Retrospective comparison of three locoregional techniques for pelvic limb surgery in dogs.

OBJECTIVE: To retrospectively compare the efficacy and duration of effect of three commonly used locoregional blocks in dogs undergoing pelvic limb orthopaedic surgery. STUDY DESIGN: Retrospective clinical study. ANIMALS: A total of 236 dogs that underwent pelvic limb surgery and were administered a locoregional technique. METHODS: A total of 236 hospital records were reviewed and 230 included in statistical analysis. Dogs were grouped as following: electrostimulation-guided pre-iliac femoral and sciatic nerve block (group PFS, n = 70); ultrasound-guided saphenous and sciatic nerve block (group SS, n = 76); or lumbosacral epidural (group EPI, n = 84). In group EPI, bupivacaine 0.5% or ropivacaine 0.75% was used with morphine. Dogs were pain scored (short form of the Glasgow Composite Measure Pain Scale) hourly following recovery from anaesthesia. Analysed data included: time to first postoperative dose of methadone, pain score at that time, intraoperative rescue analgesia, intraoperative hypotension and ability to walk and urinate overnight. Separate analyses were performed including all pelvic limb surgeries and including only elective stifle surgeries. Kruskal-Wallis and Mann-Whitney tests were performed. A p value < 0.05 was considered significant. The median (range) is reported. RESULTS: For all pelvic limb surgeries, the time to first postoperative methadone was 530 (110-1337), 440 (140-1030) and 466 (135-1094) minutes in groups EPI, PFS and SS, respectively, and was not significantly different. Postoperatively, 10/84, 15/70 and 12/76 dogs in groups EPI, PFS and SS, respectively, did not require methadone (nonsignificant). Significantly fewer dogs in group EPI (18%) required intraoperative rescue analgesia compared with group SS (38%), but not compared with PFS (30%). Significantly more dogs in group EPI had hypotension intraoperatively (30%) and urinary retention postoperatively (62%). CONCLUSIONS AND CLINICAL RELEVANCE: Intraoperative analgesia may be superior with EPI than SS for some surgeries of the pelvic limb, but not for stifle surgeries. All three techniques provided similar requirement for postoperative analgesia, but EPI caused higher incidence of intraoperative hypotension and postopertive urinary retention.

Development of a severity scoring system for acute haemorrhage in anaesthetized domestic cats: the CABSS score.

OBJECTIVE: To determine whether physiological, haematological, biochemical or electrolyte variables can predict severe haemorrhage in cats. STUDY DESIGN: Randomized crossover study whereby each cat underwent mild and severe haemorrhage, with a 2 month period between events. ANIMALS: A group of six domestic cats aged 21 ± 1 months and weighing 4.9 ± 1.2 kg, mean ± standard deviation. METHODS: Cats were anaesthetized (buprenorphine, alfaxalone, isoflurane in oxygen at a fixed end-tidal concentration of 1.7%) before the haemorrhage event. In total, 34 variables were measured twice (prehaemorrhage and posthaemorrhage). The difference and percent change for each variable were compared between haemorrhage events (paired t test). Significant variables were placed into 13 different ratios (posthaemorrhage value of one variable divided by a posthaemorrhage value of a second variable) and compared (paired t test), and Cohen's d (d) was calculated. Receiver operating characteristic curves were plotted and cut-off values for weak, moderate and strong indicators of severe haemorrhage were obtained. RESULTS: The blood loss was 4.5 ± 1.1 mL kg-1 and 26.8 ± 5.5 mL kg-1 for mild and severe haemorrhage events, respectively. The most significant variables with large effect sizes were heart rate (HR), systolic arterial blood pressure (SAP), end-tidal carbon dioxide (Pe'CO2), serum albumin, haematocrit and actual bicarbonate ion concentration [HCO3-(act)]. The most robust ratios were: 1) shock index (d = -2.8; HR:SAP); 2) HR:Pe'CO2 (d = -2.9); 3) serum albumin: haematocrit (d = 1.5); and 4) HR:HCO3-(act) (d = -1.6). These ratios were included in the final proposed Cat Acute Bleeding Scoring System (CABSS). CONCLUSIONS: and clinical relevance Cats subjected to mild and severe haemorrhage demonstrated statistically and clinically relevant changes whereby four ratios could be created to make up the CABSS. The ratios detected and quantified the presence of severe haemorrhage in anaesthetized cats.

Intraoperative anaesthetic complications in dogs undergoing general anaesthesia for thoracolumbar hemilaminectomy: a retrospective analysis.

OBJECTIVE: To establish the incidence of intraoperative anaesthetic complications in dogs undergoing general anaesthesia (GA) for thoracolumbar hemilaminectomy (TH), to determine whether GA duration affects incidence of intraoperative complications and to identify associations between intraoperative complications. STUDY DESIGN: Retrospective observational study. ANIMALS: A total of 224 client-owned dogs of various breeds undergoing TH for intervertebral disc extrusion. METHODS: Anaesthetic records of dogs undergoing TH at a university teaching hospital between 2010 and 2016 were analysed. Data recorded included breed, sex, body weight, GA duration, magnetic resonance imaging (MRI) under the same GA, pharmacological intervention to increase heart rate (PIHR), hypotension (mean arterial blood pressure < 60 mmHg for ≥ 10 minutes), mechanical ventilation (MV) for inadequate ventilation, hypothermia (oesophageal temperature < 37 °C), oesophageal temperature ≥ 39 °C (T ≥ 39 °C), temperature trend, regurgitation and use of alpha-2 adrenoreceptor agonists, acepromazine, ketamine or lidocaine. Multivariate logistic regression models were fitted for hypothermia, T ≥ 39 °C, hypotension and PIHR with forced inclusion of GA duration. RESULTS: Hypothermia was the most common complication (63.8% incidence), followed by MV implementation (63.4%), hypotension (33.9%), PIHR (24.6%), T ≥ 39 °C (20.5%) and regurgitation (4.9%). Multivariate models revealed that MRI and hypotension were associated with an increased risk of hypothermia, whilst increasing body weight, alpha-2 adrenoreceptor agonists and MV were associated with a reduced risk. Alpha-2 adrenoreceptor agonists and GA duration were associated with an increased risk of T ≥ 39 °C, whilst hypotension was associated with a reduced risk. Hypothermia and PIHR were associated with an increased risk of hypotension, whereas increased body weight was associated with a reduced risk. MV and hypothermia were associated with an increased risk of PIHR, whereas increased body weight was associated with a reduced risk. CONCLUSIONS AND CLINICAL RELEVANCE: Increasing GA duration was associated with increased risk of T ≥ 39 °C, but not any other intraoperative complications.

Effect of different analgesic techniques on hemodynamic variables recorded with an esophageal Doppler monitor during ovariohysterectomy in dogs.

This study compared the efficacy of intravenous (IV) fentanyl and ketamine with lumbosacral epidural lidocaine in dogs undergoing ovariohysterectomy. Dogs with esophageal Doppler monitoring (n = 112) were included in this retrospective study. All dogs were premedicated with dexmedetomidine and methadone, induced with IV propofol or alfaxalone and maintained using isoflurane and IV fentanyl, IV ketamine, or epidural lidocaine. Heart rate (HR), mean arterial pressure (MAP), expired fraction of isoflurane (ETIso), stroke distance (SD), minute distance (MD), peak velocity (PV) and mean acceleration (MA) were recorded before and after ligation of the ovarian pedicle (OvP). There were no differences for ETIso, HR, and MAP among fentanyl, ketamine, and control groups. Minute Distance, SD, MA and PV significantly decreased after OvP in fentanyl, ketamine, and control groups, but remained stable in the epidural group. Lumbosacral epidural lidocaine prevented hemodynamic depression changes caused by OvP ligation, whereas fentanyl and ketamine failed to do so.

Effet de différentes techniques analgésiques sur les variables hémodynamiques enregistrées avec un moniteur Doppler oesophagien lors de l'ovariohystérectomie chez la chienne. Cette étude a comparé l'efficacité du fentanyl et de la kétamine administrés par voie intraveineuse (IV) à la lidocaïne épidurale lombosacrée chez des chiennes soumis à une ovariohystérectomie. Cent douze chiennes surveillées avec du Doppler oesophagien (n = 112) ont été inclus dans cette étude rétrospective. Tous les chiens ont été prémédiqués avec de la dexmédétomidine et de la méthadone, induits avec du propofol ou de l'alfaxalone IV et maintenus en utilisant de l'isoflurane et du fentanyl IV, de la kétamine IV ou de la lidocaïne épidurale. La fréquence cardiaque (FC), la pression artérielle moyenne (PAM), la fraction expirée d'isoflurane (ETIso), la distance d'éjection (DE), la distance minute (DM), la vitesse maximale (VMax) et l'accélération moyenne (AM) ont été enregistrées avant et après la ligature du pédicule ovairien (POv). Il n'y avait pas des différences pour ETIso, HR et MAP entre les groupes fentanyl, kétamine et témoin. La DM, DE, AM et Vmax avez diminué significativement après POv dans les groupes fentanyl, kétamine et témoins, mais ils restent stables dans le groupe épidural. La lidocaïne épidurale lombosacrée a évité des changements hémodynamiques provoqués par la POv, alors que le fentanyl et la kétamine ne l'ont pas fait.(Traduit par les auteurs).

Postoperative respiratory effects of intravenous fentanyl compared to intravenous methadone in dogs following spinal surgery.

OBJECTIVE: To evaluate the 24-hour postoperative respiratory effects of either intravenous fentanyl administered as a constant rate infusion or boluses of methadone, in dogs following spinal surgery, assessed by serial arterial blood gas analyses. STUDY DESIGN: Prospective, randomized clinical study. ANIMALS: Thirty-two healthy dogs (American Society of Anesthesiologists I/II) anaesthetized for elective caudal thoracic and/or lumbar decompression spinal surgery. METHODS: Dogs were assigned randomly to be administered a fentanyl constant rate infusion (5 µg kg-1 hour-1; group F, n = 14) or methadone boluses (0.2 mg kg-1, every 4 hours; group M, n = 15) postoperatively for 24 hours. Each dog's anaesthesia protocol was customized. Arterial blood samples were collected from an arterial cannula, placed under anaesthesia, at 4, 8, 12 and 24 hours postextubation, while breathing room air. Cardiorespiratory variables, Glasgow composite pain scale (GCPS) and sedation (SED) scores were also recorded at these time points. Independent t tests, repeated measures anova and Mann-Whitney U tests were used. Significance was defined as p < 0.05. RESULTS: There were no significant differences found between groups in any of the overall mean values or at any time point for values of partial pressure of oxygen [13.9 ± 2.1 kPa (103.9 ± 16.1 mmHg) and 12.6 ± 2.0 kPa (94.7 ± 15.2 mmHg)], partial pressure of carbon dioxide [4.8 ± 0.6 kPa (36 ± 4.2 mmHg) and 4.9 ± 0.6 kPa (36.5 ± 4.5 mmHg)], pH (7.38 ± 0.03 and 7.40 ± 0.03), bicarbonate (21.5 ± 2.3 mm and 21.9 ± 6.6 mm) and base excess (-3.4 ± 2.6 mm and -2 ± 3 mm) for groups F and M, respectively. Cardiorespiratory variables, GCPS and SED scores were also similar between groups. CONCLUSIONS AND CLINICAL RELEVANCE: At the doses studied, neither fentanyl nor methadone caused respiratory depression postoperatively in dogs following caudal thoracic and/or lumbar spinal surgery.

The effect of maropitant on intraoperative isoflurane requirements and postoperative nausea and vomiting in dogs: a randomized clinical trial.

OBJECTIVE: To establish if preoperative maropitant significantly reduced intraoperative isoflurane requirements and reduced clinical signs associated with postoperative nausea and vomiting (PONV) in dogs. STUDY DESIGN: Randomized clinical trial. ANIMALS: Twenty-four healthy, client-owned dogs undergoing routine ovariohysterectomy. METHODS: Premedication involved acepromazine (0.03 mg kg-1) combined with methadone (0.3 mg kg-1) intramuscularly 45 minutes before anaesthetic induction with intravenous (IV) propofol, dosed to effect. Meloxicam (0.2 mg kg-1) was administered intravenously. Dogs were randomly assigned to administration of saline (group S; 0.1 mL kg-1, n=12) or maropitant (group M; 1 mg kg-1, n=12) subcutaneously at time of premedication. Methadone (0.1 mg kg-1 IV) was repeated 4 hours later. Anaesthesia was maintained with isoflurane in oxygen, dosed to effect by an observer unaware of group allocation. The dogs were assessed hourly, starting 1 hour postoperatively, using the short form of the Glasgow Composite Pain Score (GCPS), and for ptyalism and signs attributable to PONV [score from 0 (none) to 3 (severe)] by blinded observers. Owners completed a questionnaire at the postoperative recheck. RESULTS: Overall mean±standard deviation end-tidal isoflurane percentage was lower in group M (1.19±0.26%) than group S (1.44±0.23%) (p=0.022), but was not significantly different between groups at specific noxious events (skin incision, ovarian pedicle clamp application, cervical clamp application, wound closure). Cardiorespiratory variables and postoperative GCPS were not significantly different between groups. Overall, 50% of dogs displayed signs attributable to PONV, with no difference in PONV scores between groups (p=0.198). No difference in anaesthetic recovery was noted by owners between groups. CONCLUSIONS: Maropitant reduced overall intraoperative isoflurane requirements but did not affect the incidence of PONV. CLINICAL RELEVANCE: Maropitant provided no significant benefits to dogs undergoing ovariohysterectomy with this anaesthetic and analgesic protocol, although clinically significant reductions in isoflurane requirements were noted.

Effects of intravenous and topical laryngeal lidocaine on heart rate, mean arterial pressure and cough response to endotracheal intubation in dogs.

OBJECTIVE: To compare the effects of intravenous (IV) and topical laryngeal lidocaine on heart rate (HR), mean arterial pressure (MAP) and cough response to endotracheal intubation (ETI) in dogs. STUDY DESIGN: Prospective, randomized, blinded clinical study. ANIMALS: Forty-two client-owned dogs (American Society of Anesthesiologists class I and II status) undergoing elective orthopaedic surgery. METHODS: Dogs were randomized to three groups. Dogs in group SALIV received 0.1 mL kg(-1) IV saline. Dogs in group LIDIV received 2 mg kg(-1) IV 2% lidocaine. Dogs in group LIDTA received 0.4 mg kg(-1) topically sprayed laryngeal 2% lidocaine. All dogs were premedicated with methadone (0.2 mg kg(-1) IV). After 30 minutes, IV propofol was administered to abolish the lateral palpebral reflex and produce jaw relaxation. The allocated treatment was then administered and, after 30 seconds, further propofol was administered to abolish the medial palpebral reflex and facilitate ETI. HR and MAP were measured at four time-points using cardiac auscultation and automated oscillometry, respectively. The cough response at ETI was recorded. One-way anova and post hoc Tukey adjustment were used to analyse parametric data. The Kruskal-Wallis test was used to analyse non-parametric data. Odds ratios were calculated for the cough response. A p-value of ≤0.05 was considered to indicate statistical significance. RESULTS: In response to ETI, changes in MAP differed significantly between groups. In SALIV, MAP increased (4 ± 6 mmHg), whereas it decreased in LIDIV (6 ± 13 mmHg) (p = 0.013) and LIDTA (7 ± 11 mmHg) (p = 0.003). Dogs in SALIV were almost 10 times more likely to cough than dogs in LIDIV (odds ratio 9.75, 95% confidence interval 0.98-96.60; p = 0.05). CONCLUSIONS AND CLINICAL RELEVANCE: In propofol-anaesthetized dogs, IV and topical laryngeal lidocaine attenuated the pressor response to ETI, whereas IV lidocaine reduced the cough response.

Adverse reactions following administration of contrast media for diagnostic imaging in anaesthetized dogs and cats: a retrospective study.

OBJECTIVE: To evaluate incidences of adverse reaction after the administration of contrast media. STUDY DESIGN: Retrospective observational study. ANIMALS: Animals included 356 dogs and 58 cats receiving non-ionic iodinated contrast agents, and 425 dogs and 49 cats receiving gadolinium-based contrast agents. METHODS: Anaesthesia records of dogs and cats receiving intravenous (IV) gadobutrol for magnetic resonance imaging (MRI) or IV iohexol for computed tomography (CT) were reviewed. Changes in pulse rate, respiratory rate and mean arterial pressure at 5 minutes after administration of the contrast medium were evaluated. Changes of 10-20% were considered mild, those of >20% moderate, and reactions that required immediate treatment were considered severe. Associations of sex, age and weight with contrast reaction were investigated using logistic regression. Differences in the incidences of reactions to CT and MRI contrast media were examined with chi-squared tests. A p-value of <0.05 was considered to indicate statistical significance. RESULTS: Of cats receiving iohexol, eight (13.8%) had mild and 10 (17.2%) had moderate reactions. Of cats receiving gadobutrol, six (12.2%) had mild and six (12.2%) had moderate reactions. No cats had severe reactions and the risk for reaction was not associated with type of medium, age, weight or sex (p > 0.2). Of dogs receiving iohexol, 64 (18.0%) had mild, 65 (18.3%) had moderate and three (0.8%) had severe reactions. Of dogs receiving gadobutrol, 42 (9.9%) had mild, 87 (20.5%) had moderate and one (0.2%) had a severe reaction. When dogs receiving iohexol were compared with those receiving gadobutrol, the odds ratio of a moderate reaction was 2.0 (95% confidence interval 1.34-3.10; p = 0.001). These estimates did not change substantially after adjustment for age, weight and sex. CONCLUSIONS AND CLINICAL RELEVANCE: Severe reactions to iohexol and gadobutrol are rare in dogs and cats; moderate reactions are more likely with iohexol than with gadobutrol.

Antinociceptive effects of epidural magnesium sulphate alone and in combination with morphine in dogs.

OBJECTIVE: To compare the antinociceptive effects of magnesium sulphate (MgSO(4)) when administered epidurally alone and in combination with morphine. STUDY DESIGN: Experimental, randomized, 'blinded', crossover study. ANIMALS: Six healthy adult Beagle dogs. METHODS: Evaluated treatments were MgSO(4) (2.5 mg kg(-1)) alone (Mg), morphine (0.1 mg kg(-1)) alone (Mo), MgSO(4) in combination with morphine (Mm), and sterile water (0.115 mL kg(-1) ; Co) that were injected in the lumbosacral epidural space using an epidural catheter. Antinociception was measured using the von Frey mechanical threshold device applied to the carpal pads, both sides of the thorax and metatarsi. Measurements were obtained at time points: before treatment (baseline) and 0.5, 1, 2, 4, 6, 12, 18 and 24 hours after the epidural injection. Sedation, behaviour score and presence of motor deficits were assessed. Data were analyzed using a linear mixed model and Bonferroni adjustments, with significance set at p < 0.05. RESULTS: There were significant effects of treatment and time in all regions. Overall threshold values in grammes force [median (interquartile range)] when stimulation regions were combined were significantly higher in Mg [164 (135-200)], Mo [156 (129-195)] and Mm [158 (131-192)] compared to Co [145 (120-179)]. Thresholds were significantly higher compared to Co in Mg, Mo and Mm at the thorax and metatarsi, but only in Mg and Mo at the carpal pads. No motor deficits were observed at any time point. Thresholds (combined regions) were increased from baseline at one or more time points with all treatments, including control. CONCLUSION AND CLINICAL RELEVANCE: Epidural MgSO(4) produced an antinociceptive effect characterised by an increase in the mechanical thresholds of similar magnitude to that produced by epidural morphine, compared with the control group, without causing any motor deficits. No potentiation of morphine antinociception was observed. The onset and offset times of antinociception could not be clearly established. To what extent these results can be extrapolated to clinical cases requires further investigation.

Anaesthetic, analgesic and cardiorespiratory effects of intramuscular medetomidine-ketamine combination alone or with morphine or tramadol for orchiectomy in cats.

OBJECTIVES: To compare the anaesthetic, analgesic and cardiorespiratory effects of intramuscular (IM) medetomidine and ketamine administered alone or combined with morphine or tramadol, for orchiectomy in cats. STUDY DESIGN: Randomised, blinded, prospective clinical study. ANIMALS: Thirty client-owned cats. MATERIALS AND METHODS: Cats (n = 10 in each group) received a combination of medetomidine (60 µgkg(-1) ) and ketamine (10 mg kg(-1) ) alone (MedK); combined with morphine (0.2 mg kg(-1) ) (MedKM), or combined with tramadol (2 mg kg(-1) ) (MedKT) IM. Time of induction, surgical and recovery events were recorded, and physiological parameters measured and recorded. Analgesia was evaluated with a visual analogue scale, a composite scoring system and the von Frey mechanical threshold device, every hour from three to eight hours post-drug administration injection. Data were analyzed with a linear mixed model, Kruskal-Wallis or Chi-square tests (p < 0.05). RESULTS: Median (IQR) induction and recovery times (minutes) were not significantly (p = 0.125) different between groups: 5.6 (2.7-8.0), 7.4 (5.1-9.6) and 8.0 (5.8-14.9) for induction and 128.5 (95.1-142.8), 166.4 (123.1-210.0) and 142.9 (123.4-180.2) for recovery, with MedK, MedKT and MedKM, respectively. Two cats (MedKM) required alfaxalone for endotracheal intubation. In all groups, three or four cats required additional isoflurane for surgery. Arterial oxygen tension overall (mean ± SD: 66 ± 2 mmHg) was low. Surgery resulted in increased systolic arterial blood pressure (p < 0.001), haemoglobin saturation (p < 0.001), respiratory (p = 0.003) and heart rates (p = 0.002). Pain scores did not differ significantly between groups. Von Frey responses decreased over time; changes over time varied by treatment (p < 0.001), MedK returning to baseline values more rapidly than MedKM and MedKT. No cat required rescue analgesics. CONCLUSION AND CLINICAL RELEVANCE: All three protocols can provide adequate anaesthesia and analgesia for orchiectomy in cats. However, rescue intervention to maintain surgical anaesthesia may be required in some cats. Oxygen supplementation is advised.

Effects of xylazine, romifidine, or detomidine on hematology, biochemistry, and splenic thickness in healthy horses.

Alpha-2 agonist-induced changes in packed cell volume (PCV), total solids (TS), selected biochemical parameters, and splenic thickness were investigated in horses. Four healthy mares were treated in a blinded, randomized, cross-over design with a dose of xylazine (0.5 mg/kg), romifidine (0.04 mg/kg), or detomidine (0.01 mg/kg) IV, and detomidine (0.02 mg/kg) IM. Hematology, TS, colloid osmotic pressure (COP), plasma osmolality; glucose, lactate, urea (BUN) and electrolyte concentrations; venous blood pH and ultrasonographic splenic thickness were evaluated at intervals for 300 min. Repeated measures analysis of variance (ANOVA) were performed with P < 0.05. There was a significant change over time in PCV and TS following each treatment (P < 0.001), with median (range) reductions of 20.9% (12.9% to 27.3%) and 5.8% (3.0% to 10.3%), respectively. Red blood cell count, BUN, and COP decreased while osmolality, glucose, Na(+), and splenic thickness increased. Treatments induced clinically significant transient changes in PCV, TS, and other biochemical parameters, which should be considered when assessing horses that received these drugs.

Effets de la xylazine, de la romifidine ou de la détomidine sur l'hématologie, la biochimie et l'épaisseur splénique chez des chevaux en santé. Des changements induits à l'aide d'alpha-2 agonistes au niveau de la valeur d'hématocrite (VH), des solides totaux (ST), de paramètres biochimiques choisis et de l'épaisseur splénique ont été étudiés chez les chevaux. Quatre juments en santé ont été traitées dans une étude à l'aveugle, randomisée et croisée avec une dose de xylazine (0,5 mg/kg), de romifidine (0,04 mg/kg) ou de détomidine (0,01 mg/kg) IV et de détomidine (0,02 mg/kg) IM. L'hématologie, les ST, la pression osmotique colloïdale (POC), l'osmolalité plasmatique, le glucose, le lactate, l'urée (l'azote uréique du sang) et les concentrations d'électrolytes, le pH du sang veineux et l'épaisseur splénique échographique ont été évalués à des intervalles de 300 minutes. L'analyse de la variance des mesures répétées a été réalisée avec P < 0,05. Il y avait des changements significatifs dans le temps de VH et des ST après chaque traitement (P < 0,001), avec des réductions moyennes (écart) de 20,9 % (de 12,9 % à 27,3 %) et de 5,8 % (de 3,0 % à 10,3 %), respectivement. Le nombre de globules rouges, l'azote uréique du sang et la POC ont diminué tandis que l'osmolalité, le glucose, Na+ et l'épaisseur splénique ont augmenté. Les traitements ont induit des changements transitoires significatifs sur le plan clinique dans la VH, les ST et les autres paramètres biochimiques qui devraient être considérés lors de l'évaluation des chevaux qui ont reçu ces médicaments.(Traduit par Isabelle Vallières).

Prothrombin and activated partial thromboplastin times, thromboelastography, hematocrit, and platelet count in a feline hemorrhage/over-resuscitation model using lactated Ringer's solution or 6% tetrastarch 130/0.4.

OBJECTIVE: To describe and compare prothrombin time (PT), activated partial thromboplastin time (aPTT), thromboelastography (TEG), HCT, and platelet count measurements in a hemorrhage/over-resuscitation model. DESIGN: Randomized crossover study. SETTING: University teaching hospital. ANIMALS: Six cats. INTERVENTIONS: Anesthetized cats underwent 3 treatments at 2-month intervals. The treatments were as follows: NHR-no controlled hemorrhage and sham resuscitation; LRS-controlled hemorrhage and lactated Ringer's solution (LRS) for resuscitation; and Voluven-controlled hemorrhage and 6% tetrastarch 130/0.4 for resuscitation. The LRS and Voluven were administered at 60 and 20 mL/kg/h, respectively, for 120 minutes. Blood samples were drawn for PT, aPTT, TEG, HCT, and platelet count measurements at a healthy check (T - 7d), after controlled hemorrhage (T0), at 60 and 120 minutes of resuscitation (T60 and T120), and at 24 hours after completion of resuscitation (T24h). Data were analyzed using a general linear mixed model approach (significance was P < 0.05). MEASUREMENTS AND MAIN RESULTS: Total median blood loss (controlled hemorrhage and blood sampling from T0 to T120) at T120 was 11.4, 31.0, and 30.8 mL/kg for NHR, LRS, and Voluven, respectively. PT and aPTT during LRS and Voluven were prolonged at T60 and T120 compared to NHR (P < 0.001). On TEG, the reaction time, kinetic time, and alpha-angle were within reference intervals for cats at all time points in all treatments, while maximum amplitude was less than the reference interval (40 mm) at T0, T60, and T120 during Voluven and at T60 and T120 during LRS compared to NHR (both P < 0.001). The HCT and platelet count were significantly lower at T60 and T120 during LRS and Voluven compared to NHR (P < 0.001). CONCLUSIONS: Hypocoagulopathy was observed during hemorrhage and liberal fluid resuscitation. Prolongation of PT and aPPT and decreased clot strength may have been caused by hemodilution and platelet loss.

Clinical use of a low-dose medetomidine infusion in healthy dogs undergoing ovariohysterectomy.

Eight healthy dogs undergoing elective ovariohysterectomy were anesthetized with a standard protocol and received a low-dose medetomidine constant rate infusion during surgery. Cardiorespiratory parameters, including non-invasive cardiac output, were measured at various times. This protocol resulted in acceptable and stable cardiovascular performance, allowed low isoflurane concentrations, and provided smooth recoveries.

Utilisation clinique d'une infusion d'une faible dose de médétomidine chez les chiennes en santé subissant une ovariohystérectomie. Huit chiennes en santé subissant une ovariohystérectomie non urgente ont été anesthésiées à l'aide d'un protocole standard et ont reçu une infusion constante d'une faible dose de médétomidine durant la chirurgie. Les paramètres cardiorespiratoires, incluant le débit cardiaque non effractif, ont été mesurés à divers moments. Ce protocole a produit un rendement cardiovasculaire acceptable et stable et a permis de faibles concentrations d'isoflurane et des réveils sans problème.(Traduit par Isabelle Vallières).

Severe Hypercapnia during Anaesthesia under Mechanical Ventilation in Two Paediatric Patients.

A 2-month-old male 1.56 kg Yorkshire terrier (Case No. 1) and a 3-month-old male 2.3 kg Jack Russell Terrier (Case No. 2) were scheduled for ophthalmological surgery under general anaesthesia and neuromuscular blockade. For both patients, volume-controlled ventilation (VCV) was used with set tidal volumes (VT) of 13 mL/kg and 20 mL/kg for cases No. 1 and 2, respectively. The type of ventilator used did not take into account the intrinsic compliance of the breathing system; therefore, a significant part of the delivered VT was wasted in the expansion of the breathing system, and did not reach the patients, causing alveolar hypoventilation. Both cases developed low dynamic compliance (CD), and after a recruitment manoeuvre, EtCO2 of up to 116 mmHg and 197 mmHg were revealed for cases No. 1 and 2, respectively. The two cases had to be ventilated manually, using positive inspiratory pressures (PIP) of 20-25 mmHg, in order to improve alveolar ventilation and reduce the EtCO2, as adjustments to the VCV were ineffective. Both patients maintained an oxygen haemoglobin saturation between 94% and 100% throughout the procedure and they recovered well. Using a higher VT from the beginning, to compensate for the compliance of the breathing system, or the use of pressure-controlled ventilation (PCV), could have potentially helped to avoid these two incidences of severe hypercapnia.

Possible Brainstem Anaesthesia in a Cat after Ultrasound-Guided Retrobulbar Block.

A 13-year-old neutered, blue-eyed female Siamese cat with a bodyweight of 4.8 kg was admitted for enucleation of the right eye. An ultrasound guided retrobulbar block with 1 mL of ropivacaine was performed under general anaesthesia. When the tip of the needle was visualised inside the intraconal space, negative aspiration of the syringe before injection and no obvious resistance during injection were confirmed. Instantly, after ropivacaine was administered, the cat became apnoeic, and its heart rate and the blood pressure increased significantly for a short period of time. During surgery, the cat needed cardiovascular support to maintain blood pressure and was under continuous mechanical ventilation. Spontaneous breathing returned 20 min after the end of anaesthesia. Brainstem anaesthesia was suspected, and after recovery, the contralateral eye was examined. A reduced menace response, horizontal nystagmus, mydriasis, and absence of the pupillary light reflex were present. The following day, mydriasis was still present, but the cat was visual and was discharged. The inadvertent intra-arterial injection of ropivacaine was suspected to be the cause of the spread into the brainstem. To the current authors' knowledge, possible brainstem anaesthesia has only been reported in a cat 5 min after a retrobulbar block but never instantly.

The Outcomes of an Opioid-Free Anaesthetic Plan in Fourteen Dogs Undergoing Enucleation Using an Ultrasound-Guided Supra-Temporal Retrobulbar Block: A Retrospective Case Series.

The objective of this retrospective case series is to report the outcomes of an opioid-free anesthetic plan in dogs undergoing enucleation surgery. A total of 14 dogs were admitted for enucleation between March and December 2020. A multimodal approach to perioperative analgesia was used, with a focus on retrobulbar anesthesia. A combination of an ultrasound-guided retrobulbblock with a supratemporal approach in association with ketamine, dexmedetomidine and non-steroidal anti-inflammatory drugs was used in the reported cases. Intraoperative nociception was defined as an increase of 20% from the baseline in one or more of the following parameters: heart rate, respiratory rate or mean arterial pressure. An ultrasound-guided retrobulbar block in an opioid-free anesthesia regime was effective at managing the perioperative analgesia of 13 out of 14 dogs. In only one case, a bolus of fentanyl was administered to treat intraoperative nociception. Recovery was uneventful in all the dogs, and the postoperative pain scores remained below the intervention threshold at all time points. To the authors' knowledge, this is the first reported case series of opioid-free anesthesia for enucleation in dogs.

Comparison of three techniques for paravertebral brachial plexus blockade in dogs.

OBJECTIVE: To compare success and complication rates, based on staining of nerves and other structures, among three techniques of paravertebral brachial plexus blockade (PBPB) in dogs. STUDY DESIGN: Prospective randomized design. ANIMALS: A total of 68 thoracic limbs from 34 dogs. METHODS: Limbs were randomly assigned to blind (BL) (n = 24), nerve stimulator-guided (NS) (n = 21) or ultrasound-guided (US) (n = 23) technique. Injections were made with 0.3 mL kg(-1) of lidocaine mixed with new methylene blue. Time to perform each block and current used during NS technique were recorded. Dogs were anesthetized during the blocks and euthanized once completed. Dissections were performed to evaluate staining of nerves, spinal cord, mediastinum, pleura and vessels. An anova and Tukey adjustment for time, logistic regression for association between current and nerve staining and a generalized linear mixed model for staining of different structures were used. Significance was considered when p ≤ 0.05. RESULTS: The median (range) number of nerves stained was 2 (0-4) with BL, 1 (0-3) with NS and 1 (0-4) with US guided technique. No significant differences in staining of C6, C8 and T1 or other structures were found among techniques. Nerve C7 was more likely to be stained by BL (p = 0.05). Time to perform the blocks was significantly different among techniques, with mean ± SD duration in minutes of 3.6 ± 1.8 with BL, 6.3 ± 2.7 with US and 12.2 ± 5 with NS. The most common complication was staining of the spinal cord (29%, 38% and 39% with BL, NS and US, respectively). CONCLUSIONS: Success rates were low and complication rates were relatively high, based on staining, with the three techniques. CLINICAL RELEVANCE: The use of more advanced techniques for PBPB in dogs is not justified according to this study. Clinical significance of the complications encountered in this study should be evaluated.

Effects of a constant rate infusion of magnesium sulphate in healthy dogs anaesthetized with isoflurane and undergoing ovariohysterectomy.

OBJECTIVE: To determine the effects of intravenous (IV) magnesium sulphate (MgSO(4) ) as a bolus followed by a constant rate infusion (CRI) on anaesthetic requirements, neuroendocrine stress response to surgery, haemostasis and postoperative analgesia in healthy dogs undergoing ovariohysterectomy. STUDY DESIGN: Blinded randomized clinical trial. ANIMALS: Sixteen female dogs. METHODS: After intramuscular premedication with acepromazine (0.05 mg kg(-1) ) and morphine (0.3 mg kg(-1) ), anaesthesia was induced with diazepam (0.2 mg kg(-1) ) and propofol (2 mg kg(-1) ) intravenously and maintained with isoflurane in oxygen in all dogs. Dogs were randomly assigned to two groups, M and C. Group M received MgSO(4) (50 mg kg(-1) over 15 minutes, followed by a 15 mg kg(-1) hour(-1) CRI). Group C received an equivalent bolus and CRI of lactated Ringer's solution. In addition, all dogs received lactated Ringer's solution (10 mL kg(-1) over 15 minutes followed by 10 mL kg(-1) hour(-1) ). End-tidal isoflurane and carbon dioxide tensions, cardio-respiratory variables, arterial blood gases, electrolytes, ACTH and cortisol concentrations were measured at different time points. Thromboelastography (TEG) was performed pre- and post-anaesthesia. Postoperative pain was evaluated using the short form of the Glasgow Composite Pain Scale. Data were analysed with repeated measures anova and Mann-Whitney U tests (p < 0.05). RESULTS: No statistically significant differences between groups were found in any of the measured variables. However, the alpha angle and maximal amplitude recorded by TEG in group M were significantly increased post-anaesthesia, but remained within the reference interval. One dog in Group M and two in Group C received rescue analgesia during recovery. CONCLUSIONS AND CLINICAL RELEVANCE: As used in this study, MgSO(4) failed to decrease isoflurane requirements, postoperative pain and stress hormone concentrations; however, it did not produce any cardio-respiratory or major haemostatic side effects. Administration of intravenous MgSO(4) together with an opioid during ovariohysterectomy in dogs does not seem to provide any clinical advantage.

Perioperative risk factors for mortality and length of hospitalization in mares with dystocia undergoing general anesthesia: a retrospective study.

This study investigated associations between perioperative factors and probability of death and length of hospitalization of mares with dystocia that survived following general anesthesia. Demographics and perioperative characteristics from 65 mares were reviewed retrospectively and used in a risk factor analysis. Mortality rate was 21.5% during the first 24 h post-anesthesia. The mean ± standard deviation number of days of hospitalization of surviving mares was 6.3 ± 5.4 d. Several factors were found in the univariable analysis to be significantly associated (P < 0.1) with increased probability of perianesthetic death, including: low preoperative total protein, high temperature and severe dehydration on presentation, prolonged dystocia, intraoperative hypotension, and drugs used during recovery. Type of delivery and day of the week the surgery was performed were significantly associated with length of hospitalization in the multivariable mixed effects model. The study identified some risk factors that may allow clinicians to better estimate the probability of mortality and morbidity in these mares.