Comparison of three different inhalant anesthetic agents (isoflurane, sevoflurane, desflurane) in red-tailed hawks (Buteo jamaicensis)

Anaesthetic management and complications of a Humboldt penguin (Spheniscus humboldti) undergoing diagnostic imaging

BACKGROUND

The presence of a tracheal septum dividing the trachea into two makes intubation one of the main challenges of penguin anaesthesia. Differences in the length and location of the aforementioned tracheal septum have been described in some penguin species. However, to the best of the authors' knowledge, it has not been reported in Humboldt penguins (Spheniscus humboldti). Therefore, one of the aims of this publication is to report the septal position in this Humboldt penguin. Furthermore, this publication describes the anaesthetic protocol and complications encountered and discusses some of the more important features of penguin anaesthesia. It is anticipated that this case report will aid in future procedures requiring anaesthesia of this penguin species.

CASE PRESENTATION

A 25-year-old female Humboldt penguin was anaesthetized at the University College Dublin Veterinary Hospital for radiographs and computed tomography (CT) following three weeks of inappetence. After assessing the health status of the penguin from the clinical history and performing a physical examination, an American Society of Anesthesiologists physical status score of II was assigned and a combination of butorphanol 1 mg/kg and midazolam 1 mg/kg was administered intramuscularly to sedate the penguin. Induction of anaesthesia was performed via a face mask using sevoflurane in oxygen. The airway was intubated with a 4.0 mm Cole tube and anaesthesia was maintained with sevoflurane in oxygen during the entire procedure. Anaesthetic monitoring consisted of an electrocardiogram, pulse oximetry, non-invasive blood pressure, capnography, and body temperature.

CONCLUSIONS

Tracheal bifurcation was identified as the start of the tracheal septum 4.67 cm from the glottis using CT. Most of the anticipated complications of penguin anaesthesia, such as hyperthermia, hypothermia, regurgitation, hypoventilation, and difficulties in intubation were present in this case. However, no major sequalae occurred following the anaesthetic protocol described.

Baseline of Physiological Body Temperature and Hematological Parameters in Captive Rousettus aegyptiacus and Eidolon helvum Fruit Bats

The discovery of bats as reservoir hosts for a number of highly pathogenic zoonotic agents has led to an increasing interest of infectious disease research in experimental studies with bats. Therefore, we established breeding colonies of Rousettus aegyptiacus and Eidolon helvum fruit bats, which both have been identified as reservoir hosts for relevant zoonotic disease agents, such as Marburg virus and Lagos bat virus. Since 2013, individuals of both species have been recruited to the Friedrich-Loeffler-Institut (FLI) from zoological gardens in Europe, to where these species had been introduced from the wild several decades ago. The aviaries have been designed according to national recommendations published by the Federal Ministry of Agriculture. Under these conditions, both species have been reproducing for years. To better understand the physiology of these animals, and to generate baseline knowledge for infection experiments, we monitored the body core temperatures of R. aegyptiacus bats in the aviaries, and found a circadian variation between 34°C and 41.5°C. We also determined the hematological parameters of both species, and detected specific differences between both bat species. For values of clinical chemistry, no correlation to age or sex was observed. However, species-specific differences were detected since ALT, BUN and CREA were found to be significantly higher in R. aegyptiacus and GLU and TP were significantly higher in E. helvum bats. A higher hematocrit, hemoglobin and red blood cell level was observed in subadult R. aegyptiacus, with hemoglobin and red blood cells also being significantly increased compared to E. helvum. Lymphocytes were found to be the dominant white blood cells in both species and are higher in female E. helvum. Neutrophil granulocytes were significantly higher in E. helvum bats. This underlines the necessity to define baseline profiles for each bat species prior to their use in experimental challenge.

Backyard Poultry and Waterfowl Sedation and Anesthesia

The popularity of backyard poultry (chickens, turkey, guinea fowl) and waterfowl (ducks and geese) is increasing in the United States, and these animals frequently present for veterinary care. Like other birds, these species have unique anatomy that should be clinically considered before anesthesia. A balanced approach to an injectable, inhalational, or combination anesthesia protocol must be taken to ensure a safe outcome for the patient and to achieve the procedural needs. A well-informed clinician may use both sedation and general anesthesia to care for backyard bird patients in practice.

Longitudinal impact on rat cardiac tissue transcriptomic profiles due to acute intratracheal inhalation exposures to isoflurane

Isoflurane (ISO) is a widely used inhalation anesthetic in experiments with rodents and humans during surgery. Though ISO has not been reported to impart long-lasting side effects, it is unknown if ISO can influence gene regulation in certain tissues, including the heart. Such changes could have important implications for use of this anesthetic in patients susceptible to heart failure/other cardiac abnormalities. To test if ISO could alter gene regulation/expression in heart tissues, and if such changes were reversible, prolonged, or late onset with time, SHR (spontaneously hypertensive) rats were exposed by intratracheal inhalation to a 97.5% air/2.5% ISO mixture on two consecutive days (2 hr/d). Control rats breathed filtered air only. On Days 1, 30, 240, and 360 post-exposure, rat hearts were collected and total RNA was extracted from the left ventricle for global gene expression analysis. The data revealed differentially-expressed genes (DEG) in response to ISO (compared to naïve control) at all post-exposure timepoints. The data showed acute ISO exposures led to DEG associated with wounding, local immune function, inflammation, and circadian rhythm regulation at Days 1 and 30; these effects dissipated by Day 240. There were other significantly-increased DEG induced by ISO at Day 360; these included changes in expression of genes associated with cell signaling, differentiation, and migration, extracellular matrix organization, cell-substrate adhesion, heart development, and blood pressure regulation. Examination of consistent DEG at Days 240 and 360 indicated late onset DEG reflecting potential long-lasting effects from ISO; these included DEG associated with oxidative phosphorylation, ribosome, angiogenesis, mitochondrial translation elongation, and focal adhesion. Together, the data show acute repeated ISO exposures could impart variable effects on gene expression/regulation in the heart. While some alterations self-resolved, others appeared to be long-lasting or late onset. Whether such changes occur in all rat models or in humans remains to be investigated.

Comparison of the Anesthetic Effects of Isoflurane and Sevoflurane Inhalation on the Cardiovascular System of the Common Buzzard (Buteo buteo)

The aim of this study was to compare the effects of isoflurane (ISO) and sevoflurane (SEVO) inhalation anesthesia on the cardiovascular system of the common buzzard (Buteo buteo). Fourteen common buzzards of unknown sex and age, weighing 700-900 g each, were used for the study. The buzzards were randomly divided into an ISO group and a SEVO group, each comprising 7 buzzards. The buzzards were then anesthetized by masked induction with either ISO or SEVO. After induction, all buzzards were intubated with a 2.5-mm-diameter uncuffed endotracheal tube. Anesthesia was maintained with 3% ISO or 4% SEVO in a 3 L/min flow of 100% oxygen. Before induction, immediately after induction, and at intervals of 5, 10, 15, 20, 25, and 30 min after the patients were induced, the heart rate, respiratory rate, and body temperature of the buzzards were recorded. In addition, before and during anesthesia, serum electrolytes (sodium, ionized calcium, and potassium), blood gas measurements (arterial pH, arterial partial pressure of carbon dioxide, arterial partial pressure of oxygen, bicarbonate concentration, and oxyhemoglobin saturation), and hematocrit values were evaluated in the blood samples taken from both the ISO and SEVO groups. A statistically significant decrease in body temperature was observed in both groups. A significant decrease in heart rate was observed in the ISO group. The increases in partial pressure of carbon dioxide and bicarbonate concentration were statistically significant in both groups. The effects of ISO and SEVO anesthesia on the cardiovascular and respiratory system in the buzzards were similar based on the results of this study.

Effect of preoxygenation before isoflurane induction and rocuronium-induced apnea on time until hemoglobin desaturation in domestic chickens (Gallus gallus domesticus)

OBJECTIVE

To evaluate the time to hemoglobin oxygen desaturation in chickens (Gallus gallus domesticus) with and without preoxygenation before isoflurane induction of anesthesia and rocuronium-induced apnea.

STUDY DESIGN

Prospective, randomized crossover study.

ANIMALS

A total of 10 healthy adult Lohmann Brown-Lite hens.

METHODS

Hens were anesthetized with isoflurane for intravenous (IV) and intraarterial catheter placement and allowed to fully recover from anesthesia. Hens in the preoxygenation treatment were administered oxygen (2 L minute^-1) via a facemask for 3 minutes prior to induction of anesthesia with 3% isoflurane in oxygen. In the alternative treatment, hens were not preoxygenated prior to induction of anesthesia with isoflurane in oxygen. Apnea was then induced with rocuronium bromide (1.0 mg kg^-1) administered IV, and anesthesia was maintained with IV propofol infusion. A cloacal pulse oximeter measured hemoglobin oxygen saturation (SpO₂). Time was recorded from the start of apnea until SpO₂ was 90% (desaturation). The trachea was intubated, and anesthesia was maintained with isoflurane in oxygen with manual ventilation until spontaneous breathing returned and SpO₂ ≥ 99%. PaO₂ was measured before each treatment, after preoxygenation, postinduction and at desaturation. Data were analyzed between treatments using Wilcoxon matched-pairs signed rank tests with Holm-Šidák multiple comparison test, and within treatments using Friedman test with Dunn's multiple comparison test (p < 0.05). Data are reported as median (range).

RESULTS

Time from start of apnea until hemoglobin desaturation was not significantly different between preoxygenated and nonpreoxygenated hens [26.5 (16-50) seconds and 24.0 (5-57) seconds, respectively; p = 0.25]. No differences in PaO₂ between treatments were observed at any time point.

CONCLUSIONS AND CLINICAL RELEVANCE

Preoxygenation for 3 minutes before isoflurane mask induction of anesthesia and apnea does not significantly increase time until desaturation in hens.

Minimum anesthetic concentration of isoflurane and sparing effect of midazolam in Quaker parrots (Myiopsitta monachus)

OBJECTIVE

To determine the effects of midazolam on the minimum anesthetic concentration (MAC) reduction of end-tidal isoflurane concentration (Fe'Iso) measured using an electrical stimulus in Quaker parrots (Myiopsitta monachus).

STUDY DESIGN

Randomized crossover experimental study.

ANIMALS

A group of six adult Quaker parrots, weighing 98-124 g.

METHODS

Birds were anesthetized with isoflurane in oxygen delivered by mask, then tracheally intubated and mechanically ventilated. Three treatments were applied with a 4 day interval between anesthetic events. Each anesthetized bird was administered midazolam (1 mg kg^-1; treatment MID1), midazolam (2 mg kg^-1; treatment MID2) or electrolyte solution (control) intramuscularly. The treatments were administered using a replicated Latin square design and the observers were blinded. Based on a pilot bird, the starting Fe'Iso was 1.8%. After equilibration for 10 minutes, a supramaximal stimulus was delivered using an electrical current (20 V and 50 Hz for 10 ms) and birds were observed for non-reflex movement. The Fe'Iso was titrated by 0.1% until a crossover event was observed. The MAC was estimated using logistic regression.

RESULTS

The MAC of isoflurane (MAC_ISO) was estimated at 2.52% [95% confidence interval (CI), 2.19-2.85] with a range of 1.85-2.65%. MAC_ISO in MID1 was 2.04% (95% CI, 1.71-2.37) and in MID2 was 1.81% (95% CI, 1.48-2.14); reductions in MAC_ISO from control of 19% (p = 0.001) and 28% (p < 0.001), respectively. Heart rate, temperature, sex and anesthetic time were not different among treatments.

CONCLUSIONS

Midazolam (1-2 mg kg^-1) intramuscularly resulted in a significant isoflurane-sparing effect in response to a noxious stimulus in Quaker parrots without observable adverse effects.

CLINICAL RELEVANCE

Midazolam can be used as part of a balanced anesthetic approach using isoflurane in Quaker parrots, and potentially in other psittacine species.

SEVOFLURANE ANESTHESIA IN LIVINGSTONE'S FRUIT BATS ( PTEROPUS LIVINGSTONII)

Fourteen captive Livingstone's fruit bats ( Pteropus livingstonii) were anesthetized for routine veterinary health checks, including echocardiography, using sevoflurane. In addition, three specimens suffering from cardiac disease and a pregnant specimen were anesthetized for clinical assessment. No anesthetic complications were observed in any of the specimens. Significant differences in the core body temperature were found between the esophageal and rectal measurements. A significant decrease in blood glucose was noted through the anesthesia, suspected to be related to an extended fasting period prior to the procedure.

Advancements in Evidence-Based Anesthesia of Exotic Animals

Anesthesia and sedation of pet nondomestic species are often necessary for both invasive and noninvasive procedures. Even minimally invasive procedures can be stressful for small prey species that are not domesticated or acclimated to human contact and restraint. Recent advancements in evidence-based practice will continue to improve the field based on scientifically sound best practices and rely less on anecdotal recommendations. This article focuses on new scientific literature that has been published in the past 5 years. For ease of reading, the authors divide the article to highlight advances in anesthetic pharmacology and discoveries in anesthetic physiology and monitoring.

INTRAMUSCULAR EPINEPHRINE RESULTS IN REDUCED ANESTHETIC RECOVERY TIME IN AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) UNDERGOING ISOFLURANE ANESTHESIA

Inhalants are commonly used to anesthetize reptiles, but volatile anesthetics have been associated with prolonged recovery times. The objective of this study was to determine the effects of intramuscular (IM) epinephrine on anesthetic recovery times following isoflurane anesthesia in a population of subadult American alligators ( Alligator mississippiensis ). In this prospective randomized crossover study, five clinically healthy alligators were anesthetized for 90 min with the use of isoflurane. Alligators were randomly assigned into one of two treatment groups: Group E received IM epinephrine (0.1 mg/kg), and Group S received an equal volume of 0.9% saline administered after isoflurane was discontinued. Time from the end of inhalant administration to return of spontaneous ventilation, return of the palpebral reflex, movement in response to a standardized toe pinch, and spontaneous movement was recorded. The time of extubation was noted and occurred following the return of spontaneous ventilation and movement. Pulse rate, surface body temperature, and airway gases including expiratory and inspiratory isoflurane concentrations and end-tidal carbon dioxide were measured every 5 min throughout the study. The time from the end of anesthesia to extubation was significantly faster in Group E (51.2 ± 16.7 min) compared to Group S (107.4 ± 43.7 min). Pulse rate was significantly higher within the first 15 min following epinephrine injection compared to the saline group at these time points. Therefore, IM epinephrine administered at the end of general anesthesia can significantly hasten anesthetic recovery from isoflurane in alligators.

Physiological alteration, quality of anesthesia and economy of isoflurane in domestic chickens (Gallus domesticus)

Aim:

Aim of the study was to evaluate the effect of isoflurane anesthesia on physiological parameters, assessment of anesthetic qualities, and economy of use of isoflurane in domestic chickens (Gallus domesticus).

Materials and Methods:

In this study, 18 apparently healthy adult domestic chickens were selected randomly and divided into three groups. The birds were anesthetized by masked induction with isoflurane at a dose rate of 3.5%, 4%, and 5% and were maintained with 1.5%, 2%, and 2.5% isoflurane with oxygen by endotracheal intubation in Groups I, II, and III, respectively. Physiological parameters, viz., cloacal temperature, heart rate, and respiration rate were recorded at 0, 5, 10, 20, 30, 40, 50, and 60 min. The quality of anesthesia was assessed on the basis of induction time, induction behavior, quality of sedation, production of analgesia, degree of muscle relaxation, palpebral reflex, recovery time, and recovery behavior. The economy of anesthesia was calculated in terms of quantity of isoflurane utilized during 60 min of study. Statistical analysis was performed by analysis of variance, Duncan’s multiple range tests.

Results:

There was significant decrease (p<0.01) in physiological parameters such as in cloacal temperature, heart rate and respiration rate in the birds of all the groups from 0 to 60 min. The induction time was 5.83±0.33, 2.37±0.18, and 0.87±0.15 min, respectively, in Groups I, II, and III. Induction behavior was smooth in Group III, whereas mildly stormy in Group II and I. Quality of sedation was excellent in Group III, better in Group II as compared to Group I. Analgesia was moderate in Group III whereas poor in Group II and I. Degree of muscle relaxation was excellent in Group III, whereas good in Group I and II. Palpebral reflexes were absent in all the groups. Recovery time was 15.33±0.84, 18.83±0.94, and 26.50±0.85 in Groups I, II, and III respectively. Recovery behavior was smooth in birds of all the groups. The cost of the anesthesia was 158.22±1.04, 194.27±0.66, and 236.84±0.60 Indian National Rupee in Groups I, II, and III, respectively. Quantity of anesthesia utilized in each group was 7.62±0.05, 9.35±0.03, and 11.41±0.03 ml in Groups I, II, and III, respectively.

Conclusion:

The use of isoflurane at different concentration produces different level of physiological changes, quality of anesthesia and economy without causing any deleterious effect on the birds. The physiological parameters observed in this study can serve as reference values for the wild and endangered birds.

Comparative immunohistochemical assessment of the effect of repetitive anesthesia with isoflurane and sevoflurane on rat liver

BACKGROUND AND OBJECTIVES

Inhalation anesthetics are used in human, as well as veterinary medical practice. In the present study we investigated the effect of isoflurane and sevoflurane on rat hepatocytes.

METHODS

A total of 40 Wistar female rats were used in this study. Animals were divided in groups of 5 rats. Groups IM, SM served as control groups. Groups I1, I2, I3 were used to study isoflurane and S1, S2, S3 for sevoflurane study. They were anesthetized 3 times, for 2h long, at 2 days interval with a concentration of: 1.5% isoflurane (I1, I2, I3) and 2% sevoflurane (S1, S2, S3). The oxygen supply throughout the anesthesia was 1LO2/min. Groups IM, IS, I1, S1 were sacrificed immediately after the last anesthesia. Groups I2, S2 were sacrificed 6h after the last anesthesia, and groups I3, S3, 24h post-anesthesia. Liver samples were harvested to highlight caspase-3 in apoptotic hepatocytes.

RESULTS

Following isoflurane administration, there were less than 1% cells in apoptosis highlighted in rat livers from groups IM, I1 and I2. At 24h post-anesthesia (group I3), a small number of apoptotic hepatocytes was highlighted (around 3.23% cells in apoptosis), with a strictly periacinar disposition, randomly distributed in a small number of hepatic lobules. After sevoflurane administration, less than 1% apoptotic hepatocytes were identified at all control moments throughout the study.

CONCLUSIONS

The results suggest that the anesthetics do not present a considerable hepatotoxicity. The comparative assessment of the two anesthetics shows that sevoflurane is superior to isoflurane.

[Comparative immunohistochemical assessment of the effect of repetitive anesthesia with isoflurane and sevoflurane on rat liver]

BACKGROUND AND OBJECTIVES

Inhalation anesthetics are used in human, as well as veterinary medical practice. In the present study we investigated the effect of isoflurane and sevoflurane on rat hepatocytes.

METHODS

A total of 40 Wistar female rats were used in this study. Animals were divided in groups of 5 rats. Groups IM, SM served as control groups. Groups I1, I2, I3 were used to study isoflurane and S1, S2, S3 for sevoflurane study. They were anesthetized 3 times, for 2h long, at 2 days interval with a concentration of: 1.5% isoflurane (I1, I2, I3) and 2% sevoflurane (S1, S2, S3). The oxygen supply throughout the anesthesia was 1LO2/min. Groups IM, IS, I1, S1 were sacrificed immediately after the last anesthesia. Groups I2, S2 were sacrificed 6h after the last anesthesia, and groups I3, S3, 24h post-anesthesia. Liver samples were harvested to highlight caspase-3 in apoptotic hepatocytes.

RESULTS

Following isoflurane administration, there were less than 1% cells in apoptosis highlighted in rat livers from groups IM, I1 and I2. At 24h post-anesthesia (group I3), a small number of apoptotic hepatocytes was highlighted (around 3.23% cells in apoptosis), with a strictly periacinar disposition, randomly distributed in a small number of hepatic lobules. After sevoflurane administration, less than 1% apoptotic hepatocytes were identified at all control moments throughout the study.

CONCLUSIONS

The results suggest that the anesthetics do not present a considerable hepatotoxicity. The comparative assessment of the two anesthetics shows that sevoflurane is superior to isoflurane.

Anaesthesia with sevoflurane in pigeons: minimal anaesthetic concentration (MAC) determination and investigation of cardiorespiratory variables at 1 MAC

The objective of the study was to determine the minimal anaesthetic concentration (MAC) of sevoflurane (SEVO) in pigeons and investigate the effects of 1 MAC SEVO anaesthesia on cardiovascular and respiratory variables compared with the awake state. This is a prospective, experimental study. Animals were seven healthy adult pigeons. After acclimatisation to handling, heart rate (HR), heart rhythm, respiratory rate (fR), end-expired carbon dioxide tension (PE'CO2), inspired CO2 tension, indirect systolic arterial blood pressure (SAP) and cloacal temperature were measured to determine baseline, 'awake' values. Pigeons were then anaesthetised with SEVO and MAC was determined by the 'bracketing' method. The same variables were monitored during a 40 minute period at 1.0 MAC SEVO for each bird. Mean MAC was 3.0±0.6 per cent for SEVO. During maintenance of anaesthesia at 1.0 MAC, SAP decreased significantly (P<0.001) without any significant change in HR. Although PE'CO2 increased significantly (P=0.001) despite an increase in fR, awake PE'CO2 values were unexpectedly low. Sinus arrhythmias were detected in two birds under SEVO anaesthesia. The times to tracheal intubation and to recovery were 2.5±0.7 and 6.4±1.7 minutes, respectively. Recovery was rapid and uneventful in all birds. In conclusion, SEVO is suitable for anaesthesia in pigeons.

Cardiorespiratory parameters in the awake pigeon and during anaesthesia with isoflurane

OBJECTIVE

To determine baseline cardiovascular and respiratory variables in the awake pigeon, and to assess those variables during anaesthesia at the individual minimal anaesthetic concentration (MAC) of isoflurane during spontaneous breathing.

STUDY DESIGN

Prospective, experimental trial.

ANIMALS

Seven healthy adult pigeons weighing a mean ± standard deviation (SD) of 438 ± 38 g.

METHODS

Heart rate (HR), heart rhythm, respiratory rate (fR), end-expired carbon dioxide tension (Pe'CO2), indirect systolic arterial pressure (SAP) and cloacal temperature (T) were measured in birds in the awake state (after acclimatization to handling). Two weeks later, the pigeons were anaesthetized with isoflurane in order to determine their MAC and evaluate the same cardiovascular and respiratory variables during a further 40 minutes of isoflurane anaesthesia.

RESULTS

In the awake pigeon, mean ± SD HR, SAP, fR, Pe'CO2 and T were, respectively, 155 ± 28 beats minute(-1), 155 ± 21 mmHg, 34 ± 6 breaths minute(-1), 38 ± 8 mmHg (5.1 ± 1.1 kPa) and 41.8 ± 0.5 °C. Mean isoflurane MAC was 1.8 ± 0.4%. During maintenance of anaesthesia at MAC, although no significant decreases between values obtained in the awake and anaesthetized states emerged in HR or respiratory rate, significant decreases in SAP and cloacal temperature and an increase in Pe'CO2 were observed. No arrhythmia was identified in awake pigeons, whereas second- and third-degree atrioventricular blocks occurred under isoflurane.

CONCLUSIONS AND CLINICAL RELEVANCE

Isoflurane MAC in pigeons appeared to be higher than in other avian species. Isoflurane anaesthesia in pigeons resulted in hypercapnia, hypotension, mild hypothermia and second- and third-degree atrioventricular blocks.

Effect of Intermittent Positive Pressure Ventilation on Depth of Anaesthesia during and after Isoflurane Anaesthesia in Sulphur-Crested Cockatoos (Cacatua galerita galerita)

This study aimed to determine the effect of intermittent positive pressure ventilation (IPPV) on the depth of inhalation anaesthesia in parrots. Anaesthesia was induced with 3.0% isoflurane in six Sulphur-crested Cockatoos (Cacatua galerita galerita) and maintained using either 1.5% or 3.0% during spontaneous ventilation (SV) or IPPV at 6 (IPPV-6) or 12 (IPPV-12) breaths per minute. The time taken for the appearance of somatic reflexes and the return of SV after IPPV was recorded. During recovery, the body jerk, beak, eye, and shivering reflexes appeared after 126 ± 27 s, 133 ± 26 s, 165 ± 34 s, and 165 ± 44 s, respectively. All cockatoos developed apnoea after IPPV-12 and only some did after IPPV-6. Return of SV after IPPV-12 was delayed compared to IPPV-6. Recovery times after the SV runs were significantly different between 1.5% and 3.0% isoflurane anaesthesia. Similarly, after IPPV, the recovery times were significantly different between 1.5% and 3.0% isoflurane anaesthesia. Recovery times after 3.0% inhaled isoflurane were longer than those of 1.5% inhaled isoflurane. In conclusion, cockatoos recovering from isoflurane anaesthesia are likely to exhibit body jerk, beak, eye, and shivering reflexes in that order. IPPV increases the depth of anaesthesia in a rate and dose-related manner and prolongs recovery.

The effect of premedication with ketamine, alone or with diazepam, on anaesthesia with sevoflurane in parrots (Amazona aestiva)

BACKGROUND

Premedication is rarely used in avian species. The aim of this study was to evaluate the effect of premedication on the quality of sevoflurane induction and anaesthesia in parrots. We hypothesised that premedication would facilitate handling and decrease the minimum anaesthetic dose (MAD). Thirty-six adult parrots were randomly distributed in three groups: group S (n = 12) was premedicated with NaCl 0.9%; group KS (n = 12) was premedicated with 10 mg.kg-1 ketamine; and group KDS (n = 12) was premedicated with 10 mg.kg-1 ketamine and 0.5 mg.kg-1 diazepam, delivered intramuscularly. After induction using 4.5% sevoflurane introduced through a facemask, the MAD was determined for each animal. The heart rate (HR), respiratory rate (RR), systolic arterial blood pressure (SAP), and cloacal temperature (CT) were recorded before premedication (T0), 15 minutes after premedication (T1), and after MAD determination (T2). Arterial blood gas analyses were performed at T0 and T2. The quality of anaesthesia was evaluated using subjective scales based on animal behaviour and handling during induction, maintenance, and recovery. Statistical analyses were performed using analysis of variance or Kruskal-Wallis tests followed by Tukey's or Dunn's tests.

RESULTS

The minimal anaesthetic doses obtained were 2.4 ± 0.37%, 1.7 ± 0.39%, and 1.3 ± 0.32% for groups S, KS, and KDS, respectively. There were no differences in HR, RR, or CT among groups, but SAP was significantly lower in group S. Sedation was observed in both the premedicated S-KS and S-KDS groups. There were no differences in the quality of intubation and recovery from anaesthesia among the three groups, although the induction time was significantly shorter in the pre-medicated groups, and the KS group showed less muscle relaxation.

CONCLUSIONS

Ketamine alone or the ketamine/diazepam combination decreased the MAD of sevoflurane in parrots (Amazona aestiva). Ketamine alone or in combination with diazepam promoted a good quality of sedation, which improved handling and reduced the stress of the birds. All protocols provided safe anaesthesia in this avian species.