Anaesthetic management and complications during hypophysectomy in 37 cats with acromegaly.

OBJECTIVES: The aim of this study was to describe the anaesthetic management and perianaesthetic complications encountered during hypophysectomy surgery in acromegalic cats. We explored relationships between animal demographic data, the anaesthetic protocol used and presence of perioperative complications. METHODS: Cats having undergone hypophysectomy surgery for the treatment of feline acromegaly at a single veterinary referral hospital were identified from hospital records. The anaesthesia records and clinical notes of these animals were retrospectively reviewed. Descriptive statistics were produced and binary logistic regression run to assess for any relationship between patient factors, anaesthetic management and complications during the perioperative period. RESULTS: Perianaesthetic complications identified included hypothermia, hypotension, bradycardia and airway obstruction. Mortality at 24 h post-anaesthesia was 8%. The use of alpha (α)2 agonists was associated with a lower incidence of hypotension. Fentanyl infusion was associated with a higher incidence of airway obstruction compared with remifentanil. Subjectively assessed anaesthetic recovery quality had an association with the number of days spent in the intensive care ward postoperatively. CONCLUSIONS AND RELEVANCE: The anaesthetic management described seems effective for hypophysectomy surgery in cats. Intraoperative complications were common and, while not apparently associated with 24 h patient outcome, drugs and equipment to manage these complications should be available.

Hypercoagulability progresses to hypocoagulability during evolution of acetaminophen-induced acute liver injury in pigs.

Increases in prothrombin time (PT) and international normalised ratio (INR) characterise acute liver injury (ALI) and failure (ALF), yet a wide heterogeneity in clotting abnormalities exists. This study defines evolution of coagulopathy in 10 pigs with acetaminophen (APAP)-induced ALI compared to 3 Controls. APAP administration began at 0 h and continued to 'ALF', defined as INR >3. In APAP pigs, INR was 1.05 ± 0.02 at 0 h, 2.15 ± 0.43 at 16 h and > 3 at 18 ± 1 h. At 12 h thromboelastography (TEG) demonstrated increased clot formation rate, associated with portal vein platelet aggregates and reductions in protein C, protein S, antithrombin and A Disintegrin and Metalloprotease with Thrombospondin type 1 repeats-13 (ADAMTS-13) to 60%, 24%, 47% and 32% normal respectively. At 18 ± 1 h, INR > 3 was associated with: hypocoagulable TEG profile with heparin-like effect; falls in thrombin generation, Factor V and Factor VIII to 52%, 19% and 17% normal respectively; further decline in anticoagulants; thrombocytopenia; neutrophilia and endotoxemia. Multivariate analysis, found that ADAMTS-13 was an independent predictor of a hypercoagulable TEG profile and platelet count, endotoxin, Protein C and fibrinogen were independent predictors of a hypocoagulable TEG profile. INR remained normal in Controls. Dynamic changes in coagulation occur with progression of ALI: a pro-thrombotic state progresses to hypocoagulability.

COMPARISON OF ISOFLURANE AND SEVOFLURANE FOR SHORT-TERM ANESTHESIA IN MEERKATS (SURICATA SURICATTA)-ARE THERE BENEFITS THAT OUTWEIGH COSTS?

Meerkats ( Suricata suricatta ) are routinely anesthetized with isoflurane in zoo and field settings. Twenty healthy adult meerkats of mixed age and sex held in the Zoological Society of London's collection were anesthetized with 4% isoflurane by face mask for routine health examinations. The procedure was repeated 5 mo later in the same group of animals utilizing sevoflurane at 5% for induction, and again 3 mo later with sevoflurane at 6.5% for induction to approximate equipotency with isoflurane. The speed and quality of induction and recovery were compared between the two volatile anesthetic agents. There was no statistically significant difference in the speed of induction across any of the anesthetic regimes. There was a significant difference in recovery times between isoflurane and 6.5% sevoflurane (427 ± 218 and 253 ± 65 sec, respectively [mean ± SD]). Under the conditions of this study, sevoflurane at 6.5% induction dose resulted in better quality induction and recovery than sevoflurane at 5% induction or isoflurane. The mean heart and respiratory rates during anesthesia were higher using 5% sevoflurane for induction but there was no significant difference in either rate between isoflurane and sevoflurane used at a 6.5% induction dose. This study suggests that sevoflurane at a dose of 6.5% for induction and 4% for maintenance is a safe and effective anesthetic agent in healthy adult meerkats. Rapid return to normal behavior after anesthesia is important in all zoo species but particularly so in animals with a complex social and hierarchical structure such as meerkats. For this species, the advantage afforded by the speed of recovery with sevoflurane may offset the cost in certain circumstances.

Ventriculo-arterial coupling detects occult RV dysfunction in chronic thromboembolic pulmonary vascular disease.

Chronic thromboembolic disease (CTED) is suboptimally defined by a mean pulmonary artery pressure (mPAP) <25 mmHg at rest in patients that remain symptomatic from chronic pulmonary artery thrombi. To improve identification of right ventricular (RV) pathology in patients with thromboembolic obstruction, we hypothesized that the RV ventriculo-arterial (Ees/Ea) coupling ratio at maximal stroke work (Ees/Eamax sw) derived from an animal model of pulmonary obstruction may be used to identify occult RV dysfunction (low Ees/Ea) or residual RV energetic reserve (high Ees/Ea). Eighteen open chested pigs had conductance catheter RV pressure-volume (PV)-loops recorded during PA snare to determine Ees/Eamax sw This was then applied to 10 patients with chronic thromboembolic pulmonary hypertension (CTEPH) and ten patients with CTED, also assessed by RV conductance catheter and cardiopulmonary exercise testing. All patients were then restratified by Ees/Ea. The animal model determined an Ees/Eamax sw = 0.68 ± 0.23 threshold, either side of which cardiac output and RV stroke work fell. Two patients with CTED were identified with an Ees/Ea well below 0.68 suggesting occult RV dysfunction whilst three patients with CTEPH demonstrated Ees/Ea ≥ 0.68 suggesting residual RV energetic reserve. Ees/Ea > 0.68 and Ees/Ea < 0.68 subgroups demonstrated constant RV stroke work but lower stroke volume (87.7 ± 22.1 vs. 60.1 ± 16.3 mL respectively, P = 0.006) and higher end-systolic pressure (36.7 ± 11.6 vs. 68.1 ± 16.7 mmHg respectively, P < 0.001). Lower Ees/Ea in CTED also correlated with reduced exercise ventilatory efficiency. Low Ees/Ea aligns with features of RV maladaptation in CTED both at rest and on exercise. Characterization of Ees/Ea in CTED may allow for better identification of occult RV dysfunction.

Circulating microRNAs Reveal Time Course of Organ Injury in a Porcine Model of Acetaminophen-Induced Acute Liver Failure.

Acute liver failure is a rare but catastrophic condition which can progress rapidly to multi-organ failure. Studies investigating the onset of individual organ injury such as the liver, kidneys and brain during the evolution of acute liver failure, are lacking. MicroRNAs are short, non-coding strands of RNA that are released into the circulation following tissue injury. In this study, we have characterised the release of both global microRNA and specific microRNA species into the plasma using a porcine model of acetaminophen-induced acute liver failure. Pigs were induced to acute liver failure with oral acetaminophen over 19h±2h and death occurred 13h±3h thereafter. Global microRNA concentrations increased 4h prior to acute liver failure in plasma (P<0.0001) but not in isolated exosomes, and were associated with increasing plasma levels of the damage-associated molecular pattern molecule, genomic DNA (P<0.0001). MiR122 increased around the time of onset of acute liver failure (P<0.0001) and was associated with increasing international normalised ratio (P<0.0001). MiR192 increased 8h after acute liver failure (P<0.0001) and was associated with increasing creatinine (P<0.0001). The increase in miR124-1 occurred concurrent with the pre-terminal increase in intracranial pressure (P<0.0001) and was associated with decreasing cerebral perfusion pressure (P<0.002). Conclusions: MicroRNAs were released passively into the circulation in response to acetaminophen-induced cellular damage. A significant increase in global microRNA was detectable prior to significant increases in miR122, miR192 and miR124-1, which were associated with clinical evidence of liver, kidney and brain injury respectively.

Extracorporeal liver assist device to exchange albumin and remove endotoxin in acute liver failure: Results of a pivotal pre-clinical study.

BACKGROUND & AIMS: In acute liver failure, severity of liver injury and clinical progression of disease are in part consequent upon activation of the innate immune system. Endotoxaemia contributes to innate immune system activation and the detoxifying function of albumin, critical to recovery from liver injury, is irreversibly destroyed in acute liver failure. University College London-Liver Dialysis Device is a novel artificial extracorporeal liver assist device, which is used with albumin infusion, to achieve removal and replacement of dysfunctional albumin and reduction in endotoxaemia. We aimed to test the effect of this device on survival in a pig model of acetaminophen-induced acute liver failure. METHODS: Pigs were randomised to three groups: Acetaminophen plus University College London-Liver Dialysis Device (n=9); Acetaminophen plus Control Device (n=7); and Control plus Control Device (n=4). Device treatment was initiated two h after onset of irreversible acute liver failure. RESULTS: The Liver Dialysis Device resulted in 67% reduced risk of death in acetaminophen-induced acute liver failure compared to Control Device (hazard ratio=0.33, p=0.0439). This was associated with 27% decrease in circulating irreversibly oxidised human non-mercaptalbumin-2 throughout treatment (p=0.046); 54% reduction in overall severity of endotoxaemia (p=0.024); delay in development of vasoplegia and acute lung injury; and delay in systemic activation of the TLR4 signalling pathway. Liver Dialysis Device-associated adverse clinical effects were not seen. CONCLUSIONS: The survival benefit and lack of adverse effects would support clinical trials of University College London-Liver Dialysis Device in acute liver failure patients.

Retrospective study of the perioperative management and complications of ureteral obstruction in 37 cats.

OBJECTIVES: To describe perioperative management and complications, risk factors and mortality rates in cats anaesthetized for treatment of ureteral obstruction. STUDY DESIGN: Retrospective, clinical, cohort study. ANIMALS: Thirty-seven client-owned cats anaesthetized for ureteral surgery. METHODS: Records with sufficient data for cats treated between March 2010 and March 2013 were examined for breed, age, gender, history, concurrent diseases, pre- and post-anaesthetic biochemical and haematological parameters, American Society of Anesthesiologists classification, anaesthetic protocol, surgical technique, surgeon, perioperative complications and mortality within 48 hours after extubation. Associations between risk factors and outcome variables were evaluated using univariable analysis. Odds ratios and 95% confidence intervals were calculated for significant parameters. Sensitivity and specificity using receiving operator characteristic curve analysis were calculated for creatinine, potassium level and standard base excess (SBE) to denote survival or non-survival. RESULTS: Preoperatively, all cats were azotaemic: mean±SD urea was 31.6 ± 26.9 mmol L(-1) and median (range) creatinine was 562 µmol L(-1) (95 µmol L(-1) to off scale). Thirteen cats were hyperkalaemic (K+ 6.5 mmol L(-1)). Anaesthesia-related complications included bradycardia (n=8, 21.6%), hypotension (n=15, 40.5%) and hypothermia (n=32, 86.5%). Seven cats (18.9%) died postoperatively. Non-survivors were significantly (p=0.011) older (9.8±1.9 years) than survivors (6.4±3.1 years) and had higher potassium concentrations (p=0.040). Risk factors associated with mortality were ASA classes IV and V (p=0.022), emergency procedures (p=0.045) and bicarbonate administration (p=0.002). Non-survivors had higher creatinine concentrations (p=0.021) and lower SBE (p=0.030). CONCLUSION AND CLINICAL RELEVANCE: Intraoperative anaesthetic complications were common; increased age, poor health status, preoperative bicarbonate administration, hyperkalaemia and increased creatinine were associated with increased risk for death and can be used to predict risk for complications.

Effects of different doses of dexmedetomidine on anaesthetic induction with alfaxalone--a clinical trial.

OBJECTIVE: To document the effects of two doses of dexmedetomidine on the induction characteristics and dose requirements of alfaxalone. STUDY DESIGN: Randomized controlled clinical trial. ANIMALS: Sixty one client owned dogs, status ASA I-II. METHODS: Dogs were allocated randomly into three groups, receiving as pre-anaesthetic medication, no dexmedetomidine (D0), 1 µg kg(-1) dexmedetomidine (D1 ) intramuscularly (IM) or 3 µg kg(-1) dexmedetomidine IM (D3). All dogs also received 0.2 mg kg(-1) methadone IM. Level of sedation was assessed prior to induction of anaesthesia. Induction of general anaesthesia was performed with alfaxalone administered intravenously to effect at a rate of 1 mg kg(-1) minute(-1) ; the required dose to achieve tracheal intubation was recorded. Anaesthesia was maintained with isoflurane in oxygen. Cardiopulmonary parameters were recorded throughout the anaesthetic period. Quality of intubation, induction and recovery of anaesthesia were recorded. Quantitative data were compared with one-way anova or Kruskal-Wallis test. Repeated measures were log-transformed and analysed with repeated measures anova (p < 0.05). RESULTS: Treatment groups were similar for categorical data, with exception of sedation level (p < 0.001). The doses (mean ± SD) of alfaxalone required for intubation were D0 1.68 ± 0.24, D1 1.60 ± 0.36 and D3 1.41 ± 0.43, the difference between D0 and D3 being statistically significant (p = 0.036). Heart and respiratory rates during the anaesthetic period were significantly different over time and between groups (p < 0.001); systolic arterial blood pressure was significantly different over time (p < 0.001) but not between groups (p = 0.833). Induction quality and recovery scores were similar between groups (p = 1.000 and p = 0.414, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: The administration of alfaxalone resulted in a good quality anaesthetic induction which was not affected by the dose of dexmedetomidine. Dexmedetomidine at 3 µg kg(-1) IM combined with methadone provides good sedation and enables a reduction of alfaxalone requirements.

Use of needle enhancing software to improve injection technique amongst inexperienced anaesthetists performing ultrasound-guided peripheral nerves blocks in dogs.

OBJECTIVE: To determine if the use of needle enhancing software facilitate injection technique in ultrasound-guided peripheral nerve blocks. STUDY DESIGN: Prospective, blinded, randomized controlled trial. ANIMALS: Eight hind limbs from canine cadavers. METHODS: The limbs were randomly allocated to two groups; software on (group I) and software off (group II). Eight anaesthetists with no previous experience of ultrasound-guided regional anaesthesia were recruited. Thirty-six procedures were carried out (18 per group). After sciatic nerve visualisation via ultrasonography, the anaesthetist introduced a needle guided by ultrasonography. When the tip of the needle was considered by the anaesthetist to be as close as possible to the nerve without touching it, 0.05 mL of methylene blue dye was injected. Parameters evaluated included: number of attempts to visualise the needle with ultrasonography, time spent to perform the technique, subjective evaluation of ease of needle visualisation, proximity of the tip of the needle to the nerve, and, at dissection of the leg, inoculation site of the dye in relation to the nerve. RESULTS: Significant differences between groups were identified in relation to the number of attempts (group I: median 1, IQR: 1 - 1 attempts versus group II: median 1, IQR: 1 - 4 attempts, p = 0.019), and the relationship between the dye and the nerve during hind limb dissection (72.2% of the nerves were stained in group I versus 16.6% in group II, p = 0.003). No significant difference between groups was observed with respect to the time taken to perform the procedure (group I: median 25.5, IQR: 18.4 - 44.3 seconds versus group II: median 35.7, IQR: 18.6-78.72 seconds, p = 0.31), subjective evaluation of the needle visualization (p = 0.45) or distance between the tip of the needle and the nerve as measured from the ultrasound screen (p = 0.23). CONCLUSIONS AND CLINICAL RELEVANCE: This study identified greater success rate in nerve staining when the needle enhancing software was used. The results suggest that the use of this technique could improve injection technique amongst inexperienced anaesthetists performing ultrasound-guided peripheral nerve blocks in dogs.

A reproducible, clinically relevant, intensively managed, pig model of acute liver failure for testing of therapies aimed to prolong survival.

BACKGROUND: A clinically relevant, translational large animal model of acute liver failure (ALF) is required for testing of novel therapies to prolong survival in acute liver failure, to permit spontaneous liver recovery or to act as a bridge to transplantation. AIMS: The aim was to establish a pig model of acetaminophen-induced ALF that mimics the human clinical syndrome, is managed as in a human intensive care unit and has a predictable survival time. METHODS: Nine female pigs were anaesthetised and instrumented for continuous intensive care monitoring and management using: target-driven protocols for treatment of cardiovascular collapse, metabolic acidosis and electrolyte abnormalities; intermittent positive pressure ventilation; and continuous renal replacement therapy. Six animals were induced to ALF with acetaminophen (paracetamol). Three animals acted as controls. RESULTS: Irreversible acute liver failure, defined as rise in prothrombin time >3 times normal, occurred 19.3 ± 1.8 h after the onset of acetaminophen administration. Death occurred predictably 12.6 ± 2.7 h thereafter, with acute hepatocellular necrosis in all animals. Clinical progression of liver failure mimicked the human condition including development of coagulopathy, intracranial hypertension, hyperammonaemia, cardiovascular collapse, elevation in creatinine, metabolic acidosis and hyperlactataemia. In addition, cardiovascular monitoring clearly demonstrated progressive cardiac dysfunction in ALF. CONCLUSIONS: A reproducible, clinically relevant, intensively managed, large animal model of acute liver failure, with death as a result of multi-organ failure, has been successfully validated for translational studies of disease progression and therapies designed to prolong survival in man.

Comparison of quality of recovery from anaesthesia in cats induced with propofol or alfaxalone.

OBJECTIVE: To assess the quality and length of recovery from anaesthesia induced with either propofol or alfaxalone and maintained with isoflurane, in cats undergoing short procedures in private veterinary practice. STUDY DESIGN: Prospective, blinded, randomized study. ANIMALS: Ninety-three healthy mixed breed cats. METHODS: After premedication with intramuscular acepromazine (0.05 mg kg(-1)) and buprenorphine (0.01 mg kg(-1)), cats were randomly allocated to receive either propofol (Group P) or alfaxalone (Group A) for induction of anaesthesia. Following endotracheal intubation, anaesthesia was maintained with isoflurane vaporized in oxygen. The quality of induction, physiological parameters throughout anaesthesia and the duration of both surgery and anaesthesia were recorded. The level of ambient noise, recovery times, number of attempts to stand, reaction of the cat to touch 15 minutes after extubation, and other relevant characteristics of the recovery period were noted and a video recording of the recovery was made. The videos were assessed by a second, blinded anaesthetist, using simple descriptive and visual analogue scales. RESULTS: No statistically significant differences between groups with respect to preoperative data, premedication, surgery, anaesthesia and recovery times and scores were observed. There was a statistically significant difference in the number of patients paddling and trembling on recovery in Group A (p = 0.032) even though there was no statistically significant difference in the level of ambient noise in the recovery ward or in the overall quality of recovery. CONCLUSIONS: Both propofol and alfaxalone provide good recovery characteristics in premedicated cats undergoing short procedures in clinical settings. Alfaxalone induction was associated with more episodes of paddling and trembling during recovery. CLINICAL RELEVANCE: Both agents would appear appropriate for induction of anaesthesia in cats for short procedures.

The risk of passive regurgitation during general anaesthesia in a population of referred dogs in the UK.

OBJECTIVE: To evaluate the risk of passive regurgitation during anaesthesia, and to identify major factors associated with this in dogs attending the Queen Mother Hospital for Animals (QMHA), the Royal Veterinary College. STUDY DESIGN: A case-control study nested within the cohort of dogs undergoing anaesthesia with inhalation agents. ANIMAL POPULATION: All dogs undergoing general anaesthesia at the referral hospital between October 2006 and September 2008 (4271 cases). METHODS: All dogs anaesthetized at the QMHA during the study period were included. Regurgitating cases were defined as dogs for which reflux material was observed at the external nares or in the mouth, either during anaesthesia or before return to normal consciousness immediately after general anaesthesia. The risk of regurgitation was estimated and risk factors for regurgitation were evaluated with multivariable logistic regression (p < 0.05). RESULTS: The overall risk of regurgitation was 0.96% (41 cases out of 4271 anaesthetics, 95% confidence interval [95% CI] 0.67-1.25%). Exclusion of animals where pre-existing disease was considered a contributing factor to regurgitation (n = 14) resulted in a risk of passive regurgitation of 0.63% (27 cases of 4257 anaesthetics, 95% CI 0.40-0.87%). In the multivariable logistic regression model, procedure and patient weight were significantly associated with regurgitation. Dogs undergoing orthopaedic surgery were 26.7 times more likely to regurgitate compared to dogs undergoing only diagnostic procedures. Dogs weighing more than 40 kg were approximately five times more likely to regurgitate than those weighing <20 kg. CONCLUSIONS AND CLINICAL RELEVANCE: This study highlights the rare but important occurrence of perioperative regurgitation and identifies that dogs undergoing orthopaedic procedures, and those weighing more than 40 kg, are particularly at risk. Further work is required to evaluate the reasons for these observations.

Evaluation of the quality of the recovery after administration of propofol or alfaxalone for induction of anaesthesia in dogs anaesthetized for magnetic resonance imaging.

OBJECTIVE: To compare the quality of the recovery when propofol or alfaxalone were administered for the induction of anaesthesia in dogs undergoing neurological diagnostic procedures. EXPERIMENTAL DESIGN: Prospective, randomized clinical trial. ANIMALS: Forty two client-owned dogs, 21 females and 21 males, weighing between 5.7 and 55 kg. METHODS: Each dog was sedated with methadone (0.2 mg kg(-1) intramuscularly or 0.1 mg kg(-1) intravenously). Sedation was scored after 30 minutes. Anaesthesia was induced either with propofol or alfaxalone, administered to enable orotracheal intubation, after which anaesthesia was maintained with sevoflurane in oxygen. At the end of the procedure, the animals recovered in the clinical area. Quality of recovery was scored (early recovery) using simple descriptive and visual analogue scales (SDS and VAS). When sternal recumbency was achieved, dogs were moved to the recovery room and recovery was scored again (late recovery). Quantitative data were assessed with the Mann-Whitney U test, Kruskal-Wallis test, Spearman's rank correlation and Bland Altman plots as appropriate, whilst categorical data were analysed with the Chi square test and weighted kappa. RESULTS: Sex, behaviour and duration of anaesthesia did not influence recovery scores. Dogs had poorer late recovery scores in the alfaxalone group compared to the propofol group (SDS, p = 0.014; VAS, p = 0.017). Degree of sedation after premedication influenced assessed SDS scores during early (p = 0.038) and late recovery (p = 0.008) (dogs more heavily sedated recovered better). However by VAS scores, sedation did not statistically influence early recovery (p = 0.299) but did affect late recovery (p = 0.013). Rescue sedation (medetomidine) was required only in two dogs in the alfaxalone group. CONCLUSIONS: Induction of anaesthesia with alfaxalone was associated with poorer recovery than with propofol in animals receiving premedication with methadone. CLINICAL RELEVANCE: Greater attention to the recovery environment may be advisable when using alfaxalone for induction of anaesthesia where minimal premedication has been used. Further sedation in recovery may be required.

Clinical efficacy and cardiorespiratory effects of alfaxalone, or diazepam/fentanyl for induction of anaesthesia in dogs that are a poor anaesthetic risk.

OBJECTIVE: To evaluate the clinical efficacy and cardiorespiratory effects of alfaxalone as an anaesthetic induction agent in dogs with moderate to severe systemic disease. STUDY DESIGN: Randomized prospective clinical study. ANIMALS: Forty dogs of physical status ASA III-V referred for various surgical procedures. METHODS: Dogs were pre-medicated with intramuscular methadone (0.2 mg kg(-1) ) and allocated randomly to one of two treatment groups for induction of anaesthesia: alfaxalone (ALF) 1-2 mg kg(-1) administered intravenously (IV) over 60 seconds or fentanyl 5 µg kg(-1) with diazepam 0.2 mg kg(-1) ± propofol 1-2 mg kg(-1) (FDP) IV to allow endotracheal intubation. Anaesthesia was maintained with isoflurane in oxygen and fentanyl infusion following both treatments. All dogs were mechanically ventilated to maintain normocapnia. Systolic blood pressure (SAP) was measured by Doppler ultrasound before and immediately after anaesthetic induction, but before isoflurane administration. Parameters recorded every 5 minutes throughout subsequent anaesthesia were heart and respiratory rates, end-tidal partial pressure of carbon dioxide and isoflurane, oxygen saturation of haemoglobin and invasive systolic, diastolic and mean arterial blood pressure. Quality of anaesthetic induction and recovery were recorded. Continuous variables were assessed for normality and analyzed with the Mann Whitney U test. Repeated measures were log transformed and analyzed with repeated measures anova (p<0.05). RESULTS: Treatment groups were similar for continuous and categorical data. Anaesthetic induction quality was good following both treatments. Pre-induction and post-induction systolic blood pressure did not differ between treatments and there was no significant change after induction. The parameters measured throughout the subsequent anaesthetic procedures did not differ between treatments. Quality of recovery was very, quite or moderately smooth. CONCLUSIONS AND CLINICAL RELEVANCE: Induction of anaesthesia with alfaxalone resulted in similar cardiorespiratory effects when compared to the fentanyl-diazepam-propofol combination and is a clinically acceptable induction agent in sick dogs.

Incidence of elevation of cardiac troponin I prior to and following routine general anaesthesia in dogs.

OBJECTIVE: To estimate the incidence of raised cTnI after general anaesthesia in dogs and to explore major risk factors influencing this. STUDY DESIGN: Prospective clinical study. Animals A total of 107 (ASA physical status 1-2) dogs, 63% male and 37% female, median age 5 years (range 0.3-13.4), median weight 24.4 kg (range 4.2-66.5 kg) undergoing anaesthesia for clinical purposes. METHODS: Venous blood samples were taken within 24 hours prior to induction and 24 hours after the termination of anaesthesia. Serum concentrations of cardiac troponin I were measured using a chemiluminescent enzyme immunometric assay with a lower level of detection of 0.20 ng mL(-1) (below this level <0.20 ng mL(-1)). Continuous data were assessed graphically for normality and paired and unpaired data compared with the Wilcoxon signed ranks and Mann-Whitney U-tests respectively. Categorical data were compared with the Chi squared or Fisher's exact test as appropriate (p < 0.05). RESULTS: Of the 107 dogs recruited, 100 had pre- and post-anaesthetic cTnI measured. The median pre-anaesthesia cTnI was '<0.20' ng mL(-1) (range '<0.20'-0.43 ng mL(-1)) and the median increase from pre-anaesthesia level was 0.00 ng mL(-1) (range -0.12 to 0.61 ng mL(-1)). Fourteen dogs had increased cTnI after anaesthesia relative to pre-anaesthesia (14%, 95% CI 7.2-20.8%, range of increase 0.03-0.61 ng mL(-1)). Six animals had cTnI levels that decreased (range 0.02-0.12 ng mL(-1)). Older dogs were more likely to have increased cTnI prior to anaesthesia (OR = 5.32, 95% CI 1.35-21.0, p = 0.007) and dogs 8 years and over were 3.6 times as likely to have an increased cTnI after anaesthesia (95% CI 1.1-12.4, p = 0.028). CONCLUSION AND CLINICAL RELEVANCE: Increased cTnI after anaesthesia relative to pre-anaesthesia levels was observed in a number of apparently healthy dogs undergoing routine anaesthesia.

A comparison of the duration and quality of recovery from isoflurane, sevoflurane and desflurane anaesthesia in dogs undergoing magnetic resonance imaging.

OBJECTIVE: To compare the recovery after anaesthesia with isoflurane, sevoflurane and desflurane in dogs undergoing magnetic resonance imaging (MRI) of the brain. STUDY DESIGN: Prospective, randomized clinical trial. ANIMALS: Thirty-eight dogs weighing 23.7 +/- 12.6 kg. METHODS: Following pre-medication with meperidine, 3 mg kg(-1) administered intramuscularly, anaesthesia was induced intravenously with propofol (mean dose 4.26 +/- 1.3 mg kg(-1)), the trachea was intubated, and an inhalational anaesthetic agent was administered in oxygen. The dogs were randomly allocated to one of three groups: group I (n = 13) received isoflurane, group S (n = 12) received sevoflurane and group D (n = 13) received desflurane. Parameters recorded included cardiopulmonary data, body temperature, end-tidal anaesthetic concentration, duration of anaesthesia, and recovery times and quality. Qualitative data were compared using chi-squared and Fisher's exact tests and quantitative data with anova and Kruskal-Wallis test. Post-hoc comparisons for quantitative data were undertaken with the Mann-Whitney U-test. RESULTS: The duration of anaesthesia [mean and standard deviation (SD)] in group I was: 105.3 (27.48) minutes, group S: 120.67 (19.4) minutes, and group D: 113.69 (26.68) minutes (p = 0.32). Times to extubation [group I: 8 minutes, (interquartile range 6-9.5), group S: 7 minutes (IQR 5-7), group D: 5 minutes (IQR 3.5-7), p = 0.017] and to sternal recumbency [group I: 11 minutes (IQR 9.5-13.5), group S: 9.5 minutes (IQR 7.25-11.75), group D: 7 minutes (range 3.5-11.5), p = 0.048] were significantly different, as were times to standing. One dog, following sevoflurane, had an unacceptable quality of recovery, but most other recoveries were calm, with no significant difference between groups. CONCLUSIONS AND CLINICAL RELEVANCE: All three agents appeared suitable for use. Dogs' tracheas were extubated and the dogs recovered to sternal recumbency most rapidly after desflurane. This may be advantageous for animals with some neurological diseases and for day case procedures.