Prothrombin and activated partial thromboplastin times, thromboelastography, hematocrit, and platelet count in a feline hemorrhage/over-resuscitation model using lactated Ringer's solution or 6% tetrastarch 130/0.4.

OBJECTIVE: To describe and compare prothrombin time (PT), activated partial thromboplastin time (aPTT), thromboelastography (TEG), HCT, and platelet count measurements in a hemorrhage/over-resuscitation model. DESIGN: Randomized crossover study. SETTING: University teaching hospital. ANIMALS: Six cats. INTERVENTIONS: Anesthetized cats underwent 3 treatments at 2-month intervals. The treatments were as follows: NHR-no controlled hemorrhage and sham resuscitation; LRS-controlled hemorrhage and lactated Ringer's solution (LRS) for resuscitation; and Voluven-controlled hemorrhage and 6% tetrastarch 130/0.4 for resuscitation. The LRS and Voluven were administered at 60 and 20 mL/kg/h, respectively, for 120 minutes. Blood samples were drawn for PT, aPTT, TEG, HCT, and platelet count measurements at a healthy check (T - 7d), after controlled hemorrhage (T0), at 60 and 120 minutes of resuscitation (T60 and T120), and at 24 hours after completion of resuscitation (T24h). Data were analyzed using a general linear mixed model approach (significance was P < 0.05). MEASUREMENTS AND MAIN RESULTS: Total median blood loss (controlled hemorrhage and blood sampling from T0 to T120) at T120 was 11.4, 31.0, and 30.8 mL/kg for NHR, LRS, and Voluven, respectively. PT and aPTT during LRS and Voluven were prolonged at T60 and T120 compared to NHR (P < 0.001). On TEG, the reaction time, kinetic time, and alpha-angle were within reference intervals for cats at all time points in all treatments, while maximum amplitude was less than the reference interval (40 mm) at T0, T60, and T120 during Voluven and at T60 and T120 during LRS compared to NHR (both P < 0.001). The HCT and platelet count were significantly lower at T60 and T120 during LRS and Voluven compared to NHR (P < 0.001). CONCLUSIONS: Hypocoagulopathy was observed during hemorrhage and liberal fluid resuscitation. Prolongation of PT and aPPT and decreased clot strength may have been caused by hemodilution and platelet loss.

MEDETOMIDINE-KETAMINE-BUPRENORPHINE ANESTHESIA OF THE SOLITARY SUBTERRANEAN CAPE DUNE MOLE-RAT (BATHYERGUS SUILLUS) AND THE CAPE MOLE-RAT (GEORYCHUS CAPENSIS).

A prospective, descriptive study was conducted to evaluate the safety and efficacy of a field-ready anesthetic drug combination of medetomidine-ketamine-buprenorphine for data logger implantation surgery or recheck in free-ranging Cape dune (Bathyergus suillus: n = 41) and Cape (Georychus capensis: n = 37) mole-rats. All anesthesia data were reported as mean (±standard deviation). Medetomidine-ketamine-buprenorphine doses were 0.1 (±0.03), 10.6 (±2.8), and 0.06 (±0.03) mg/kg, respectively, for Cape dune mole-rats; and 0.2 (±0.03), 19.4 (±4.0), and 0.14 (±0.03) mg/kg, respectively, for Cape mole-rats. Induction was calm and took 2.00 (range: 1.00-6.00) min for the Cape dune and 1.75 (range 1.25 to 8.16) min for Cape mole-rats. A surgical plane of anesthesia was achieved in most Cape dune mole-rats (92%) and Cape mole-rats (90%). The remainder required supplementation with a single intramuscular injection of ketamine (3-9 mg/kg) during surgery. Heart and respiratory rates were 149 (±37) beats and 24 (±8) breaths per minute, respectively, for Cape dune mole-rats and 179 (±40) beats and 25 (±10) and breaths per minute, respectively for Cape mole-rats. Surgical time for mole-rats ranged from 25 to 38 min. Recovery was calm and took 8.50 (range: 2.00-19.00) min for Cape dune mole-rats and 9.75 (range: 2.00-34.00) min for Cape mole-rats to recover. For recovery, atipamezole was administered intramuscularly at 0.5 (±0.15) mg/kg for Cape dune mole-rats and 1 (±0.15) mg/kg for Cape mole-rats. All mole-rats were returned to their original burrows within 48 h of recovery. The medetomidine-ketamine-buprenorphine combination induced a predictable, safe anesthesia in Cape dune and Cape mole-rats suitable for short intraabdominal surgery. This combination is suited to in situ studies where the use of a formal surgery or laboratory is not feasible.

Comparative effects of three different ventilatory treatments on arterial blood gas values and oxygen extraction in healthy anaesthetized dogs.

OBJECTIVE: To compare the effect of invasive continuous positive airway pressure (CPAP), pressure-controlled ventilation (PCV) with positive end-expiratory pressure (PEEP) and spontaneous breathing (SB) on PaO2, PaCO2 and arterial to central venous oxygen content difference (CaO2-CcvO2) in healthy anaesthetized dogs. STUDY DESIGN: Prospective randomized crossover study. ANIMALS: A group of 15 adult male dogs undergoing elective orchidectomy. METHODS: Dogs were anaesthetized [buprenorphine, medetomidine, propofol and isoflurane in an air oxygen (FiO2= 0.5)]. All ventilatory treatments (CPAP: 4 cmH2O; PCV: 10 cmH2O driving pressure; PEEP, 4 cmH2O; respiratory rate of 10 breaths minute-1 and inspiratory-to-expiratory ratio of 1:2; SB: no pressure applied) were applied in a randomized order during the same anaesthetic. Arterial and central venous blood samples were collected immediately before the start and at 20 minutes after each treatment. Data were compared using a general linear mixed model (p < 0.05). RESULTS: Median PaO2 was significantly higher after PCV [222 mmHg (29.6 kPa)] than after CPAP [202 mmHg (26.9 kPa)] and SB [208 mmHg (27.7 kPa)] (p < 0.001). Median PaCO2 was lower after PCV [48 mmHg (6.4 kPa)] than after CPAP [58 mmHg (7.7 kPa)] and SB [56 mmHg (7.5 kPa)] (p < 0.001). Median CaO2-CcvO2 was greater after PCV (4.36 mL dL-1) than after CPAP (3.41 mL dL-1) and SB (3.23 mL dL-1) (p < 0.001). PaO2, PaCO2 and CaO2-CcvO2 were no different between CPAP and SB (p > 0.99, p = 0.697 and p = 0.922, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: CPAP resulted in similar arterial oxygenation, CO2 elimination and tissue oxygen extraction to SB. PCV resulted in improved arterial oxygenation and CO2 elimination. Greater oxygen extraction occurred with PCV than with CPAP and SB, offsetting its advantage of improved arterial oxygenation. The benefit of invasive CPAP over SB in the healthy anaesthetized dog remains uncertain.

Immobilization, cardiopulmonary and blood gas effects of ketamine-butorphanol-medetomidine versus butorphanol-midazolam-medetomidine in free-ranging serval (Leptailurus serval).

OBJECTIVE: To compare ketamine-butorphanol-medetomidine (KBM) with butorphanol-midazolam-medetomidine (BMM) immobilization of serval. STUDY DESIGN: Blinded, randomized trial. ANIMALS: A total of 23 captures [KBM: five females, six males; 10.7 kg (mean); BMM: 10 females, two males; 9.6 kg]. METHODS: Serval were cage trapped and immobilized using the assigned drug combination delivered via a blow dart into gluteal muscles. Prior to darting, a stress score was assigned (0: calm; to 3: markedly stressed). Drug combinations were dosed based on estimated body weights: 8.0, 0.4 and 0.08 mg kg-1 for KBM and 0.4, 0.3 and 0.08 mg kg-1 for BMM, respectively. Time to first handling, duration of anaesthesia and recovery times were recorded. Physiological variables including blood glucose and body temperature were recorded at 5 minute intervals. Atipamezole (5 mg mg-1 medetomidine) and naltrexone (2 mg mg-1 butorphanol) were administered intramuscularly prior to recovery. Data, presented as mean values, were analysed using general linear mixed model and Spearman's correlation (stress score, glucose, temperature); significance was p < 0.05. RESULTS: Doses based on actual body weights were 8.7, 0.4 and 0.09 mg kg-1 for KBM and 0.5, 0.4 and 0.09 mg kg-1 for BMM, respectively. Time to first handling was 10.2 and 13.3 minutes for KBM and BMM, respectively (p = 0.033). Both combinations provided cardiovascular stability during anaesthesia that lasted a minimum of 35 minutes. Recovery was rapid and calm overall, but ataxia was noted in KBM. Stress score was strongly correlated to blood glucose (r2 = 0.788; p = 0.001) and temperature (r2 = 0.634; p = 0.015). CONCLUSIONS AND CLINICAL RELEVANCE: Both combinations produced similar effective immobilization that was cardiovascularly stable in serval. Overall, BMM is recommended because it is fully antagonizable. A calm, quiet environment before drug administration is essential to avoid capture-induced hyperglycaemia and hyperthermia.

What hinders pulmonary gas exchange and changes distribution of ventilation in immobilized white rhinoceroses (Ceratotherium simum) in lateral recumbency?

This study used electrical impedance tomography (EIT) measurements of regional ventilation and perfusion to elucidate the reasons for severe gas exchange impairment reported in rhinoceroses during opioid-induced immobilization. EIT values were compared with standard monitoring parameters to establish a new monitoring tool for conservational immobilization and future treatment options. Six male white rhinoceroses were immobilized using etorphine, and EIT ventilation variables, venous admixture, and dead space were measured 30, 40, and 50 min after becoming recumbent in lateral position. Pulmonary perfusion mapping using impedance-enhanced EIT was performed at the end of the study period. The measured impedance (∆Z) by EIT was compared between pulmonary regions using mixed linear models. Measurements of regional ventilation and perfusion revealed a pronounced disproportional shift of ventilation and perfusion toward the nondependent lung. Overall, the dependent lung was minimally ventilated and perfused, but remained aerated with minimal detectable lung collapse. Perfusion was found primarily around the hilum of the nondependent lung and was minimal in the periphery of the nondependent and the entire dependent lung. These shifts can explain the high amount of venous admixture and physiological dead space found in this study. Breath holding redistributed ventilation toward dependent and ventral lung areas. The findings of this study reveal important pathophysiological insights into the changes in lung ventilation and perfusion during immobilization of white rhinoceroses. These novel insights might induce a search for better therapeutic options and is establishing EIT as a promising monitoring tool for large animals in the field.NEW & NOTEWORTHY Electrical impedance tomography measurements of regional ventilation and perfusion applied to etorphine-immobilized white rhinoceroses in lateral recumbency revealed a pronounced disproportional shift of the measured ventilation and perfusion toward the nondependent lung. The dependent lung was minimally ventilated and perfused, but still aerated. Perfusion was found primarily around the hilum of the nondependent lung. These shifts can explain the gas exchange impairments found in this study. Breath holding can redistribute ventilation.

Effects of thiopentone, propofol and alfaxalone on laryngeal motion during oral laryngoscopy in healthy dogs.

OBJECTIVE: To compare the effects of thiopentone, propofol and alfaxalone on arytenoid cartilage motion and establish the dose rates to achieve a consistent oral laryngoscopy examination. STUDY DESIGN: Randomised crossover study. ANIMALS: Six healthy adult Beagle dogs. METHODS: Each dog was randomly administered three induction agents with a 1-week washout period between treatments. Thiopentone (7.5 mg kg-1), propofol (3 mg kg-1) or alfaxalone (1.5 mg kg-1) was administered over 1 minute for induction of anaesthesia. If the dog was deemed inadequately anaesthetised, then supplemental boluses of 1.8, 0.75 and 0.4 mg kg-1 were administered, respectively. Continual examination of the larynx, using a laryngoscope, commenced once an adequate anaesthetic depth was reached until examination end point. The number of arytenoid motions and vital breaths were counted during three time periods and compared over time and among treatments. Data were analysed using Friedman and Mann-Whitney U tests, Spearman rho and a linear mixed model with post hoc pairwise comparison with Tukey correction. RESULTS: The median (range) induction and examination times were 2.8 (2.0-3.0), 2.7 (2.0-3.3) and 2.5 (1.7-3.3) minutes (p = 0.727); and 14.1 (8.0-41.8), 5.4 (3.3-14.8) and 8.5 (3.8-31.6) minutes (p = 0.016) for thiopentone, propofol and alfaxalone, respectively. The median dose rates required to achieve an adequate anaesthetic depth were 6.3 (6.0-6.6), 2.4 (2.4-2.4) and 1.2 (1.2-1.2) mg kg-1 minute-1, respectively. There was no significant difference for the total number of arytenoid motions (p = 0.662) or vital breaths (p = 0.789) among induction agents. CONCLUSION AND CLINICAL RELEVANCE: The number of arytenoid motions were similar among the induction agents. However, at the dose rates used in this study, propofol provided adequate conditions for evaluation of the larynx with a shorter examination time which may be advantageous during laryngoscopy in dogs.

Anaesthetic, analgesic and cardiorespiratory effects of intramuscular medetomidine-ketamine combination alone or with morphine or tramadol for orchiectomy in cats.

OBJECTIVES: To compare the anaesthetic, analgesic and cardiorespiratory effects of intramuscular (IM) medetomidine and ketamine administered alone or combined with morphine or tramadol, for orchiectomy in cats. STUDY DESIGN: Randomised, blinded, prospective clinical study. ANIMALS: Thirty client-owned cats. MATERIALS AND METHODS: Cats (n = 10 in each group) received a combination of medetomidine (60 µgkg(-1) ) and ketamine (10 mg kg(-1) ) alone (MedK); combined with morphine (0.2 mg kg(-1) ) (MedKM), or combined with tramadol (2 mg kg(-1) ) (MedKT) IM. Time of induction, surgical and recovery events were recorded, and physiological parameters measured and recorded. Analgesia was evaluated with a visual analogue scale, a composite scoring system and the von Frey mechanical threshold device, every hour from three to eight hours post-drug administration injection. Data were analyzed with a linear mixed model, Kruskal-Wallis or Chi-square tests (p < 0.05). RESULTS: Median (IQR) induction and recovery times (minutes) were not significantly (p = 0.125) different between groups: 5.6 (2.7-8.0), 7.4 (5.1-9.6) and 8.0 (5.8-14.9) for induction and 128.5 (95.1-142.8), 166.4 (123.1-210.0) and 142.9 (123.4-180.2) for recovery, with MedK, MedKT and MedKM, respectively. Two cats (MedKM) required alfaxalone for endotracheal intubation. In all groups, three or four cats required additional isoflurane for surgery. Arterial oxygen tension overall (mean ± SD: 66 ± 2 mmHg) was low. Surgery resulted in increased systolic arterial blood pressure (p < 0.001), haemoglobin saturation (p < 0.001), respiratory (p = 0.003) and heart rates (p = 0.002). Pain scores did not differ significantly between groups. Von Frey responses decreased over time; changes over time varied by treatment (p < 0.001), MedK returning to baseline values more rapidly than MedKM and MedKT. No cat required rescue analgesics. CONCLUSION AND CLINICAL RELEVANCE: All three protocols can provide adequate anaesthesia and analgesia for orchiectomy in cats. However, rescue intervention to maintain surgical anaesthesia may be required in some cats. Oxygen supplementation is advised.

Assessment of behavioural changes in domestic cats during short-term hospitalisation.

We evaluated behavioural changes in domestic cats during short-term hospitalisation using a novel cat demeanour scoring system. Thirty-five healthy, client-owned cats admitted for neutering were enrolled. Cats were housed in a standardised cat ward for a short-term hospitalisation period (3-5 days) and demeanour scores were recorded once daily. The scoring system classified cats into one of five behavioural groupings: friendly and confident, friendly and shy, withdrawn and protective, withdrawn and aggressive, and overtly aggressive. Total demeanour score decreased over time (P <0.001) and the demeanour category improved (P <0.001). The intra-class correlation was 0.843 (P <0.001) and kappa was 0.606 (P <0.001), suggesting good repeatability and agreement among investigators. The demeanour scoring system was effective in detecting a change in behaviour in healthy cats undergoing short-term hospitalisation. The findings suggest that healthy cats require 2 days to acclimatise to hospitalisation.

Anaesthetic management of a 10-month-old white rhinoceros (Ceratotherium simum) calf for emergency exploratory celiotomy.

A 10-month-old, 580 kg, hand-reared white rhinoceros (Ceratotherium simum) calf was presented for emergency exploratory celiotomy. Anaesthesia was safely induced with three successive intravenous (IV) boluses of diazepam (10 mg) and ketamine (100 mg) until the trachea could be intubated. Anaesthesia was adequately maintained with isoflurane-inoxygen (mean end-tidal isoflurane concentration of 1.1% ± 0.2%) on a circle anaesthetic machine with carbon dioxide absorption and an intravenous infusion of ketamine and medetomidine at a mean rate of 0.02 mg/kg/min and 0.02 µg/kg/min, respectively. Mean values recorded during anaesthesia and surgery were heart rate (56.9 ± 11 beats/min), mean arterial blood pressure (6.16 kPa ± 1.75 kPa), end-tidal carbon dioxide concentration (6.23 kPa ± 0.30 kPa). Abdominal gas distension contributed to hypoventilation that resulted in hypercapnoea, confirmed by arterial blood gas analysis (PaCO2 14.69 kPa), which required controlled ventilation for correction. Blood volume was maintained with the intravenous infusion of a balanced electrolyte solution at 10 mL/kg/h and blood pressure supported with a continuous infusion of dobutamine and phenylephrine. Duration of anaesthesia was 3.5 h. It was concluded that anaesthesia was safely induced in a compromised white rhinoceros calf with a combination of diazepam and ketamine. A constant-rate infusion of medetomidine and ketamine allowed for a reduction in the dose of isoflurane required during maintenance of anaesthesia and improved intra-operative blood pressure management.