A review of equine anesthetic induction: Are all equine anesthetic inductions "crash" inductions?

Horses are the most challenging of the common companion animals to anesthetize. Induction of anesthesia in the horse is complicated by the fact that it is accompanied by a transition from a conscious standing position to uncconconscious recumbency. The purpose of this article is to review the literature on induction of anesthesia with a focus on the behavioral and physiologic/pharmacodynamic responses and the actions and interactions of the drugs administered to induce anesthesia in the healthy adult horse with the goal of increasing consistency and predictability.

A Retrospective Study of the Incidence and Management of Complications Associated With Regional Nerve Blocks in Equine Dental Patients.

Regional anesthesia of the equine head is commonly performed to allow oral extraction of diseased teeth in the standing horse. The use of 4 blocks (infraorbital nerve, maxillary nerve, mental nerve, and mandibular nerve) is well documented for desensitization of dental quadrants for oral surgery for exodontia, but descriptions of associated complications are limited. A total of 270 regional nerve blocks were performed on 162 equine patients in a second opinion referral hospital setting. Criteria for inclusion in the study included a 24-hour stay in hospital, that the blocks be performed by one clinician and at minimum, a 2-week follow-up examination be performed. A total of 8 complications were identified in 7 patients representing a 2.96% incidence of complication. Complications included supraorbital hematoma (3), local hematoma (2), lingual self-trauma (2), and nerve block failure to desensitize (1). Treatment and management of complications are discussed. Complications associated with regional anesthesia may be reduced by reducing anesthetic volumes, precise needle placement, familiarity with the facial anatomy relevant to nerve blocks, adequate restraint, aseptic technique, postprocedural muzzling, and the use of a newly opened bottle of local anesthetic.

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).

Pharmacokinetics and pharmacodynamics of buprenorphine and sustained-release buprenorphine after administration to adult alpacas.

OBJECTIVE To determine pharmacokinetics and pharmacodynamics of buprenorphine after IV and SC administration and of sustained-release (SR) buprenorphine after SC administration to adult alpacas. ANIMALS 6 alpacas. PROCEDURES Buprenorphine (0.02 mg/kg, IV and SC) and SR buprenorphine (0.12 mg/kg, SC) were administered to each alpaca, with a 14-day washout period between administrations. Twenty-one venous blood samples were collected over 96 hours and used to determine plasma concentrations of buprenorphine. Pharmacokinetic parameters were calculated by use of noncompartmental analysis. Pharmacodynamic parameters were assessed via sedation, heart and respiratory rates, and thermal and mechanical antinociception indices. RESULTS Mean ± SD maximum concentration after IV and SC administration of buprenorphine were 11.60 ± 4.50 ng/mL and 1.95 ± 0.80 ng/mL, respectively. Mean clearance was 3.00 ± 0.33 L/h/kg, and steady-state volume of distribution after IV administration was 3.8 ± l.0 L/kg. Terminal elimination half-life was 1.0 ± 0.2 hours and 2.7 ± 2.8 hours after IV and SC administration, respectively. Mean residence time was 1.3 ± 0.3 hours and 3.6 ± 3.7 hours after IV and SC administration, respectively. Bioavailability was 64 ± 28%. Plasma concentrations after SC administration of SR buprenorphine were below the LLOQ in samples from 4 alpacas. There were no significant changes in pharmacodynamic parameters after buprenorphine administration. Alpacas exhibited mild behavioral changes after all treatments. CONCLUSIONS AND CLINICAL RELEVANCE Buprenorphine administration to healthy alpacas resulted in moderate bioavailability, rapid clearance, and a short half-life. Plasma concentrations were detectable in only 2 alpacas after SC administration of SR buprenorphine.

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).

Recovery from desflurane anesthesia in horses with and without post-anesthetic xylazine.

The objective of this study was to compare recovery from desflurane anesthesia in horses with or without post-anesthetic xylazine. Six adult horses were anesthetized on 2 occasions, 14 d apart using a prospective, randomized crossover design. Horses were sedated with xylazine, induced to lateral recumbency with ketamine and diazepam, and anesthesia was maintained with desflurane. One of 2 treatments was administered intravenously at the end of anesthesia: xylazine [0.2 mg/kg body weight (BW)] or an equivalent volume of saline. Recovery parameters were recorded and assessed by 2 blinded observers. A Wilcoxon signed-rank test was used to analyze recovery data. Heart rate, arterial blood pressures, and arterial blood gas data were analyzed using 2-way analysis of variance (ANOVA) for repeated measures. Values of P < 0.05 were considered significant. Duration of anesthesia was not different between groups. Administration of xylazine at the end of desflurane anesthesia was associated with significantly longer times to first movement, endotracheal tube removal, first attempt to achieve sternal recumbency, sternal recumbency, first attempt to stand, and standing. Number of attempts to stand and quality of recovery scores were not different between groups. Administering xylazine after desflurane anesthesia resulted in longer recovery times. Recovery scores were not significantly different between groups.

L'objectif de la présente étude était de comparer la récupération suite à une anesthésie au desflurane chez des chevaux avec ou sans administration post-anesthésie de xylazine. Six chevaux adultes furent anesthésiés à deux occasions à 14 j d'intervalle, en utilisant un design expérimental croisé aléatoire. Les chevaux ont été soumis à une sédation à la xylazine, mis en décubitus latéral avec de la kétamine et du diazépam, et l'anesthésie maintenue avec du desflurane. Un des deux traitements suivants fut administré par voie intraveineuse à la fin de l'anesthésie : xylazine (0,2 mg/kg de poids corporel) ou un volume équivalent de saline. Les paramètres de récupération furent enregistrés et évalués à l'aveugle par deux observateurs. Le test de comparaison des données de Wilcoxon fut utilisé pour analyser les données de récupération. Le rythme cardiaque, la pression artérielle, et les données des gaz sanguins artériels furent analysés par analyse de variance (ANOVA) pour des mesures répétées. Des valeurs de P < 0,05 étaient considérées comme significatives. La durée de l'anesthésie n'était pas différente entre les groupes. L'administration de xylazine à la fin de l'anesthésie au desflurane était associée à des délais significativement plus longs avant : un premier mouvement, le retrait du tube endotrachéal, un premier essai pour se mettre en décubitus sternal, le décubitus sternal, un premier essai pour se mettre debout, et se tenir debout. Le nombre d'essais pour se tenir debout et la qualité des pointages de récupération n'étaient pas différents entre les groupes. L'administration de xylazine suite à l'anesthésie au desflurane a entraîné des temps de récupération plus longs. Les pointages de récupération n'étaient pas significativement différents entre les groupes.(Traduit par Docteur Serge Messier).

Postoperative comparison of four perioperative analgesia protocols in dogs undergoing stifle joint surgery.

OBJECTIVE: To compare 4 analgesic protocols in dogs undergoing stifle joint surgery. DESIGN: Randomized, blinded, prospective clinical trial. Animals-48 client-owned dogs that underwent stifle joint surgery. PROCEDURES: Dogs undergoing tibial plateau leveling osteotomy were randomly assigned to receive a constant rate infusion of a combination of morphine, lidocaine, and ketamine; a lumbosacral epidural with morphine and ropivacaine; both treatments (ie, constant rate infusion and lumbosacral epidural); or only IM premedication with morphine. Indices of cardiorespiratory function and isoflurane requirement were recorded at 5-minute intervals during anesthesia. A validated sedation scoring system and the modified Glasgow composite measure pain score were used to assess comfort and sedation after surgery and anesthesia once the swallowing reflex returned and a body temperature of ≥ 36.7°C (98.1°F) was attained. Pain and sedation scores were acquired at 60-minute intervals for 4 hours, then at 4-hour intervals for 24 hours. Dogs with a postoperative pain score > 5 of 24 were given morphine as rescue analgesia. RESULTS: No differences in heart rate, respiratory rate, systolic arterial blood pressure, end-tidal Pco2, end-tidal isoflurane concentration, and vaporizer setting were detected among groups. No differences in pain score, sedation score, rescue analgesia requirement, or time to first rescue analgesia after surgery were detected. CONCLUSIONS AND CLINICAL RELEVANCE: Pain scores were similar among groups, and all 4 groups had similar rescue analgesia requirements and similar times to first administration of rescue analgesia. All 4 analgesic protocols provided acceptable analgesia for 24 hours after stifle joint surgery.

Effect of dexmedetomidine, morphine-lidocaine-ketamine, and dexmedetomidine-morphine-lidocaine-ketamine constant rate infusions on the minimum alveolar concentration of isoflurane and bispectral index in dogs.

OBJECTIVE: To determine the effect of dexmedetomidine, morphine-lidocaine-ketamine (MLK), and dexmedetomidine-morphine-lidocaine-ketamine (DMLK) constant rate infusions on the minimum alveolar concentration (MAC) of isoflurane and bispectral index (BIS) in dogs. ANIMALS: 6 healthy adult dogs. PROCEDURES: Each dog was anesthetized 4 times with a 7-day washout period between anesthetic episodes. During the first anesthetic episode, the MAC of isoflurane (baseline) was established. During the 3 subsequent anesthetic episodes, the MAC of isoflurane was determined following constant rate infusion of dexmedetomidine (0.5 µg/kg/h), MLK (morphine, 0.2 mg/kg/h; lidocaine, 3 mg/kg/h; and ketamine, 0.6 mg/kg/h), or DMLK (dexmedetomidine, 0.5 µg/kg/h; morphine, 0.2 mg/kg/h; lidocaine, 3 mg/kg/h; and ketamine 0.6 mg/kg/h). Among treatments, MAC of isoflurane was compared by means of a Friedman test with Conover posttest comparisons, and heart rate, direct arterial pressures, cardiac output, body temperature, inspired and expired gas concentrations, arterial blood gas values, and BIS were compared with repeated-measures ANOVA and a Dunn test for multiple comparisons. RESULTS: Infusion of dexmedetomidine, MLK, and DMLK decreased the MAC of isoflurane from baseline by 30%, 55%, and 90%, respectively. Mean heart rates during dexmedetomidine and DMLK treatments was lower than that during MLK treatment. Compared with baseline values, mean heart rate decreased for all treatments, arterial pressure increased for the DMLK treatment, cardiac output decreased for the dexmedetomidine treatment, and BIS increased for the MLK and DMLK treatments. Time to extubation and sternal recumbency did not differ among treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Infusion of dexmedetomidine, MLK, or DMLK reduced the MAC of isoflurane in dogs.

Pharmacokinetics and pharmacodynamics of midazolam after intravenous and intramuscular administration in alpacas.

OBJECTIVE: To determine pharmacokinetic and pharmacodynamic properties of midazolam after IV and IM administration in alpacas. ANIMALS: 6 healthy alpacas. PROCEDURES: Midazolam (0.5 mg/kg) was administered IV or IM in a randomized crossover design. Twelve hours prior to administration, catheters were placed in 1 (IM trial) or both (IV trial) jugular veins for drug administration and blood sample collection for determination of serum midazolam concentrations. Blood samples were obtained at intervals up to 24 hours after IM and IV administration. Midazolam concentrations were determined by use of tandem liquid chromatography-mass spectrometry. RESULTS: Maximum concentrations after IV administration (median, 1,394 ng/mL [range, 1,150 to 1,503 ng/mL]) and IM administration (411 ng/mL [217 to 675 ng/mL]) were measured at 3 minutes and at 5 to 30 minutes, respectively. Distribution half-life was 18.7 minutes (13 to 47 minutes) after IV administration and 41 minutes (30 to 80 minutes) after IM administration. Elimination half-life was 98 minutes (67 to 373 minutes) and 234 minutes (103 to 320 minutes) after IV and IM administration, respectively. Total clearance after IV administration was 11.3 mL/min/kg (6.7 to 13.9 mL/min/kg), and steady-state volume of distribution was 525 mL/kg (446 to 798 mL/kg). Bioavailability of midazolam after IM administration was 92%. Peak onset of sedation occurred at 0.4 minutes (IV) and 15 minutes (IM). Sedation was significantly greater after IV administration. CONCLUSIONS AND CLINICAL RELEVANCE: Midazolam was well absorbed after IM administration, had a short duration of action, and induced moderate levels of sedation in alpacas.

Evaluation of a midazolam-ketamine-xylazine infusion for total intravenous anesthesia in horses.

OBJECTIVE: To evaluate the use of midazolam, ketamine, and xylazine for total IV anesthesia (TIVA) in horses. ANIMALS: 6 healthy Thoroughbred mares. PROCEDURES: Horses were sedated with xylazine (1.0 mg/kg, IV). Anesthesia was induced with midazolam (0.1 mg/kg, IV) followed by ketamine (2.2 mg/kg, IV) and was maintained with an IV infusion of midazolam (0.002 mg/kg/min), ketamine (0.03 mg/kg/min), and xylazine (0.016 mg/kg/min). Horses underwent surgical manipulation and injection of the palmar digital nerves; duration of the infusion was 60 minutes. Additional ketamine (0.2 to 0.4 mg/kg, IV) was administered if a horse moved its head or limbs during procedures. Cardiopulmonary and arterial blood variables were measured prior to anesthesia; at 10, 20, 30, 45, and 60 minutes during infusion; and 10 minutes after horses stood during recovery. Recovery quality was assessed by use of a numeric (1 to 10) scale with 1 as an optimal score. RESULTS: Anesthesia was produced for 70 minutes after induction; supplemental ketamine administration was required in 4 horses. Heart rate, respiratory rate, arterial blood pressures, and cardiac output remained similar to preanesthetic values throughout TIVA. Arterial partial pressure of oxygen and oxygen saturation of arterial hemoglobin were significantly decreased from preanesthetic values throughout anesthesia; oxygen delivery was significantly decreased at 10- to 30-minute time points. Each horse stood on its first attempt, and median recovery score was 2. CONCLUSIONS AND CLINICAL RELEVANCE: Midazolam, ketamine, and xylazine in combination produced TIVA in horses. Further studies to investigate various dosages for midazolam and ketamine or the substitution of other α(2)-adrenoceptor for xylazine are warranted.

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.

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

Hematuria and transitional cell papilloma of the renal pelvis treated via unilateral nephrectomy in an alpaca.

CASE DESCRIPTION: An 11-year-old 72-kg (158-lb) sexually intact female alpaca was examined for diagnosis and treatment of hematuria of 4 months' duration. CLINICAL FINDINGS: Pigmenturia was detected by the owner when the alpaca was 8 months pregnant. Radiographic, ultrasonographic, vaginal speculum, and cystoscopic evaluation of the urinary tract revealed normal vaginal and urethral epithelia and increased bladder vessel tortuosity, with pulses of hemorrhage from the left ureter. Regenerative anemia and mild leukopenia were detected and serum urea nitrogen and creatinine concentrations were within reference ranges. TREATMENT AND OUTCOME: Chronic hematuria resolved after unilateral nephrectomy of the left kidney, and no dysfunction was detected in the remaining kidney. Histologic evaluation of the kidney revealed a transitional cell tumor in the renal pelvis. CLINICAL RELEVANCE: Although anemia is common in South American camelids, hematuria is an uncommon sign of this condition. Chronic urinary tract infection, toxin ingestion, and neoplasia causing hematuria or hemoglobinuria should be considered in South American camelids with pigmenturia. Thorough and systematic evaluation of the urinary tract should be performed to locate the site of hemorrhage to treat hematuria appropriately.

Veterinary teaching hospitals: current challenges and pathways for the future.

University-based veterinary teaching hospitals must change to maintain their viability. A number of factors both internal and external to universities and the veterinary profession have contributed to the need for change. A task force formed by the Association of American Veterinary Medical Colleges and the American Association of Veterinary Clinicians was convened to identify the issues and propose individual and collective strategies for the future. Primary issues include a shortage of faculty and staff, the nature of the case load, the need for fiscal management strategies, and the need to manage stakeholder expectations. The majority of the proposed strategies for the future will be managed individually by the colleges. Proposed collective strategies center on increasing the number of specialists and improving recruitment and retention of faculty and staff.