Effects of tasipimidine premedication with and without methadone and dexmedetomidine on cardiovascular variables during propofol-isoflurane anaesthesia in Beagle dogs.

OBJECTIVE: To evaluate cardiovascular effects of oral tasipimidine on propofol-isoflurane anaesthesia with or without methadone and dexmedetomidine at equianaesthetic levels. STUDY DESIGN: Prospective, placebo-controlled, blinded, experimental trial. ANIMALS: A group of seven adult Beagle dogs weighing (mean ± standard deviation) 12.4 ± 2.6 kg and a mean age of 20.6 ± 1 months. METHODS: The dogs underwent four treatments 60 minutes before induction of anaesthesia with propofol. PP: placebo orally and placebo (NaCl 0.9%) intravenously (IV); TP: tasipimidine 30 µg kg-1 orally and placebo IV; TMP: tasipimidine 30 µg kg-1 orally and methadone 0.2 mg kg-1 IV; and TMPD: tasipimidine 30 µg kg-1 orally with methadone 0.2 mg kg-1 and dexmedetomidine 1 µg kg-1 IV followed by 1 µg kg-1 hour-1. Isoflurane in oxygen was maintained for 120 minutes at 1.2 individual minimum alveolar concentration preventing motor movement. Cardiac output (CO), tissue blood flow (tbf), tissue oxygen saturation (stO2) and relative haemoglobin content were determined. Arterial and mixed venous blood gases, arterial and pulmonary artery pressures and heart rate (HR) were measured at baseline; 60 minutes after oral premedication; 5 minutes after IV premedication; 15, 30, 60, 90 and 120 minutes after propofol injection; and 30 minutes after switching the vaporiser off. Data were analysed by two-way anova for repeated measures; p < 0.05. RESULTS: Tasipimidine induced a significant 20-30% reduction in HR and CO with decreases in MAP (10-15%), tbf (40%) and stO2 (43%). Blood pressure and oxygenation variables were mainly influenced by propofol-isoflurane-oxygen anaesthesia, preceded by short-lived alterations related to IV methadone and dexmedetomidine. CONCLUSIONS AND CLINICAL RELEVANCE: Tasipimidine induced mild to moderate cardiovascular depression. It can be incorporated into a common anaesthetic protocol without detrimental effects in healthy dogs, when anaesthetics are administered to effect and cardiorespiratory function is monitored.

Evaluation of the analgesic effects of diclofenac as a premedication drug in dogs undergoing ovariohysterectomy.

Pre-emptive analgesia consists of administering drugs such as opioids and nonsteroid anti-inflammatory drugs. This study aims to evaluate the intraoperative antinociceptive effects of diclofenac administered alone in premedication or combined with morphine along with its potential influence on recovery of dogs undergoing ovariohysterectomy. A total of 34 dogs (ASA I or II) admitted for ovariohysterectomy were randomly allocated into three groups according to the drugs given in premedication: Diclofenac (D) (n = 11), Morphine (M) (n = 13) and Diclofenac-Morphine (DM) (n = 10) groups. Induction and maintenance of anesthesia were standardized in all dogs. To assess intraoperative nociception, the heart rate (HR) and mean arterial pressure (MAP) were recorded during the surgery and at predefined time points: St (steady-state), Cut (cutaneous incision), P1 (first ovarian manipulation), P2 (second ovarian manipulation) and Cerv (cervical manipulation). The dynamic variation of HR (ΔHR) and MAP (ΔMAP) over 2 min was calculated at each time point. After extubation, early quality of recovery was assessed. Compared to St, a significant increase in HR and MAP at P1, P2 and Cerv was shown in all groups. MAP in the M group was lower at St than in the other groups. The dynamic variation of HR (ΔHR) and MAP (ΔMAP) was significantly less important at P2 and Cerv compared to P1 only in the DM group. Also, a better quality of recovery was shown in the D group compared to the M and DM groups. Diclofenac may be considered a suitable premedication drug and a part of a multimodal anesthetic approach in dogs.

Intranasal dexmedetomidine as premedication for magnetic resonance imaging examinations in dogs with neurological disorders mitigates hypotension and hypothermia.

OBJECTIVE: This study aimed to evaluate the safety and feasibility of intranasal administration of dexmedetomidine as a premedication for preventing hypotension and hypothermia in canine patients undergoing MRI examinations. ANIMALS: Dogs undergoing MRI examinations for neurological disorders were enrolled in this study. The dogs were randomly assigned: 15 to the N-Dex group (without premedication) and 13 to the Dex group (125 µg/m2 of dexmedetomidine, intranasally, as a premedication). METHODS: During the examination, pulse rate, systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure were recorded every 5 minutes for the first 30 minutes. Body temperature was measured before and after the examination. Any adverse events during the procedure were documented. RESULTS: Significant changes in pulse rate during the examination were not distinguishable. Although blood pressure and body temperature decreased in both groups under anesthesia, dogs in the Dex group had a significantly smaller drop in blood pressure and body temperature and fewer hypotension events than those in the N-Dex group MRI examinations of 1 hour's duration. Two dogs in the Dex group exhibited bradycardia at 45 and 60 minutes of MRI examination, which resolved after receiving atipamezole. CLINICAL RELEVANCE: Our results indicate that intranasal administration of 125 µg/m2 of dexmedetomidine as premedication is safe and can potentially mitigate hypothermia and hypotension in dogs with neurological disorders during MRI examinations.

COMPARISON OF KETAMINE-MIDAZOLAM AND KETAMINE-MIDAZOLAM-BUTORPHANOL PREMEDICATION PRIOR TO SEVOFLURANE ANESTHESIA IN WOODCHUCKS (MARMOTA MONAX).

Cardiovascular disease is a frequent cause of death in the critically endangered Vancouver Island marmots (Marmota vancouverensis). This warrants the use of anesthetic protocols with minimal cardiovascular adverse effects. In this study, 12 adult male woodchucks (Marmota monax) were used as models for Vancouver Island marmots. The objective was to compare the physiological effects of two premedication protocols during induction and maintenance of anesthesia with sevoflurane. The two premedications were ketamine 10 mg/kg and midazolam 0.5 mg/kg (KM) or ketamine 10 mg/kg, midazolam 0.5 mg/kg, and butorphanol 1.0 mg/kg (KMB), administered intramuscularly prior to mask induction. Each marmot underwent three anesthetic events and protocols were assigned using a blinded randomized crossover design. Heart rate, respiratory rate, oxygen saturation, and body temperature were recorded throughout, and blood gases were assessed following induction. Resistance to induction was scored and time to induction was recorded. Although mask induction with sevoflurane was successful in all events (mean induction time of 2.1 min), KMB premedication resulted in a faster induction (mean induction time reduced by 1.2 ± 0.3 min) and lower resistance scores. Both protocols resulted in significant cardiovascular and respiratory depression; however, animals that received KMB were more hypercapnic than KM by 8.8 ± 2.8 mm Hg (P = 0.03) (mean venous partial pressure of carbon dioxide [PvCO2] for all: 79.9 mm Hg). In conclusion, if shorter induction times are desired, KMB premedication is preferred. However, cardiorespiratory variables including blood pressure should be monitored, and endotracheal intubation is recommended to allow for ETCO2 monitoring and provision of intermittent positive pressure ventilation.

The effect of age on the induction dose of propofol for general anesthesia in dogs.

OBJECTIVE: In people, the dose of propofol (DOP) required for procedural sedation and anesthesia decreases significantly with age. The objective of this study was to determine if the DOP required to perform endotracheal intubation decreases with age in dogs. STUDY DESIGN: Retrospective case series. ANIMALS: 1397 dogs. METHODS: Data from dogs anesthetized at referral center (2017-2020) were analyzed with three multivariate linear regression models with backward elimination using a combination of either absolute age, physiologic age, or life expectancy (ratio between age at the time of anesthetic event and expected age of death for each breed obtained from previous literature) as well as other factors as independent variables, and DOP as the dependent variable. The DOP for each quartile of life expectancy (<25%, 25-50%, 50-75%, 75-100%, >100%) was compared using one-way ANOVA. Significance was set at alpha = 0.025. RESULTS: Mean age was 7.2 ± 4.1 years, life expectancy 59.8 ± 33%, weight 19 ± 14 kg, and DOP 3.76 ± 1.8 mg kg-1. Among age models, only life expectancy was a predictor of DOP (-0.37 mg kg-1; P = 0.013) but of minimal clinical importance. The DOP by life age expectancy quartile was 3.9 ± 2.3, 3.8 ± 1.8, 3.6 ± 1.8, 3.7 ± 1.7, and 3.4 ± 1.6 mg kg-1, respectively (P = 0.20). Yorkshire Terrier, Chihuahua, Maltese, mixed breed dogs under 10 kg, and Shih Tzu required higher DOP. Status of neutered male, ASA E, and Boxer, Labrador and Golden Retriever breeds decreased DOP, along with certain premedication drugs. CONCLUSIONS AND CLINICAL RELEVANCE: In contrast to what is observed in people, an age cut-off predictive of DOP does not exist. Percentage of elapsed life expectancy along with other factors such as breed, premedication drug, emergency procedure, and reproductive status significantly alter DOP. In older dogs, the dose of propofol can be adjusted based on their elapsed life expectancy.

Premedication with acetazolamide: Is its use for postoperative pain and stress control after laparoscopic ovariectomy in dogs ruled out?

BACKGROUND: Studies in human medicine have concluded that acetazolamide reduces pain associated with carbon dioxide insufflation during laparoscopic surgery. However, there are no published reports regarding the use of acetazolamide for this purpose in companion animals, despite the increasing popularity of laparoscopic techniques in veterinary medicine due to their advantages over open surgeries. OBJECTIVES: Thirty mixed-breed female dogs were included in the study and randomly assigned to one of three groups: OVE (median celiotomy ovariectomy; n = 10), OVEL (laparoscopic ovariectomy, n = 10) and OVELA (laparoscopic ovariectomy with acetazolamide preoperative administration; n = 10). Experienced surgeons performed all procedures, and the anaesthetic and analgesic protocols were identical for all animals. Acetazolamide was administered orally (at a dose of 25 mg/kg) 2 h prior to induction in the OVELA group. Postoperative pain was evaluated using serum cortisol, salivary cortisol, and the University of Melbourne Pain Scale (UMPS) Score. RESULTS: Any statistical differences were observed in the UMPS scores when the OVELA group was compared to the OVEL group at 1 h after surgery (p = 0.515), 12 h (p = 0.375) and 24 h (p = 0.242). Animals undergoing open surgery (OVE group) had significantly higher pain scores at all times after surgery when compared with OVEL and OVELA groups. A high positive correlation (r = 0.792; p = 0.01) was found between serum and saliva cortisol concentrations. Mean saliva cortisol concentration was not significantly lower for the OVELA group compared to the other groups. CONCLUSIONS: This study found evidence that preoperative administration of acetazolamide may be beneficial in managing postoperative pain in dogs after laparoscopic surgeries. However, further research with a larger sample size is needed to confirm this and to determine if acetazolamide should be included in a multimodal postoperative analgesia protocol for laparoscopic ovariectomy in dogs.

Ketamine-propofol for total intravenous anaesthesia in rabbits: a comparison of premedication with acepromazine-medetomidine, acepromazine-midazolam or acepromazine-morphine.

OBJECTIVE: To describe ketamine-propofol total intravenous anaesthesia (TIVA) following premedication with acepromazine and either medetomidine, midazolam or morphine in rabbits. STUDY DESIGN: Randomized, crossover experimental study. ANIMALS: A total of six healthy female New Zealand White rabbits (2.2 ± 0.3 kg). METHODS: Rabbits were anaesthetized on four occasions, each separated by 7 days: an intramuscular injection of saline alone (treatment Saline) or acepromazine (0.5 mg kg-1) in combination with medetomidine (0.1 mg kg-1), midazolam (1 mg kg-1) or morphine (1 mg kg-1), treatments AME, AMI or AMO, respectively, in random order. Anaesthesia was induced and maintained with a mixture containing ketamine (5 mg mL-1) and propofol (5 mg mL-1) (ketofol). Each trachea was intubated and the rabbit administered oxygen during spontaneous ventilation. Ketofol infusion rate was initially 0.4 mg kg-1 minute-1 (0.2 mg kg-1 minute-1 of each drug) and was adjusted to maintain adequate anaesthetic depth based on clinical assessment. Ketofol dose and physiological variables were recorded every 5 minutes. Quality of sedation, intubation and recovery times were recorded. RESULTS: Ketofol induction doses decreased significantly in treatments AME (7.9 ± 2.3) and AMI (8.9 ± 4.0) compared with treatment Saline (16.8 ± 3.2 mg kg-1) (p < 0.05). The total ketofol dose to maintain anaesthesia was significantly lower in treatments AME, AMI and AMO (0.6 ± 0.1, 0.6 ± 0.2 and 0.6 ± 0.1 mg kg-1 minute-1, respectively) than in treatment Saline (1.2 ± 0.2 mg kg-1 minute-1) (p < 0.05). Cardiovascular variables remained at clinically acceptable values, but all treatments caused some degree of hypoventilation. CONCLUSIONS AND CLINICAL RELEVANCE: Premedication with AME, AMI and AMO, at the doses studied, significantly decreased the maintenance dose of ketofol infusion in rabbits. Ketofol was determined to be a clinically acceptable combination for TIVA in premedicated rabbits.

Sedative effects and changes in cardiac rhythm with intravenous premedication of medetomidine, butorphanol and ketamine in dogs.

OBJECTIVE: To determine the sedative effects and characteristics of cardiac rhythm with intravenous (IV) premedication of medetomidine, butorphanol and ketamine in dogs. STUDY DESIGN: Prospective, blinded, randomized clinical trial. ANIMALS: A total of 116 client-owned healthy dogs undergoing elective surgery. METHODS: Dogs were randomly allocated one of four groups: group M, medetomidine 5 µg kg-1; group B, butorphanol 0.2 mg kg-1; group MB, medetomidine 5 µg kg-1 and butorphanol 0.2 mg kg-1; or group MBK, medetomidine 5 µg kg-1, butorphanol 0.2 mg kg-1 and ketamine 1 mg kg-1 IV. Sedation was assessed using a numerical descriptive scale. Heart rate (HR) and rhythm were monitored; propofol dose (mg kg-1 IV) to allow orotracheal intubation was documented. Data were analysed using anova, accounting for multiple testing with the Tukey honest significant difference test. RESULTS: Sedation scores varied significantly between all groups at all time points, except between groups MB and MBK at four time points. HR decreased in all groups: most in groups M and MB, least in group B. HR was initially higher in group MBK than in groups M and MB. Arrhythmias occurred in all groups: group B showed second-degree atrioventricular blocks occasionally, all other groups showed additionally ventricular escape complexes and bundle branch blocks. Dose of propofol required for orotracheal intubation was significantly higher in group B (5.0 ± 2.0 mg kg-1) than in group M (2.6 ± 0.6 mg kg-1). Although no difference could be demonstrated between groups MB (1.4 ± 0.6 mg kg-1) and MBK (0.9 ± 0.8 mg kg-1), both groups required significantly less propofol than group M. CONCLUSION AND CLINICAL RELEVANCE: Medetomidine-based premedication protocols led to various bradyarrhythmias. Addition of subanaesthetic doses of ketamine to medetomidine-based protocols resulted in higher HRs, fewer bradyarrhythmias and fewer animals that required propofol for intubation without causing side effects in healthy dogs.

Analgesic and cardiopulmonary effects of premedication with tramadol in calves anesthetized with the infusion of guaifenesin and thiamylal.

This study examined the analgesic and cardiopulmonary effects of intravenous (IV) tramadol during general intravenous anesthesia in calves. Calves were premedicated with diazepam (0.2 mg/kg, IV) with tramadol (2 mg/kg, IV) (group T) or saline (group S). Anesthesia was induced by thiamylal sodium (4 mg/kg, IV) and maintained with an infusion (2 ml/kg/hr) of 5% guaifenesin containing thiamylal sodium (2 mg/ml). Additional thiamylal sodium (1-2 mg/kg, IV) was administered when interference from the calves was observed during surgery. The total counts of additional thiamylal sodium administration, analgesia score using a visual analog scale, recovery time, and cardiopulmonary function in the different groups were assessed and compared. Group T showed significantly fewer counts of additional drug administration and a significantly higher analgesia score. Tramadol may provide adequate analgesia with minimal cardiopulmonary changes in calves during general anesthesia.

Randomized, blinded, controlled clinical trial to assess gastroesophageal reflux and regurgitation in dogs undergoing general anesthesia after hydromorphone premedication with or without acepromazine or dexmedetomidine.

OBJECTIVE: To investigate whether premedication with hydromorphone alone or combined with acepromazine or dexmedetomidine affects the incidence of gastroesophageal reflux (GER) and regurgitation in dogs undergoing general anesthesia for elective orthopedic surgery. ANIMALS: 39 healthy client-owned dogs undergoing general anesthesia for elective orthopedic surgery between November 2016 and November 2018. PROCEDURES: For this prospective, randomized, controlled, blinded clinical trial, dogs were randomly assigned to be premedicated with hydromorphone (0.1 mg/kg, IM) alone (group H [control group]) or with either acepromazine (0.05 mg/kg, IM; group AH) or dexmedetomidine (6 µg/kg, IM; group DH) before undergoing general anesthesia induced with propofol and maintained with isoflurane. A pH sensor-tipped probe was used to identify episodes of GER (esophageal pH < 4 or > 7.5 for ≥ 30 seconds). Results for GER, regurgitation, vomiting, propofol dose, and durations of food withholding and anesthesia were compiled and compared across groups. RESULTS: There were 13 dogs in each group, and no meaningful differences were detected in age, body weight, sex, breed, or durations of anesthesia or food withholding across groups. Overall, 16 of the 39 (41%) dogs developed GER: 9 in group H, 6 in group AH, and 1 in group DH. The incidence of GER was significantly lower for group DH versus group H. Six of the 39 (15%) dogs regurgitated: 4 in group H and 2 in group AH. CONCLUSIONS AND CLINICAL RELEVANCE: The combined use of dexmedetomidine and hydromorphone as premedication may be a better choice to reduce GER in healthy dogs undergoing orthopedic surgery than would the use of hydromorphone with or without acepromazine. Additional research is warranted.

Comparison between dexmedetomidine and acepromazine in combination with methadone for premedication in brachycephalic dogs undergoing surgery for brachycephalic obstructive airway syndrome.

OBJECTIVE: To compare dexmedetomidine with acepromazine for premedication combined with methadone in dogs undergoing brachycephalic obstructive airway syndrome (BOAS) surgery. STUDY DESIGN: Randomized, blinded clinical study. ANIMALS: A group of 40 dogs weighing mean (± standard deviation) 10.5 ± 6 kg, aged 2.6 ± 1.9 years. METHODS: Dogs received either acepromazine 20 µg kg-1 (group A) or dexmedetomidine 2 µg kg-1 (group D) intramuscularly with methadone 0.3 mg kg-1. Anaesthesia was induced with propofol and maintained with sevoflurane. Sedation (0-18), induction (0-6) and recovery (0-5) qualities were scored. Propofol dose, hypotension incidence, mechanical ventilation requirement, extubation time, additional sedation, oxygen supplementation, regurgitation and emergency intubation following premedication or during recovery were recorded. Data were analysed using t tests, Mann-Whitney U or Chi-square tests. RESULTS: Group A dogs were less sedated [median (range): 1.5 (0-12)] than group D [5 (1-18)] (p = 0.021) and required more propofol [3.5 (1-7) versus 2.4 (1-8) mg kg-1; p = 0.018]. Induction scores [group A: 5 (4-5); group D 5 (3-5)] (p = 0.989), recovery scores [group A 5 (4-5); group D 5(3-5)](p = 0.738) and anaesthesia duration [group A:93 (50-170); group D 96 (54-263) minutes] (p = 0.758) were similar between groups. Time to extubation was longer in group A 12.5 (3-35) versus group D 5.5 (0-15) minutes; (p = 0.005). During recovery, two dogs required emergency intubation (p > 0.99) and five dogs required additional sedation (p > 0.99). Oxygen supplementation was required in 16 and 12 dogs in group A and D, respectively (p = 0.167); no dogs in group A and one dog in group D regurgitated (p = 0.311). CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine 2 µg kg-1 produces more sedation but similar recovery quality to acepromazine 20 µg kg-1 combined with methadone in dogs undergoing BOAS surgery.

Comparison of the effects of methadone and butorphanol combined with acepromazine for canine gastroduodenoscopy.

OBJECTIVE: To evaluate the feasibility of gastroduodenoscopy in dogs premedicated with acepromazine in combination with butorphanol or methadone. STUDY DESIGN: Prospective, randomized, double-blinded clinical trial. ANIMALS: A group of 40 client-owned dogs. METHODS: Dogs were randomly allocated to one of two groups and give intramuscular acepromazine 0.02 mg kg-1 combined with either butorphanol 0.3 mg kg-1 (group ACEBUT) or methadone 0.2 mg kg-1 (group ACEMET). General anaesthesia was induced with propofol and ketamine and maintained with sevoflurane (2.3%) in oxygen. Cardiopulmonary variables were recorded at 5 minute intervals during anaesthesia. Feasibility of the entire gastroduodenoscopy was evaluated with a visual analogue scale (VAS) from 0 (best) to 100 (worst) (primary outcome of the study). Lower oesophageal sphincter dilatation and duodenal intubation were scored. Pylorus diameter was measured with standard endoscopic inflatable balloons. Overall cardiovascular stability was assessed during anaesthesia, using a VAS (0-100), as was the presence of fluid in the oesophagus, regurgitation, need for mechanical ventilation, and intraoperative and postoperative rescue analgesia (secondary outcomes of the study). Differences between treatments were analysed with Mann-Whitney U, Student t test, Fisher exact test or mixed model analysis of variance as appropriate. Subsequently, feasibility VAS of the gastroduodenoscopy was assessed for noninferiority between groups. The noninferiority margin was set as -10. RESULTS: All gastroduodenoscopies were successfully completed in both groups using an endoscope tip diameter of 12.8 mm in all but one dog. Feasibility of gastroduodenoscopy was evaluated as 2.9 ± 5.6 in group ACEBUT and 5.1 ± 5.8 in group ACEMET. No significant differences between groups were detected in any measured or assessed variables, and noninferiority was confirmed. CONCLUSION AND CLINICAL RELEVANCE: In our study population, the effects of methadone and butorphanol when combined with acepromazine were comparable.

ORAL HALOPERIDOL PREMEDICATION TO REDUCE CAPTURE STRESS PRIOR TO XYLAZINE-KETAMINE ANESTHESIA IN CAPTIVE SPOTTED DEER (AXIS AXIS).

A prospective clinical trial was performed to evaluate the efficacy of haloperidol premedication prior to xylazine-ketamine anesthesia with a goal of reducing capture stress in adult male captive spotted deer (Axis axis). On the morning of the study, deer were fed a banana either containing haloperidol tablets (1 mg/kg) (haloperidol group, n = 10) or without haloperidol (placebo group, n = 10). Six hours postadministration, xylazine (3 mg/kg) and ketamine (2 mg/kg) was administered intramuscularly via a dart. Rectal temperature, heart rate, respiratory rate, and SpO2 (percent hemoglobin saturation) were recorded at 5-min intervals. Blood gas analysis was performed at time 0 (venous blood) and 10 and 20 min (arterial blood) postinduction. Serum cortisol was determined from venous blood (35 min postinduction), following which yohimbine was administered at a dose of 0.15 mg/kg intramuscular and 0.15 mg/kg intravenous. Statistical analysis of repeated measures data was performed with a two-way analysis of variance. Paired data were analyzed with a Wilcoxon rank-sum test (categorical data) or a paired t-test (continuous data). Significance was set at P ≤ 0.05, and results were expressed as mean ± SEM. There was no significant difference in induction time or recovery time between treatment groups. Rectal temperature and heart rate were significantly lower in the haloperidol group. Both groups demonstrated acidosis with venous pH being significantly lower in the placebo group when compared to the haloperidol group. Serum cortisol and arterial plasma lactate were lower in the haloperidol group indicative of reduced stress and physical exertion. Haloperidol premedication proved to be beneficial in reducing capture stress, when administered prior to xylazine-ketamine anesthesia, in spotted deer.

The effect of intravenous maropitant on blood pressure in healthy awake and anesthetized dogs.

OBJECTIVE: To evaluate the effects of intravenous maropitant on arterial blood pressure in healthy dogs while awake and under general anesthesia. DESIGN: Experimental crossover study. ANIMALS: Eight healthy adult Beagle dogs. PROCEDURE: All dogs received maropitant (1 mg kg-1) intravenously under the following conditions: 1) awake with non-invasive blood pressure monitoring (AwNIBP), 2) awake with invasive blood pressure monitoring (AwIBP), 3) premedication with acepromazine (0.005 mg kg-1) and butorphanol (0.2 mg kg-1) intramuscularly followed by propofol induction and isoflurane anesthesia (GaAB), and 4) premedication with dexmedetomidine (0.005 mg kg-1) and butorphanol (0.2 mg kg-1) intramuscularly followed by propofol induction and isoflurane anesthesia (GaDB). Heart rate (HR), systolic (SAP), diastolic (DAP), and mean blood pressures (MAP) were recorded before injection of maropitant (baseline), during the first 60 seconds of injection, during the second 60 seconds of injection, at the completion of injection and every 2 minutes post injection for 18 minutes. The data were compared over time using a Generalized Linear Model with mixed effects and then with simple effect comparison with Bonferroni adjustments (p <0.05). RESULTS: There were significant decreases from baseline in SAP in the GaAB group (p < 0.01) and in MAP and DAP in the AwIBP and GaAB (p < 0.001) groups during injection. A significant decrease in SAP (p < 0.05), DAP (p < 0.05), and MAP (p < 0.05) occurred at 16 minutes post injection in GaDB group. There was also a significant increase in HR in the AwIBP group (p < 0.01) during injection. Clinically significant hypotension occurred in the GaAB group with a mean MAP at 54 ± 6 mmHg during injection. CONCLUSION: Intravenous maropitant administration significantly decreases arterial blood pressure during inhalant anesthesia. Patients premedicated with acepromazine prior to isoflurane anesthesia may develop clinically significant hypotension.

[Euthanasia in horses - Results of a survey addressing horse owners and veterinarians]. / Euthanasie von Pferden ­ Ergebnisse einer Tierärzte- und Besitzerbefragung.

OBJECTIVE: Euthanasia represents a procedure with high responsibility for veterinarians in equine practice. The procedure should avoid pain and suffering for the horse and be carried out with the least possible stress for the patient and its owner. The presented study investigated the emotional impact of a horse's euthanasia procedure on the owner in order to enable development of future recommendations in improving the management of this procedure in horses. MATERIAL AND METHODS: Questionnaires concerning euthanasia of a horse for horse owners and veterinarians, respectively were developed and sent by mail or published online. RESULTS: Questionnaire for veterinarians: A total of 12 equine clinics participated. The main reason for performing euthanasia was stated to be acute disease, especially colic. In 75 % of the cases the owner was present. The location of the euthanasia procedure as well as the premedication used varied strongly between hospitals. In most clinics (n = 8) T61™, a combination of embutramid, tetracain hydrochloride and mebezoniumiodid, was used for euthanasia. Muscle twitching and "final gasps" were frequently observed during the procedure. Analysis of the 273 completed owner questionnaires revealed chronic disease, especially in older patients and colic as main reasons for euthanasia. Most owners assessed the attending veterinarian's empathy as being good and felt well-informed about the procedure. In addition, 64.8 % of the owners stated that their presence during the euthanasia aided them to emotionally cope with the loss of their horse. A subset of owners that had their horse euthanized in an equine clinic criticised the hospital's atmosphere as well as being insufficiently educated about the procedure. CONCLUSIONS: According to the obtained data, detailed information of the horses' owners regarding the euthanasia procedure and its costs is advisable. In addition, owners should be educated about possible accompanying symptoms, such as muscle twitching or "final gasps".

Investigation of the Effects of Spinal Dexamethasone Injection as a Premedication in Rabbit Anesthesia.

Anesthesia and analgesia are important in human and veterinary medicine, especially in surgical procedures. Rodents, avians, and exotic species are required to be anesthetized using an appropriate anesthetic regimen. This study aimed to suggest a new anesthetic drug and method in order to facilitate anesthesia as well as analgesia among rabbits, laboratory animals, and humans. Spinal injection of dexamethasone combined with intramuscular ketamine among rabbits can play the role of premedication agents. A total of 24 healthy white adult rabbits from New-Zealand were equally assigned into four groups. Groups 1, 2, 3, and 4 were subjected to spinal xylazine (5mg/kg) with ketamine (35mg/kg,IM), spinal dexamethasone (0.37mg/kg-four times diluted) with ketamine (35mg/kg,IM), dexamethasone (4mg/kg,IM) with ketamine (35mg/kg,IM), and spinal dexamethasone (0.37mg/kg-four times diluted), respectively. The results showed that there was a significant difference in terms of clinical reflexes recorded for group 2, compared to groups 1 and 3. A significant difference was also observed regarding clinical reflexes between group 2 and the other groups. Furthermore, no abnormality was observed in terms of histological sections within groups 2 and 4. Spinal dexamethasone can be used as a premedication combined with ketamine in rabbit anesthesia.

Clinical pharmacokinetics and pharmacodynamics of intravenous alfaxalone in young Thoroughbred horses premedicated with medetomidine and midazolam.

To investigate the clinical pharmacokinetics and pharmacodynamics of intravenous alfaxalone in young Thoroughbred horses, seven Thoroughbred horses were randomly anaesthetised twice with either 1 or 2 mg/kg of intravenous alfaxalone after premedication with medetomidine (6 µg/kg intravenous) and midazolam (20 µg/kg intravenous). Blood samples were collected at predetermined time points up to two hours after administration. Plasma alfaxalone concentrations were quantified by a liquid chromatography tandem-mass spectrometry method and analysed by non-compartmental pharmacokinetic analysis. Induction and recovery qualities were good to excellent for both doses. Recovery time for the 2 mg/kg (median 90 minutes) was significantly longer than that for the 1 mg/kg (median 50 minutes). Respiratory rate for the 2 mg/kg was significantly lower than that for the 1 mg/kg, resulting in hypoxaemia. The median (range) elimination half-life, total clearance and volume of distribution were 58.2 (42.3-70.7) minutes, 11.6 (10.3-14.5) ml/minute/kg and 0.8 (0.7-0.9) l/kg for the 1 mg/kg and 59.8 (47.5-68.0) minutes, 14.7 (12.1-16.0) ml/minute/kg and 0.9 (0.9-1.2) l/kg for the 2 mg/kg, respectively. Alfaxalone is rapidly eliminated from the plasma in young Thoroughbred horses. Respiratory depression should be especially noted when alfaxalone is used in clinical practice.

Effect of propofol and ketamine-diazepam on intraocular pressure in healthy premedicated dogs.

OBJECTIVE: To compare the effect of propofol and ketamine/diazepam for induction following premedication on intraocular pressure (IOP) in healthy dogs. STUDY DESIGN: Prospective, quasi-experimental, unmasked, longitudinal. ANIMALS: A total of 61 client-owned dogs. METHODS: Dogs were anesthetized twice with a 4 week washout period. Premedication with dexmedetomidine (5 µg kg-1) and hydromorphone (0.1 mg kg-1) intramuscularly was followed by either propofol (4 mg kg-1) or ketamine (5 mg kg-1) and diazepam (0.25 mg kg-1) intravenously for induction and inhaled isoflurane for maintenance. IOP was measured by applanation tonometry using TonoPen-XL before premedication and after 5, 10, 20 and 30 minutes. IOP was measured again immediately after induction and after 3, 5, 10, 15, 20, 30 and 40 minutes. Data were analyzed using one- or two-way repeated measures ANOVA. RESULTS: No difference was found between right and left IOP (p = 0.45), and data from both the eyes of each dog were averaged and considered as one set of data. Following premedication, IOP was significantly lower at all time points than at baseline when animals were grouped together, mean difference -1.6 ± 0.2 mmHg (p < 0.05). IOP increased immediately (12.2 ± 2.4 mmHg before versus 17.1 ± 3.8 mmHg after) and at 3, 5 (p < 0.001), 10 and 40 minutes (p = 0.009 and 0.045, respectively) after propofol administration. For ketamine/diazepam, IOP was increased immediately post-induction (13.0 ± 2.7 mmHg before versus 14.7 ± 2.8 mmHg after) and at 3, 5 (p < 0.001), 30 and 40 minutes (p = 0.010 and 0.037, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Sedation with hydromorphone and dexmedetomidine significantly decreased IOP in normal dogs and may be an appropriate choice for dogs that cannot tolerate acute increases in IOP. However, IOP increased significantly after both induction protocols, abolishing the effect of premedication.

Use of midazolam in combination with medetomidine for premedication in healthy dogs.

OBJECTIVE: To assess the sedative effects, propofol sparing properties and impact on quality of induction and intubation of intravenous (IV) medetomidine and midazolam administered consecutively at different doses compared to medetomidine alone in healthy dogs for premedication. STUDY DESIGN: Prospective, randomized, blinded, clinical study. ANIMALS: A total of 40 adult healthy client owned dogs, weighing 18 ± 7 kg (mean ± standard deviation). METHODS: Dogs were assigned to four groups: medetomidine 15 µg kg-1 (positive control group), medetomidine 10 µg kg-1 and midazolam 0.2 mg kg-1, medetomidine 5 µg kg-1 and midazolam 0.3 mg kg-1, and medetomidine 5 µg kg-1 and midazolam 0.2 µg kg-1. The same clinician assessed sedation after administration at T2.5 minutes and T5 minutes using a composite simple descriptive sedation scale ranging between 0 and 15 (0 = no sedation; 15 = profound sedation). The dose of propofol for induction, quality of induction, ease of intubation and any adverse events were recorded. RESULTS: There was no significant difference in sedation scores between treatment groups at T2.5 minutes or T5 minutes (p = 0.82 and p = 0.63, respectively). Administration of midazolam in combination with medetomidine resulted in 71% of dogs displaying paradoxical behaviours (p < 0.0001) such as agitation, excitation, restlessness, aggression and vocalization, which was different from pre-sedation. Propofol requirement was not different between groups. Induction and tracheal intubation quality was smooth in all groups. CONCLUSION: In healthy dogs, at the doses studied, the combination of medetomidine-midazolam administered IV for premedication provided moderate sedation but was associated with a high incidence of paradoxical behaviours. This drug combination IV is not recommended for premedication in healthy dogs.

Cardiac troponin I in dogs anaesthetized with propofol and sevoflurane: the influence of medetomidine premedication and inspired oxygen fraction.

OBJECTIVE: To investigate changes in serum cardiac troponin I (cTnI) concentrations in dogs in which medetomidine was used for sedation or for premedication prior to anaesthesia with propofol and sevoflurane. STUDY DESIGN: Prospective clinical study. ANIMALS: A total of 66 client-owned dogs. METHODS: The dogs were sedated with medetomidine (0.04 mg kg-1) intravenously (IV) (group M; n = 20) and left to breath room air or anaesthetized with propofol (6.5 ± 0.76 mg kg-1 IV) and sevoflurane (4.5% vaporizer setting) in oxygen (group P + S; n = 20) or with medetomidine (0.04 mg kg-1 IV), propofol (1.92 ± 0.63 mg kg-1) and sevoflurane (3% vaporizer setting) in oxygen (group M + P + S; n = 26), respectively. After 35 minutes, medetomidine was antagonized with atipamezole (0.1 mg kg-1 intramuscularly). Blood samples for serum cTnI determination were taken before sedation or anaesthesia, 6 and 12 hours and 4 days thereafter. Serum cTnI concentrations were measured with the Architect STAT Troponin-I assay. RESULTS: Before sedation or anaesthesia, cTnI concentrations were above the detection limit in 22 out of 66 (33%) of dogs. Compared to basal values, cTnI concentrations significantly increased at 6 and 12 hours in all groups and at day 4 in group M. There were no differences in cTnI concentration between groups at baseline, at 6 hours and at 4 days. At 12 hours, cTnI concentrations were significantly higher in groups M and P + S, respectively, compared to group M + P + S. CONCLUSIONS AND CLINICAL RELEVANCE: Oxygenation during anaesthesia and reduction of propofol and sevoflurane dose due to the sparing effects of medetomidine might have played a role in alleviation of myocardial hypoxic injury as indicated by the less severe and short-lived increase of cTnI in the M + P + S group.