Assessment of effects of methylene blue on intestinal ischemia and reperfusion in a rabbit model: hemodynamic, histological and immunohistochemical study.

BACKGROUND: Intestinal ischemia-reperfusion (IR) is an important clinical occurrence seen in common diseases, such as gastric dilatation-volvulus in dogs or colic in horses. Limited data is available on the use of methylene blue in veterinary medicine for intestinal ischemia-reperfusion. The present study aimed to compare the hemodynamic, histopathological, and immunohistochemical effects of two doses of methylene blue in two rabbit model groups In one group, 5 mg/kg IV was administered, and in another, 20 mg/kg IV was administered following a constant rate infusion (CRI) of 2 mg/kg/h that lasted 6 h. All the groups, including a control group had intestinal ischemia-reperfusion. Immunohistochemical analysis was performed using caspase-3. RESULTS: During ischemia, hemodynamic depression with reduced perfusion and elevated lactate were observed. During reperfusion, methylene blue (MB) infusion generated an increase in cardiac output due to a positive chronotropic effect, an elevation of preload, and an intense positive inotropic effect. The changes in heart rate and blood pressure were significantly greater in the group in which methylene blue 5 mg/kg IV was administered (MB5) than in the group in which methylene blue 20 mg/kg IV dose was administered (MB20). In addition, lactate and stroke volume variations were significantly reduced, and vascular resistance was significantly elevated in the MB5 group compared with the control group and MB20 group. The MB5 group showed a significant decrease in the intensity of histopathological lesion scores in the intestines and a decrease in caspase-3 areas, in comparison with other groups. CONCLUSIONS: MB infusion produced improvements in hemodynamic parameters in rabbits subjected to intestinal IR, with increased cardiac output and blood pressure. An MB dosage of 5 mg/kg IV administered at a CRI of 2 mg/kg/h exhibited the most protective effect against histopathological damage caused by intestinal ischemia-reperfusion. Further studies with MB in clinical veterinary pathologies are recommended to fully evaluate these findings.

Systemic and local effects of lidocaine or mepivacaine when used for intravenous regional anaesthesia of the distal limb in standing sedated horses.

BACKGROUND: Local anaesthetics are being combined clinically with amikacin in intravenous regional limb perfusion (IVRLP), with limited knowledge on the analgesia provided and its onset and duration of action after tourniquet application and release. OBJECTIVE: To evaluate the systemic clinical effect, limb withdrawal to nociceptive stimulation, and plasma and synovial fluid concentrations after IVRLP with lidocaine or mepivacaine in standing sedated horses. STUDY DESIGN: Prospective, controlled, randomised, cross-over study. METHODS: Six healthy adult horses were sedated and received IVRLP with lidocaine, mepivacaine or saline (negative control), or perineural anaesthesia of the medial and lateral palmar and palmar metacarpal nerves (positive control) in one forelimb with a 3-week washout period between trials. Electrical and mechanical stimuli were used to test nociceptive threshold of the limb before and after IVRLP/perineural anaesthesia. For lidocaine and mepivacaine trials, blood was collected from the jugular vein and synovial fluid from the radiocarpal joint before, during and out to 24 hours after IVRLP. Drug concentrations were measured using high-performance liquid chromatography. RESULTS: Nociceptive thresholds for lidocaine, mepivacaine and perineural anaesthesia trials were significantly increased compared with saline and baseline values at 10, 20 and 30 minutes, with no differences between anaesthetic trials. During this time, horses had lower heart rates than IVRLP with saline. After tourniquet release at 30 minutes, nociceptive thresholds for lidocaine and mepivacaine trials gradually returned to baselines, whereas perineural anaesthesia trial remained unchanged out to an hour. Plasma lidocaine and mepivacaine concentrations were ≤50 ng/mL while the tourniquet was in place, significantly increasing 10 minutes after tourniquet release. Maximal lidocaine and mepivacaine concentrations in synovial fluid were reached 25 minutes after IVRLP injection. MAIN LIMITATIONS: Amikacin was not included in the perfusate. CONCLUSION: Similar to perineural anaesthesia, IVRLP with lidocaine or mepivacaine provides anti-nociception to the distal limb in standing sedated horses while a tourniquet is applied with concentrations remaining below toxic levels in plasma and synovial fluid.

Comparison of bispectral index and spectral entropy during isoflurane and medetomidine general anaesthesia in horses.

BACKGROUND: The bispectral index (BIS) has been evaluated as an indicator of central nervous system (CNS) depression in horses during general anaesthesia. The spectral entropy is another electroencephalographic device and it has not been evaluated yet in horses. OBJECTIVES: To determine if spectral entropy can assess anaesthetic depth during the different phases of anaesthesia, define the value of state and response entropy during surgical plane of anaesthesia and compare them with BIS. STUDY DESIGN: Clinical, prospective, non-blinded observational study. METHODS: Thirty-five horses ASA I or II undergoing scheduled surgical procedure were used. BIS and electromyography (EMG) with a BIS monitor and state and response entropy with a spectral entropy monitor were recorded at baseline after receiving 5 µg/kg bwt i.v. of medetomidine (sedation period), during the anaesthetic maintenance with isoflurane and medetomidine (intraoperative period) and once the trachea was extubated (recovery period). A general linear model for repeated measurements was employed. Correlation and agreement between methods were also assessed. Data are presented as mean ± SD. RESULTS: State entropy, response entropy and EMG showed significant differences according to the anaesthetic period (P < .001). There was no significant difference in BIS between baseline and sedation period, but there were differences between the remainder of the periods (P < .001). BIS (53.4 ± 11.2) was significantly higher (P < .001) than response entropy (35.1 ± 7.1) and state entropy (27.4 ± 4.8) during surgical plane of anaesthesia. The ICC between BIS and response entropy was 0.56 and between BIS and state entropy was 0.43, without agreement between them. MAIN LIMITATIONS: The need to shave the skin in contact with the sensors and the difficulty in taking measurements during recovery period. CONCLUSIONS: Spectral entropy can be used to detect the different periods of an anaesthetic protocol, with the lowest values during the intraoperative period. A low correlation and no concordance were observed between both methods.

Comparative pharmacokinetics and a clinical laboratory evaluation of intravenous acetaminophen in Beagle and Galgo Español dogs.

OBJECTIVE: To assess the pharmacokinetics (PK) and conduct a clinical laboratory evaluation of acetaminophen in Beagle and Galgo Español (GE) dogs. STUDY DESIGN: Prospective randomized experimental trial. ANIMALS: A total of 20 healthy dogs - 10 Beagles and 10 GE (six males and four females in both groups). METHODS: Acetaminophen (10 and 20 mg kg-1) was administered intravenously (IV) to the dogs on two different occasions. Plasma concentrations were analysed by high-performance liquid chromatography. PK analysis was undertaken using compartmental modelling with ADAPT 5 software. Simulations after multiple IV doses were investigated. Clinical laboratory values such as red blood cell (RBC) count, haemoglobin (Hb), haematocrit (Ht), white blood cell (WBC) count, platelet count, total proteins, alanine aminotransferase (ALT), aspartate aminotransferase, urea and creatinine were measured before and 24 hours after acetaminophen administration in combination with clinical examination to assess side effects resulting from the drug. RESULTS: A two-compartmental model best described time-concentration profiles of acetaminophen. PK parameters were different as a result of a breed effect. For doses of 10 and 20 mg kg-1, respectively, clearance values were 1.70 (1.15-2.27) and 1.62 (1.06-2.86) L kg-1 hour-1 for Beagles and 1.18 (0.70-1.39) and 1.08 (0.67-1.35) L kg-1 hour-1 for GE; elimination half-life values were 2.64 (0.52-4.46) and 2.86 (0.87-4.63) hours for Beagles and 3.49 (1.89-7.80) and 4.57 (2.08-8.90) hours for GE. Significant differences were also found between GE and Beagles in the RBC count, Ht, Hb, WBC count and serum ALT before drug administration, and these differences were maintained 24 hours later, independent of the dosage used. For each breed, no side effects resulting from IV acetaminophen administration were observed at doses of either 10 or 20 mg kg-1. CONCLUSIONS AND CLINICAL RELEVANCE: IV PK of acetaminophen was different between Beagles and GE dogs. Side effects were not detected. Further studies are necessary to evaluate the PK in a clinical context.

Evaluation and comparison of postoperative analgesic effects of dexketoprofen and methadone in dogs.

OBJECTIVE: To evaluate and compare the analgesic efficacy and adverse effects of dexketoprofen and methadone using a noninferiority trial, during the first 24 postoperative hours in dogs undergoing orthopaedic surgery. STUDY DESIGN: Randomized, blinded clinical study. ANIMALS: A total of 38 healthy dogs undergoing orthopaedic surgery. METHODS: Dogs were premedicated with dexmedetomidine [1 µg kg-1 intravenously (IV)] followed by dexketoprofen (1 mg kg-1 IV; group DK) or methadone (0.2 mg kg-1 IV; group M). Anaesthesia was induced with propofol and maintained with isoflurane in 60% oxygen. Postoperatively, dexketoprofen was administered every 8 hours (group DK) and methadone every 4 hours (group M). Analgesia was assessed at baseline and at 1, 2, 4, 6, 18 and 24 hours after extubation using a dynamic and interactive visual analogue scale (DIVAS), the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF), mechanical wound thresholds (MWTs) and plasma cortisol levels. If CMPS-SF score was ≥5, rescue analgesia was administered. Data were analysed using a general linear mixed model, Mann-Whitney U test and chi-squared test as appropriate; a p value <0.05 was considered significant. RESULTS: The CMPS-SF and DIVAS scores were significantly higher in group M compared with group DK and remained higher for a longer period in group M, although the differences were not clinically significant. No significant differences were found in MWT assessment between groups. Plasma cortisol level significantly increased 2 hours after extubation, without significant differences between treatments. Rescue analgesia was administered to three animals (one in group DK; two in group M). CONCLUSION AND CLINICAL RELEVANCE: We conclude that 1 mg kg-1 IV dexketoprofen administered every 8 hours during the first 24 hours postoperatively is noninferior to methadone in controlling pain after orthopaedic surgery in dog, although frequent pain assessments are recommended to adjust the analgesia plan.

A comparison of cardiopulmonary effects and anaesthetic requirements of two dexmedetomidine continuous rate infusions in alfaxalone-anaesthetized Greyhounds.

OBJECTIVE: To determine the effects of two dexmedetomidine continuous rate infusions on the minimum infusion rate of alfaxalone for total intravenous anaesthesia (TIVA), and subsequent haemodynamic and recovery effects in Greyhounds undergoing laparoscopic ovariohysterectomy. STUDY DESIGN: Prospective, randomized and blinded clinical study. ANIMALS: Twenty-four female Greyhounds. METHODS: Dogs were premedicated with dexmedetomidine 3 µg kg-1 and methadone 0.3 mg kg-1 intramuscularly. Anaesthesia was induced with IV alfaxalone to effect and maintained with a TIVA mixture of alfaxalone in combination with two different doses of dexmedetomidine (0.5 µg kg-1 hour-1 or 1 µg kg-1 hour-1; groups DEX0.5 and DEX1, respectively). The alfaxalone starting dose rate was 0.07 mg kg-1 minute-1 and was adjusted (± 0.02 mg kg-1 minute-1) every 5 minutes to maintain a suitable depth of anaesthesia. A rescue alfaxalone bolus (0.5 mg kg-1 IV) was administered if dogs moved or swallowed. The number of rescue boluses was recorded. Heart rate, arterial blood pressure and arterial blood gas were monitored. Qualities of sedation, induction and recovery were scored. Differences between groups were tested for statistical significance using a Student's t test or Mann-Whitney U test as appropriate. RESULTS: There were no differences between groups in sedation, induction and recovery quality, the median (range) induction dose of alfaxalone [DEX0.5: 2.2 (1.9-2.5) mg kg-1; DEX1: 1.8 (1.2-2.9) mg kg-1], total dose of alfaxalone rescue boluses [DEX0.5: 21.0 (12.5-38.8) mg; DEX1: 22.5 (15.5-30.6) mg] or rate of alfaxalone (DEX0.5: 0.12±0.04 mg kg-1 minute-1; DEX1: 0.12±0.03 mg kg-1 minute-1). CONCLUSIONS AND CLINICAL RELEVANCE: Co-administration of dexmedetomidine 1 µg kg-1 hour-1 failed to reduce the dose rate of alfaxalone compared with dexmedetomidine 0.5 µg kg-1 hour-1 in Greyhounds undergoing laparoscopic ovariohysterectomy. The authors recommend an alfaxalone starting dose rate of 0.1 mg kg-1 minute-1. Recovery quality was good in the majority of dogs.

Effect of dexmedetomidine constant rate infusion on the bispectral index during alfaxalone anaesthesia in dogs.

OBJECTIVE: To assess the effect of two rates of infusion of dexmedetomidine on the bispectral index (BIS) in dogs anaesthetized with alfaxalone constant rate infusion (CRI). STUDY DESIGN: Prospective, randomized, 'blinded' experimental study. ANIMALS: Six healthy Beagles (three females and three males). METHODS: Dogs received as premedication saline (group D0), 1 µg kg(-1) (group D1) or 2 µg kg(-1) (group D2) dexmedetomidine, intravenously (IV). Anaesthesia was induced with alfaxalone (6 mg kg(-1) to effect IV) and maintained with alfaxalone at 0.07 mg kg(-1)  minute(-1) and a CRI of saline (D0) or dexmedetomidine 0.5 µg kg(-1)  hour(-1) (D1) or 1 µg kg(-1)  hour(-1) (D2) for 90 minutes. BIS, electromyography (EMG), signal quality index (SQI) and suppression ratio (SR) were measured at 10 minute intervals and the median values were calculated. Nociceptive stimuli were applied every 30 minutes and BIS and cardiorespiratory values were compared before and after stimuli. Cardiorespiratory parameters were recorded throughout the study. RESULTS: BIS and EMG values differed significantly among groups, being lower in D2 (71 ± 8) than in D0 (85 ± 10) and D1 (84 ± 9). SQI was always over 90% and SR was zero throughout all the treatments. There were no significant differences between pre- and post-stimulus values of BIS, EMG and SQI for any treatment, although in D0 and D1, heart rate, respiratory rate and arterial pressures increased significantly after the nociceptive stimulus. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of dexmedetomidine (2 µg kg(-1)  + CRI 1 µg kg(-1)  hour(-1) ) decreases the BIS values and avoids the autonomic responses of a nociceptive stimulus during alfaxalone anaesthesia at 0.07 mg kg(-1)  minute(-1) in dogs. However, further studies are needed to verify whether this combination produces an adequate degree of hypnosis under surgical situations.

Effectiveness of pre-peritoneal continuous wound infusion with lidocaine for pain control following ovariohysterectomy in dogs.

This study compared the post-operative analgesic efficacy of continuous lidocaine administration with that of intramuscular (IM) methadone in dogs undergoing ovariohysterectomy. Thirty-eight dogs were divided randomly into two groups. Following surgery, the lidocaine group (L) received a continuous lidocaine infusion (2 mg/kg/h) through a wound catheter inserted in the pre-peritoneal space; the control group (C) received methadone (0.2 mg/kg IM). A dynamic and interactive visual analogue scale (DIVAS), the Scale-Form Glasgow Composite Measure Scale (CMPS-SF), mechanical wound thresholds, heart rate, respiratory rate and blood pressure were assessed pre-operatively and 2, 4, 6, 18, and 24 h after surgery. The presence of the wound catheter prevented the evaluator from remaining blinded to group allocations. Plasma lidocaine and cortisol levels were measured 2, 6, 18, and 24 h after surgery. There were no intergroup differences in any pain assessment scale scores at any time point. Stable intravenous lidocaine levels were observed. Four animals in the control group but none in the lidocaine group required rescue analgesia. There were no differences in complication rates between groups. Continuous locoregional lidocaine delivered via a wound catheter between the parietal peritoneum and abdominal muscle offers effective analgesia in dogs during ovariohysterectomy and appears to be a promising analgesic option in veterinary surgery.

Comparison of thermodilution, lithium dilution, and pulse contour analysis for the measurement of cardiac output in 3 different hemodynamic states in dogs.

OBJECTIVE: To (1) evaluate lithium dilution (LiDCO) and transpulmonary thermodilution (PiCCOTD ) in relation to traditional thermodilution (PAC-TD) for determining cardiac output (CO) in 3 different hemodynamic states in dogs and to (2) compare the continuous CO values obtained using power analysis (PulseCO) with continuous PiCCO (PiCCOc). DESIGN: Prospective randomized study. SETTING: University research laboratory. ANIMALS: Fourteen healthy Beagles. INTERVENTIONS: CO was measured using PAC-TD, LiDCO, and PiCCOTD in 3 different hemodynamic states induced in random order and defined on the basis of the mean arterial pressure (MAP). Normodynamic state was defined as the baseline MAP and 1 MAC sevoflurane. The hypodynamic state was induced with a deep level of sevoflurane anesthesia. The hyperdynamic state was induced with noradrenaline. After these measurements were obtained in each hemodynamic state, CO was monitored continuously for 30 min using PulseCO and PiCCOc. Agreement was assessed using Bland-Altman analysis and intraclass correlation coefficients, and a trend score was determined for the continuous CO measurements. MEASUREMENTS AND MAIN RESULTS: There was good agreement among the 3 modalities of CO measurement in each hemodynamic state. The mean CIPAC-TD /CIPICCOTD bias was -0.04 ± 1.19 L/min/m(2) (limits of agreement, -2.37/1.93 L/min/m(2) ), and the mean CIPAC-TD /CILiDCO bias was -0.11 ± 1.55 L/min/m(2) (limits of agreement, -3.04/2.93 L/min/m(2) ). The mean CIPulseCO -CIPiCCOc bias was -0.04 ± 1.91 L/min/m(2) (limits of agreement, -1.95/1.87 L/min/m(2) ), which suggested good agreement. The CIPulseCO -CIPiCCOc trend score, calculated from 252 paired comparisons, was 93.3% positive after zone exclusion (∆CI < 15%). CONCLUSIONS: Both LiDCO and PiCCOTD agreed well with PAC-TD for the measurement of CO under different hemodynamic conditions. Moreover, PiCCOc appears to be an accurate method for monitoring continuous CO in dogs as its performance for measurement was similar to that of PulseCO.

Romifidine and low doses of tiletamine-zolazepam in dogs.

OBJECTIVE: To evaluate clinical effects of romifidine and low doses of tiletamine-zolazepam (TZ) in dogs. STUDY DESIGN: Randomized "blinded" cross-over study. ANIMALS: Six healthy beagle dogs (two males, four females). METHODS: In separate preliminary experiments dogs received intravenous (IV) tiletamine-zolazepam (TZ) at 1 and 2 mg kg(-1). For the main trial, dogs received romifidine (R) followed 5 minutes later by IV at six dose regimens: R40TZ1, R60TZ1, R80TZ1 (Romifidine at 40, 60, 80 µg kg(-1) and TZ at 1 mg kg(-1)), R40TZ2, R60TZ2 and R80TZ2 (Romifidine at 40, 60, 80 µg kg(-1) and TZ at 2 mg kg(-1)). Dogs underwent endotracheal intubation, but breathed room air. Cardiorespiratory variables were measured and arterial blood analyzed. Quality of sedation, duration of anaesthesia and time to recovery (TR) were recorded. Data were analysed by anova or Friedman test as relevant. RESULTS: Endotracheal intubation was possible with all romifidine/TZ combinations but not with TZ alone. Mean times (minutes) from TZ injection to return of pedal reflex were 1-3 minutes for TZ alone, and 9-17 minutes for romifidine combinations. In the main trial (romifidine combinations) mean time (minutes) to standing increased with increasing dosage (R40TZ1 13; R80TZ2 32). Five minutes after TZ administration, when compared with baseline arterial blood pressures and arterial carbon dioxide had increased, and respiratory rate, pH and arterial oxygen tensions decreased, these changes becoming statistically significant with the higher dose rates. One dog in R60TZ2 and three dogs in R80TZ2 became hypoxaemic. CONCLUSIONS AND CLINICAL RELEVANCE: Romifidine improves the quality and lengthens the duration of anaesthesia induced by TZ. The combination provides a suitable protocol for induction of or short-term anaesthesia in healthy dogs. However, the higher doses cause cardiovascular stimulation and respiratory depression, and precautions should be taken accordingly.

Histological study of the influence of plasma rich in growth factors (PRGF) on the healing of divided Achilles tendons in sheep.

BACKGROUND: The use of plasma rich in growth factors (PRGF) has been proposed to improve the healing of Achilles tendon injuries, but there is debate about the effectiveness of this therapy. The objective of the present study was to evaluate the histological effects of PRGF, which is a type of leukocyte-poor platelet-rich plasma, on tendon healing. METHODS: The Achilles tendons of twenty-eight sheep were divided surgically. The animals were randomly divided into four groups of seven animals each. The repaired tendons in two groups received an infiltration of PRGF intraoperatively and every week for the following three weeks under ultrasound guidance. The tendons in the other two groups received injections with saline solution. The animals in one PRGF group and one saline solution group were killed at four weeks, and the animals in the remaining two groups were killed at eight weeks. The Achilles tendons were examined histologically, and the morphometry of fibroblast nuclei was calculated. RESULTS: The fibroblast nuclei of the PRGF-treated tendons were more elongated and more parallel to the tendon axis than the fibroblast nuclei of the tendons in the saline solution group at eight weeks. PRGF-treated tendons showed more packed and better oriented collagen bundles at both four and eight weeks. In addition to increased maturation of the collagen structure, fibroblast density was significantly lower in PRGF-infiltrated tendons. PRGF-treated tendons exhibited faster vascular regression than tendons in the control groups, as demonstrated by a lower vascular density at eight weeks. CONCLUSIONS: PRGF was associated with histological changes consistent with an accelerated early healing process in repaired Achilles tendons in sheep after experimental surgical disruption. PRGF-treated tendons showed improvements in the morphometric features of fibroblast nuclei, suggesting a more advanced stage of healing. At eight weeks, histological examination revealed more mature organization of collagen bundles, lower vascular densities, and decreased fibroblast densities in PRGF-treated tendons than in tendons infiltrated with saline solution. These findings were consistent with a more advanced stage of the healing process. CLINICAL IMPLICATIONS: Based on the findings in this animal model, PRGF infiltration may improve the early healing process of surgically repaired Achilles tendons.

Cardiotrophin-1 reduces ischemia/reperfusion injury during liver transplant.

BACKGROUND: Orthotopic liver transplantation (OLT) is currently the elective treatment for advanced liver cirrhosis and acute liver failure. Ischemia/reperfusion damage may jeopardize graft function during the postoperative period. Cardiotrophin-1 (CT-1) has demonstrated cytoprotective properties in different experimental models of liver injury. There is no evidence to demonstrate its potential use in the prevention of the ischemia/reperfusion injury that occurs during OLT. The present study is the first report to show that the administration of CT-1 to donors would benefit the outcome of OLT. MATERIALS AND METHODS: We tested the cytoprotective effect of CT-1 administered to the donor prior to OLT in an experimental pig model. Hemodynamic changes, hepatic histology, cell death parameters, activation of cell signaling pathways, oxidative and nitrosative stress, and animal survival were analyzed. RESULTS: Our data showed that CT-1 administration to donors increased animal survival, improved cardiac and respiratory functions, and reduced hepatocellular injury as well as oxidative and nitrosative stress. These beneficial effects, related to the activation of AKT, ERK, and STAT3, reduced caspase-3 activity and diminished IL-1ß and TNF-α expression together with IL-6 upregulation in liver tissue. CONCLUSIONS: The administration of CT-1 to donors reduced ischemia/reperfusion injury and improved survival in an experimental pig model of OLT.

Comparison of the cardiopulmonary parameters after induction of anaesthesia with alphaxalone or etomidate in dogs.

OBJECTIVE: To compare the cardiorespiratory effects and quality of induction of and recovery from anaesthesia following etomidate or alphaxalone-HPCD IV. STUDY DESIGN: Randomized 'blinded' cross-over study. Twenty-four hours was allowed between phases. ANIMALS: Eight healthy adult Beagles (four male, four female). METHODS: Dogs were anaesthetized with sevoflurane for instrumentation, then allowed to awake. They then received etomidate (treatment E) or alphaxalone-HPCD (treatment A) intravenously to effect. Heart rate (HR), body temperature, invasive arterial pressures (AP), systemic vascular resistance index (SVRI), stroke volume index, cardiac index (CI), contractility, respiratory rate, central venous pressure, and capnometry were obtained before anaesthetic induction (baseline), 30 seconds and 1 minute after induction, after intubation, one minute after intubation, and for every 5 minutes afterwards until the dog began to swallow and the trachea was extubated. Arterial bloods were taken for analyses before induction, after intubation and every 10 minutes thereafter. The dogs breathed room air. The quality of induction of and recovery from anaesthesia were scored categorically. Statistical analyses used anova for repeated measures, paired t-tests or Wilcoxon signed rank-test as relevant. Significance was set at p < 0.05. RESULTS: The induction doses required were (mean ± SD) 2.91 ± 0.41 mg kg(-1) and 4.15 ± 0.7 mg kg(-1) for treatment E and A respectively. No significant changes in cardiovascular parameters were observed with treatment E. Treatment A resulted in statistically significant increases in HR and CI and reductions of APs and SVRI. Time to extubation was longer with treatment A (25 ± 7 minutes) than with treatment E (17 ± 4 minutes). Dogs became hypoxic with both treatments. The quality of induction and recovery were excellent with treatment A, but significantly less satisfactory with treatment E (recovery score, treatment E median 1, range 0-2; treatment A median 0, range 0-1). CONCLUSIONS AND CLINICAL RELEVANCE: Alphaxalone-HPCD caused significant tachycardia and increase in CI, and statistically (but not clinically) significant decreases in APs and SVRI. Etomidate caused no statistically significant cardiovascular changes. Quality of recovery was better with alfaxalone-HPCD. Both agents caused short-lived hypoxia, and oxygen supplementation is advisable.

Sedative effects of three doses of romifidine in comparison with medetomidine in cats.

OBJECTIVE: To compare the sedative effects of three doses of romifidine with one dose of medetomidine. STUDY DESIGN: Prospective blinded experimental cross-over. ANIMALS: Five adult Domestic Short Hair cats. METHODS: Cats were administered romifidine at 80, 120 and 160 µg kg(-1) or medetomidine at 20 µg kg(-1) (M20) intramuscularly (IM). Sedative effects were assessed for 3 hours by summing the scores given to posture, auditory response, resistance to positioning, muscular relaxation, and response to noxious stimuli, giving a total sedation score (TS). The area under the curve (AUC) of TS ≥7 (the score considered as clinically useful sedation) was calculated. Times to stages of sedation were determined. Some physiological parameters were measured. Data to compare treatments were analysed by anova or Kruskal-Wallis test as relevant. RESULTS: All treatments gave a TS considered clinically useful. There were no significant differences between treatments for times to onset of sedation, maximum TS reached, or AUC. Differences between romifidine treatments for other sedation parameters were not significant but the time to maximum TS and to recovery was shortest in M20. Heart rate (HR) fell significantly with all treatments and, although with M20 it recovered at 65 minutes, it remained significantly depressed for 3 hours after all romifidine treatments. Most cats vomited, and/or hypersalivated after all treatments. CONCLUSIONS: Doses of 80, 120 and 160 µg kg(-1) romifidine IM produce sedation in cats which is similar to that following medetomidine 20 µg kg(-1) . Recovery from sedation and of physiological parameters was quickest after M20. CLINICAL RELEVANCE: Doses of romifidine considerably lower than those investigated by previous authors give a clinically useful level of sedation, and their use might result in less side effects and a quicker recovery.

Evaluation of spectral entropy to measure anaesthetic depth and antinociception in sevoflurane-anaesthetised Beagle dogs.

The use of spectral entropy to determine anaesthetic depth and antinociception was evaluated in sevoflurane-anaesthetised Beagle dogs. Dogs were anaesthetised at each of five multiples of their individual minimum alveolar concentrations (MAC; 0.75, 1, 1.25, 1.5 and 1.75 MAC), and response entropy (RE), state entropy (SE), RE-SE difference, burst suppression rate (BSR) and cardiorespiratory parameters were recorded before and after a painful stimulus. RE, SE and RE-SE difference did not change significantly after the stimuli. The correlation between MAC-entropy parameters was weak, but these values increased when 1.75 MAC results were excluded from the analysis. BSR was different to zero at 1.5 and 1.75 MAC. It was concluded that RE and RE-SE differences were not adequate indicators of antinociception and SE and RE were unable to detect deep planes of anaesthesia in dogs, although they both distinguished the awake and unconscious states.

Cardiorespiratory effects of desflurane in dogs given romifidine or medetomidine before induction of anesthesia with propofol.

The objective of this study was to evaluate the use of desflurane after induction of anesthesia with propofol in dogs sedated with romifidine or medetomidine. Each of 8 healthy dogs received intravenously, in random order, 3 preanesthetic protocols: romifidine, 40 microg/kg of body weight (BW) (R40); romifidine, 80 microg/kg BW (R80); and medetomidine, 10 microg/kg BW (MED). Cardiovascular and respiratory variables were recorded during the procedure. Time to extubation, time to sternal recumbency, and time to standing were also recorded. Heart rate and respiratory rate decreased significantly during sedation from baseline values, but there were no differences between the means for the 3 preanesthetic protocols. Mean values for heart rate, mean arterial blood pressure, systolic arterial pressure, diastolic arterial pressure, respiratory rate, tidal volume, arterial oxygen saturation, end-tidal CO2 level, pH, and arterial blood gas values during anesthesia were similar for the 3 protocols. The mean end-tidal desflurane concentration was significantly lower with the R80 protocol than with the R40 protocol. The mean time to extubation was significantly shorter with the R40 protocol than with the R80 and MED protocols.