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).

The effect of laparoscopy on intracranial pressure as measured by optic nerve sheath diameter: A review.

Laparoscopic surgery has many benefits over open surgery including lower complication rates, and shorter duration and lower cost of hospitalization. However, recent human literature suggests laparoscopy and carbon dioxide insufflation can result in intracranial hypertension. Invasive monitoring of intracranial pressure is not routinely performed in veterinary medicine, and ultrasonographic evaluation of the optic nerve sheath has been employed as an indirect measure of intracranial pressure in many species. The optic nerve sheath is continuous with the meninges of the brain and becomes distended with intracranial hypertension. Optic nerve sheath diameter is a reliable and consistent measure of intracranial pressure and has been utilized in humans to evaluate patients for intracranial hypertension secondary to laparoscopy and capnoperitoneum. No thorough evaluation of the effects of laparoscopy on intracranial pressure has been performed in dogs. Ultrasonographic evaluation of the optic nerve sheath is a safe, non-invasive, and inexpensive procedure that may allow for the evaluation of intracranial pressure without the need for invasive monitoring systems. As laparoscopic procedures are performed increasingly often, this review aims to inform the reader on the effects of capnoperitoneum and to facilitate appropriate patient selection, anesthetic considerations, and surgical planning.

L'effet de la laparoscopie sur la pression intracrânienne mesurée par le diamètre de la gaine du nerf optique : une revue. La chirurgie laparoscopique présente de nombreux avantages par rapport à la chirurgie ouverte, notamment des taux de complications plus faibles, une durée d'hospitalisation plus courte et un coût moindre. Cependant, la littérature humaine récente suggère que la laparoscopie et l'insufflation de dioxyde de carbone peuvent entraîner une hypertension intracrânienne. La surveillance invasive de la pression intracrânienne n'est pas systématiquement effectuée en médecine vétérinaire, et l'évaluation échographique de la gaine du nerf optique a été utilisée comme mesure indirecte de la pression intracrânienne chez de nombreuses espèces. La gaine du nerf optique est continue avec les méninges du cerveau et se distend avec l'hypertension intracrânienne. Le diamètre de la gaine du nerf optique est une mesure fiable et cohérente de la pression intracrânienne et a été utilisé chez l'homme pour évaluer les patients atteints d'hypertension intracrânienne secondaire à la laparoscopie et au capnopéritoine. Aucune évaluation approfondie des effets de la laparoscopie sur la pression intracrânienne n'a été réalisée chez le chien. L'évaluation échographique de la gaine du nerf optique est une procédure sûre, non invasive et peu coûteuse qui peut permettre l'évaluation de la pression intracrânienne sans avoir besoin de systèmes de surveillance invasifs. Les procédures laparoscopiques étant de plus en plus pratiquées, cette revue vise à informer le lecteur sur les effets du pneumopéritoine et à faciliter la sélection appropriée des patients, les considérations anesthésiques et la planification chirurgicale.(Traduit par Dr Serge Messier).

Dose and cardiopulmonary effects of propofol alone or with midazolam for induction of anesthesia in critically ill dogs.

OBJECTIVE: To determine the dose and cardiopulmonary effects of propofol alone or with midazolam for induction of anesthesia in American Society of Anesthesiologists status ≥III dogs requiring emergency abdominal surgery. STUDY DESIGN: Prospective, randomized, blinded, clinical trial. ANIMALS: A total of 19 client-owned dogs. METHODS: Dogs were sedated with fentanyl (2 µg kg-1) intravenously (IV) for instrumentation for measurement of heart rate, arterial blood pressure, cardiac index, systemic vascular resistance index, arterial blood gases, respiratory rate and rectal temperature. After additional IV fentanyl (3 µg kg-1), the quality of sedation was scored and cardiopulmonary variables recorded. Induction of anesthesia was with IV propofol (1 mg kg-1) and saline (0.06 mL kg-1; group PS; nine dogs) or midazolam (0.3 mg kg-1; group PM; 10 dogs), with additional propofol (0.25 mg kg-1) IV every 6 seconds until endotracheal intubation. Induction/intubation quality was scored, and anesthesia was maintained with isoflurane. Variables were recorded for 5 minutes with the dog in lateral recumbency, breathing spontaneously, and then in dorsal recumbency with mechanical ventilation for the next 15 minutes. A general linear mixed model was used with post hoc analysis for multiple comparisons between groups (p < 0.05). RESULTS: There were no differences in group demographics, temperature and cardiopulmonary variables between groups or within groups before or after induction. The propofol doses for induction of anesthesia were significantly different between groups, 1.9 ± 0.5 and 1.1 ± 0.5 mg kg-1 for groups PS and PM, respectively, and the induction/intubation score was significantly better for group PM. CONCLUSIONS AND CLINICAL RELEVANCE: Midazolam co-induction reduced the propofol induction dose and improved the quality of induction in critically ill dogs without an improvement in cardiopulmonary variables, when compared with a higher dose of propofol alone.

Modeling and Characterization of Scaling Factor of Flexible Spiral Coils for Wirelessly Powered Wearable Sensors.

Wearable sensors are a topic of interest in medical healthcare monitoring due to their compact size and portability. However, providing power to the wearable sensors for continuous health monitoring applications is a great challenge. As the batteries are bulky and require frequent charging, the integration of the wireless power transfer (WPT) module into wearable and implantable sensors is a popular alternative. The flexible sensors benefit by being wirelessly powered, as it not only expands an individual's range of motion, but also reduces the overall size and the energy needs. This paper presents the design, modeling, and experimental characterization of flexible square-shaped spiral coils with different scaling factors for WPT systems. The effects of coil scaling factor on inductance, capacitance, resistance, and the quality factor (Q-factor) are modeled, simulated, and experimentally validated for the case of flexible planar coils. The proposed analytical modeling is helpful to estimate the coil parameters without using the time-consuming Finite Element Method (FEM) simulation. The analytical modeling is presented in terms of the scaling factor to find the best-optimized coil dimensions with the maximum Q-factor. This paper also presents the effect of skin contact with the flexible coil in terms of the power transfer efficiency (PTE) to validate the suitability as a wearable sensor. The measurement results at 405 MHz show that when in contact with the skin, the 20 mm× 20 mm receiver (RX) coil achieves a 42% efficiency through the air media for a 10 mm distance between the transmitter (TX) and RX coils.

Comparison of 3 blind brachial plexus block techniques during maintenance of anesthesia and postoperative pain scores in dogs undergoing surgical procedures of the thoracic limb.

The degree of analgesia provided by blind techniques for brachial plexus blocks (BPBs) has not been compared in clinical cases undergoing surgery of the thoracic limb. The objective of this study was to evaluate the anesthetic conditions and postoperative analgesia resulting from 3 different BPB local anesthetic techniques in canine patients undergoing such surgery. Twenty-four client-owned dogs received a standardized premedication/induction protocol (hydromorphone and acepromazine/propofol), maintained with isoflurane in oxygen using mechanical ventilation, in a prospective, randomized, blinded clinical trial. Before surgery, dogs received 1 of 3 anatomical BPB techniques: traditional, perpendicular, or axillary, with 0.2 mL/kg body weight (BW) of bupivacaine 0.5%. Cardiorespiratory variables and isoflurane end-tidal concentrations were recorded throughout anesthesia. Scores for anesthetic maintenance (0-best to 4-responsive), recovery quality (0-not responsive to 3-responsive), and Glasgow pain scale were recorded for up to 24 h postoperatively. All dogs recovered uneventfully from anesthesia and no differences in the measured variables or scores were noted among groups, during and after anesthesia. When thoracic limb amputations in each of the 3 groups (n = 9; 4 in traditional, 3 in perpendicular, 2 in axillary) were compared to the other surgical procedures (n = 15); however, scores for anesthetic maintenance were higher [0 (0 to 1) versus 0 (0 to 0); median (interquartile range)], recovery [1 (0 to 2) versus 0 (0 to 0)], and pain [2.4 (2.4 to 3.0) versus 1.6 (1.4 to 2.2)] in the first 3 h post-extubation. Surgery times were also longer with amputations [115 min (100 to 138 min) versus 50 min (41 to 90 min)]. The 3 BPB techniques provided similar anesthesia and postoperative pain scores. Despite higher pain scores in thoracic limb amputations than in less invasive surgeries, the BPB appeared to provide significant comfort.

Le degré d'analgésie fournie par les blocs à l'aveugle du plexus brachial (BPBs) n'a pas été comparé lors de cas cliniques soumis à une chirurgie du membre thoracique. La présente étude visait à évaluer les conditions anesthésiques et l'analgésie post-opératoire résultant de trois techniques différentes d'anesthésie locale par BPB chez des patients canins soumis à une chirurgie. Vingt-quatre chiens appartenant à des propriétaires ont reçu une prémédication/induction standardisée (hydromorphone et acépromazine/propofol), avec maintien à l'isoflurane dans de l'oxygène en utilisant une ventilation mécanique, dans une étude clinique prospective, randomisée, et à l'aveugle. Avant la chirurgie, les chiens ont reçu un BPB par une des trois techniques anatomiques : traditionnelle, perpendiculaire, ou axillaire, avec 0,2 mL/kg de poids corporel de bupivacaïne 0,5 %. Les variables cardiorespiratoires et les concentrations d'isoflurane en fin d'expiration furent enregistrées tout au long de l'anesthésie. Les pointages pour le maintien de l'anesthésie (0-meilleur à 4-réactif), la qualité du rétablissement (0-non réactif à 3-réactif), et l'échelle de la douleur de Glasgow ont été notés jusqu'à 24 h post-opération. Tous les chiens ont récupéré sans problème de l'anesthésie et aucune différence mesurable dans les variables mesurées ou les pointages ne fut notée parmi les groupes, durant ou après l'anesthésie. Toutefois, lorsque les amputations du membre thoracique dans chacun des trois groupes (n = 9; 4 dans la traditionnelle, 3 dans la perpendiculaire, 2 dans l'axillaire) furent comparées aux autres procédures chirurgicales (n = 15), les pointages pour le maintien de l'anesthésie étaient plus élevés [0 (0 à 1) versus 0 (0 à 0); médiane (écart interquartile)], rétablissement [1 (0 à 2) versus 0 (0 à 0)], et douleur [2,4 (2,4 à 3,0) versus 1,6 (1,4 à 2,2)] dans les 3 h suivant l'extubation. La durée des chirurgies étaient également plus longues lors des amputations [115 min (100 à 138 min) versus 50 min (41 à 90 min)]. Les trois techniques de BPB produisaient des pointages similaires d'anesthésie et de douleur postopératoire. Malgré des pointages de douleur plus élevés lors d'amputations du membre thoracique que lors de chirurgies moins invasives, les BPB semblent fournir un confort significatif.(Traduit par Docteur Serge Messier).

COMPARISON OF INTRAMUSCULAR FENTANYL-MIDAZOLAM, FENTANYL-MIDAZOLAM-KETAMINE, AND KETAMINE-MEDETOMIDINE FOR IMMOBILIZATION OF JAPANESE MACAQUES ( MACACA FUSCATA).

The combination of fentanyl and midazolam is commonly used as a sedative in humans. The objective of this study was to evaluate the sedative properties and physiological effects of fentanyl-midazolam and fentanyl-midazolam-ketamine compared with medetomidine-ketamine given intramuscularly in Japanese macaques ( Macaca fuscata). In a randomized crossover design, eight Japanese macaques were hand-injected with either 30 µg/kg fentanyl + 0.3 mg/kg midazolam (FM), 15 µg/kg fentanyl + 0.3 mg/kg midazolam + 5.0 mg/kg ketamine (FMK), or 0.05 mg/kg medetomidine + 5.0 mg/kg ketamine (MedK). Heart rate; indirect systolic, mean, and diastolic arterial pressure; respiratory rate; blood gas concentrations; rectal temperature; and duration of immobilization were recorded. Mixed linear models were used to evaluate the effects of drug treatment on all continuous variables, with a significance level of P < 0.05. Only three of seven animals receiving FM were successfully immobilized. All eight animals in both the FMK and MedK treatment groups had a rapid, smooth induction and were successfully immobilized. Both FMK and MedK treatments resulted in significant hypoxia and the animals required supplemental oxygen via face mask. The mean duration of FMK immobilization was 42 ± 10 min, significantly shorter than the 65 ± 14 min for the animals receiving MedK. Immobilization with MedK resulted in significantly lower heart rates, and significantly higher arterial pressure compared with FMK. Hypoventilation was significantly more pronounced in FMK-treated animals compared with MedK treatments. Immobilization with FMK resulted in a gradual, slow recovery whereas MedK-treated animals woke up more rapidly. Fentanyl-midazolam alone is not a useful sedative in Japanese macaques. A combination of fentanyl and midazolam with ketamine can be used as an alternative to medetomidine-ketamine in this species.

Anatomical characterization of the brachial plexus in dog cadavers and comparison of three blind techniques for blockade.

OBJECTIVES: To describe the ventral spinal nerve rami contribution to the formation of the brachial plexus (BP), and to compare ease of performing and nerve staining between three blind techniques for BP blockade in dogs. STUDY DESIGN: Prospective, randomized, blind study. ANIMALS: A total of 18 dog cadavers weighing 28.2 ± 9.7 kg (mean ± standard deviation). METHODS: Dogs were randomly assigned to two of three BP treatments: traditional approach (TA), perpendicular approach (PA), and axillary approach (AA). Dye (0.2 mL kg-1) was injected in the left BP using a spinal needle; another BP treatment was used in the right BP. Landmarks (L) included: L1, midpoint between point of the shoulder and sixth cervical (C6) transverse process; L2, scapulohumeral joint; and L3, first rib. For TA, the needle was introduced craniocaudally through L1, medial to the limb and cranial to L3. For PA, the needle was directed perpendicular and caudal to L2, aligned with L1, until cranial to L3. For AA, the needle was directed ventrodorsally, parallel and cranial to L3 until at L1. All BPs were scored for dyeing quality [0 (poor) to 5 (excellent)]. The left BP was dissected for nerve origins. Durbin test was used to compare scores (p < 0.05). RESULTS: In all dogs, the musculocutaneous nerve originated from C7 and C8; the radial nerve from C8, the first thoracic vertebra (T1) (16/18 dogs) and C7 (2/18); and the median and ulnar nerves from C8, T1 (17/18) and C7 (1/18). Respective raw scores and adjusted scores for the incomplete block design were not significantly different (p = 0.72; ranks TA 16.5, PA 19.0, AA 18.5). CONCLUSIONS AND CLINICAL RELEVANCE: The musculocutaneous, median, ulnar and radial nerves originate from C7, C8 and T1. Regardless of the technique, knowledge of anatomy and precise landmarks are relevant for correct dye dispersion.

Induction dose and recovery quality of propofol and alfaxalone with or without midazolam coinduction followed by total intravenous anesthesia in dogs.

OBJECTIVES: To compare propofol and alfaxalone, with or without midazolam, for induction of anesthesia in fentanyl-sedated dogs, and to assess recovery from total intravenous anesthesia (TIVA). STUDY DESIGN: Prospective, incomplete, Latin-square study. ANIMALS: Ten dogs weighing 24.5 ± 3.1 kg (mean ± standard deviation). METHODS: Dogs were randomly assigned to four treatments: treatment P-M, propofol (1 mg kg-1) and midazolam (0.3 mg kg-1); treatment P-S, propofol and saline; treatment A-M, alfaxalone (0.5 mg kg-1) and midazolam; treatment A-S, alfaxalone and saline, administered intravenously (IV) 10 minutes after fentanyl (7 µg kg-1) IV. Additional propofol or alfaxalone were administered as necessary for endotracheal intubation. TIVA was maintained for 35-55 minutes by infusions of propofol or alfaxalone. Scores were assigned for quality of sedation, induction, extubation and recovery. The drug doses required for intubation and TIVA, times from sedation to end of TIVA, end anesthesia to extubation and to standing were recorded. Analysis included a general linear mixed model with post hoc analysis (p < 0.05). RESULTS: Significant differences were detected in the quality of induction, better in A-M than A-S and P-S, and in P-M than P-S; in total intubation dose, lower in P-M (1.5 mg kg-1) than P-S (2.1 mg kg-1), and A-M (0.62 mg kg-1) than A-S (0.98 mg kg-1); and lower TIVA rate in P-M (268 µg kg-1 minute-1) than P-S (310 µg kg-1 minute-1). TIVA rate was similar in A-M and A-S (83 and 87 µg kg-1 minute-1, respectively). Time to standing was longer after alfaxalone than propofol, but was not influenced by midazolam. CONCLUSIONS AND CLINICAL RELEVANCE: Addition of midazolam reduced the induction doses of propofol and alfaxalone and improved the quality of induction in fentanyl-sedated dogs. The dose rate of propofol for TIVA was decreased.

Antihistaminic and cardiorespiratory effects of diphenhydramine hydrochloride in anesthetized dogs undergoing excision of mast cell tumors.

OBJECTIVE To evaluate the effects of IV diphenhydramine hydrochloride administration on cardiorespiratory variables in anesthetized dogs undergoing mast cell tumor (MCT) excision. DESIGN Randomized, blinded clinical trial. ANIMALS 16 client-owned dogs with MCTs. PROCEDURES In a standardized isoflurane anesthesia session that included mechanical ventilation, dogs received diphenhydramine hydrochloride (1 mg/kg [0.45 mg/lb], IV; n = 8) or an equivalent volume of saline (0.9% NaCl) solution (IV; control treatment; 8) 10 minutes after induction. Cardiorespiratory variables were recorded throughout anesthesia and MCT excision, and blood samples for determination of plasma diphenhydramine and histamine concentrations were collected prior to premedication (baseline), throughout anesthesia, and 2 hours after extubation. RESULTS Cardiorespiratory values in both treatment groups were acceptable for anesthetized dogs. Mean ± SD diastolic arterial blood pressure was significantly lower in the diphenhydramine versus control group during tumor dissection (52 ± 10 mm Hg vs 62 ± 9 mm Hg) and surgical closure (51 ± 10 mm Hg vs 65 ± 9 mm Hg). Mean arterial blood pressure was significantly lower in the diphenhydramine versus control group during surgical closure (65 ± 12 mm Hg vs 78 ± 11 mm Hg), despite a higher cardiac index value. Plasma histamine concentrations were nonsignificantly higher than baseline during maximal manipulation of the tumor and surgical preparation in the diphenhydramine group and during surgical dissection in the control group. CONCLUSIONS AND CLINICAL RELEVANCE IV administration of diphenhydramine prior to MCT excision had no clear clinical cardiorespiratory benefits over placebo in isoflurane-anesthetized dogs.

DISTRIBUTION AND SHORT- AND LONG-TERM EFFECTS OF INJECTED GELIFIED ETHANOL INTO THE LUMBOSACRAL INTERVERTEBRAL DISC IN HEALTHY DOGS.

Radiopaque gelified ethanol preparation has been described as a useful agent for treatment of humans with intervertebral disc protrusion. The material is injected into the nucleus pulposus under image guidance with intention to cause the protruded disc material to recede. Because treatment options for dogs with chronic protrusions are limited, new and minimally invasive treatments are desirable. The aim of this experimental, descriptive, prospective study was to assess the feasibility and safety of percutaneous injection of gelified ethanol into the lumbosacral intervertebral disc of dogs. Lumbosacral intervertebral discs of normal dogs (n = 9) were imaged with magnetic resonance imaging and then injected with gelified ethanol using image guidance. The accuracy of gelified ethanol placement in the nucleus pulposus and presence of leakage of the injected material were documented. Postinjection computed tomography (CT) findings (n = 9), short-term (n = 9) and long-term (n = 4) follow-up magnetic resonance imaging and CT findings were compared to document the distribution of the injected preparation and identify effects on adjacent tissues. Percutaneous injection of the intervertebral disc was successful in delivering radiopaque gelified ethanol to the nucleus pulposus in all dogs. Leakage of the injected material into the vertebral canal was present in three dogs immediately following injection and in another additional dog at 1 year following injection. All dogs tolerated the injection well and had no clinical adverse reactions within the study period. Findings indicated that injection of the nucleus pulposus of healthy dogs was well tolerated, even in the presence of mild leakage of material from the intervertebral disc.

Influence of prior determination of baseline minimum alveolar concentration (MAC) of isoflurane on the effect of ketamine on MAC in dogs.

The objective of this study was to determine if prior measurement of the minimum alveolar concentration (MAC) of isoflurane influences the effect of ketamine on the MAC of isoflurane in dogs. Eight mixed-breed dogs were studied on 2 occasions. Anesthesia was induced and maintained using isoflurane. In group 1 the effect of ketamine on isoflurane MAC was determined after initially finding the baseline isoflurane MAC. In group 2, the effect of ketamine on isoflurane MAC was determined without previous measure of the baseline isoflurane MAC. In both groups, MAC was determined again 30 min after stopping the CRI of ketamine. Plasma ketamine concentrations were measured during MAC determinations. In group 1, baseline MAC (mean ± SD: 1.18 ± 0.14%) was decreased by ketamine (0.88 ± 0.14%; P < 0.05). The MAC after stopping ketamine was similar (1.09 ± 0.16%) to baseline MAC and higher than with ketamine (P < 0.05). In group 2, the MAC with ketamine (0.79 ± 0.11%) was also increased after stopping ketamine (1.10 ± 0.17%; P < 0.05). The MAC values with ketamine were different between groups (P < 0.05). Ketamine plasma concentrations were similar between groups during the events of MAC determination. The MAC of isoflurane during the CRI of ketamine yielded different results when methods of same day (group-1) versus separate days (group-2) are used, despite similar plasma ketamine concentrations with both methods. However, because the magnitude of this difference was less than 10%, either method of determining MAC is deemed acceptable for research purposes.

L'objectif de la présente étude était de déterminer si une mesure antérieure de la concentration alvéolaire minimum (MAC) d'isoflurane influence l'effet de la kétamine sur la MAC d'isoflurane chez les chiens. Huit chiens de race croisée ont été examinés à deux occasions. L'anesthésie fut induite et maintenue à l'aide d'isoflurane. Dans le groupe 1, l'effet de la kétamine sur la MAC d'isoflurane fut déterminé après avoir initialement trouvé la MAC de base de l'isoflurane. Dans le groupe 2, l'effet de la kétamine sur la MAC d'isoflurane fut déterminé sans mesure préalable de la MAC de base de l'isoflurane. Dans les deux groupes la MAC fut déterminée de nouveau 30 min après l'arrêt de la CRI de kétamine. Les concentrations de kétamine plasmatiques furent mesurées durant les déterminations de MAC.Dans le groupe 1, la MAC de base (moyenne ± SD : 1,18 ± 0,14 %) fut diminuée par la kétamine (0,88 ± 0,14 %; P < 0,05). La MAC après l'arrêt de la kétamine était similaire (1,09 ± 0,16 %) à la MAC de base et plus élevée qu'avec la kétamine (P < 0,05). Dans le groupe 2, la MAC avec kétamine (0,79 ± 0,11 %) était également augmentée après l'arrêt de la kétamine (1,10 ± 0,17 %; P < 0,05). Les valeurs de MAC avec la kétamine étaient différentes entre les groupes (P < 0,05). Les concentrations plasmatiques de kétamine étaient similaires durant la détermination des MAC.La MAC d'isoflurane durant la CRI de kétamine a donné des résultats différents lorsque les méthodes d'un jour unique (le groupe 1) versus des jours séparés (le groupe 2) étaient utilisées, malgré des concentrations plasmatiques de kétamine similaires avec les deux méthodes. Toutefois, étant donné que l'ampleur de cette différence était de moins de 10 %, chacune des deux méthodes pour déterminer la MAC est considérée comme acceptable à des fins de recherche.(Traduit par Docteur Serge Messier).

Comparison of isoflurane and propofol for maintenance of anesthesia in dogs with intracranial disease undergoing magnetic resonance imaging.

OBJECTIVE: To compare isoflurane and propofol for maintenance of anesthesia and quality of recovery in client-owned dogs with intracranial disease undergoing magnetic resonance imaging (MRI). STUDY DESIGN: Prospective, randomized, clinical trial. ANIMALS: Twenty-five client-owned dogs with intracranial pathology, 13 females and 12 males, ages 11 months to 13 years, weighing between 3.0 and 48.0 kg. METHODS: Each dog was randomly assigned to receive propofol or isoflurane for maintenance of anesthesia. All dogs were not premedicated, were administered propofol intravenously to effect for induction, intubated and mechanically ventilated to maintain an end-tidal carbon dioxide tension 30-35 mmHg (4.0-4.7 kPa). Temperature and cardiac output were measured pre- and post-MRI. Scores for mentation, neurological status, ease of maintenance, and recovery were obtained pre- and post-anesthesia. Pulse oximetry, end-tidal gases, arterial blood pressure, heart rate (HR) and requirements for dopamine administration to maintain mean arterial pressure (MAP) >60 mmHg were recorded throughout anesthesia. RESULTS: End-tidal isoflurane concentration was 0.73 ± 0.35% and propofol infusion rate was 292 ± 119 µg kg(-1)  minute(-1) . Cardiac index was higher, while HR was lower, with propofol than isoflurane in dogs younger than 5 years, but not in older dogs. Dogs maintained with isoflurane were 14.7 times more likely to require dopamine than propofol dogs. Mentation and maintenance scores and temperature were not different. MAP and diastolic arterial pressure were higher in the propofol group. Recovery scores were better with propofol, although times to extubation were similar. Change in neurological score from pre- to post-anesthesia was not different between treatments. CONCLUSIONS: Dogs maintained with propofol during MRI had higher arterial pressures, decreased requirements for dopamine, and better recovery scores, compared to dogs maintained with isoflurane. CLINICAL RELEVANCE: Propofol anesthesia offered cardiovascular and recovery advantages over isoflurane during MRI in dogs with intracranial disease in this study.

Evaluation of cerebrospinal fluid lactate and plasma lactate concentrations in anesthetized dogs with and without intracranial disease.

The objectives of this study were to establish a reference interval for canine cerebrospinal fluid lactate (CSFL) and to compare CSFL and plasma lactate (PL) concentrations in anesthetized dogs with and without intracranial disease. Using a prospective study, canine blood and cerebrospinal fluid were collected for lactate analysis in 11 dogs with intracranial disease after undergoing magnetic resonance imaging (MRI) (Group ID-MRI), in 10 healthy dogs post-MRI (Group H-MRI), and in 39 healthy dogs after induction of anesthesia (Group H-Sx). Dogs were anesthetized for the procedures using different anesthetic protocols. Neurological scores (NS) and sedation scores (SS) were assessed pre-anesthesia in ID-MRI dogs. The CSFL reference interval [90% confidence interval (CI) for lower and upper limits] was 1.1 (1.0 to 1.2) to 2.0 (2.0 to 2.1) mmol/L. Mean ± SD CSFL concentrations were: ID-MRI, 2.1 ± 0.8; H-MRI, 1.6 ± 0.4; and H-Sx, 1.6 ± 0.2 mmol/L. There was a tendency for higher CSFL in dogs in the ID-MRI group than in those in the H-MRI or H-Sx groups (P = 0.12). There was agreement between CSFL and PL in ID-MRI dogs (P = 0.007), but not in dogs in H-MRI (P = 0.5) or H-Sx (P = 0.2). Of the ID-MRI dogs, those with worse NS had higher CSFL (r (2) = 0.44). The correlation between CSFL and PL in dogs with intracranial disease and between worse NS and higher CSFL warrants further investigation into the use of CSFL and PL for diagnostic and prognostic purposes.

Les objectifs de la présente étude étaient d'établir un intervalle de référence pour la valeur du lactate du liquide céphalo-rachidien (CSFL) chez le chien et de comparer les concentrations du lactate plasmatique (PL) chez des chiens anesthésiés avec et sans maladie intracrânienne. Lors d'une étude prospective du sang et du liquide céphalo-rachidien ont été prélevés pour analyse du lactate chez 11 chiens avec maladie intracrânienne après un examen d'imagerie par résonnance magnétique (MRI) (Groupe ID-MRI), chez 10 chiens en santé post-MRI (Groupe H-MRI), et chez 39 chiens après induction de l'anesthésie (Groupe H-Sx). Les chiens ont été anesthésiés pour les procédures en utilisant différents protocoles d'anesthésie. Les scores neurologiques (NS) et les scores de sédation (SS) furent évalués pré-anesthésie chez les chiens ID-MRI. L'intervalle de référence pour le CSFL [intervalle de confiance 90 % (CI) pour les limites inférieure et supérieure] était 1,1 (1,0 à 1,2) à 2,0 (2,0 à 2,1) mmol/L. Les concentrations moyennes ± écart-type du CSFL étaient : ID-MRI, 2,1 ± 0,8; H-MRI, 1,6 ± 0,4; et H-Sx 1,6 ± 0,2 mmol/L. Il y avait tendance à observer des valeurs de CSFL plus élevées chez les chiens du groupe ID-MRI que chez les chiens des groupes H-MRI ou H-Sx (P = 0,12). Il y avait concordance entre le CSFL et le PL chez les chiens ID-MRI (P = 0,007), mais pas chez les chiens H-MRI (P = 0,5) ou H-Sx (P = 0,2). Parmi les chiens ID-MRI, ceux avec les pires NS avaient un CSFL élevé (r2 = 0,44). La corrélation entre le CSFL et le PL chez les chiens avec une maladie intracrânienne et entre le pire NS et un CSFL élevé mérite une investigation plus poussée sur l'utilisation du CSFL et du PL pour fin de diagnostic et de pronostic.(Traduit par Docteur Serge Messier).

The impact of acepromazine on the efficacy of crystalloid, dextran or ephedrine treatment in hypotensive dogs under isoflurane anesthesia.

OBJECTIVE: To determine the impact of acepromazine on the cardiovascular responses to three treatments for hypotension in dogs during deep isoflurane anesthesia. STUDY DESIGN: Prospective blinded randomized cross-over experimental design. ANIMALS: Six adult (2.5 ± 0.5 year old) healthy mixed breed dogs (24.2 ± 7.6 kg). METHODS: Anesthesia was induced with propofol (4-6 mg kg(-1) , IV) and maintained with isoflurane. Each dog received six treatments separated by at least 5 days. Once instrumented, dogs randomly received acepromazine (0.05 mg kg(-1) ) (Ace) or saline (equal volume) (Sal) IV and end-tidal isoflurane (E'Iso) was adjusted to achieve hypotension, defined as a mean blood pressure between 45 and 50 mmHg. Dogs randomly received dextran (D) (7 mL kg(-1) ) or lactated Ringer's (LR) (20 mL kg(-1) ) over 14 minutes, or ephedrine (Eph) (0.1 mg kg(-1) followed by 10 µg kg(-1) minute(-1) ) throughout the study. Measurements were taken at baseline, 5, 10, 15, 20, 30, and 40 minutes. Data were analyzed with a Latin Square in two factors (Ace/Sal and treatment) for repeated measures, with further comparisons if appropriate (p < 0.05). RESULTS: E'Iso producing hypotension was significantly less following Ace (2.07 ± 0.23%) than Sal (2.43 ± 0.23%). No improvement in cardiac output (CO) was observed with D or LR. LR initially intensified hypotension with a significant reduction in SVR, while D caused a minor improvement in ABP. Eph produced a significant increase in ABP, CO, hemoglobin, oxygen content and delivery. Pre-treatment with Ace minimized ABP improvements with all treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Acepromazine (0.05 mg kg(-1) IV) enhanced the hypotensive effect of isoflurane, although it maintained CO. Administration of LR significantly worsens ABP initially by further vasodilation. D caused minimal improvement in ABP. At the infusion studied, Eph effectively countered the cardiovascular depression produced by deep isoflurane anesthesia, but extremes in ABP associated with initial vasoconstriction prevent our recommendation at this dose.

Comparison of three techniques for paravertebral brachial plexus blockade in dogs.

OBJECTIVE: To compare success and complication rates, based on staining of nerves and other structures, among three techniques of paravertebral brachial plexus blockade (PBPB) in dogs. STUDY DESIGN: Prospective randomized design. ANIMALS: A total of 68 thoracic limbs from 34 dogs. METHODS: Limbs were randomly assigned to blind (BL) (n = 24), nerve stimulator-guided (NS) (n = 21) or ultrasound-guided (US) (n = 23) technique. Injections were made with 0.3 mL kg(-1) of lidocaine mixed with new methylene blue. Time to perform each block and current used during NS technique were recorded. Dogs were anesthetized during the blocks and euthanized once completed. Dissections were performed to evaluate staining of nerves, spinal cord, mediastinum, pleura and vessels. An anova and Tukey adjustment for time, logistic regression for association between current and nerve staining and a generalized linear mixed model for staining of different structures were used. Significance was considered when p ≤ 0.05. RESULTS: The median (range) number of nerves stained was 2 (0-4) with BL, 1 (0-3) with NS and 1 (0-4) with US guided technique. No significant differences in staining of C6, C8 and T1 or other structures were found among techniques. Nerve C7 was more likely to be stained by BL (p = 0.05). Time to perform the blocks was significantly different among techniques, with mean ± SD duration in minutes of 3.6 ± 1.8 with BL, 6.3 ± 2.7 with US and 12.2 ± 5 with NS. The most common complication was staining of the spinal cord (29%, 38% and 39% with BL, NS and US, respectively). CONCLUSIONS: Success rates were low and complication rates were relatively high, based on staining, with the three techniques. CLINICAL RELEVANCE: The use of more advanced techniques for PBPB in dogs is not justified according to this study. Clinical significance of the complications encountered in this study should be evaluated.

Prior determination of baseline minimum alveolar concentration (MAC) of isoflurane does not influence the effect of ketamine on MAC in rabbits.

The objective of this study was to compare the effect on the minimum alveolar concentration (MAC) of isoflurane when ketamine was administered either after or without prior determination of the baseline MAC of isoflurane in rabbits. Using a prospective randomized crossover study, 8 adult, female New Zealand rabbits were allocated to 2 treatment groups. Anesthesia was induced and maintained with isoflurane. Group 1 (same-day determination) had the MAC-sparing effect of ketamine [1 mg/kg bodyweight (BW) bolus followed by a constant rate infusion (CRI) of 40 µg/kg BW per min, given by intravenous (IV)], which was determined after the baseline MAC of isoflurane was determined beforehand. A third MAC determination was started 30 min after stopping the CRI. Group 2 (separate-day determination) had the MAC-sparing effect of ketamine determined without previous determination of the baseline MAC of isoflurane. A second MAC determination was started 30 min after stopping the CRI. In group 1, the MAC of isoflurane (2.15 ± 0.09%) was significantly decreased by ketamine (1.63 ± 0.07%). After stopping the CRI, the MAC was significantly less (2.04 ± 0.11%) than the baseline MAC of isoflurane and significantly greater than the MAC during the CRI. In group 2, ketamine decreased isoflurane MAC (1.53 ± 0.22%) and the MAC increased significantly (1.94 ± 0.25%) after stopping the CRI. Minimum alveolar concentration (MAC) values did not differ significantly between the groups either during ketamine administration or after stopping ketamine. Under the study conditions, prior determination of the baseline isoflurane MAC did not alter the effect of ketamine on MAC. Both methods of determining MAC seemed to be valid for research purposes.

L'objectif de la présente étude était de comparer l'effet de la concentration alvéolaire minimale (MAC) d'isoflurane lorsque de la kétamine était administrée soit après ou sans détermination préalable de la MAC de base d'isoflurane chez les lapins. Au moyen d'une étude prospective aléatoire croisée, huit lapines adultes de race Nouvelle-Zélande ont été réparties dans deux groupes de traitement. Une anesthésie a été induite et maintenue avec de l'isoflurane. Le groupe 1 (détermination le même jour), a eu l'effet atténuant sur la MAC de la kétamine [bolus de 1 mg/kg de poids corporel (BW) suivi d'une infusion à taux constant (CRI) de 40 µg/kg BW par minute, administré par voie intraveineuse (IV)], déterminé après que la MAC de base de l'isoflurane fut déterminée préalablement. Une troisième détermination de la MAC a débuté 30 min après l'arrêt de la CRI. Le groupe 2 (détermination lors de jours distincts) a eu l'effet atténuant de la kétamine déterminé sans détermination préalable de MAC de base de l'isoflurane. Une deuxième détermination de la MAC fut débutée 30 min après l'arrêt de la CRI. Dans le groupe 1, la MAC d'isoflurane (2,15 ± 0,09 %) était significativement réduite par la kétamine (1,63 ± 0,07 %). Après l'arrêt de la CRI, la MAC était significativement moindre (2,04 ± 0,11 %) que la valeur de MAC de base d'isoflurane et significativement plus élevée que la MAC durant la CRI. Dans le groupe 2, la kétamine diminua la MAC d'isoflurane (1,53 ± 0,22 %) et la MAC augmenta de manière significative (1,94 ± 0,25 %) après l'arrêt de la CRI. Les valeurs de MAC n'ont pas différé significativement entre les groupes durant soit l'administration de kétamine ou après l'arrêt de kétamine. Dans les présentes conditions expérimentales, la détermination préalable de la MAC de base d'isoflurane n'a pas altéré l'effet de la kétamine sur la MAC. Les deux méthodes pour déterminer la MAC ont semblé être valides pour des besoins de recherche.(Traduit par Docteur Serge Messier).

Use of ephedrine and dopamine in dogs for the management of hypotension in routine clinical cases under isoflurane anesthesia.

OBJECTIVE: To determine the cardiovascular responses of ephedrine and dopamine for the management of presurgical hypotension in anesthetized dogs. STUDY DESIGN: Prospective, randomized, clinical trial. ANIMALS: Twelve healthy client-owned dogs admitted for orthopedic surgery; six per group METHODS: Prior to surgery, 58 anesthetized dogs were monitored for hypotension [mean arterial pressure (MAP) <60 mmHg] that was not associated with bradycardia or excessive anesthetic depth. Ephedrine (0.2 mg kg(-1), IV) or dopamine (5 microg kg(-1) minute(-1), IV) was randomly assigned for treatment in 12 hypotensive dogs. Ten minutes after the first treatment (Tx(1)-10), ephedrine was repeated or the dopamine infusion rate was doubled. Cardiovascular assessments taken at baseline, Tx(1)-10, and 10 minutes following treatment adjustment (Tx(2)-10) were compared for differences within and between treatments (p < 0.05). RESULTS: Ephedrine increased cardiac index (CI), stroke volume index (SVI), oxygen delivery index (DO(2)I), and decreased total peripheral resistance (TPR) by Tx(1)-10, while MAP increased transiently (<5 minutes). The second ephedrine bolus produced no further improvement. Dopamine failed to produce significant changes at 5 microg kg(-1) minute(-1), while 10 microg kg(-1) minute(-1) increased MAP, CI, SVI significantly from baseline, and DO(2)I compared with Tx(1)-10. The improvement in CI, SVI, and DO(2)I was not significantly different between treatments at Tx(2)-10. CONCLUSIONS AND CLINICAL RELEVANCE: In anesthetized hypotensive dogs, ephedrine and dopamine improved cardiac output and oxygen delivery. However, the pressure-elevating effect of ephedrine is transient, while an infusion of dopamine at 10 microg kg(-1) minute(-1) improved MAP significantly by additionally maintaining TPR.

Response of hypotensive dogs to dopamine hydrochloride and dobutamine hydrochloride during deep isoflurane anesthesia.

OBJECTIVE: To evaluate the dose-related cardiovascular and urine output (UrO) effects of dopamine hydrochloride and dobutamine hydrochloride, administered individually and in combination at various ratios, and identify individual doses that achieve target mean arterial blood pressure (MAP; 70 mm Hg) and cardiac index (CI; 150 mL/kg/min) in dogs during deep isoflurane anesthesia. ANIMALS: 10 young clinically normal dogs. PROCEDURES: Following isoflurane equilibration at a baseline MAP of 50 mm Hg on 3 occasions, dogs randomly received IV administration of dopamine (3, 7, 10, 15, and 20 microg/kg/min), dobutamine (1, 2, 4, 6, and 8 microg/kg/min), and dopamine-dobutamine combinations (3.5:1, 3.5:4, 7:2, 14:1, and 14:4 microg/kg/min) in a crossover study. Selected cardiovascular and UrO effects were determined following 20-minute infusions at each dose. RESULTS: Dopamine caused significant dose-dependent responses and achieved target MAP and CI at 7 microg/kg/min; dobutamine at 2 microg/kg/min significantly affected only CI values. At any dose, dopamine significantly affected UrO, whereas dobutamine did not. Target MAP and CI values were achieved with a dopamine-dobutamine combination at 7:2 microg/kg/min; a dopamine-related dose response for MAP and dopamine- and dobutamine-related dose responses for CI were identified. Changes in UrO were associated with dopamine only. CONCLUSIONS AND CLINICAL RELEVANCE: In isoflurane-anesthetized dogs, a guideline dose for dopamine of 7 microg/kg/min is suggested; dobutamine alone did not improve MAP. Data regarding cardiovascular and UrO effects indicated that the combination of dopamine and dobutamine did not provide greater benefit than use of dopamine alone in dogs.

Comparison of cardiopulmonary responses during sedation with epidural and local anesthesia for laparoscopic-assisted jejunostomy feeding tube placement with cardiopulmonary responses during general anesthesia for laparoscopic-assisted or open surgical jejunostomy feeding tube placement in healthy dogs.

OBJECTIVE: To evaluate the use of laparoscopic-assisted jejunostomy feeding tube (J-tube) placement in healthy dogs under sedation with epidural and local anesthesia and compare cardiopulmonary responses during this epidural anesthetic protocol with cardiopulmonary responses during general anesthesia for laparoscopic-assisted or open surgical J-tube placement. ANIMALS: 15 healthy mixed-breed dogs. PROCEDURES: Dogs were randomly assigned to receive open surgical J-tube placement under general anesthesia (n = 5 dogs; group 1), laparoscopic-assisted J-tube placement under general anesthesia (5; group 2), or laparoscopic-assisted J-tube placement under sedation with epidural and local anesthesia (5; group 3). Cardiopulmonary responses were measured at baseline (time 0), every 5 minutes during the procedure (times 5 to 30 minutes), and after the procedure (after desufflation [groups 2 and 3] or at the start of abdominal closure [group 1]). Stroke volume, cardiac index, and O(2) delivery were calculated. RESULTS: All group 3 dogs tolerated laparoscopic-assisted J-tube placement under sedation with epidural and local anesthesia. Comparison of cardiovascular parameters revealed a significantly higher cardiac index, mean arterial pressure, and O(2) delivery in group 3 dogs, compared with group 1 and 2 dogs. Minimal differences in hemodynamic parameters were found between groups undergoing laparoscopic-assisted and open surgical J-tube placement under general anesthesia (ie, groups 1 and 2); these differences were not considered to be clinically important in healthy research dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Sedation with epidural and local anesthesia provided satisfactory conditions for laparoscopic-assisted J-tube placement in healthy dogs; this anesthetic protocol caused less cardiopulmonary depression than general anesthesia and may represent a better choice for J-tube placement in critically ill patients.

Impact of dopamine or dobutamine infusions on cardiovascular variables after rapid blood loss and volume replacement during isoflurane-induced anesthesia in dogs.

OBJECTIVE: To determine the cardiovascular effects of dopamine and dobutamine infusions during nor-movolemia, hypovolemia (HV) through blood loss of 10 mL/kg (HV(10)), further loss to 25 mL/kg (HV(25)), and volume replacement (VR) in isoflurane-anesthetized dogs. ANIMALS: 7 healthy young dogs. PROCEDURES: Dogs were anesthetized with isoflurane 2 times (3 weeks apart). Cardiovascular measurements were obtained for each volume state. The cardiac index (CI) determined by the lithium dilution technique was compared with CI assessed by the arterial pulse contour technique. At each volume state, random treatment with dobutamine or dopamine was assessed (CI by the arterial pulse contour technique). Ten-minute treatments with 3 and 6 microg of dobutamine/kg/min or 7 and 14 microg of dopamine/kg/min (low and high doses, respectively) were administered sequentially. Differences from baseline were determined for volume, drug, and dose effects. RESULTS: Significant proportional changes in blood pressure (BP), stroke index (SI), and CI were evident with changes in volume state. Systemic vascular resistance (SVR) decreased after VR. Dobutamine induced little change in BP; increased heart rate (HR), SI, and CI; and decreased SVR (high dose). Dopamine increased BP and SI, did not change CI, and increased SVR (high dose). The arterial pulse contour technique underestimated changes in CI associated with volume changes. CONCLUSIONS AND CLINICAL RELEVANCE: Isoflurane eliminates clinically obvious compensatory increases in HR during HV. Dopamine is suitable for temporary management of blood loss in isoflurane-anesthetized dogs. Dobutamine increased CI without an associated improvement in BP. The arterial pulse contour monitor should be recalibrated when volume status changes.