, observational study. Anesthetic records were allocated to two groups: Sevo-Op (sevoflurane and short acting opioid infusion): 8 dogs and Sevo-Dex (sevoflurane and dexmedetomidine infusion): 13 dogs. Average mean arterial pressure (MAP), heart rate, end-tidal carbon dioxide, end-tidal sevoflurane and intraoperative infusion rates during surgery were calculated. Presence of intra-operative and post-operative bradycardia, tachycardia, hypotension, hypertension, hypothermia, hyperthermia was recorded. Time to endotracheal extubation, intraoperative occurrence of atrioventricular block, postoperative presence of agitation, seizures, use of labetalol and dexmedetomidine infusion were also recorded. Data from the two groups were compared with Fisher's exact test and unpaired t tests with Welch's correction. Odds ratio (OR) and 95% confidence interval (CI) were calculated for categorical variables. Intra-operatively, MAP was lower in Sevo-Op [85 (± 6.54) vs. 97.69 (± 7.8) mmHg, p = 0.0009]. Time to extubation was longer in Sevo-Dex [37.69 (10-70) vs. 19.63 (10-25), p = 0.0033]. No differences were found for the other intra-operative and post-operative variables investigated. Post-operative hypertension and agitation were the most common complications (11 and 12 out of 21 animals, respectively). These results suggest that the infusion of dexmedetomidine provides similar intra-operative conditions and post-operative course to a short acting opioid infusion during sevoflurane anesthesia in dogs undergoing elective rostrotentorial or transfrontal intracranial surgery.

Peripheral nerve block versus systemic analgesia in dogs undergoing tibial plateau levelling osteotomy: Analgesic efficacy and pharmacoeconomics comparison.

OBJECTIVE: To compare the perioperative effects and pharmacoeconomics of peripheral nerve blocks (PNBs) versus fentanyl target-controlled infusion (fTCI) in dogs undergoing tibial plateau levelling osteotomy (TPLO). STUDY DESIGN: Randomized clinical study. ANIMALS: A total of 39 dogs undergoing unilateral TPLO. METHODS: After acepromazine and methadone, anaesthesia was induced with propofol and maintained with isoflurane. Dogs were allocated to group fTCI [target plasma concentration (TPC) 1 ng mL-1] or group PNB (nerve stimulator-guided femoral-sciatic block using 0.2 and 0.1 mL kg-1 of levobupivacaine 0.5%, respectively). If nociceptive response occurred, isoflurane was increased by 0.1%, and TPC was increased by 0.5 ng mL-1 in group fTCI; a fentanyl bolus (1 µg kg-1) was administered in group PNB. During the first 24 postoperative hours, methadone (0.2 mg kg-1) was administered intramuscularly according to the Short Form Glasgow Composite Pain Scale, or if pain was equal to 5/24 or 4/20 for two consecutive assessments, or if the dog was non-weight bearing. The area under the curve (AUC) of pain scores, cumulative postoperative methadone requirement, food intake and pharmacoeconomic implications were calculated. RESULTS: Incidence of bradycardia (p = 0.025), nociceptive response to surgery (p = 0.041) and AUC of pain scores (p < 0.0001) were greater in group fTCI. Postoperatively, 16/19 (84.2%) and eight/20 (40%) dogs in groups fTCI and PNB, respectively, were given at least one dose of methadone (p = 0.0079). Food intake was greater in group PNB (p = 0.049). Although total cost was not different (p = 0.083), PNB was more cost-effective in dogs weighing >15 kg. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with group fTCI, incidence of bradycardia, nociceptive response to surgery, postoperative pain scores, cumulative methadone requirement were lower, and food intake was greater in group PNB, with an economic advantage in dogs weighing >15 kg.

A retrospective comparison of two analgesic strategies after uncomplicated tibial plateau levelling osteotomy in dogs.

OBJECTIVE: To compare the efficacy and side effects of postoperative methadone administered according to pain score (PS) or every 4 hours (Q4), after unilateral uncomplicated tibial plateau levelling osteotomy (TPLO) in dogs in which a peripheral nerve block (PNB) was administered. STUDY DESIGN: Retrospective, case-control study. ANIMALS: Clinical records of dogs that underwent a TPLO in 2015 were retrieved; 136 out of 174 dogs were included: 52 assigned to group PS, 84 to group Q4. METHODS: In group PS, methadone was administered according to the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF), whereas in group Q4 methadone was administered at 4 hour intervals. Demographic data, anaesthetic technique, surgery time, American Society of Anesthesiologists classification, PNB performed, local anaesthetic used and dose, anti-inflammatory drugs administered, end-expiratory fraction of isoflurane, perioperative opioid consumption, time to first postoperative methadone administration, pain scores, time to first pain score, food intake, number of postoperative observations, presence/absence of specific keywords representing the general state and behaviour of the animal, use of the operated limb and reaction to wound palpation were retrieved. Fisher's exact test, chi-square test, Student t test or Mann-Whitney U test were used, considering p<0.05 significant. Odds ratios and 95% confidence intervals were calculated, when indicated. RESULTS: Four times more methadone was administered to dogs in group Q4, and whilst not having lower pain scores or better short-term outcome (e.g. toe-touching and weight bearing), were 23.42 times (1.37 to 400.40) more likely to vomit, 3.76 (1.50 to 9.49) more likely to vocalize, and their food intake was 38% less than dogs in group PS. No dogs in group PS vomited postoperatively. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of methadone Q4 caused more side effects than administration guided by CMPS-SF. This should be considered when planning postoperative analgesia in dogs undergoing uncomplicated TPLO and in which a PNB has been performed.

Comparison of intramuscular butorphanol and buprenorphine combined with dexmedetomidine for sedation in cats.

Objectives The objective of this study was to compare the sedative effect of butorphanol-dexmedetomidine with buprenorphine-dexmedetomidine following intramuscular (IM) administration in cats. Methods Using a prospective, randomised, blinded design, 40 client-owned adult cats were assigned to receive IM dexmedetomidine (10 µg/kg) combined with either butorphanol (0.4 mg/kg) ('BUT' group) or buprenorphine (20 µg/kg) ('BUP' group). Sedation was scored using a previously published multidimensional composite scale before administration (T0) and 5, 10, 15 and 20 mins afterwards (T5, T10, T15 and T20, respectively). Alfaxalone (1.5 mg/kg) was administered IM at T20 if the cat was not deemed adequately sedated to place an intravenous catheter. Adverse events were recorded. Friedman two-way ANOVA analysed sedation scores within groups. Mann-Whitney Rank Sum test compared sedation scores between groups; Fisher's exact test analysed the frequency of alfaxalone administration and adverse events. P <0.05 was considered statistically significant. Results Sedation scores between groups were similar at baseline, but at T5, T10, T15 and T20 scores were higher in the BUT group ( P <0.01). Within both groups, sedation scores changed over time and the highest sedation scores were reached at T10. Requirement for additional sedation was similar between groups: two cats in the BUT group and five cats in the BUP group. One cat and 11 cats vomited ( P = 0.002) in the BUT and BUP groups, respectively. No other adverse events were recorded. Conclusions and relevance At these doses, IM buprenorphine-dexmedetomidine provides inferior sedation and a higher incidence of vomiting than butorphanol-dexmedetomidine in cats. Butorphanol-dexmedetomidine may be preferred for feline sedation, especially where vomiting is contraindicated.

Severe upper airway obstruction following bilateral ventral bulla osteotomy in a cat.

A cat that underwent bilateral ventral bulla osteotomy (VBO) for treatment of otitis media and otitis interna secondary to bilateral inflammatory polyps, developed upper airway obstruction (UAO) soon after tracheal extubation. The cat was re-intubated but the UAO did not resolve at the next extubation. Eventually, tracheostomy was performed. Upper airway obstruction is a potential postoperative complication of bilateral VBO in cats.

Grave obstruction des voies respiratoires supérieures chez un chat après ostéotomie bilatérale des bulles ventrales. Un chat qui a subi une ostéotomie bilatérale des bulles ventrales (OBBV) pour le traitement d'une otite moyenne et d'une otite interne secondaire à des polypes inflammatoires bilatéraux a développé une obstruction des voies respiratoires supérieures (OVRS) peu de temps après l'extubation trachéale. Le chat a été réintubé mais l'OVRS ne s'est pas résorbée à l'intubation suivante. Finalement, une trachéostomie a été réalisée. L'OVRS est une complication postopératoire potentielle de l'OBBV chez les chats.(Traduit par Isabelle Vallières).

Retrospective assessment of peripheral nerve block techniques used in cats undergoing hindlimb orthopaedic surgery.

OBJECTIVES: The aim of this study was to assess retrospectively the efficacy and complication rate of hindlimb peripheral nerve blocks (PNBs) in cats. METHODS: Clinical records of cats that received PNBs and underwent hindlimb orthopaedic surgery from February 2010 to October 2014 were examined. Type of PNB, type and dose of local anaesthetic used, end-expiratory fraction of isoflurane (FE'Iso) administered, additional intraoperative analgesia, incidence of hypotension, postoperative opioid requirement, postoperative contralateral limb paralysis and neurological complications at the 6 week re-examination were investigated. RESULTS: Eighty-nine records were retrieved but only 69 were analysed. Four combinations of PNBs were used: 34 lateral preiliac (LPI) approach to lumbar plexus (LP) associated with lumbar paravertebral approach to sciatic nerve (SN); 20 LPI-LP associated with the lateral approach to SN; three LPI-LP associated with gluteal approach to SN; 12 dorsal-paravertebral (DPV) approach to LP associated with lateral SN. Levobupivacaine was used for the majority of PNBs. The mean intraoperative FE'Iso was 1.15%; hypotension was documented in 55.1% of anaesthetics, while 31.8% of cats received fentanyl and/or ketamine intraoperatively. Postoperatively, 72.7% of cats received at least one dose of opioid, while five cats required further postoperative analgesia (ketamine constant rate infusion and/or gabapentin). No cats showed contralateral limb paralysis and neurological complications at the 6 week re-examination. No differences were found when comparing the different PNBs used. CONCLUSIONS AND RELEVANCE: PNBs contributed to perioperative anaesthesia/analgesia in cats undergoing hindlimb orthopaedic surgery. However, the clinical relevance of intraoperative hypotension needs further investigation.

Modulation of spinal shape with growth following implantation of a novel surgical implant.

PURPOSE: First, to determine whether scoliosis development could be limited or reversed by growth when a novel modular hinged implant was fixed to the convexity of a scoliosis created by contralateral rib and laminar tethering and unilateral rib resection in a sheep model. Second, to assess the effect and performance of the implant in normal non-tethered sheep. METHODS: At 5 weeks, 20 Scottish Blackface lambs underwent surgery to create a right sided scoliosis by (i) tethering the left lamina of T5-L1 and the left lower six ribs and (ii) resecting a segment of their right lower six ribs [1, 2]. Twelve weeks later, through an antero-lateral thoracotomy, a mobile bi-planar hinged implant was inserted onto the right side of the spine of eight animals (group 1). For comparison, 12 sheep were tethered only but had no implant insertion (group 2). In addition, seven had no tethering but were implanted (group 3) and normal growth patterns were observed in five that had no surgery (group 4). Curve progression was assessed by plain radiography and CT over a 1-year period. RESULTS: Before implant insertion the trial animals had a scoliosis of 35º ± 16º and a lordosis of 44º ± 20º (n = 8, mean ± SD). Surgery immediately reduced these values to 25º ± 14º, p < 0.01 and 35º ± 18º, p < 0.001, with scoliosis continuing to decrease during the next three months. Spinal flexibility was retained. In the un-tethered sheep, a scoliosis of 10º ± 6º was created on the opposite side to the implant (p < 0.05) with no significant change in alignment in the sagittal plane (1º ± 6º). The implant did not cause any adverse effect on growth or affect neurological function. CONCLUSIONS: In the un-tethered animals the effect of the implant was to create a scoliotic deformity and in the tethered to improve deformity while maintaining spinal motion. We believe that the results are promising and that devices of similar construct may be of use in children with scoliosis, potentially changing current methods of clinical care.

Effect of extradurally administered morphine on postoperative analgesia in dogs undergoing surgery for thoracolumbar intervertebral disk extrusion.

OBJECTIVE: To investigate the effect of intraoperative extradural morphine administration on postoperative analgesia in dogs undergoing thoracolumbar spinal surgery to treat disk extrusion. DESIGN: Prospective clinical trial. ANIMALS: 26 client-owned dogs undergoing thoracolumbar spinal surgery. PROCEDURES: Animals were randomly allocated to receive morphine (0.1 mg/kg [0.045 mg/lb], extradurally) or no treatment (control group). Following preanesthetic medication with methadone (0.25 mg/kg [0.11 mg/lb], IM), anesthesia was induced with propofol and maintained with isoflurane or sevoflurane in oxygen. Lidocaine and fentanyl were administered during surgery in both groups at fixed rates. In the morphine administration group, morphine was splashed over the dura mater immediately prior to wound closure. Postoperative analgesia was assessed for 48 hours by assessors unaware of group allocation, and methadone was administered as rescue analgesic. Demographic characteristics, urinary output, days of hospitalization, and perioperative use of analgesics were compared via a Mann-Whitney U test. RESULTS: Demographic data were similar between groups. In the morphine administration group, 2 of 13 dogs required postoperative methadone, and in the control group, methadone was administered to 11 of 13 dogs. The total number of doses of methadone administered in the 48 hours after surgery was 28 in the control group and 3 in the morphine administration group. No adverse effects were recorded in any group. CONCLUSIONS AND CLINICAL RELEVANCE: Intraoperative extradural morphine administration was effective in reducing postoperative analgesic requirement. Dogs undergoing thoracolumbar spinal surgery benefited from topical administration of preservative-free morphine administered directly on the dura mater as part of analgesic management.

Clinical effects of isoflurane and sevoflurane in lambs.

OBJECTIVE: To compare isoflurane and sevoflurane in lambs undergoing prolonged anaesthesia for spinal surgery. STUDY DESIGN: Prospective randomised clinical study. ANIMALS: Eighteen Scottish blackface lambs 3-6 weeks of age and weighing 10-17 kg. METHODS: After intramuscular medetomidine, anaesthesia was induced and maintained with either isoflurane (group I) or sevoflurane (group S) delivered in oxygen. Meloxicam, morphine, a constant rate infusion of ketamine and atracurium were given intravenously (IV) during surgery. Lungs were ventilated to maintain normocapnia. with peak inspiratory pressures of 20-25 cmH(2) O. Ephedrine or dextran 40% was administered when mean arterial pressure (MAP) was <55 mmHg. Intrathecal morphine, and IV meloxicam and edrophonium were injected before recovery. Time to loss of palpebral reflex (TLPR) upon induction, cardiorespiratory variables, time at first swallowing and other movement, tracheal extubation, vocalisation, spontaneous head lifting (>1 minute), reunion with the ewe, and the number of MAP treatments were recorded. Statistical analysis utilised anova, Mann-Whitney, t-test or Pearson's correlation test as relevant. p < 0.05 was considered significant. RESULTS: End-tidal carbon dioxide (mean ± SD) was significantly lower in group S (5.5 ± 0.6 kPa) than in group I (5.8 ± 0.5 kPa) while MAP (70 ± 11 mmHg) and diastolic arterial blood pressure (60 ± 11 mmHg) were higher in group S than in group I (65 ± 12 and 54 ± 11 mmHg, respectively). No differences were found with TLPR and MAP treatments. Time (median, range) from end of anaesthesia to ewe-lamb reunion was briefer (p = 0.018) in group S (48, 20-63 minutes). CONCLUSION: Isoflurane and sevoflurane are both suitable for maintaining general anaesthesia in lambs although sevoflurane, as used in this study, allows a more rapid reunion with the ewe. CLINICAL RELEVANCE: The principal advantage of sevoflurane over isoflurane during prolonged anaesthesia in lambs is a more rapid recovery.

The effects of age, isoflurane and sevoflurane on atracurium in lambs.

OBJECTIVE: To determine the effects of age, sevoflurane and isoflurane on atracurium-induced neuromuscular blockade in 3-16 week-old lambs. STUDY DESIGN: Prospective randomized experimental trial. ANIMALS: Twenty-six Scottish blackface ewe-lambs were anaesthetized for spinal surgery when either 3-6 (mean age 4.6 weeks; n = 18) or 12-16 weeks (mean age 13.7 weeks; n = 15) of age; seven animals were anaesthetized at both ages. METHODS: After intramuscular injection of medetomidine (10 µg kg(-1)) anaesthesia was induced in the younger lambs either with isoflurane or sevoflurane in oxygen delivered by mask, and in the older lambs with ketamine (4 mg kg(-1)), and midazolam (0.2 mg kg(-1) ) administered intravenously (IV). In both groups anaesthesia was maintained with fixed end-tidal concentrations of either sevoflurane (2.8%) or isoflurane (1.8%) delivered in oxygen. Before surgery meloxicam (0.6 mg kg(-1)), morphine (0.5 mg kg(-1)) and ketamine (1 mg kg(-1) followed by 10 µg kg(-1) minute(-1) ) were administered IV. The lungs were ventilated mechanically to maintain normocapnia. Neuromuscular block was achieved with a loading dose (LD) of atracurium (0.5 mg kg(-1) IV). The peroneal nerve was stimulated (train-of-four every 12 seconds). Evoked responses in the digital extensor muscles were evaluated by palpation and observation. Maintenance doses (MD) of atracurium (0.17 mg kg(-1) IV) were administered when the first twitch (T1) returned. The onset and duration of LD action (T1 absent) and the duration of MD were recorded. Data were analysed using Student's t test, Mann-Whitney U test, repeated-measures anova, Wilcoxon's matched pairs test or Pearson correlation coefficient as relevant (p < 0.05). RESULTS: Onset of LD action developed significantly (p < 0.05) more rapidly in isoflurane compared with sevoflurane-anaesthetized lambs (55 ± 18 cf. 80 ± 37 seconds). Duration of action of LDs and MDs was longer (p < 0.05) in lambs aged 12-16 than 3-6 weeks (33 ± 5.4 cf. 25 ± 6.4 and 26 ± 4.2 cf. 18 ± 5.5 minutes) but were independent of the anaesthetic used. CONCLUSIONS AND CLINICAL RELEVANCE: The effect of atracurium is age-dependent in lambs being prolonged in older animals. The onset of neuromuscular blockade is more rapid in isoflurane compared with sevoflurane-anaesthetized lambs.

Severe cardiovascular depression in a cat following a mandibular nerve block with bupivacaine.

OBSERVATIONS: A 12 year old cat was presented for anaesthesia to remove a mandibular squamous cell carcinoma. After intramuscular premedication with dexmedetomidine and methadone, anaesthesia was induced with alfaxalone, administered intravenously (IV) to effect, and maintained with isoflurane vaporized in oxygen, following oro-tracheal intubation. Approximately 5 minutes after performing a mandibular nerve block with 1.16 mg kg(-1) of bupivacaine, the cat developed severe cardiovascular depression. Anaesthetic delivery was discontinued and cardiopulmonary resuscitation instituted. Drug administration consisted of atropine (0.02 mg kg(-1) IV, repeated three times), followed by atipamezole (0.08 mg kg(-1) IV). Dobutamine was subsequently administered (1 µg kg(-1) minute(-1) IV) until cardiovascular performance was considered satisfactory. During recovery from anaesthesia the cat exhibited seizure-like activity, which was controlled by a variable rate infusion of propofol. The cat made an uneventful recovery following discontinuation of propofol infusion, without residual neurological signs, and the surgical procedure was postponed. CONCLUSIONS: This clinical report describes successful management of cardiovascular and neurological complications following a mandibular nerve block with bupivacaine in a cat. Although treatment was successful, the role played by the drugs administered during resuscitation remains uncertain.

Postoperative complications in a lamb after major surgery.

INTRODUCTION: Anaesthesia in lambs undergoing experimental surgery may develop problems associated with age-related immune incompetency: a postoperative complication in a 3 week old Scottish blackface lamb after spinal surgery is presented. CASE HISTORY AND MANAGEMENT: Both lamb and ewe were in good condition. The ewe was vaccinated against Clostridium perfringens and Clostridium tetani 5 weeks pre-partum. There were no apparent problems with the lamb's intake of colostrum. Pre-anaesthetic medication was intramuscular medetomidine (10 µg kg(-1)). Anaesthesia was induced and maintained with sevoflurane in oxygen. Morphine (0.5 mg kg(-1)), meloxicam (0.6 mg kg(-1)) and ketamine (1 mg kg(-1) followed by 10 µg kg(-1) minute(-1)) were administered intravenously (IV) for perioperative analgesia. Atracurium (0.5 mg kg(-1) IV, followed by 0.17 mg kg(-1) injected when the first twitch of the four, train-of four count was palpated) was used to improve muscle relaxation. The lamb's trachea was intubated and the lungs mechanically ventilated to maintain normocapnia. Intrathecal morphine (0.2 mg kg(-1)), IV meloxicam (0.3 mg kg(-1)) and edrophonium (0.5 mg kg(-1)) were administered before recovery. Operative and initial recovery periods were unremarkable. Three hours after surgery the lamb became depressed. Tachycardia (180-250 beats minute(-1)), tachypnoea (30 breaths minute(-1)), poor peripheral perfusion and cold pelvic limb extremities were present mimicking severe pain, and/or hypovolaemic shock. Analgesics - morphine (total dose 1.3 mg kg(-1)) - and IV fluid therapy boluses - crystalloids (300 mL), colloids (120 mL) and fresh whole blood (60 mL) - failed to ameliorate clinical signs and so the lamb was euthanized 10 hours after surgery. Post-mortem findings supported a possible diagnosis of peracute Clostridium perfringens enterotoxaemia. CONCLUSION: Clostridium perfringens enterotoxaemia should be considered when clinical signs of severe pain and/or hypovolaemic shock fail to respond to analgesics and fluid resuscitation in lambs after major surgery.