Sedative and antinociceptive effects of dexmedetomidine and buprenorphine after oral transmucosal or intramuscular administration in cats

ObjectiveTo compare sedation and antinociception after oral transmucosal (OTM) and intramuscular (IM) administration of a dexmedetomidine-buprenorphine combination in healthy adult cats.Study designRandomized, ‘blinded’ crossover study, with 1 month washout between treatments.AnimalsSix healthy neutered female cats, weighing 5.3–7.5 kg.MethodsA combination of dexmedetomidine (40 μg kg^?1) and buprenorphine (20 μg kg^?1) was administered by either the OTM (buccal cavity) or IM (quadriceps muscle) route. Sedation was measured using a numerical rating scale, at baseline and at various time points until 6 hours after treatment. At the same time points, analgesia was scored using a dynamic and interactive visual analogue scale, based on the response to an ear pinch, and by the cat’s response to a mechanical stimulus exerted by a pressure rate onset device. Physiological and adverse effects were recorded, and oral pH measured. Signed rank tests were performed, with significance set at p < 0.05. Data are presented as median and range.ResultsThere were no differences in sedation or antinociception scores between OTM and IM dosing at any of the time points. Nociceptive thresholds increased after both treatments but without significant difference between groups. Buccal pH remained between 8 and 8.5. Salivation was noted after OTM administration (n = 2) and vomiting after both OTM (n = 4), and IM (n = 3) dosing.Conclusions and clinical relevanceIn healthy adult cats, OTM administration of dexmedetomidine and buprenorphine resulted in comparable levels of sedation and antinociception to IM dosing. The OTM administration may offer an alternative route to administer this sedative-analgesic combination in cats.     

Sedative and analgesic effects of buprenorphine,combined with either acepromazine or dexmedetomidine,for premedication prior to elective surgery in cats and dogs

ObjectiveTo evaluate the sedative and analgesic effects of intramuscular buprenorphine with either dexmedetomidine or acepromazine, administered as premedication to cats and dogs undergoing elective surgery.Study designProspective, randomized, blinded clinical study.AnimalsForty dogs and 48 cats.MethodsAnimals were assigned to one of four groups, according to anaesthetic premedication and induction agent: buprenorphine 20 μg kg^?1 with either dexmedetomidine (dex) 250 μg m^?2 or acepromazine (acp) 0.03 mg kg^?1, followed by alfaxalone (ALF) or propofol (PRO). Meloxicam was administered preoperatively to all animals and anaesthesia was always maintained using isoflurane. Physiological measures and assessments of pain, sedation and mechanical nociceptive threshold (MNT) were made before and after premedication, intraoperatively, and for up to 24 hours after premedication. Data were analyzed with one-way, two-way and mixed between-within subjects anova, Kruskall–Wallis analyses and Chi squared tests. Results were deemed significant if p ≤ 0.05, except where multiple comparisons were performed (p ≤ 0.005).ResultsCats premedicated with dex were more sedated than cats premedicated with acp (p < 0.001) and ALF doses were lower in dex cats (1.2 ± 1.0 mg kg^?1) than acp cats (2.5 ± 1.9 mg kg^?1) (p = 0.041). There were no differences in sedation in dogs however PRO doses were lower in dex dogs (1.5 ± 0.8 mg kg^?1) compared to acp dogs (3.3 ± 1.1 mg kg^?1) (p < 0.001). There were no differences between groups with respect to pain scores or MNT for cats or dogs.ConclusionChoice of dex or acp, when given with buprenorphine, caused minor, clinically detectable, differences in various characteristics of anaesthesia, but not in the level of analgesia.Clinical relevanceA combination of buprenorphine with either acp or dex, followed by either PRO or ALF, and then isoflurane, accompanied by an NSAID, was suitable for anaesthesia in dogs and cats undergoing elective surgery. Choice of sedative agent may influence dose of anaesthetic induction agent.     

RESEARCH PAPER: Sedative and cardiorespiratory effects of dexmedetomidine and buprenorphine administered to cats via oral transmucosal or intramuscular routes

ObjectiveTo determine if buprenorphine plus dexmedetomidine administered via the oral transmucosal route produces sufficient sedation in cats so that students can insert intravenous catheters.Study DesignProspective, randomized, blinded, clinical trial.AnimalsEighty‐seven shelter‐owned female cats aged 4–48 months, weighing 1.1–4.9 kg.MethodsCats were randomly allocated to two treatment groups based on route of drug administration: oral transmucosal (OTM), or intramuscular (IM). Buprenorphine (20 μg kg^?1) plus dexmedetomidine (20 μg kg^?1) were administered as pre‐medicants via one of these two routes. Prior to and 20 minutes after drug administration, heart and respiratory rates, systolic arterial pressure, and posture were measured and recorded. Twenty minutes after drug administration the same variables plus each cat’s response to clipper sound, clipping, and restraint were recorded; higher scores indicated more sedation.ResultsThere were no significant differences between the two groups prior to pre‐medication. Within each treatment group heart rate was significantly lower 20 minutes after treatment, but it did not differ significantly between the two groups. Twenty minutes after treatment, respiratory rate was significantly less in the OTM group, but did not differ significantly between the two groups. Systolic arterial pressure did not differ within or between the two groups at either time. Scores for posture increased significantly within both groups, and cats in the IM group had higher scores after treatment. Twenty minutes after treatment, cats in the IM group had higher scores for clipping and restraint than OTM cats. Ketamine (IM) was necessary to facilitate catheterization in 25% and 16% of cats in the OTM and IM groups, respectively, but this was not significantly different.Conclusions and clinical relevanceAdministration of dexmedetomidine plus buprenorphine by the OTM route is easy to perform, but produces less sedation than the IM route for IV catheterization in cats.     

Sedative, cardiovascular, haematologic and biochemical effects of four different drug combinations administered intramuscularly in cats

ObjectiveTo compare effects of four drug combinations on sedation, echocardiographic, haematologic and biochemical variables and recovery in cats.Study designExperimental randomized ‘blinded’ cross-over study.AnimalsSix healthy cats.Materials and MethodsTreatments were administered intramuscularly: midazolam 0.4 mg kg^?1 and butorphanol 0.4 mg kg^?1 (MB); midazolam 0.4 mg kg^?1, butorphanol 0.4 mg kg^?1 and ketamine 3 mg kg^?1 (MBK); midazolam 0.4 mg kg^?1, butorphanol 0.4 mg kg^?1 and dexmedetomidine 5 μg kg^?1 (MBD); ketamine 3 mg kg^?1 and dexmedetomidine 5 μg kg^?1(KD). Sedation was evaluated at time-points over 10 minutes post injection. Echocardiography, systolic arterial blood pressure (SAP) measurement and blood sampling were performed at baseline and from 10 minutes after treatment. Quality of recovery was scored. Data were analysed by anova for repeated measures. p < 0.05 was considered significant.ResultsThe lowest sedation score was obtained by MB, (median 10.5 [7; 20]), highest by KD (36.5 [32; 38]). Quality of recovery was best with KD (0.5 [0; 2]), and worst with MB (7.5 [4; 11]). Relative to baseline measurements, treatments decreased SAP by 17%, 25%, 13%, 5% in MB, MBK, MBD and KD, respectively. Heart rate decreased (p < 0.05) after MBD (44%) and KD (34%). All treatments decreased stroke volume by 24%, 21%, 24%, 36%, and cardiac output by 23%, 34%, 54%, 53% in MB, MBK, MBD and KD, respectively. Packed cell volume was decreased (p < 0.05) by 20%, 31%, 29% in MBK, MBD and KD, respectively. Plasma glucose was increased after MBD (31%) and KD (52%) and lactate concentration was decreased (p < 0.05) after MBK (58%), MBD (72%) and KD (65%).Conclusions and clinical relevanceThe MB combination did not produce sedation in healthy cats. Treatment MBK led to acceptable sedation and minimal cardiovascular changes. Both treatments with dexmedetomidine produced excellent sedation and recovery but induced more cardiovascular depression and haematologic changes.     

The effect of butorphanol on the incidence of dexmedetomidine‐induced emesis in cats

ObjectiveTo evaluate the antiemetic effect of butorphanol (BUT) when co-administered with dexmedetomidine (DEX) in cats.Study designDouble-blind, randomized controlled cross-over experimental study.AnimalsFourteen purpose-bred healthy Domestic Short Hair cats, seven females and seven males, aged median (range) 14–84 (78) months and weighing 1.7–5.5 (4.0) kg.MethodsEach cat received five different treatment protocols intramuscularly (IM): (A) 25 μg kg⁻¹ DEX; (B) 20 μg kg⁻¹ DEX and 0.2 mg kg⁻¹ BUT; (C) 20 μg kg⁻¹ DEX and 0.1 mg kg⁻¹ BUT; (D) 25 μg kg⁻¹ DEX and 0.2 mg kg⁻¹ BUT; and (E) 20 μg kg⁻¹ DEX. Episodes of emesis, incidence and severity of nausea, and time to lateral recumbency were recorded for a period of 8 minutes after treatment administration, and the sedation was scored at the end of this period. The Friedman test and the Cochran’s Q-test were used to analyse the data. Significance was evaluated at the 5% level.ResultsThe proportion of cats that vomited was significantly lower with the treatment protocols that included BUT (B, C and D) compared with the protocols that included only DEX (A and E). The proportion of cats that had nausea was significantly higher with the protocols that included only DEX (A and E) compared with protocols B and D. Time to lateral recumbency (p = 0.09) and sedation score (p = 0.07) was not statistically different between the treatment protocols.Conclusions and clinical relevanceButorphanol can be used to prevent emesis and reduce the incidence and the severity of nausea caused by DEX in cats. It seems that the combination of BUT and DEX is very useful not only when emesis could result in serious complications, but also to provide comfort and well-being in cats sedated for minor procedures.     

Effects of opioids and anesthetic drugs on body temperature in cats

ObjectiveTo determine which class of opioid alone or in conjunction with other anesthetic drugs causes post-anesthetic hyperthermia in cats.Study designProspective, randomized, crossover study.AnimalsEight adult, healthy, cats (four spayed females and four castrated males weighing 3.8 ± 0.6 kg).MethodsEach cat was instrumented with a wireless thermistor in the abdominal cavity. Temperature in all phases was recorded every 5 minutes for 5 hours. Population body temperature (PBT) was recorded for ～8 days. Baseline body temperature is the final 24 hours of the PBT. All injectable drugs were given intramuscularly. The cats were administered drugs in four phases: 1) hydromorphone (H) 0.05, 0.1, or 0.2 mg kg^?1; 2) morphine (M) (0.5 mg kg^?1), buprenorphine (BUP) (0.02 mg kg^?1), or butorphanol (BUT) (0.2 mg kg^?1); 3) ketamine (K) (5 mg kg^?1) or ketamine (5 mg kg^?1) plus hydromorphone (0.1 mg kg^?1) (KH); 4) isoflurane in oxygen for 1 hour. Fifteen minutes prior to inhalant anesthetic, cats received either no premed (I), hydromorphone (0.1 mg kg^?1) (IH), or hydromorphone (0.1 mg kg^?1) plus ketamine (5 mg kg^?1) (IHK).ResultsMean PBT for all unmedicated cats was 38.9 ± 0.6 °C (102.0 ± 1 °F). The temperature of cats administered all doses of hydromorphone increased from baseline (p < 0.03) All four opioids (H, M, BUP and BUT) studied increased body temperature compared with baseline (p < 0.005). A significant difference was observed between baseline temperature values and those in treatment KH (p < 0.03). Following recovery from anesthesia, temperature in treatments IH and IHK was different from baseline (p < 0.002).Conclusions and clinical relevanceAll of the opioids tested, alone or in combination with ketamine or isoflurane, caused an increase in body temperature. The increase seen was mild to moderate (<40.1 °C (104.2 °F) and self limiting.     

Two doses of dexmedetomidine in combination with buprenorphine for premedication in dogs; a comparison with acepromazine and buprenorphine

ObjectiveTo assess as premedicants, the sedative, cardiorespiratory and propofol-sparing effects in dogs of dexmedetomidine and buprenorphine compared to acepromazine and buprenorphine.Study designProspective, randomised, blinded clinical studyAnimalsSixty healthy dogs (ASA grades I/II). Mean (SD) body mass 28.0 ± 9.1 kg, and mean age 3.4 ± 2.3 years.MethodsDogs were allocated randomly to receive 15 μg kg^?1 buprenorphine combined with either 30 μg kg^?1 acepromazine (group 1), 62.5 μg m^?2 dexmedetomidine (group 2), or 125 μg m^?2 dexmedetomidine (group 3) intramuscularly. After 30 minutes, anaesthesia was induced using a propofol target controlled infusion. Heart rate, respiratory rate, and oscillometric arterial blood pressure were recorded prior to induction, at endotracheal intubation and at 3 and 5 minutes post-intubation. Induction quality and pre-induction sedation were scored on 4 point scales. Propofol target required for endotracheal intubation was recorded. Data were analysed using Chi-squared tests, Kruskal-Wallis, one way and general linear model anova (p < 0.05).ResultsAge was significantly lower in group 1 (1.0 (1.0–3.8) years) than group 2 (5.0 (2.0–7.0) years), (median, (IQR)). There were no significant differences in sedation or quality of induction between groups. After premedication, heart rate was significantly lower and arterial blood pressures higher in groups 2 and 3 than group 1, but there was no significant difference between groups 2 and 3. Propofol targets were significantly lower in group 3 (1.5 (1.0–2.5) μg mL^?1) than group 1 (2.5 (2.0–3.0) μg mL^?1); no significant differences existed between group 2 (2.0 (1.5–2.5) μg mL^?1) and the other groups (median, (interquartile range)).Conclusions and Clinical relevanceWhen administered with buprenorphine, at these doses, dexmedetomidine had no advantages in terms of sedation and induction quality over acepromazine. Both doses of dexmedetomidine produced characteristic cardiovascular and respiratory effects of a similar magnitude.     

Cardiopulmonary and isoflurane‐sparing effects of epidural or intravenous infusion of dexmedetomidine in cats undergoing surgery with epidural lidocaine

ObjectiveTo compare the cardiorespiratory, anesthetic-sparing effects and quality of anesthetic recovery after epidural and constant rate intravenous (IV) infusion of dexmedetomidine (DEX) in cats given a low dose of epidural lidocaine under propofol-isoflurane anesthesia and submitted to elective ovariohysterectomy.Study designRandomized, blinded clinical trial.AnimalsTwenty-one adult female cats (mean body weight: 3.1 ± 0.4 kg).MethodsCats received DEX (4 μg kg^?1, IM). Fifteen minutes later, anesthesia was induced with propofol and maintained with isoflurane. Cats were divided into three groups. In GI cats received epidural lidocaine (1 mg kg^?1, n = 7), in GII cats were given epidural lidocaine (1 mg kg^?1) + DEX (4 μg kg^?1, n = 7), and in GIII cats were given epidural lidocaine (1 mg kg^?1) + IV constant rate infusion (CRI) of DEX (0.25 μg kg^?1 minute^?1, n = 7). Variables evaluated included heart rate (HR), respiratory rate (f_R), systemic arterial pressures, rectal temperature (RT), end-tidal CO₂, end-tidal isoflurane concentration (e′ISO), arterial blood gases, and muscle tone. Anesthetic recovery was compared among groups by evaluation of times to recovery, HR, f_R, RT, and degree of analgesia. A paired t-test was used to evaluate pre-medication variables and blood gases within groups. anova was used to compare parametric data, whereas Friedman test was used to compare muscle relaxation.ResultsEpidural and CRI of DEX reduced HR during anesthesia maintenance. Mean ± SD e′ISO ranged from 0.86 ± 0.28% to 1.91 ± 0.63% in GI, from 0.70 ± 0.12% to 0.97 ± 0.20% in GII, and from 0.69 ± 0.12% to 1.17 ± 0.25% in GIII. Cats in GII and GIII had longer recovery periods than in GI.Conclusions and clinical relevanceEpidural and CRI of DEX significantly decreased isoflurane consumption and resulted in recovery of better quality and longer duration, despite bradycardia, without changes in systemic blood pressure.     

Combination of dexmedetomidine with buprenorphine enhances the antinociceptive effect to a thermal stimulus in the cat compared with either agent alone

ObjectiveTo evaluate the sedative and antinociceptive effects of combinations of dexmedetomidine and buprenorphine in cats.Study designExperimental randomized study.AnimalsTwelve purpose-bred neutered domestic short-hair cats (4 male and 8 female) weighing 4.6 kg (range 3.7–5.5 kg) aged from 2 to 5 years.MethodsSix cats per group were administered buprenorphine (B) at 10 (B10) or 20 μg kg^?1 (B20) or dexmedetomidine (D) at 20 (D20) or 40 μg kg^?1 (D40) or a combination of B10/D20. A feline thermal nociceptive threshold testing device was used to evaluate the antinociceptive effects of the drugs before and up to 24 hours after drug treatment. Sedation was scored using a 100 mm visual analogue scale (VAS).ResultsThermal thresholds increased significantly after administration of all but D20. Area under the curve (AUC, hours °C) for the first 6 hours (mean ± SD) for B20 (281 ± 17.8) was significantly greater than B10 (260 ± 11.4), D20 (250 ± 7.9) and D40 (255 ± 11.4). The AUC for B10/D20 (273 ± 12.2) was significantly greater than D20 but not the other treatments. No sedation was seen after administration of B10 or B20 and maximal sedation was seen for all animals in the D40 and B10/D20 groups and most animals in the D20 group.ConclusionsD20 alone had the smallest analgesic effect; B10 alone provided no sedation but their combination gave good sedation with analgesia comparable with B20.Clinical relevanceThis combination could be a useful multimodal sedative/analgesic regimen in cats.     

Alfaxalone for total intravenous anaesthesia in dogs undergoing ovariohysterectomy: a comparison of premedication with acepromazine or dexmedetomidine

ObjectiveTo describe alfaxalone total intravenous anaesthesia (TIVA) following premedication with buprenorphine and either acepromazine (ACP) or dexmedetomidine (DEX) in bitches undergoing ovariohysterectomy.Study designProspective, randomised, clinical study.AnimalsThirty-eight healthy female dogs.MethodsFollowing intramuscular buprenorphine (20 μg kg^?1) and acepromazine (0.05 mg kg^?1) or dexmedetomidine (approximately 10 μg kg^?1, adjusted for body surface area), anaesthesia was induced and maintained with intravenous alfaxalone. Oxygen was administered via a suitable anaesthetic circuit. Alfaxalone infusion rate (initially 0.07 mg kg^?1 minute^?1) was adjusted to maintain adequate anaesthetic depth based on clinical assessment. Alfaxalone boluses were given if required. Ventilation was assisted if necessary. Alfaxalone dose and physiologic parameters were recorded every 5 minutes. Depth of sedation after premedication, induction quality and recovery duration and quality were scored. A Student's t-test, Mann–Whitney U and Chi-squared tests determined the significance of differences between groups. Data are presented as mean ± SD or median (range). Significance was defined as p < 0.05.ResultsThere were no differences between groups in demographics; induction quality; induction (1.5 ± 0.57 mg kg^?1) and total bolus doses [1.2 (0 – 6.3) mg kg^?1] of alfaxalone; anaesthesia duration (131 ± 18 minutes); or time to extubation [16.6 (3–50) minutes]. DEX dogs were more sedated than ACP dogs. Alfaxalone infusion rate was significantly lower in DEX [0.08 (0.06–0.19) mg kg^?1 minute^?1] than ACP dogs [0.11 (0.07–0.33) mg kg^?1 minute^?1]. Cardiovascular variables increased significantly during ovarian and cervical ligation and wound closure compared to baseline values in both groups. Apnoea and hypoventilation were common and not significantly different between groups. Arterial haemoglobin oxygen saturation remained above 95% in all animals. Recovery quality scores were significantly poorer for DEX than for ACP dogs.Conclusions and clinical relevanceAlfaxalone TIVA is an effective anaesthetic for surgical procedures but, in the protocol of this study, causes respiratory depression at infusion rates required for surgery.     

Efficacy of maropitant in preventing vomiting in dogs premedicated with hydromorphone

ObjectiveThe goal of this study was to evaluate the effectiveness of maropitant (Cerenia^®) in preventing vomiting after premedication with hydromorphone.Study designRandomized, blinded, prospective clinical study.AnimalsEighteen dogs ASA I/II admitted for elective orthopedic surgical procedures. The dogs were a mixed population of males and females, purebreds and mixed breeds, 1.0–10.2 years of age, weighing 3–49.5 kg.MethodsDogs were admitted to the study if they were greater than 1 year of age, healthy and scheduled to undergo elective orthopedic surgery. Dogs were randomly selected to receive one of two treatments administered by subcutaneous injection. Group M received 1.0 mg kg^?1 of maropitant, Group S received 0.1 mL kg^?1 of saline 1 hour prior to anesthesia premedication. Dogs were premedicated with 0.1 mg kg^?1 of hydromorphone intramuscularly. A blinded observer documented the presence of vomiting, retching and/or signs of nausea for 30 minutes after premedication.ResultsAll dogs in S vomited (6/9), retched (1/9) or displayed signs of nausea (2/9). None (0/9) of the dogs in M vomited, retched or displayed signs of nausea. Dogs in M had significantly fewer incidences of vomiting (p = 0.0090), vomiting and retching (p = 0.0023) and vomiting, retching and nausea (p < 0.0001) when compared to S.Conclusion and clinical relevanceMaropitant prevents vomiting, retching and nausea associated with intramuscular hydromorphone administration in dogs.     

A study to evaluate buprenorphine at 40 μg kg(-1) compared to 20 μg kg(-1) as a post-operative analgesic in the dog

ObjectiveComparison of the analgesic effect of buprenorphine at 20 or 40 μg kg^?1.Study designAn investigator ‘blinded’, randomised study.AnimalsTwenty six dogs presented for ovariohysterectomy.MethodsDogs were premedicated intramuscularly with acepromazine 0.03 mg kg^?1 and buprenorphine at either 20 (B20, n = 12) or 40 μg kg^?1 (B40, n= 14) followed by anaesthetic induction with propofol and maintenance with isoflurane. During anaesthesia non invasive blood pressure, heart rate, respiratory rate, blood oxygen saturation, inspired and expired volatile agent, end-tidal carbon dioxide and ECG were recorded. Pain and sedation were assessed using interactive VAS scores; mechanical nociceptive thresholds were measured at the wound and hindlimb - all were assessed before and up to 22 hours after administration. Carprofen was used for rescue analgesia.ResultsThere were no significant differences between the two groups for any of the parameters examined. Rescue analgesia was required around 5 hours after administration of buprenorphine in a significant number of animals. Sedation was good preoperatively and scores decreased over time postoperatively. Hock thresholds did not change over time; wound thresholds decreased significantly compared to the baseline value from 3 hours onwards.ConclusionsAdministration of buprenorphine at either 20 or 40 μg kg^?1 IM with acepromazine provided good pre-operative sedation. Cardiovascular and respiratory values remained within clinically acceptable limits during anaesthesia. There was no evidence that increasing dose increased adverse events that may be associated with opioid administration (e.g. bradycardia and respiratory depression).Clinical relevanceIncreasing the dose of buprenorphine from 20 to 40 μg kg^?1 did not provide any benefits with respect to analgesia after ovariohysterectomy as assessed using the VAS scoring system.     

Evaluation of alfaxalone total intravenous anesthesia in rabbits (Oryctolagus cuniculus) premedicated with dexmedetomidine or dexmedetomidine and buprenorphine

ObjectiveTo evaluate alfaxalone for total intravenous anesthesia (TIVA) in rabbits premedicated with dexmedetomidine or dexmedetomidine and buprenorphine.Study designCrossover study (part 1) with observational study (part 2).AnimalsA total of eight New Zealand White rabbits (Oryctolagus cuniculus), four female and four male, aged 12–16 weeks and weighing 2.8–3.5 kg in part 1. Separately, four additional rabbits in part 2.MethodsCrossover study design with eight rabbits per treatment. Rabbits were administered treatment D, dexmedetomidine (0.2 mg kg^–1), or treatment DB, dexmedetomidine (0.1 mg kg^–1) and buprenorphine (0.05 mg kg^–1) intramuscularly. Anesthesia was induced with alfaxalone intravenously until a supraglottic airway device was placed to deliver 100% oxygen. Anesthesia was maintained with alfaxalone (TIVA). Infusion rates were adjusted to achieve an absent pedal withdrawal reflex. Heart rate, respiratory rate, noninvasive blood pressure, end-tidal carbon dioxide partial pressure and peripheral hemoglobin oxygen saturation (SpO₂) were recorded every 5 minutes. Subsequently, four rabbits underwent ovariohysterectomy using treatment DB and alfaxalone TIVA.ResultsThe mean ± standard deviation alfaxalone infusion rate was 9.6 ± 2.6 and 4.5 ± 1.3 mg kg^–1 hour^–1 for treatments D and DB, respectively. In both treatments, blood pressure remained within acceptable range and SpO₂ was > 95%. Postinduction apnea and respiratory depression were observed in both treatments and managed with manual positive pressure ventilation. Four separate rabbits underwent successful ovariohysterectomy with treatment DB and alfaxalone TIVA. One rabbit required supplementation with inhalant anesthesia; three rabbits were successfully maintained using alfaxalone TIVA alone.Conclusions and clinical relevancePremedication with dexmedetomidine–buprenorphine combined with alfaxalone TIVA may be a viable alternative for performing abdominal surgery in the rabbit. The use of supplemental oxygen and ability to provide respiratory support are advised.     

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

ObjectiveTo document the effects of two doses of dexmedetomidine on the induction characteristics and dose requirements of alfaxalone.Study designRandomized controlled clinical trial.AnimalsSixty one client owned dogs, status ASA I-II.MethodsDogs 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).ResultsTreatment 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 relevanceThe 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.     

Comparison of intraperitoneal ropivacaine and ropivacaine–dexmedetomidine for postoperative analgesia in cats undergoing ovariohysterectomy

ObjectiveTo investigate the intraperitoneal (IP) administration of ropivacaine or ropivacaine–dexmedetomidine for postoperative analgesia in cats undergoing ovariohysterectomy.Study designProspective, randomized, blinded, positively controlled clinical study.AnimalsA total of 45 client-owned cats were enrolled.MethodsThe cats were administered intramuscular (IM) meperidine (6 mg kg⁻¹) and acepromazine (0.05 mg kg⁻¹). Anesthesia was induced with propofol and maintained with isoflurane. Meloxicam (0.2 mg kg⁻¹) was administered subcutaneously in all cats after intubation. After the abdominal incision, the cats were administered one of three treatments (15 cats in each treatment): IP instillation of 0.9% saline solution (group Control), 0.25% ropivacaine (1 mg kg⁻¹, group ROP) or ropivacaine and dexmedetomidine (4 μg kg⁻¹, group ROP–DEX). During anesthesia, heart rate (HR), electrocardiography, noninvasive systolic arterial pressure (SAP) and respiratory variables were monitored. Sedation and pain were assessed preoperatively and at various time points up to 24 hours after extubation using sedation scoring, an interactive visual analog scale, the UNESP-Botucatu multidimensional composite pain scale (MCPS) and mechanical nociceptive thresholds (MNT; von Frey anesthesiometer). Rescue analgesia (morphine, 0.1 mg kg⁻¹) IM was administered if the MCPS ≥6. Data were analyzed using the chi-square test, Tukey test, Kruskal–Wallis test and Friedman test (p < 0.05).ResultsHR was significantly lower in ROP–DEX compared with Control (p = 0.002). The pain scores, MNT, sedation scores and the postoperative rescue analgesia did not differ statistically among groups.Conclusions and clinical relevanceAs part of a multimodal pain therapy, IP ropivacaine–dexmedetomidine was associated with decreased HR intraoperatively; however, SAP remained within normal limits. Using the stated anesthetic protocol, neither IP ropivacaine nor ropivacaine–dexmedetomidine significantly improved analgesia compared with IP saline in cats undergoing ovariohysterectomy.     

A preliminary investigation comparing pre-operative morphine and buprenorphine for postoperative analgesia and sedation in cats

Objective To compare the postoperative analgesic and sedative properties of buprenorphine and morphine in cats. Study Design Prospective, randomized, blinded study. Animals Thirty‐two domestic cats undergoing surgery. Methods Cats received pre‐anaesthetic medication with acepromazine (0.05 mg kg^?1) given intramuscularly and were randomly allocated to group M and given morphine (0.1 mg kg^?1) intramuscularly (IM) or to group B and given buprenorphine (0.01 mg kg^?1) IM. Anaesthesia was induced with propofol and maintained with halothane in oxygen and nitrous oxide. Pain and sedation scores using visual analogue scales, and heart and respiratory rates, were measured immediately before, and 30, 60, 120, 180, 300 and 420 minutes after anaesthesia. Results Pain scores were significantly lower at 60, 120 and 180 minutes after anaesthesia in group B. Group B also had higher heart rates at 30 minutes. There were no other statistically significant differences between the groups. Clinical relevance Buprenorphine (0.01 mg kg^?1) appeared to provide better postoperative analgesia than morphine (0.1 mg kg^?1) and may also have a longer duration of action.