Risk of anesthesia-related complications in draft horses: a retrospective, single-center analysis.

OBJECTIVE: To report anesthetic-related complications and determine risks associated with anesthesia in draft horses. STUDY DESIGN: Retrospective study. ANIMALS: A total of 401 anesthetic records for draft horse breeds that underwent general anesthesia from January 2010 through December 2020 were reviewed; horses euthanized during general anesthesia were excluded. METHODS: Demographics, perioperative drugs used, procedure type and duration, time to extubation, number of attempts to stand, use of sling in recovery and perioperative morbidity and mortality were investigated. Morbidity and mortality statistical evaluation included univariable logistic regression analysis and ordinal regression analysis. RESULTS: American Society of Anesthesiologists (ASA) status I-II, ASA III-V and total mortality rate for all cases was 0.69% (2/288), 6.19% (7/113) and 2.24% (9/401), respectively, with Belgian horses being overrepresented (6/9). Cardiac arrest occurred in six out of nine horses that died without euthanasia, and five out of six of these horses underwent colic surgery. Factors associated with increased mortality risk included ASA status of III-V, increased body weight, emergency status and horses presenting for colic. Hypotension, hypercarbia and hypoxemia occurred in 56% (224/401), 46% (186/401) and 14% (58/401) of horses, respectively. During recovery from anesthesia, lighter horses and horses undergoing shorter anesthetic procedures were more likely to be successful on the first or second attempt to stand and were less likely to require a sling in recovery. CONCLUSIONS AND CLINICAL RELEVANCE: Draft horses undergoing general anesthesia had a higher mortality rate than previously reported for all types and breeds of horses.

Evaluation of intramuscular anesthetic protocols in healthy domestic horses.

OBJECTIVE: To assess anesthetic induction, recovery quality and cardiopulmonary variables after intramuscular (IM) injection of three drug combinations for immobilization of horses. STUDY DESIGN: Randomized, blinded, three-way crossover prospective design. ANIMALS: A total of eight healthy adult horses weighing 470-575 kg. METHODS: Horses were administered three treatments IM separated by ≥1 week. Combinations were tiletamine-zolazepam (1.2 mg kg-1), ketamine (1 mg kg-1) and detomidine (0.04 mg kg-1) (treatment TKD); ketamine (3 mg kg-1) and detomidine (0.04 mg kg-1) (treatment KD); and tiletamine-zolazepam (2.4 mg kg-1) and detomidine (0.04 mg kg-1) (treatment TD). Parametric data were analyzed using mixed model linear regression. Nonparametric data were compared using Skillings-Mack test. A p value <0.05 was considered statistically significant. RESULTS: All horses in treatment TD became recumbent. In treatments KD and TKD, one horse remained standing. PaO2 15 minutes after recumbency was significantly lower in treatments TD (p < 0.0005) and TKD (p = 0.001) than in treatment KD. Times to first movement (25 ± 15 minutes) and sternal recumbency (55 ± 11 minutes) in treatment KD were faster than in treatments TD (57 ± 17 and 76 ± 19 minutes; p < 0.0005, p = 0.001) and TKD (45 ± 18 and 73 ± 31 minutes; p = 0.005, p = 0.021). There were no differences in induction quality, muscle relaxation score, number of attempts to stand or recovery quality. CONCLUSIONS AND CLINICAL RELEVANCE: In domestic horses, IM injections of tiletamine-zolazepam-detomidine resulted in more reliable recumbency with a longer duration when compared with ketamine-detomidine and tiletamine-zolazepam-ketamine-detomidine. Recoveries were comparable among protocols.

Evaluation of perfusion index as a noninvasive tool to determine epidural anesthesia effectiveness in dogs.

OBJECTIVE: To evaluate perfusion index (PI) as a noninvasive tool to determine effectiveness and onset of epidural anesthesia in dogs. STUDY DESIGN: Prospective clinical trial. ANIMALS: A total of 21 adult dogs, aged 6.5 ± 3 years and weighing 34.9 ± 6.4 kg, undergoing a tibial plateau leveling osteotomy. METHODS: Dogs were premedicated intramuscularly with acepromazine (0.03 mg kg-1) and hydromorphone (0.1 mg kg-1) and anesthetized with intravenous propofol (to effect) and isoflurane in oxygen. A surface transflectance probe was secured to the tail base to monitor PI and a dorsal pedal artery catheter was placed for invasive blood pressure monitoring. A lumbosacral epidural was performed with the dog in sternal recumbency. Dogs were randomly assigned for inclusion of epidural morphine (0.1 mg kg-1) or morphine (0.1 mg kg-1) and lidocaine (4 mg kg-1). PI was recorded following instrumentation of each dog just prior to the epidural (baseline), at 10 minute intervals for 30 minutes, before and after the surgical skin incision and before and after completion of the osteotomy. Physiological variables and end-tidal isoflurane were recorded at the same time points. RESULTS: There was no significant difference in PI between the groups at any time point. There was a significant change in end-tidal isoflurane before and after the skin incision in the epidural morphine and epidural morphine-lidocaine groups (p = 0.04, p = 0.05, respectively) and before and after the osteotomy in each group for heart rate (p = 0.001, p = 0.04), diastolic (p = 0.01, p = 0.01) and mean arterial blood pressure (p = 0.03, p = 0.05). CONCLUSIONS AND CLINICAL RELEVANCE: PI did not provide an objective means for determining the onset or effectiveness of epidural anesthesia in anesthetized dogs and alternate methods of noninvasive assessment should be investigated.

Effectiveness of tapentadol hydrochloride for treatment of orthopedic pain in dogs: A pilot study.

This pilot study evaluated the short-term analgesic effect of oral tapentadol hydrochloride (tapentadol) in dogs with unilateral hind limb lameness secondary to naturally occurring cranial cruciate ligament rupture. Baseline data including pharmacodynamic parameters, sedation scores, lameness scores, and objective gait analyses were collected. Tapentadol was administered orally (30 mg/kg body weight). Four hours following administration of tapentadol all data were collected again. Plasma concentrations of tapentadol 4 hours after administration were assessed using high performance liquid chromatography tandem mass spectrometry. No significant side effects were noted. All dogs had measurable plasma concentrations of tapentadol (mean concentration: 18.9 ng/mL). There were no significant differences in pharmacodynamic parameters or sedation over time. Subjective lameness scores were significantly lower than baseline at 4 hours post-drug administration. No significant improvement was seen in objective gait analysis. Further studies are needed to assess dosing regimens which may lead to effective treatment of acute pain and long-term use.

Efficacité de l'hydrochlorure de tapentadol pour le traitement de douleur orthopédique chez des chiens : une étude pilote. La présente étude pilote a évalué l'effet analgésique à court terme d'hydrochlorure de patentadol (tapentadol) chez des chiens avec une boiterie unilatérale d'un membre arrière secondaire à une rupture du ligament croisé antérieur se produisant naturellement. Les données de base obtenues incluaient des paramètres pharmacodynamiques, des pointages de sédation, des pointages de boiterie et des analyses objectives de la posture. Du tapentadol fut administré oralement (30 mg/kg de poids corporel). Quatre heures suivant l'administration de tapentadol toutes les données furent prises à nouveau. Les concentrations plasmatiques de tapentadol 4 heures après l'administration furent déterminées en utilisant la chromatographie à haute performance en phase liquide en tandem avec la spectrométrie de masse. Aucun effet secondaire significatif ne fut noté. Tous les chiens avaient des concentrations plasmatiques mesurables de tapentadol (concentration moyenne : 18,9 ng/mL). Il n'y avait pas de différence significative dans le temps pour les paramètres pharmacodynamiques ou la sédation. Les pointages subjectifs de boiterie 4 heures postadministration du médicament étaient significativement plus faibles que les valeurs de base. Aucune amélioration significative ne fut observée dans l'analyse objective de la posture. Des études supplémentaires sont requises pour évaluer les régimes de dosage qui pourraient mener à un traitement efficace de la douleur aiguë et de l'utilisation à long-terme.(Traduit par Dr Serge Messier).

Effect of oral trazodone on the minimum alveolar concentration of isoflurane in dogs.

OBJECTIVE: To determine the effect of oral trazodone on the minimum alveolar concentration (MAC) of isoflurane in dogs. STUDY DESIGN: Prospective blinded, single-observer, randomized crossover experimental study. ANIMALS: Six adult (age 6.8 ± 1.6 months) healthy dogs (three males and three females), weighing 24.8 ± 3.4 kg (mean ± standard deviation). METHODS: Each dog was anesthetized twice with a minimum of 7 days between anesthetic episodes. Dogs were randomly assigned to be administered two treatments in a crossover design: premedication with trazodone (8 mg kg-1; TRAZ-ISO) orally 2 hours prior to an anesthetic episode or no (ISO). Dogs were anesthetized with intravenous propofol (6 mg kg-1) and isoflurane in >95% oxygen. Isoflurane MAC was determined using an iterative bracketing technique with electrodes placed in the buccal mucosa. Hemodynamic variables were compared at the lowest end-tidal isoflurane concentration at which each dog did not respond. A paired t test was used to assess the effect of treatment on outcome variables with significance set to a value of p < 0.05. RESULTS: The MAC concentration (mean ± standard deviation) in dogs administered TRAZ-ISO was 0.85 ± 0.17% compared with 1.02 ± 0.11% in those administered ISO (p = 0.01, 95% confidence interval -0.25 to -0.05), resulting in a mean MAC reduction of 17 ± 12%. There were no differences in hemodynamic variables between treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Premedication of dogs with oral trazodone (8 mg kg-1) 2 hours prior to anesthetic induction has a significant isoflurane MAC sparing effect with no significant observed hemodynamic benefit.

Total intravenous anesthesia using a midazolam-ketamine-xylazine infusion in horses: 46 cases (2011-2014).

This study evaluated use of midazolam, ketamine, and xylazine (MKX) for total intravenous (IV) anesthesia (TIVA) in horses. Medical records of 46 horses undergoing a clinical procedure using MKX for TIVA were reviewed. Age, breed, procedure, heart rate (HR), respiratory rate (RR), pre-anesthetic drugs, induction drugs, and total volume of MKX were recorded. Duration of anesthesia, time to standing, number of attempts to stand, and recovery score were also recorded. All horses were premedicated with an alpha-2 adrenoceptor agonist and anesthesia was induced with ketamine and midazolam. Duration of MKX infusion was 33 ± 14 min. Heart rate and RR decreased during the infusion of MKX. Time to endotracheal extubation was 19 ± 12 min. Horses stood at 33 ± 13 min. Median number of attempts to stand was 1. Maintenance of anesthesia of horses with MKX was useful for a variety of procedures and recovery from anesthesia was good.

Anesthésie intraveineuse totale à l'aide d'une infusion de midazolam-kétamine-xylazine chez les chevaux : 46 cas (2011­2014). Cette étude a évalué l'usage du midazolam, de la kétamine et de la xylazine (MKX) pour l'anesthésie intraveineuse (IV) totale (AITT) chez les chevaux. Les dossiers médicaux de 46 chevaux subissant une intervention clinique à l'aide de MKX pour l'AITT ont été évalués. L'âge, la race, l'intervention, la fréquence cardiaque, la fréquence respiratoire, les médicaments pré-anesthésiques, les médicaments d'induction et le volume total de MKX ont été consignés. La durée de l'anesthésie, le délai pour se tenir debout, le nombre de tentatives pour se tenir debout et la note de rétablissement ont aussi été consignés. Tous les chevaux ont reçu une prémédication avec un agoniste alpha-2 adrénocepteur et l'anesthésie a été induite avec de la kétamine et du midazolam. La durée de l'infusion de MKX a été de 33 ± 14 min. La fréquence cardiaque et la fréquence respiratoire ont diminué durant l'infusion de MKX. Le délai jusqu'à l'extubation endotrachéale a été de 19 ± 12 min. Les chevaux se sont tenus debout à 33 ± 13 min. Le nombre médian de tentatives pour se tenir debout était de 1. Le maintien de l'anesthésie chez les chevaux avec MKX était utile pour une diversité d'interventions et le rétablissement de l'anesthésie a été bon.(Traduit par Isabelle Vallières).

Effect of pre-warming on perioperative hypothermia and anesthetic recovery in small breed dogs undergoing ovariohysterectomy.

This study compared perianesthetic body temperatures and times to recovery from general anesthesia in small dogs that were either warmed for 20 minutes prior to anesthesia or not warmed. Twenty-eight client-owned dogs that were presented for ovariohysterectomy were included in the study. Small (<10 kg body weight) dogs with normal circulatory status were randomly assigned to receive pre-warming for 20 minutes or no treatment. Body temperature was measured during the procedure using a calibrated rectal probe. Duration of anesthesia and surgery, time to rescue warming, time to extubation, presence and duration of shivering, and time to return to normal temperature were recorded. Temperature at the end of surgery was significantly higher in the control group than the pre-warmed group. There was no difference in time to extubation or duration of postoperative shivering between groups. Pre-warming did not result in improved temperature or recovery from anesthesia.

Effet du préchauffement sur l'hypothermie périopératoire et le réveil après l'anesthésie chez des chiennes de petites races subissant une ovario-hystérectomie. Cette étude a comparé les températures corporelles périanesthésiques et la durée du réveil après l'anesthésie générale chez des petites chiennes qui étaient soit réchauffées pendant 20 minutes avant l'anesthésie ou non réchauffées. Vingt-huit chiennes appartenant à des clients qui ont été présentées pour l'ovario-hystérectomie étaient incluses dans l'étude. Les petites chiennes (< 10 kg de poids corporel) avec un état circulatoire normal ont été assignées au hasard pour recevoir le préchauffement de 20 minutes ou aucun traitement. La température corporelle a été mesurée durant l'intervention à l'aide d'une sonde rectale calibrée. La durée de l'anesthésie et de la chirurgie, le temps jusqu'au réchauffement de secours, le temps jusqu'à l'extubation, la présence et la durée des frissons et le temps jusqu'au retour à la normale ont été consignés. La température à la fin de la chirurgie était significativement supérieure dans le groupe témoin comparativement au groupe préchauffé. Il n'y avait aucune différence au niveau du temps jusqu'à l'extubation ni de la durée des frissons postopératoires entre les groupes. Le préchauffement n'a pas amélioré la température ni le réveil après l'anesthésie.(Traduit par Isabelle Vallières).

The effects of preoperative oral administration of carprofen or tramadol on postoperative analgesia in dogs undergoing cutaneous tumor removal.

This prospective, blinded, controlled clinical study compared the effects of pre-emptive oral administration of carprofen or tramadol on pain scores and analgesic requirement in dogs undergoing cutaneous tumor removal. Thirty-six client-owned dogs presenting for cutaneous tumor removal were randomly assigned to receive carprofen, tramadol, or no treatment prior to surgery. Pain was assessed using a visual analog scale (VAS), the Modified Glasgow Composite Measure Pain Score (MGCMPS), and algometry at enrollment, prior to premedication, at extubation, then hourly for the first 4 h, and every 4 h for 24 h. Dogs scoring ≥ 7 (MGCMPS), or having a VAS measurement ≥ 40 mm were given rescue analgesia. There were no significant differences in pain VAS, MGCMPS, or algometry. There were no differences in rescue analgesia requirement, or time to rescue analgesia among groups. Carprofen, tramadol, or no pre-emptive analgesia, combined with pre-operative hydromorphone and rescue analgesia, resulted in satisfactory analgesia in the 24-hour postoperative period.

Les effets de l'administration orale préopératoire du carprofène ou du tramadol à l'analgésie postopératoire chez les chiens subissant l'enlèvement d'une tumeur cutanée. Cette étude clinique prospective contrôlée, et réalisée à l'insu, a comparé les effets d'une administration orale préventive de carprofène ou de tramadol sur les évaluations de la douleur et les besoins analgésiques des chiens subissant l'enlèvement d'une tumeur cutanée. Trente-six chiens appartenant à des propriétaires présentés pour l'enlèvement d'une tumeur cutanée ont été assignés de manière aléatoire afin de recevoir du carprofène, du tramadol ou aucun traitement avant la chirurgie. La douleur a été évaluée à l'aide d'une échelle analogue visuelle (ÉAV), de l'évaluation Modified Glasgow Composite Measure Pain Score (MGCMPS) et de l'algométrie au recrutement, avant la prémédication, à l'extubation, puis toutes les heures pendant les quatre premières heures et ensuite toutes les 4 heures pendant 24 heures. Les chiens qui avaient une cote de ≥ 7 (MGCMPS) ou une mesure d'ÉAV de ≥ 40 mm ont reçu une analgésie de secours. Il n'y avait aucune différence dans la douleur ÉAV, MGCMPS ou l'algométrie. Il n'y avait aucune différence au niveau du besoin d'analgésie de secours ou du délai avant l'analgésie de secours parmi les groupes. Le carprofène, le tramadol ou aucune analgésie préventive, conjointement avec de l'hydromorphone préopératoire et de l'analgésie de secours, ont produit une analgésie satisfaisante durant la période postopératoire de 24 heures.(Traduit par Isabelle Vallières).

Comparison of cardiorespiratory variables in dorsally recumbent horses anesthetized with guaifenesin-ketamine-xylazine spontaneously breathing 50% or maximal oxygen concentrations.

This study compared cardiorespiratory variables in dorsally recumbent horses anesthetized with guaifenesin-ketamine-xylazine and spontaneously breathing 50% or maximal (> 90%) oxygen (O2) concentrations. Twelve healthy mares were randomly assigned to breathe 50% or maximal O2 concentrations. Horses were sedated with xylazine, induced to recumbency with ketamine-diazepam, and anesthesia was maintained with guaifenesin-ketamine-xylazine to effect. Heart rate, arterial blood pressures, respiratory rate, lithium dilution cardiac output (CO), inspired and expired O2 and carbon dioxide partial pressures, and tidal volume were measured. Arterial and mixed-venous blood samples were collected prior to sedation (baseline), during 30 minutes of anesthesia, 10 minutes after disconnection from O2, and 30 minutes after standing. Shunt fraction, O2 delivery, and alveolar-arterial O2 partial pressures difference [P(A-a)O2] were calculated. Recovery times were recorded. There were no significant differences between groups in cardiorespiratory parameters or in P(A-a)O2 at baseline or 30 minutes after standing. Oxygen partial pressure difference in the 50% group was significantly less than in the maximal O2 group during anesthesia.

Comparaison des variables cardiorespiratoires chez les chevaux en décubitus dorsal anesthésiés à l'aide de la guaifénésine-kétamine-xylazine respirant spontanément des concentrations de 50 % ou des concentrations maximales d'oxygène. Cette étude a comparé les variables cardiorespiratoires chez les chevaux en décubitus dorsal anesthésiés à l'aide de guaifénésine-kétamine-xylazine et respirant spontanément des concentrations de 50 % ou des concentrations maximales (> 90 %) d'oxygène (O2). Douze juments en santé ont été assignées au hasard à la respiration de concentrations 50 % ou de concentrations maximales d' O2. Les chevaux ont été mis sous sédation avec de la xylazine, induits au décubitus à l'aide de kétamine-diazépam et l'anesthésie a été maintenue à l'aide de guaifénésine-kétamine-xylazine jusqu'à l'effet. Le rythme cardiaque, la pression artérielle, la fréquence respiratoire, le débit cardiaque par dilution au lithium, l' O2 à l'inspiration et à l'expiration ainsi que les pressions partielles de gaz carbonique et le volume courant ont été mesurés. Des échantillons sanguins artériels et veineux mixtes ont été prélevés avant la sédation (données de référence), durant 30 minutes d'anesthésie, 10 minutes après le débranchement de l'oxygène et 30 minutes après s'être mis debout. La fraction du shunt, l'alimentation en O2 et la différence des pressions partielles d' O2 alvéolaire-artérielle [P(A-a)O2] ont été calculées. Les temps de réveil ont été consignés. Il n'y avait pas de différences significatives entre les groupes dans les paramètres cardiorespiratoires ou dans P(A-a)O2 aux données de référence ou 30 minutes après s'être mis debout. La différence entre la pression partielle de l' O2 dans le groupe 50 % était significativement inférieure à celle du groupe avec des concentrations maximales d' O2 durant l'anesthésie.(Traduit par Isabelle Vallières).

Comparison of invasive and oscillometric blood pressure measurement techniques in anesthetized sheep, goats, and cattle.

OBJECTIVE: To determine the level of agreement between an oscillometric (O-NIBP) and an invasive method (IBP) of monitoring arterial blood pressure (ABP) in anesthetized sheep, goats, and cattle. STUDY DESIGN: Prospective clinical study. ANIMALS: Twenty sheep and goats, 20 cattle weighing < 150 kg body weight, and 20 cattle weighing 150 kg body weight. METHODS: Animals were anesthetized and systolic ABP (SABP), mean ABP (MABP), and diastolic ABP (DABP) were measured using IBP and O-NIBP. Differences between IBP and O-NIBP, and 95% limits of agreement (LOA) between SABP, MABP, and DABP values were assessed by the Bland-Altman method. RESULTS: Mean difference ± standard deviation (range) between SABP, DABP, and MABP measurements in sheep and goats was 0 ± 16 (-57 to 38) mmHg, 13 ± 16 (-37 to 70) mmHg, and 8 ± 13 (-34 to 54) mmHg, respectively. Mean difference between SABP, DABP, and MABP measurements in small cattle was 0 ± 19 (-37 to 37) mmHg, 6 ± 18 (-77 to 48) mmHg, and 4 ± 16 (-73 to 48) mmHg, respectively. Mean difference between SABP, DABP, and MABP measurements in large cattle was -18 ± 32 (-107 to 71) mmHg, 7 ± 29 (-112 to 63) mmHg, and -5 ± 28 (-110 to 60) mmHg, respectively. The 95% LOAs for SABP, DABP, and MABP were -31 to +31, -19 to +44, and -19 to +34 mmHg, respectively in sheep and goats; were -37 to +37, -19 to +44, and -19 to +34 mmHg, respectively in small cattle; and were -81 to +45, -50 to +63, and -59 to +50 mmHg, respectively in large cattle. CONCLUSIONS: Agreement was poor between O-NIBP and IBP monitoring techniques. CLINICAL RELEVANCE: Arterial BP should be monitored in anesthetized sheep, goats, and cattle using IBP.

Total intravenous anesthesia in horses.

Total intravenous anesthesia (TIVA) is the mainstay of short-term (up to 60 minutes) and field anesthesia in horses. This article discusses the pros and cons of TIVA, commonly used TIVA protocols, and their use, monitoring during, and recovery from, TIVA.

Pharmacokinetics and pharmacodynamics of intramuscular dexmedetomidine in dogs.

OBJECTIVE: To determine the pharmacokinetics and pharmacodynamics of dexmedetomidine after IM administration in dogs. ANIMALS: 6 healthy adult purpose-bred dogs (3 males, 3 females) with a mean ± SD body weight of 25.2 ± 1.8 kg. PROCEDURES: Each dog received 10 µg/kg dexmedetomidine, IM. Heart rate and respiratory rate were counted via cardiac auscultation and visual assessment of chest excursions. Sedation was assessed utilizing 2 sedation scoring systems. Plasma concentrations were determined using ultra performance liquid chromatography-mass spectrometry. Plasma concentrations versus time data after IM dexmedetomidine were analyzed using noncompartmental analysis for extravascular administration. RESULTS: Over the first 2 hours following IM injection of dexmedetomidine, plasma concentrations fluctuated in each dog. The geometric mean (range) maximum plasma concentration was 109.2 (22.4 to 211.5) ng/mL occurring at 20.5 (5 to 75) minutes, and the mean half-life was 25.5 (11.5 to 41.5) minutes. Heart rate was significantly lower than baseline from 30 minutes to 2 hours postdexmedetomidine administration, and respiratory rate was significantly lower than baseline from 45 minutes to 1.75 hours. Dogs were significantly more sedated from 30 minutes to 1.5 hours postdexmedetomidine administration. Median time to onset of sedation was 7.5 minutes (range, 2 to 10 minutes), and median time to peak sedation was 30 minutes (range, 15 to 60 minutes). CLINICAL RELEVANCE: Variations in plasma concentrations occurred in all dogs for the 2 hours postinjection of dexmedetomidine at 10 µg/kg, IM. This was likely due to alterations in absorption due to dexmedetomidine-induced local vasoconstriction. Despite variable plasma concentrations, all dogs were sedated following IM dexmedetomidine administration.

Comparison of invasive and oscillometric blood pressure measurement techniques in anesthetized camelids.

This study assessed the accuracy of the oscillometric method for arterial blood pressure (ABP) monitoring in anesthetized camelids. Twenty camelids were anesthetized and systolic ABP (SABP), mean ABP (MABP), and diastolic ABP (DABP) were measured directly and using the oscillometric method. The mean difference between SABP measurements was -9.9 ± 21.9 mmHg with a range of -76 to 54 mmHg, and the 95% limits of agreement (LOA) were -33 to 53 mmHg. The difference between DABP measurements was -1.8 ± 15.6 mmHg with a range of -81 to 36 mmHg, and the 95% LOA were -32 to 29 mmHg. The difference between MABP measurements was -2.9 ± 17.0 mmHg with a range of -81 to 36 mmHg, and the 95% LOA were -30 to 36 mmHg. Accurate ABP monitoring in anesthetized camelids cannot be accomplished using the oscillometric method.

RésuméComparaison des techniques invasives et oscillométriques de mesure de la tension artérielle chez les camélidés anesthésiés. Cette étude évalue l'exactitude de la méthode oscillométrique pour la surveillance de la tension artérielle (TA) chez les camélidés anesthésiés. Vingt camélidés ont été anesthésiés et la TA systolique (TAS), la TA moyenne (TAM) et la TA diastolique (TAD) ont été mesurées directement et en utilisant la méthode oscillométrique. La différence moyenne entre les mesures TAS était de −9,9 ± 21,9 mmHg avec un écart de −76 à 54 mmHg et les limites de 95 % de concordance (LC) étaient de −33 à 53 mmHg. La différence entre les mesures TAD était de −1,8 ± 15,6 mmHg avec un écart de −81 à 36 mmHg et les LC de 95 % étaient de −32 à 29 mmHg. La différence entre les mesures de TAM était de −2,9 ± 17,0 mmHg avec un écart de −81 à 36 mmHg et la LC de 95 % étaient de −30 à 36 mmHg. Une surveillance exacte de la TA chez les camélidés ne peut pas être réalisée en utilisant la méthode oscillométrique.(Traduit par Isabelle Vallières).

Effect of 50% and maximal inspired oxygen concentrations on respiratory variables in isoflurane-anesthetized horses.

BACKGROUND: The purpose of this study was to compare the effects of 0.5 fraction of inspired oxygen (FiO2) and >0.95 FiO2 on pulmonary gas exchange, shunt fraction and oxygen delivery (DO2) in dorsally recumbent horses during inhalant anesthesia. The use of 0.5 FiO2 has the potential to reduce absorption atelectasis (compared to maximal FiO2) and augment alveolar oxygen (O2) tensions (compared to ambient air) thereby improving gas exchange and DO2. Our hypothesis was that 0.5 FiO2 would reduce ventilation-perfusion mismatching and increase the fraction of pulmonary blood flow that is oxygenated, thus improving arterial oxygen content and DO2. RESULTS: Arterial partial pressures of O2 were significantly higher than preanesthetic levels at all times during anesthesia in the >0.95 FiO2 group. Arterial partial pressures of O2 did not change from preanesthetic levels in the 0.5 FiO2 group but were significantly lower than in the >0.95 FiO2 group from 15 to 90 min of anesthesia. Alveolar to arterial O2 tension difference was increased significantly in both groups during anesthesia compared to preanesthetic values. The alveolar to arterial O2 tension difference was significantly higher at all times in the >0.95 FiO2 group compared to the 0.5 FiO2 group. Oxygen delivery did not change from preanesthetic values in either group during anesthesia but was significantly lower than preanesthetic values 10 min after anesthesia in the 0.5 FiO2 group. Shunt fraction increased in both groups during anesthesia attaining statistical significance at varying times. Shunt fraction was significantly increased in both groups 10 min after anesthesia but was not different between groups. Alveolar dead space ventilation increased after 3 hr of anesthesia in both groups. CONCLUSIONS: Reducing FiO2 did not change alveolar dead space ventilation or shunt fraction in dorsally recumbent, mechanically ventilated horses during 3 hr of isoflurane anesthesia. Reducing FiO2 in dorsally recumbent isoflurane anesthetized horses does not improve oxygenation or oxygen delivery.

Case Report: Use of PET/CT to Guide Treatment in a Cat With Presentation Consistent With Hodgkin's-Like Lymphoma.

An 8-year-old male neutered Domestic Long Hair cat was presented for a cervical swelling that was suspected to be an enlarged left retropharyngeal lymph node. In the absence of other lymphadenopathy, this was initially suspected to be Hodgkin's-like lymphoma. A positron emission tomography-computed tomography (PET/CT) scan was performed using 2-deoxy-2-[18F]-fluorodeoxyglucose (18F-FDG) to assess for evidence of disease in other locations to guide treatment. Multifocal increased radiopharmaceutical uptake was identified, indicating disease in multiple organs. High-grade lymphoma was confirmed on tissue biopsy. As such, systemic cytotoxic chemotherapy was recommended instead of lymph node extirpation surgery. The cat received a modified CHOP chemotherapy protocol and attained a temporary partial remission. After 2 months of treatment, the cat stopped responding to chemotherapy and was eventually euthanized due to a relapse of disease and decreased quality of life. This case describes the utility of PET/CT to guide treatment in a cat with a presentation consistent with Hodgkin's-like lymphoma.

Investigation of escalating and large bolus doses of a novel, nano-droplet, aqueous 1% propofol formulation in cats.

OBJECTIVE: Identify, describe, and quantitate effects of an escalating dose of a nano-droplet formulation of 1% w/v propofol in telemetered cats. STUDY DESIGN: Prospective two-period parallel design with one treatment procedure per period. ANIMALS: Four female intact, purpose-bred domestic short-hair cats. METHODS: Each animal served as its own control in each period. Telemetered cats were anesthetized on two separate occasions. In Phase I, cats received propofol (8 mg kg(-1)) over 90 seconds. Unless a severe adverse event (SAE) had occurred by this time, repeated doses of 4 mg kg(-1) intravenous (IV) propofol were administered every 3 minutes until the onset of an SAE. In Phase 2, the IV dose of propofol required to produce at least one SAE in Phase I was administered unless an SAE occurred before the dose was completed. Propofol infusion ceased after development of the first SAE. Heart rate, heart rhythm, respiratory rate, systolic, diastolic, and mean arterial blood pressure, SpO(2) and body temperature were continuously recorded before, during and after propofol administration. The incidence and time to onset of an SAE and dose of propofol required to produce an SAE were recorded. The response criteria included time to lateral recumbency, times to orotracheal intubation and extubation, time to sternal recumbency during recovery, time to and duration of first adverse event(s), and total dose of propofol administered. RESULTS: The dose of propofol required to produce an SAE in Phase I was 16.6 and 15.2 mg kg(-1) in Phase 2. Hypotension was the first and most frequently observed SAE. CONCLUSIONS: Larger doses of a novel, nano-droplet propofol formulation can produce SAEs similar to those reported for lipid emulsion formulations. CLINICAL RELEVANCE: Systemic arterial blood pressure should be monitored in cats administered IV propofol.

Sedative and cardiorespiratory effects of intramuscular administration of alfaxalone and butorphanol combined with acepromazine, midazolam, or dexmedetomidine in dogs.

OBJECTIVE: To evaluate the sedative and cardiorespiratory effects of IM administration of alfaxalone and butorphanol combined with acepromazine, midazolam, or dexmedetomidine in dogs. ANIMALS: 6 young healthy mixed-breed hounds. PROCEDURES: Dogs received each of 3 treatments (alfaxalone [2 mg/kg] and butorphanol [0.4 mg/kg] combined with acepromazine [0.02 mg/kg; AB-ace], midazolam [0.2 mg/kg; AB-mid], or dexmedetomidine [0.005 mg/kg; AB-dex], IM) in a blinded, randomized crossover-design study with a 1-week washout period between treatments. Sedation scores and cardiorespiratory variables were recorded at predetermined time points. Data were analyzed by use of mixed-model ANOVA and linear generalized estimating equations with post hoc adjustments. RESULTS: All treatments resulted in moderate to deep sedation (median score, ≥ 15/21) ≤ 5 minutes after injection. Sedation scores did not differ among treatments until the 40-minute time point, when the score was higher for AB-dex than for other treatments. Administration of AB-dex resulted in median scores reflecting deep sedation until 130 minutes, versus 80 and 60 minutes for AB-ace and AB-mid, respectively, after injection. Heart rate, cardiac output, and oxygen delivery decreased significantly after AB-dex, but not AB-ace or AB-mid administration. Respiratory variables remained within clinically acceptable ranges after all treatments. Undesirable recovery characteristics were observed in 4 dogs after AB-mid treatment. Four dogs required atipamezole administration 180 minutes after AB-dex injection. CONCLUSIONS AND CLINICAL RELEVANCE: All protocols produced reliable sedation. The results indicated that in young, healthy dogs, AB-mid may produce undesirable recovery characteristics; AB-dex treatment caused cardiovascular depression and should be used with caution.

Effects of intravenous administration of perzinfotel, fentanyl, and a combination of both drugs on the minimum alveolar concentration of isoflurane in dogs.

OBJECTIVE-To determine the effects of IV administration of perzinfotel and a perzinfotel-fentanyl combination on the minimum alveolar concentration (MAC) of isoflurane in dogs. ANIMALS-6 healthy sexually intact Beagles (3 males and 3 females). PROCEDURES-All dogs were instrumented with a telemetry device for continuous monitoring of heart rate, arterial blood pressure, and core body temperature (at a femoral artery). Dogs were anesthetized with propofol (6 mg/kg, IV) and isoflurane. Isoflurane MAC values were determined in 3 experiments in each dog, separated by at least 7 days, before (baseline) and after the following treatments: no treatment (anesthetic only), perzinfotel (20 mg/kg, IV), fentanyl (5 microg/kg bolus, IV, followed by a continuous IV infusion at 0.15 microg/kg/min), and a fentanyl-perzinfotel combination (20 mg of perzinfotel/kg, IV, plus the fentanyl infusion). Bispectral index and oxygen saturation as measured by pulse oximetry were also monitored throughout anesthesia. RESULTS-Without treatment, the mean +/- SD isoflurane MAC for all 6 dogs was 1.41 +/- 0.10%. Baseline MAC was 1.42 +/- 0.08%. Intravenous administration of perzinfotel, fentanyl, and the perzinfotel-fentanyl combination significantly decreased the MAC by 39%, 35%, and 66%, respectively. Perzinfotel and perzinfotel-fentanyl administration yielded significant increases in the bispectral index. Mean, systolic, and diastolic arterial blood pressures significantly increased from baseline values when perzinfotel was administered. Systolic arterial blood pressure significantly increased from the baseline value when perzinfotel-fentanyl was administered. No adverse effects were detected. CONCLUSIONS AND CLINICAL RELEVANCE-IV administration of perzinfotel, fentanyl, or a perzinfotel-fentanyl combination reduced isoflurane MAC in dogs and increased arterial blood pressure.

Effect of intravenous administration of lactated Ringer's solution or hetastarch for the treatment of isoflurane-induced hypotension in dogs.

OBJECTIVE: To determine the effect of IV administration of crystalloid (lactated Ringer's solution [LRS]) or colloid (hetastarch) fluid on isoflurane-induced hypotension in dogs. ANIMALS: 6 healthy Beagles. PROCEDURES: On 3 occasions, each dog was anesthetized with propofol and isoflurane and instrumented with a thermodilution catheter (pulmonary artery). Following baseline assessments of hemodynamic variables, end-tidal isoflurane concentration was increased to achieve systolic arterial blood pressure (SABP) of 80 mm Hg. At that time (0 minutes), 1 of 3 IV treatments (no fluid, LRS [80 mL/kg/h], or hetastarch [80 mL/kg/h]) was initiated. Fluid administration continued until SABP was within 10% of baseline or to a maximum volume of 80 mL/kg (LRS) or 40 mL/kg (hetastarch). Hemodynamic variables were measured at intervals (0 through 120 minutes and additionally at 150 and 180 minutes in LRS- or hetastarch-treated dogs). Several clinicopathologic variables including total protein concentration, PCV, colloid osmotic pressure, and viscosity of blood were assessed at baseline and intervals thereafter (0 through 120 minutes). RESULTS: Administration of 80 mL of LRS/kg did not increase SABP in any dog, whereas administration of

The cardiorespiratory and anesthetic effects of clinical and supraclinical doses of alfaxalone in cats.

OBJECTIVE: To determine the cardiorespiratory and anesthetic effects of 0, 5, 15, and 50 mg kg(-1) intravenous (IV) alfaxalone in hydroxypropyl beta cyclodextrin (Alfaxan; Jurox Pty Ltd, Rutherford, NSW, Australia) in cats. STUDY DESIGN: Four treatments of alfaxalone were administered in sequential order. ANIMALS: Eight healthy adult cats (four male; four female) weighing between 3.71 and 5.91 kg. METHODS: Cats were instrumented for hemodynamic measurements. Four (0, 5, 15, and 50 mg kg(-1)) IV doses of alfaxalone were administered over one minute, with a 3-hour washout period between doses 0, 5, and 15 mg kg(-1) on Day 0. The 50 mg kg(-1) treatment was administered 24 hours later. Measurements of heart rate, aortic systolic, mean, and diastolic blood pressures, pulmonary arterial and right atrial mean pressures, cardiac output, respiratory rate, tidal and minute volumes, and arterial blood pH and blood gases (PaO(2), PaCO(2)) were performed at pre-determined intervals. Systemic vascular resistance and rate pressure product were calculated. The quality of induction, maintenance, and recovery from anesthesia and the response to noxious stimulation were categorically scored. RESULTS: Alfaxalone administration resulted in dose-dependent cardiorespiratory depression. Decreases in arterial blood pressure and increases in heart rate occurred at higher doses. Most variables returned to baseline by 15-30 minutes. Respiratory rate, minute volume, and PaO(2) decreased. Apnea was the most common side effect. Induction and maintenance quality were judged to be good to excellent at all doses and quality of recovery good to excellent at all but the 50 mg kg(-1) dose. The duration of anesthesia and unresponsiveness to noxious stimulation increased with dose. The administration of the 50 mg kg(-1) dose produced marked cardiorespiratory depression and apnea. CONCLUSIONS AND CLINICAL RELEVANCE: Alfaxalone produced dose-dependent anesthesia, cardiorespiratory depression and unresponsiveness to noxious stimulation in unpremedicated cats. Hypoventilation and apnea were the most common side effects.