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Objective : To evaluate the cardiovascular effects of a preload of hydroxyethylstarch 6% (HES), preceding an epidural administration of ropivacaine 0.75% in isoflurane anaesthetized dogs. Animals : Six female, neutered Beagle dogs (mean 13.3 +/- SD 1.0 kg; 3.6 +/- 0.1 years). Study design : Randomized experimental cross-over study (washout of 1 month). Methods : Anaesthesia was induced with propofol and maintained with isoflurane in oxygen/air. All dogs were anaesthetized twice to receive either treatment HESR (continuous rate infusion [CRI] of 7 mL kg(-1) HES started 30 minutes [T-30] prior to epidural administration of ropivacaine 0.75% 1.65 mg kg(-1) at T0) or treatment R (no HES preload and similar dose and timing of epidural ropivacaine administration). Baseline measurements were obtained at T-5. Heart rate (HR), mean (MAP), diastolic (DAP) and systolic (SAP) invasive arterial pressures, cardiac output (Lithium dilution and pulse contour analysis) and derived parameters were recorded every 5 minutes for 60 minutes. Statistical analysis was performed on five dogs, due to the death of one dog. Results : Clinically relevant decreases in MAP (

Objective To compare the cardiovascular effects of four epidural treatments in isoflurane anaesthetised dogs. Study design Prospective, randomized. experimental study. Animals Six female, neutered Beagle dogs (13.3 +/- 1.0 kg), aged 3.6 +/- 0.1 years. Methods Anaesthesia was induced with propofol (8.3 +/- 1.1 mg kg(-1)) and maintained with isoflurane in a mixture of oxygen and air [inspiratory fraction of oxygen (FiO(2)) = 40%], using intermittent positive pressure ventilation. Using a cross-over model, NaCl 0.9% (P); methadone 1% 0.1 mg kg(-1) (M); ropivacaine 0.75% 1.65 mg kg(-1) (R) or methadone 1% 0.1 mg kg(-1) + ropivacaine 0.75% 1.65 mg kg(-1) (RM) in equal volumes (0.23 mL kg(-1)) using NaCl 0.9%, was administered epidurally at the level of the lumbosacral space. Treatment P was administered to five dogs only. Cardiovascular and respiratory variables, blood gases, and oesophageal temperature were recorded at T-15 and for 60 minutes after epidural injection (T0). Results Mean overall heart rate (HR in beats minute(-1)) was significantly lower after treatment M (119 +/- 16) (p = 0.0019), R (110 +/- 18) (p < 0.0001) and RM (109 +/- 13) (p < 0.0001), compared to treatment P (135 +/- 21). Additionally, a significant difference in HR between treatments RM and M was found (p = 0.04). After both ropivacaine treatments, systemic arterial pressures (sAP) were significantly lower compared to other treatments. No significant overall differences between treatments were present for central venous pressure, cardiac output, stroke volume, systemic vascular resistance, oxygen delivery and arterial oxygen content (CaO2). Heart rate and sAP significantly increased after treatment P and M compared to baseline (T-15). With all treatments significant reductions from baseline were observed in oesophageal temperature, packed cell volume and CaO2. A transient unilateral Horner's syndrome occurred in one dog after treatment R. Conclusions and clinical relevance Clinically important low sAPs were observed after the ropivacaine epidural treatments in isoflurane anaesthetised dogs. Systemic arterial pressures were clinically acceptable when using epidural methadone.

Objective To investigate the cardiovascular effects of epidural romifidine in isoflurane-anaesthetized dogs. Study design Prospective, randomized, blinded experiment. Animals A total of six healthy adult female Beagles aged 1.25 ± 0.08 years and weighing 12.46 ± 1.48 (10.25–14.50) kg. Methods Anaesthesia was induced with propofol (6–9 mg kg −1 ) and maintained with 1.8–1.9% end-tidal isoflurane in oxygen. End-tidal CO 2 was kept between 35 and 45 mmHg (4.7–6.0 kPa) using intermittent positive pressure ventilation. Heart rate (HR), arterial blood pressure and cardiac output (CO) were monitored. Cardiac output was determined using a LiDCO monitor and the derived parameters were calculated. After baseline measurements, either 10 μg kg −1 romifidine or saline (total volume 1 mL 4.5 kg −1 ) was injected into the lumbosacral epidural space. Data were recorded for 1 hour after epidural injection. A minimum of 1 week elapsed between treatments. Results After epidural injection, the overall means (± standard deviation, SD) of HR (95 ± 20 bpm), mean arterial blood pressure (MAP) (81 ± 19 mmHg), CO (1.63 ± 0.66 L minute −1 ), cardiac index (CI) (2.97 ± 1.1 L minute −1 m −2 ) and stroke volume index (SI) (1.38 ± 0.21 mL beat −1 kg −1 ) were significantly lower in the romifidine treatment compared with the overall means in the saline treatment [HR (129 ± 24 bpm), MAP (89 ± 17 mmHg), CO (3.35 ± 0.86 L minute −1 ), CI (6.17 ± 1.4 L minute −1 m −2 ) and SI (2.21 ± 0.21 mL beat −1 kg −1 )]. The overall mean of systemic vascular resistance index (SVRI) (7202 ± 2656 dynes seconds cm −5 m −2 ) after epidural romifidine injection was significantly higher than the overall mean of SVRI (3315 ± 1167 dynes seconds cm −5 m −2 ) after epidural saline injection. Conclusion Epidural romifidine in isoflurane-anaesthetized dogs caused significant cardiovascular effects similar to those reportedly produced by systemic romifidine administration. Clinical relevance Similar cardiovascular monitoring is required after epidural and systemically administered romifidine. Further studies are required to evaluate the analgesic effects of epidural romifidine.

Objective To investigate the sedative, anaesthetic and cardiorespiratory effects of intramuscular (IM) administration of alfaxalone alone or in combination with dexmedetomidine in cats. Study design Blinded, randomized crossover study with a washout period of 15 days. Animals Seven adult cats, weighing 3.5 ± 0.7 kg. Methods Cats were assigned randomly to each of three treatments: A5 (alfaxalone 5 mg kg-1), D20A5 (dexmedetomidine 20 μg kg-1 and alfaxalone 5 mg kg-1) and D40A5 (dexmedetomidine 40 μg kg-1 and alfaxalone 5 mg kg-1). Drugs were administered IM into the epaxial muscles. Sedation or anaesthesia scores were evaluated by a modified numerical rating scale. Times to extubation, head-lift, sternal recumbency and standing were recorded. Heart and respiratory rates, systolic arterial pressure, arterial oxygen saturation of haemoglobin, end-tidal carbon dioxide tension and rectal temperature were measured at 5, 10, 15, 20, 30, 45, 60, 90, 120 and 150 minutes after drug administration. Adverse events were recorded. Data were analysed by one-way anova with Tukey’s post-hoc test for parametric values and, for non-normally distributed parameters, a Kruskal–Wallis test and Mann–Whitney U-test for two independent samples (p Results Sedation scores were significantly different among the treatments. Cats in A5 were deeply sedated, whereas cats administered dexmedetomidine were anaesthetized. The onset of action and the duration of anaesthesia were related to the dose of dexmedetomidine. Cardiorespiratory parameters remained stable in the A5 group. Lower heart rates, higher systolic blood pressures and occasional low pulse oximetry readings were observed in the dexmedetomidine groups. A limited number of adverse events (hyperkinesia, emesis) occurred during recovery. Conclusions and clinical relevance Alfaxalone administered IM induced sedation in cats. The addition of dexmedetomidine to alfaxalone induced general anaesthesia with a mild decrease in the heart rate and arterial oxygen saturation of haemoglobin.

Objective To compare sedation and antinociception after oral transmucosal (OTM) and intramuscular (IM) administration of a dexmedetomidine-buprenorphine combination in healthy adult cats. Study design Randomized, ‘blinded’ crossover study, with 1 month washout between treatments. Animals Six healthy neutered female cats, weighing 5.3–7.5 kg. Methods A 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. Results There 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 relevance In 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.

Objective To investigate the clinical efficacy of four analgesia protocols in dogs undergoing tibial tuberosity advancement (TTA). Study design Prospective, randomized, blinded study. Animals Thirty-two client owned dogs undergoing TTA-surgery. Methods Dogs ( n = 8 per treatment) received an oral placebo (PM and PRM) or tepoxalin (10 mg kg −1 ) tablet (TM and TRM) once daily for 1 week before surgery. Epidural methadone (0.1 mg kg −1 ) (PM and TM) or the epidural combination methadone (0.1 mg kg −1 )/ropivacaine 0.75% (1.65 mg kg −1 ) (PRM and TRM) was administered after induction of anaesthesia. Intra-operative fentanyl requirements (2 μg kg −1 IV) and end-tidal isoflurane concentration after 60 minutes of anaesthesia (F e ′ISO 60 ) were recorded. Post-operative analgesia was evaluated hourly from 1 to 8 and at 20 hours post-extubation with a visual analogue scale (VAS) and the University of Melbourne Pain Scale (UMPS). If VAS > 50 and/or UMPS > 10, rescue methadone (0.1 mg kg −1 ) was administered IV. Analgesic duration (time from epidural until post-operative rescue analgesia) and time to standing were recorded. Normally distributed variables were analysed with an F -test (α = 0.05) or t -test for pairwise inter-treatment comparisons (Bonferonni adjusted α = 0.0083). Non-normally distributed data were analysed with the Kruskall–Wallis test (α = 0.05 or Bonferonni adjusted α = 0.005 for inter-treatment comparison of post-operative pain scores). Results More intra-operative analgesia interventions were required in PM [2 (0–11)] [median (range)] and TM [2 (1–2)] compared to PRM (0) and TRM (0). F e ′ISO 60 was significantly lower in (PRM + TRM) compared to (PM + TM). Analgesic duration was shorter in PM (459 ± 276 minutes) (mean ± SD) and TM (318 ± 152 minutes) compared to TRM (853 ± 288 minutes), but not to PRM (554 ± 234 minutes). Times to standing were longer in the ropivacaine treatments compared to TM. Conclusions and clinical relevance Inclusion of epidural ropivacaine resulted in reduction of F e ′ISO 60 , avoidance of intra-operative fentanyl administration, a longer duration of post-operative analgesia (in TRM) and a delay in time to standing compared to TM.