Evaluation of a noncontrolled, pre-euthanasia, intramuscular sedation drug protocol including alfaxalone 4%, medetomidine, and acepromazine for injured or ill raccoons.

Background: As a major animal control service provider in the city of Guelph and Wellington County in Ontario, the Guelph Humane Society transports and presents injured or ill raccoons requiring humane euthanasia to the Ontario Veterinary College Health Sciences Centre (OVC-HSC). Issues around handling, transportation, and delays before euthanasia have recently raised some concerns for welfare and the need for means of improving this process. Objective: Investigation of a noncontrolled sedation and analgesia protocol for injured or ill raccoons intended to improve animal welfare by allowing humane handling, transport, and euthanasia following administration by an animal protection officer (APO). Animals and procedure: Twenty-seven injured or ill raccoons requiring transport and euthanasia, as determined by the Guelph Humane Society APOs, were included in the study. Each raccoon was administered acepromazine (0.05 mg/kg), alfaxalone (4 mg/kg), and medetomidine (0.15 mg/kg), intramuscularly, before being transported to the OVC-HSC for humane euthanasia. Results: The combination of acepromazine, alfaxalone, and medetomidine was suitable for administration by APOs and provided the desired sedation depth to allow transport and humane euthanasia. Transit time was the only predictor of sedation depth upon arrival at the OVC-HSC. Two raccoons showed mild physical response to intracardiac injection for euthanasia. Numerical cutoff points of an in-hospital visual analog score of sedation of ≥ 70/100 and duration of sedation of < 62 min showed zero probability of response to euthanasia. Conclusion and clinical relevance: Administration of acepromazine, alfaxalone, and medetomidine at the stated doses provided acceptable sedation and analgesia to improve animal welfare during transport and eventual euthanasia of raccoons.

Évaluation d'un protocole médicamenteux sans groupe témoin de sédation intramusculaire, pré-euthanasie, comprenant de l'alfaxalone 4 %, de la médétomidine et de l'acépromazine pour les ratons laveurs blessés ou malades. Contexte: En tant que fournisseur majeur de services de contrôle des animaux dans la ville de Guelph et dans le comté de Wellington en Ontario, la Guelph Humane Society transporte et présente les ratons laveurs blessés ou malades nécessitant une euthanasie sans cruauté au Ontario Veterinary College Health Sciences Centre (OVC-HSC). Les problèmes liés à la manutention, au transport et aux délais avant l'euthanasie ont récemment soulevé des inquiétudes quant au bien-être et à la nécessité de trouver des moyens d'améliorer ce processus. Objectif: Enquête sur un protocole de sédation et d'analgésie sans groupe témoin pour les ratons laveurs blessés ou malades destiné à améliorer le bien-être des animaux en permettant une manipulation, un transport et une euthanasie sans cruauté après administration par un agent de protection des animaux (APO). Animaux et procédure: Vingt-sept ratons laveurs blessés ou malades nécessitant un transport et une euthanasie, tel que déterminé par les APO de la Guelph Humane Society, ont été inclus dans l'étude. Chaque raton laveur a reçu de l'acépromazine (0,05 mg/kg), de l'alfaxalone (4 mg/kg) et de la médétomidine (0,15 mg/kg), par voie intramusculaire, avant d'être transporté à l'OVC-HSC pour une euthanasie sans cruauté. Résultats: La combinaison d'acépromazine, d'alfaxalone et de médétomidine convenait à l'administration par un APO et fournissait la profondeur de sédation souhaitée pour permettre le transport et l'euthanasie sans cruauté. Le temps de transit était le seul prédicteur de la profondeur de la sédation à l'arrivée à l'OVC-HSC. Deux ratons laveurs ont montré une légère réponse physique à une injection intracardiaque pour l'euthanasie. Les seuils numériques d'un score analogique visuel de sédation à l'hôpital ≥ 70/100 et d'une durée de sédation < 62 min ont montré une probabilité nulle de réponse à l'euthanasie. Conclusion et pertinence clinique: L'administration d'acépromazine, d'alfaxalone et de médétomidine aux doses indiquées a fourni une sédation et une analgésie acceptables pour améliorer le bien-être des animaux pendant le transport et l'euthanasie éventuelle des ratons laveurs.(Traduit par Dr Serge Messier).

A PRELIMINARY STUDY TO EVALUATE THE EFFECTIVENESS OF LARYNGEAL MASK AIRWAYS IN ANESTHETIZED BIGHORN SHEEP (OVIS CANADENSIS) LAMBS.

Chemical immobilization of wildlife, required for many biological studies and management events, often induces hypoxemia and respiratory depression. Laryngeal mask airways (LMAs) have shown promise as an efficient method of airway protection during anesthesia. Nineteen wild bighorn sheep (Ovis canadensis) lambs were immobilized using an IM combination of medetomidine (0.16 ± 0.062 mg/kg), azaperone (0.20 ± 0.058 mg/kg), and alfaxalone (0.54 ± 0.21 mg/kg) via remote injection. Upon recumbency, arterial blood gas parameters, minute ventilation (VE), tidal volume (VT), and respiratory rate were measured before and after LMA placement. The VE and VT were measured via respirometer. Time to LMA placement, cuff pressure, cuff volume, and ease of placement were measured. Medetomidine was reversed with IM atipamezole at five times the medetomidine dose upon completion of procedures. Pre- and post-LMA measurements were compared using a t test or a Wilcoxon signed-rank test based on normality of the data. The LMA provided a patent airway in all lambs with a significant (P < 0.0001) increase in VE (mean [95% CI]; pre-LMA: VE = 17.3 [16.2-18.5] L/min, post-LMA: VE = 19.8 [18.6-21.0] L/min) but did not have a significant impact on partial pressure of oxygen (PaO2; pre-LMA: corrected PaO2 = 45.2 [41.2-49.2] mm Hg, post-LMA: corrected PaO2 = 47.5 [43.3-51.7] mm Hg; P = 0.19) or partial pressure of carbon dioxide (PaCO2; pre-LMA: PaCO2 = 50.4 [46.6-53.2] mm Hg, post-LMA: PaCO2 = 51.6 [48.8-55.7] mm Hg; P = 0.035) following placement. This study demonstrated that the LMA is a viable option for airway protection in wild bighorn sheep.

The utility of a novel formulation of alfaxalone in a remote delivery system.

OBJECTIVE: To quantify induction time, reliability, physiological effects, recovery quality and dart volume of a novel formulation of alfaxalone (40 mg mL-1) used in combination with medetomidine and azaperone for the capture and handling of wild bighorn sheep. STUDY DESIGN: Prospective clinical study. ANIMALS: A total of 23 wild bighorn sheep (Ovis canadensis) in Sheep River Provincial Park, AB, Canada. METHODS: Free-ranging bighorn sheep were immobilized using medetomidine, azaperone and alfaxalone delivered with a remote delivery system. Arterial blood was collected for measurement of blood gases, physiologic variables (temperature, heart and respiratory rates) were recorded and induction and recovery length and quality were scored. RESULTS: Data from 20 animals were included. Administered dose rates were alfaxalone (0.99 ± 0.20 mg kg-1; 40 mg mL-1), azaperone (0.2 ± 0.04 mg kg-1; 10 mg mL-1) and medetomidine (0.16 ± 0.03 mg kg-1; 30 mg mL-1). The mean drug volume injected was 1.51 mL. The median (range) induction time was 7.7 (5.8-9.7) minutes, and recovery was qualitatively smooth. CONCLUSIONS AND CLINICAL RELEVANCE: An increased concentration formulation of alfaxalone was administered in combination with medetomidine and azaperone, and resulted in appropriate anesthesia for the capture and handling of bighorn sheep. The dart volume was small, with potential for reducing capture-related morbidity.

Evaluation of intramuscular sodium nitroprusside injection to improve oxygenation in white-tailed deer (Odocoileus virginianus) anesthetized with medetomidine-alfaxalone-azaperone.

OBJECTIVE: In ungulates, α2-adrenergic agonists can decrease oxygenation possibly through alteration of pulmonary perfusion. Sodium nitroprusside can decrease pulmonary vascular resistance (PVR) and increase cardiac output (Q˙t) through vasodilation. The objective was to determine if sodium nitroprusside would improve pulmonary perfusion and attenuate the increased alveolar-arterial (a-a) gradient resulting from medetomidine-azaperone-alfaxalone (MAA) administration. STUDY DESIGN: Prospective, randomized, crossover study with a 2 week rest period. ANIMALS: A group of eight adult female captive white-tailed deer (Odocoileus virginianus). METHODS: Deer were administered MAA intramuscularly (IM), and auricular artery and pulmonary artery balloon catheters were placed. Deer spontaneously breathed air. Saline or sodium nitroprusside (0.07 mg kg-1) were administered IM 40 minutes after MAA injection. Heart rate (HR), mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), pulmonary artery occlusion pressure (PAOP), right atrial pressure (RAP), Q˙t, arterial pH, PaCO2 and PaO2 were obtained immediately before nitroprusside injection (baseline) and 5, 10 and 15 minutes afterwards. Mixed venous blood samples were obtained at baseline and at 5 minutes. Systemic vascular resistance (SVR), PVR, intrapulmonary shunt fraction (Q˙s/Q˙t), a-a gradient, oxygen delivery (D˙O2) and oxygen extraction ratio (O2ER) were calculated. Statistical analysis was performed with repeated measures analysis of variance with correction factors. A p value < 0.05 was considered significant. RESULTS: With nitroprusside, MAP, MPAP, PAOP, RAP, SVR and O2ER significantly decreased and HR, Q˙t and D˙O2 increased compared with baseline and between treatments. There was a significant decrease in PVR and a-a gradient and increase in PaO2 compared with baseline and saline treatment. Changes were not sustained. CONCLUSIONS AND CLINICAL RELEVANCE: Nitroprusside temporarily changed hemodynamic variables, increased PaO2 and decreased a-a gradient. Nitroprusside possibly led to better pulmonary perfusion of ventilated alveoli. However, IM nitroprusside at this dose is not recommended because of severe systemic hypotension and short action.

Anesthesia techniques used for field castration of 10 intractable horses.

Dealing with an intractable horse is a reality for nearly every equine or mixed animal veterinarian. Establishing an adequate level of sedation prior to induction of anesthesia for various clinical procedures involves little margin for error regarding the safety of the veterinarian, handler, and patient. This is further compounded by the extreme difficulty of gaining venous access required to obtain rapid and reliable results. This case series describes a technique of intramuscular sedation used for field castration of 10 captive, formerly wild horses, which may be useful for various other types of intractable horses. Key clinical message: An alternative method to sedate intractable horses for induction of anesthesia is outlined. The techniques described are accessible for most veterinary practitioners, providing small-volume, fast, and reliable intramuscular sedation.

Techniques d'anesthésie utilisées pour la castration sur le terrain de 10 chevaux réfractaires. Faire face à un cheval réfractaire est une réalité pour presque tous les vétérinaires équins ou mixtes. L'établissement d'un niveau adéquat de sédation avant l'induction de l'anesthésie pour diverses procédures cliniques implique peu de marge d'erreur en ce qui concerne la sécurité du vétérinaire, du manipulateur et du patient. Ceci est encore aggravé par l'extrême difficulté d'obtenir l'accès veineux nécessaire pour obtenir des résultats rapides et fiables. Cette série de cas décrit une technique de sédation intramusculaire utilisée pour la castration au champ de 10 chevaux captifs, autrefois sauvages, qui peut être utile pour divers autres types de chevaux réfractaires.Message clinique clé :Une méthode alternative pour calmer les chevaux réfractaires pour l'induction de l'anesthésie est décrite. Les techniques décrites sont accessibles à la plupart des vétérinaires praticiens, fournissant une sédation intramusculaire de petit volume, rapide et fiable.(Traduit par Dr Serge Messier).

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.

An investigation of the effects of intratesticular alfaxalone and lidocaine during castration in piglets.

OBJECTIVE: To determine whether intratesticular injection of an alfaxalone-lidocaine combination can induce anesthesia and provide a rapid recovery in piglets undergoing surgical castration. STUDY DESIGN: Randomized experimental study. ANIMALS: A group of 30 male piglets, aged 2-10 days, weighing 1.3-4.6 kg. METHODS: Animals were randomly divided into three equal groups for intratesticular administration of alfaxalone + lidocaine: high dose (group HD; 8 mg kg-1 + 2.5 mg kg-1), medium dose (group MD; 6 mg kg-1 + 2 mg kg-1) and low dose (group LD; 4 mg kg-1 + 1.5 mg kg-1). Induction and recovery times, movement and vocalization were recorded. Pulse rate (PR), oxygen saturation, respiratory rate (fR), rectal temperature, blood pressure and end-tidal carbon dioxide were recorded until recovery. RESULTS: Induction time did not differ significantly among groups (p = 0.19); mean time of 2.2, 3.3 and 3.7 minutes for HD, MD and LD, respectively. Recovery time to sternal recumbency was significantly faster in LD compared with HD and MD (p = 0.005). Time to standing was mean 34.1, 31.6 and 29.6 minutes for HD, MD and LD, respectively (p = 0.58). Incidences of movement and vocalization during the castration procedure were decreased in HD and MD compared with LD, but were not statistically different. There were no differences in the physiologic data among the groups except for PR, which decreased in all three groups (p < 0.05), and fR, which increased in MD and LD (p < 0.05). CONCLUSIONS AND CLINICAL RELEVANCE: The alfaxalone-lidocaine combinations investigated in this study induced deep sedation in all piglets. Physiologic data remained within clinically acceptable ranges, suggesting that this drug combination by intratesticular injection prior to castration in neonatal piglets is well tolerated. The authors recommend the alfaxalone (6 mg kg-1) + lidocaine (2 mg kg-1) dose.

COMPARISON OF THE EFFICACY AND SAFETY OF MEDETOMIDINE-KETAMINE VERSUS MEDETOMIDINE-AZAPERONE-ALFAXALONE COMBINATION IN FREE-RANGING ROCKY MOUNTAIN BIGHORN SHEEP ( OVIS CANADENSIS).

Chemical immobilization is a key aspect of wildlife management. To minimize dose-dependent adverse effects, immobilization protocols often include two or more synergistic agents, which allows for reductions in individual drug dosages. Free-ranging bighorn sheep ( Ovis canadensis) in Canada ( n = 74) were remotely injected with a combination of medetomidine (0.16 ± 0.04 mg/kg) and ketamine (4.0 ± 1.4 mg/kg) (MK), or combination of medetomidine (0.14 ± 0.06 mg/kg), azaperone (0.21 ± 0.11 mg/kg), and alfaxalone (0.45 ± 0.21 mg/kg) (MAA). Once recumbency was achieved, arterial blood samples were collected and immediately analyzed for blood gas and acid-base status. Rectal temperature, heart rate, and respiratory rate were recorded upon recumbency and throughout anesthesia at 5-15 min intervals. At conclusion of the procedures, medetomidine was reversed by intramuscular atipamezole at five times the medetomidine dose. Induction times (mean ± standard deviation) of animals that became immobilized with one dart (8.7 ± 3.2 min, 7.3 ± 3.9 min) and recovery times of all animals (3.4 ± 1.5 min, 3.9 ± 1.6 min) were not significantly different between MK and MAA groups, respectively. Both MK and MAA groups experienced severe hypoxemia (PaO2 42 ± 9 mmHg, 40 ± 10 mmHg, respectively). PaCO2 was significantly higher ( P = 0.0248) in the MK group (median 54 mmHg) than the MAA group (median 48 mmHg) with a trend towards lower pH (7.40 vs 7.42, respectively, P = 0.07). Initially, MK animals had higher heart rates than MAA animals (median 49 vs 40 beats/min), which decreased over time. In bighorn sheep, both MK and MAA produced reliable, reversible immobilization with smooth inductions and recoveries. However, less respiratory depression was seen with MAA than MK.

Comparison of tranexamic acid plasma concentrations when administered via intraosseous and intravenous routes.

INTRODUCTION: There is a lack of information regarding intraosseous (IO) administration of tranexamic acid (TXA). Our hypothesis was that a single bolus IO injection of TXA will have a similar pharmacokinetic profile to TXA administered at the same dose IV. METHODS: Sixteen male Landrace cross swine (mean body weight 27.6±2.6kg) were divided into an IV group (n=8) and an IO group (n=8). Each animal received 30mg/kg TXA via an IV or IO catheter, respectively. Jugular blood samples were collected for pharmacokinetic analysis over a 3h period. The maximum TXA plasma concentration (Cmax) and corresponding time as well as distribution half-life, elimination half-life, area under the curve, plasma clearance and volume of distribution were calculated. One- and two-way analysis of variance for repeated measures (time, group) with Tukey's and Bonferonni post hoc tests were used to compare TXA plasma concentrations within and between groups, respectively. RESULTS: Plasma concentrations of TXA were significantly higher (p<0.0001) in the IV group during the TXA infusion. Cmax occurred at 4min after initiation of the bolus in the IV group (9.36±3.20ng/µl) and at 5min after initiation of the bolus in the IO group (4.46±0.49ng/µl). Plasma concentrations were very similar from the completion of injection onwards. There were no significant differences between the two administration routes for any other pharmacokinetic variables measured. CONCLUSION: The results of this study support pharmacokinetic bioequivalence of IO and IV administration of TXA.

Evaluation of a portable oxygen concentrator to provide fresh gas flow to dogs undergoing anesthesia.

This study evaluated the ability of a portable oxygen concentrator (POC) to provide fresh gas to an anesthetic machine via an Ayre's T-piece or a Bain circuit. Fraction of inspired oxygen (FiO2) was compared at flows of 0.5 to 3.0 L/min. Measured FiO2 was 96% at flow rates ≥ 1 L/min. Mean battery life at 1.0, 2.0, and 3.0 L/min was 4.21 ± 0.45, 2.62 ± 0.37 and 1.5 ± 0.07 hours, respectively. The POC proved to be useful and effective during 2 power outages. The POC was sufficient to prevent rebreathing in 70% of dogs using a T-piece circuit and 20% of dogs with a Bain circuit. A significant negative correlation between inspired CO2 and O2 flow rates was noted. A significant positive correlation between inspired CO2 and ETCO2 was documented. The occurrence of hypercarbia was associated with low O2 flow. Battery back-up was essential during power outages. The POC can be effectively used for delivery of anesthesia.

Évaluation d'un concentrateur d'oxygène portable pour fournir une circulation de gaz frais aux chiens subissant une anesthésie. Cette étude a évalué la capacité d'un concentrateur d'oxygène portable (COP) à fournir du gaz frais à l'aide d'une pièce en T d'Ayre ou d'un circuit de Bain. La fraction d'oxygène inspiré (FiO2) a été comparée à des débits de 0,5 à 3,0 L/min. La FiO2 mesurée était de 96 % à des taux de débit de ≥ 1 L/min. La durée de vie moyenne de la batterie à 1,0, à 2,0 et à 3,0 L/min était de 4,21 ± 0,45, de 2,62 ± 0,37 et 1,5 ± 0,07 heures, respectivement. Le COP s'est avéré utile et efficace durant deux pannes d'électricité. Le COP a été suffisant pour prévenir la réinspiration chez 70 % des chiens en utilisant un circuit de pièce en T et un circuit de Bain chez 20 % des chiens. Une corrélation négative importante entre le CO2 inspiré et les taux de débit d'O2 a été observée. Une corrélation positive importante entre le CO2 inspiré et l' ETCO2 a été documentée. L'occurrence de l'hypercarbie était associée à un faible débit d'O2. Une batterie de secours était essentielle durant les pannes d'électricité. Le COP peut être efficacement utilisé pour fournir de l'anesthésie.(Traduit par Isabelle Vallières).

EFFICACY AND SAFETY OF A MEDETOMIDINE-AZAPERONE-ALFAXALONE COMBINATION IN CAPTIVE WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS).

Alfaxalone is a neurosteroid that interacts with gamma-aminobutyric type A receptors to produce central nervous system depression and muscle relaxation. The effects of alfaxalone vary from sedation to general anesthesia. Alfaxalone is synergistic with other tranquilizers and sedatives and therefore has the potential to improve existing alpha-2 adrenergic agonist-based combinations used for wildlife immobilization. The objective of this study was to determine the efficacy and cardiopulmonary effects of a medetomidine-azaperone-alfaxalone (MAA) combination in captive white-tailed deer (Odocoileus virginianus). Eight captive white-tailed deer were restrained in a drop-floor chute; hand injected i.m. with 0.15 mg/kg medetomidine, 0.2 mg/kg azaperone, and 0.5 mg/kg alfaxalone; and released into a small enclosure for observation. The deer were maintained in lateral recumbency for a total time from postinjection (PI) of the drug of 60 min. At 60 min PI, atipamezole was administered i.m. at five times the medetomidine dose. Heart rate, respiratory rate, rectal temperature, and direct systolic, mean, and diastolic arterial blood pressures were recorded every 5 min. Arterial blood samples were taken every 15 min for blood gas analysis. Level of sedation and quality of recovery were scored. Statistical analysis was performed using analysis of variance and descriptive statistics with a significance level of P < 0.05. Induction (time to lateral recumbency, 7.1 ± 2.4 min (mean ± SD) and recovery times (time to standing, 9.1 ± 3.1 min) were comparable to currently used medetomidine-based combinations in white-tailed deer. Major cardiopulmonary effects observed (values reported are 15 min PI of immobilizing drugs) were hypoxemia (PaO2, 54 ± 9 mm Hg), hypoventilation (PaCO2, 55 ± 3 mm Hg), and mixed acid-base disturbances (pH, 7.22 ± 0.04). No adverse effects were observed after recovery from anesthesia. MAA produced a satisfactory level of deep sedation for safe handling and minor procedures in captive white-tailed deer.

Efficacy of a portable oxygen concentrator with pulsed delivery for treatment of hypoxemia during equine field anesthesia.

OBJECTIVE: Hypoxemia is common during equine field anesthesia. Our hypothesis was that oxygen therapy from a portable oxygen concentrator would increase PaO2 during field anesthesia compared with the breathing of ambient air. STUDY DESIGN: Prospective clinical study. ANIMALS: Fifteen yearling (250 - 400 kg) horses during field castration. METHODS: Horses were maintained in dorsal recumbency during anesthesia with an intravenous infusion of 2000 mg ketamine and 500 mg xylazine in 1 L of 5% guaifenesin. Arterial samples for blood gas analysis were collected immediately post-induction (PI), and at 15 and 30 minutes PI. The control group (n = 6) breathed ambient air. The treatment group (n = 9) were administered pulsed-flow oxygen (192 mL per bolus) by nasal insufflation during inspiration for 15 minutes PI, then breathed ambient air. The study was performed at 1300 m above sea level. One-way and two-way repeated-measures anova with post-hoc Bonferroni tests were used for within and between-group comparisons, respectively. Significance was set at p ≤ 0.05. RESULTS: Mean ± SD PaO2 in controls at 0, 15 and 30 minutes PI were 46 ± 7 mmHg (6.1 ± 0.9 kPa), 42 ± 9 mmHg (5.6 ± 1.1 kPa), and 48 ± 7 mmHg (6.4 ± 0.1 kPa), respectively (p = 0.4). In treatment animals, oxygen administration significantly increased PaO2 at 15 minutes PI to 60 ± 13 mmHg (8.0 ± 1.7 kPa), compared with baseline values of 46 ± 8 mmHg (6.1 ± 1 kPa) (p = 0.007), and 30 minute PI values of 48 ± 7 mmHg (6.5 ± 0.9 kPa) (p = 0.003). CONCLUSIONS: These data show that a pulsed-flow delivery of oxygen can increase PaO2 in dorsally recumbent horses during field anesthesia with ketamine-xylazine-guaifenesin. CLINICAL RELEVANCE: The portable oxygen concentrator may help combat hypoxemia during field anesthesia in horses.

EFFECT OF ACTIVE COOLING AND α-2 ADRENOCEPTOR ANTAGONISM ON CORE TEMPERATURE IN ANESTHETIZED BROWN BEARS (URSUS ARCTOS).

Hyperthermia is a common complication during anesthesia of bears, and it can be life threatening. The objective of this study was to evaluate the effectiveness of active cooling on core body temperature for treatment of hyperthermia in anesthetized brown bears (Ursus arctos). In addition, body temperature after reversal with atipamezole was also evaluated. Twenty-five adult and subadult brown bears were captured with a combination of zolazepam-tiletamine and xylazine or medetomidine. A core temperature capsule was inserted into the bears' stomach or 15 cm into their rectum or a combination of both. In six bears with gastric temperatures≥40.0°C, an active cooling protocol was performed, and the temperature change over 30 min was analyzed. The cooling protocol consisted of enemas with 2 L of water at approximately 5°C/100 kg of body weight every 10 min, 1 L of intravenous fluids at ambient temperature, water or snow on the paws or the inguinal area, intranasal oxygen supplementation, and removing the bear from direct sunlight or providing shade. Nine bears with body temperature>39.0°C that were not cooled served as control for the treated animals. Their body temperatures were recorded for 30 min, prior to administration of reversal. At the end of the anesthetic procedure, all bears received an intramuscular dose of atipamezole. In 10 bears, deep rectal temperature change over 30 min after administration of atipamezole was evaluated. The active cooling protocol used in hyperthermic bears significantly decreased their body temperatures within 10 min, and it produced a significantly greater decrease in their temperature than that recorded in the control group.

Evaluation of the accuracy of different methods of monitoring body temperature in anesthetized brown bears (Ursus arctos).

There is some evidence that the handheld rectal thermometer does not accurately measure core temperature in bears. The objective of this study was to compare body temperature measured by the handheld digital thermometer (HDT), deep rectally inserted core temperature capsules (CTCs), and gastrically inserted CTCs in anesthetized brown bears (Ursus arctos). Twenty-two brown bears were immobilized with a combination of zolazepam-tiletamine and xylazine or medetomidine. After immobilization, one CTC was inserted 15 cm deep into the animal's rectum (DRTC) with a standard applicator, and another CTC was inserted into the stomach (GTC) via a gastric tube inserted orally. Temperature was measured every 5-10 min with an HDT. Paired temperature data points were analyzed with the Bland-Altman technique for repeated measurements and regression analysis with a significance level of 0.05. The mean difference ± SD of the difference between HDT and GTC readings was 0.27 ± 0.47 degrees C and the 95% limits of agreement (LoA) were 1.20 and -0.66 degrees C. The determination coefficient (r2) found between these methods was 0.68 (P < 0.0001). The mean difference ± SD of the difference between HDT and DRTC readings was 0.36 ± 0.32 degreesC and the 95% LoA were 1.0 and -0.28 degrees C. The r2 between HDT and DRTC was 0.83 (P < 0.0001). The mean difference ± SD of the difference between the two insertions of the VitalSense capsules was -0.06 ± 0.24 degrees C and the 95% LoA were 0.42 and -0.54 degrees C. The r2 found between GTC and DRTC was 0.91 (P < 0.0001). This study demonstrates that DRTC provided accurate measurement of core temperature and that HDT did not accurately measure core temperature, compared with GTC in anesthetized brown bears.

Low flow oxygen therapy from a portable oxygen concentrator or an oxygen cylinder effectively treats hypoxemia in anesthetized white-tailed deer (Odocoileus virginianus).

For treatment of hypoxemia, delivery of the minimum effective oxygen flow rate is advantageous during field anesthesia because it prolongs the life of the oxygen cylinder. Portable oxygen concentrators as the oxygen source require less logistical considerations than cylinders and are a safer alternative during helicopter field work because they are nonexplosive devices. The objective of this study was to evaluate low oxygen flow rates by continuous or pulsed intranasal delivery for treatment of hypoxemia in anesthetized white-tailed deer (Odocoileus virginianus). Nine captive adult female deer (body mass 56-72 kg) were physically restrained in a drop-floor chute and hand injected intramuscularly with medetomidine (0.1-0.14 mg/kg) and ketamine (2.5-4.3 mg/kg). Intranasal oxygen was delivered from an oxygen cylinder at continuous flow rates of 1 and 2 L/min or from a battery driven oxygen concentrator (EverGo Portable Oxygen Concentrator, Respironics) with pulse-dose delivery (maximum capacity of 1.05 L/min). The pulse-dose setting (pulse volume 12-70 ml) was adjusted according to the respiratory rate. Arterial blood gases were analyzed before, during, and after O2 supplementation. A 10-min washout period was allowed between treatment groups. All three treatments adequately treated hypoxemia. The partial pressure of arterial oxygenation increased significantly from baseline values of 55 +/- 10 to 115 +/- 31 mm Hg during supplementation from the oxygen concentrator, to 138 +/- 21 mm Hg during supplementation from the oxygen cylinder at 1 L/min, and to 201 +/- 42 mm Hg at 2 L/min. In conclusion, low flow rates of intranasal oxygen supplemented continuously from an oxygen cylinder or by pulsed delivery from a portable oxygen concentrator effectively treated hypoxemia in anesthetized white-tailed deer.

Patterns of gastrointestinal parasite infections in bighorn sheep, Ovis canadensis, with respect to host sex and seasonality.

Males and females in sexually dimorphic species show differences in their physiology and behaviour due to differences in energetic investment into reproduction and soma. This means that the two sexes may show different patterns of parasitism at different times of the year. In this study, we evaluate the abundance of fecal eggs and larvae of 5 parasite types (Strongyles, Nematodirus spp., Marshallagia marshalli., Protostrongylus spp. lungworms, and Eimeria spp.) in relation to season and sex in Rocky Mountain bighorn sheep (Ovis canadensis). We use fecal egg counts (FEC) as a proxy for infection intensity. Parasite FECs differed between male and female bighorn sheep and varied with season. We found pronounced fluctuations in fecal egg counts of various parasite species in males and females across different seasons and reproductive stages. Strongyle counts were significantly higher during late gestation and lactation/summer, and particularly pronounced in males. Nematodirus counts were highest during late gestation in females and during the rut in males. Marshallagia counts peaked during late gestation in females and during the rut in males. Protostrongylus spp. lungworm counts were highest during late gestation in females and in males during lactation/summer and the rut. Eimeria oocyst counts varied across seasons, with higher counts in males during the rut and in females during winter and late gestation. Additionally, significant differences in Strongyle counts were observed between coursing and tending rams, with tending rams exhibiting higher counts. We discuss why the sexes might differ in FECs and suggest that differences between FECs of the parasites across seasons may be due to different life cycles and cold tolerance of the parasites themselves.

Transport versus on-farm slaughter of bison: physiological stress, animal welfare, and avoidable trim losses.

Ranched bison are typically less acclimated to handling than are domesticated livestock, suggesting that they might be more vulnerable to handling and transportation stressors. Grain-finished bison were slaughtered on-farm (n = 11), or held for 48 h, transported to a research abattoir, held in lairage for 18 h, and then slaughtered (n = 11). An additional group (n = 10) was sampled at a conventional fixed location abattoir. Measures included serum cortisol and corticosterone concentrations during on-farm handling and exsanguination, serum glucose, creatinine phosphokinase (CPK), aspartate aminotransferase (AST), and trim losses. Transport was associated with an increase in trim loss. On-farm, glucose was elevated, CPK was positively associated with handling order over 12 h, and corticosterone concentration, although lower than cortisol concentration, showed a greater response to prolonged disturbance. With appropriate on-farm handling facilities, the use of on-farm slaughter and mobile abattoir could avoid muscle damage and trim losses, and mitigate injuries sustained during handling and transport of bison.

Transport ou abattage des bisons à la ferme : stress physiologique, bien-être animal et pertes de viande évitables. Les bisons élevés dans un ranch sont habituellement moins accoutumés à la manipulation que le bétail domestiqué, ce qui suggère qu'ils sont plus vulnérables aux facteurs de stress liés à la manipulation et au transport. Des bisons engraissés au grain ont été abattus à la ferme (n = 11), ou détenus pendant 48 h, transportés à un abattoir de recherche, mis dans des installations d'attente pendant 18 h, puis abattus (n = 11). Un groupe additionnel (n = 10) a été échantillonné à un abattoir fixe conventionnel. Les mesures incluaient les concentrations de cortisol sérique et de corticostérone durant la manipulation et l'exsanguination à la ferme, le glucose sérique, la créatinine phosphokinase (CPK), l'aspartate aminotransférase (AST) et les pertes de viande. Le transport était associé à une hausse de la perte de viande. À la ferme, le glucose était élevé, la CPK était positivement associée à l'ordre de manipulation pendant 12 heures et la concentration de corticostérone, quoique inférieure à la concentration de cortisol, a montré une réponse plus élevée lors d'une perturbation prolongée. Avec des installations de manipulation à la ferme appropriées, l'utilisation de l'abattage à la ferme et d'un abattoir mobile pourrait éviter les dommages musculaires et les pertes de viande et atténuer les blessures subies durant la manipulation et le transport des bisons.(Traduit par Isabelle Vallières).

Onset, duration and efficacy of four methods of local anesthesia of the horn bud in calves.

OBJECTIVE: To determine the onset, duration and efficacy of four local anesthetic methods for the horn bud in calves. STUDY DESIGN: Crossover study. ANIMALS: Eight, 2 month-old Holstein Friesian bull calves. METHODS: Calves were subjected to one of the four following treatments: 1) cornual nerve block (C), 2) ring block (R), 3) cornual nerve block using a percutaneous jet delivery technique (JET) all using 2% lidocaine with epinephrine (0.01 mg mL(-1)), and 4) topical eutectic mixture of local anesthetics (EMLA) cream. A peripheral nerve stimulator was used to assess cutaneous sensation over the horn bud using a graded response. Onset, duration and efficacy of anesthesia were determined. RESULTS: The efficacy of the blocks was as follows: C 87.5%, R 100%, JET 37.5%, EMLA 0%. The median onset time and duration of anesthesia for C and R were: 2 (range 0.5-5) and 304 (range 107-512), and 3.25 (range 1-9) and 147 (range 62-299) minutes, respectively. Three of eight JET injections had a median onset and duration of 8 (range 0.5-9) and 132 (range 101-155) minutes, respectively. The duration of the C block was significantly longer than the R block (p = 0.047). CONCLUSIONS AND CLINICAL RELEVANCE: The relatively rapid onset and long duration of anesthesia with C or R blocks using 2% lidocaine with epinephrine validates their practical use in dehorning calves while jet injection and EMLA cream provided insufficient analgesia to be clinically useful. The efficacy of the C block requires further study.

Open-drop anesthesia for small laboratory animals.

This study examined the effect of temperature on volatile concentrations of 2 inhalant anesthetics, isoflurane (ISO) and sevoflurane (SEVO), delivered via open-drop technique, as well as the characteristics of induction and recovery using the open-drop method in mice. Testing revealed that temperature had no effect on the volatile concentration of either ISO or SEVO. However, it was determined that open-drop delivery of ISO or SEVO is a viable means of anesthetizing mice under certain conditions. The volatile concentration required to induce anesthesia in mice following the application of 0.5 mL of anesthetic in an induction chamber of 725 mL volume at 87.6 kPa and 20°C was measured with a precision gas analyzer. For ISO, anesthesia was induced at concentrations of 6.80 ± 0.57% [mean ± standard deviation (s)] after 35.70 ± 6.95 s (n = 10), while SEVO induction took significantly longer (45.50 ± 9.96 s) and required higher volatile concentrations [7.41 ± 0.57% (n = 10)]. The animals recovered rapidly from both ISO and SEVO-based induction.

Efficacy of a portable oxygen concentrator with pulsed delivery for treatment of hypoxemia during anesthesia of wildlife.

Portable battery-driven oxygen concentrators provide an alternative to the use of oxygen cylinders for treatment of hypoxemia during field anesthesia. The aim of this study was to evaluate the use of the EverGo Portable Oxygen Concentrator (Respironics, Murrysville, Pennsylvania 15668, USA) with pulse-dose delivery for improvement of arterial oxygenation during anesthesia of wildlife. This concentrator delivers oxygen in a pulsed flow with pulse volumes from 12 to 70 ml, up to a maximum capacity of 1.05 L/min. The pulse-dose setting shall be adjusted according to the respiratory rate of the animal, e.g., setting 6 for a respiratory rate < or = 15/min. The study included 16 free-ranging brown bears (Ursus arctos), 18 free-ranging bighorn sheep (Ovis canadensis), and five captive reindeer (Rangifer tarandus). Oxygen was administered via two nasal lines that were inserted through the nostrils to the level of the medial canthus of the eyes. Arterial blood samples were collected before, during, and after oxygen therapy and immediately analyzed. When providing oxygen from the portable concentrator, the arterial oxygenation markedly improved in all brown bears and some reindeer, whereas no or minor improvement was seen in the bighorn sheep. The mean +/- SD (range) PaO2 during oxygen supplementation was 134 +/- 29 (90-185) mmHg in the brown bears, 52 +/- 11 (32-67) mmHg in the bighorn sheep, and 79 +/- 19 (61-110) mmHg in the reindeer. The efficacy of the evaluated method may be influenced by ambient temperature, altitude, pulse-dose setting on the concentrator, the animal's respiratory rate, and species-specific physiology during anesthesia. Advantages of the portable oxygen concentrator included small size and low weight, ease of operate, and rechargeablity.