Antinociceptive effects of bupivacaine injected within the internal abdominis rectus sheath in standing healthy horses.

OBJECTIVE: To evaluate a regional anesthetic technique for blocking the abdominal midline in horses. STUDY DESIGN: Anatomical description and prospective, crossover, placebo-controlled, blinded study. ANIMALS: Adult horses; two cadavers, six healthy animals. METHODS: In stage 1, 0.5% methylene blue with 0.25% bupivacaine (0.5 mL kg-1) was injected using ultrasonography into the internal rectus abdominis sheath (RAS) of two cadavers with a one-point or two-point technique. The dye spread was described after the dissection of the abdomens. In stage 2, each horse was injected with 1 mL kg-1 of 0.9% NaCl (treatment PT) or 0.2% bupivacaine (treatment BT) using a two-point technique. The abdominal midline mechanical nociceptive threshold (MNT) was measured with a 1 mm blunted probe tip and results analyzed with mixed-effect anova. Signs of pelvic limb weakness were recorded. RESULTS: The cadaver dissections showed staining of the ventral branches from the eleventh thoracic (T11) to the second lumbar (L2) nerve with the one-point technique and T9-L2 with the two-point technique. Baseline MNTs were, mean ± standard deviation, 12.6 ± 1.6 N and 12.4 ± 2.4 N in treatments PT and BT, respectively. MNT increased to 18.9 ± 5.8 N (p = 0.010) at 30 minutes, and MNT was between 9.4 ± 2.0 and 15.3 ± 3.4 N from 1 to 8 hours (p > 0.521) in treatment PT. MNTs in treatment BT were 21.1 ± 5.9 to 25.0 ± 0.1 N from 30 minutes to 8 hours (p < 0.001). MNTs after the RAS injections were higher in treatment BT than PT (p = 0.007). No pelvic limb weakness was observed. CONCLUSIONS AND CLINICAL RELEVANCE: Antinociception of at least 8 hours without pelvic limb weakness was observed in the abdominal midline in standing horses after the RAS block. Further investigations are necessary to evaluate suitability for ventral celiotomies.

Influence of doxapram and intermittent 10% carbon dioxide inspiration on cardiovascular and laryngeal functions in anesthetized dogs.

OBJECTIVE: To compare the effects of two doses of doxapram intravenous injection and carbon dioxide inhalation on the cardiovascular and laryngeal functions of anesthetized hounds. STUDY DESIGN: Experimental study. ANIMALS: Six healthy adult dogs. METHODS: In a Latin-square design, the mean arterial blood pressure (MABP) and heart rate (HR) were recorded continuously. The inspiratory normalized glottic gap areas (iNGGA) were measured before and after each stimulation with 0.55 mg/kg of doxapram (L-DOX), 2.2 mg/kg of doxapram (H-DOX), or 90 s of inhalation of 10% carbon dioxide in oxygen (I-CO2 ). The stimulations were tested in duplicate or triplicate. Video clips of the laryngeal movement were scored by board-certified surgeons masked to the treatment. RESULTS: The MABP increased with L-DOX and H-DOX up to 81% (both p < .001 compared to I-CO2 ), and persisted during the other stimulations (both p < .001). An intermittent tachycardic effect of up to 79% increase in HR was observed with doxapram. The HR following H-DOX was higher than L-DOX and I-CO2 (both p < .016). Neither hypertension nor tachycardia was observed with I-CO2 . The iNGGA increased with all treatments (p < .001). The iNGGA was greater with H-DOX than L-DOX and I-CO2 (both p < .007). All treatments received higher scores (all p < .001) with acceptable inter- and intra-observers Krippendorff's alphas. CONCLUSION: All treatments were effective respiratory stimulants in anesthetized dogs; however, doxapram caused hypertension and tachycardia. CLINICAL SIGNIFICANCE: Carbon dioxide inhalation might improve arytenoid motion without cardiovascular effects in dogs during clinical airway examinations.

Pharmacokinetics and pharmacodynamics of meperidine after intramuscular and subcutaneous administration in horses.

OBJECTIVE: To describe the pharmacokinetics and pharmacodynamics of meperidine after IM and subcutaneous administration in horses. STUDY DESIGN: prospective, randomized, blinded, crossover trial. ANIMALS: Six adult horses weighing 494 ± 33 kg. METHODS: Treatments included meperidine 1 mg/kg IM with saline 6 mL subcutaneously, meperidine 1 mg/kg subcutaneously with saline 6 mL IM, and saline 6 mL subcutaneously and 6 mL IM, with a 7-day washout between treatments. Plasma meperidine concentrations and pharmacodynamic values (thermal and mechanical thresholds, physiological variables, fecal production) were collected at various time points for 24 hours. Accelerometry data were obtained for 8 hours to measure locomotor activity. Data were analyzed with a mixed effects model, and α was set at .05. RESULTS: Meperidine terminal half-life (T1/2 ), maximal plasma concentrations, and time to maximal concentration were 186 ± 59 and 164 ± 56 minutes, 265.7 ± 47.2 and 243.1 ± 80.1 ng/mL at 17 ± 6, and 24 ± 13 minutes for IM at subcutaneous administration, respectively. No effect of treatment or time was observed on thermal or mechanical thresholds, heart rate, respiratory rate, locomotor activity, frequency of defecations, or fecal weight (P > .2 for all). CONCLUSION: Maximum meperidine concentrations were achieved quickly with a short T1/2 in both treatment groups. Neither IM nor subcutaneous meperidine influenced thermal or mechanical threshold or physiological variables. CLINICAL SIGNIFICANCE: The short half-life and lack of detectable antinociceptive effect do not support IM or subcutaneous administration meperidine at 1 mg/kg for analgesia in horses.

Reliability of video recordings to evaluate quality of anesthesia recovery in dogs.

OBJECTIVE: To assess the reliability of using video recordings to evaluate anesthesia recovery in dogs. STUDY DESIGN: Prospective study. ANIMALS: A total of 30 dogs undergoing surgery. METHODS: Recovery monitoring and video recording lasted from extubation until 1 hour later. Scoring was done in real time at the end of the hour by a graduate student using three systems: a simple descriptive scale, visual analog scale and numeric rating scale. Videos were distributed to three American College of Veterinary Anesthesia and Analgesia board-certified anesthesiologist raters as well as the original rater to score. These videos were revisited 4 months later, and the recoveries were scored again. To assess reliability, Cohen's and Fleiss' kappa values evaluated the agreement between sessions. Wilcoxon signed-rank tests were run comparing each observer's two sessions. Recoveries were classified as 'good' or 'bad' according to the cut-off values for each system. RESULTS: Correlation values among raters ranged from 0.50 to 0.82 and from 0.26 to 0.60 in the first and second session, respectively. Bland-Altman plots revealed biases between 0.133 and 1.633 points for each of the three scoring systems. Cohen's kappa had agreement ranging from 0.29 to 0.79 during the first viewing and from 0.17 to 0.44 during the second. Fleiss' kappa values were 0.06, 0.16, 0.22 and 0.26 for various data combinations. Considering overall recovery, Fleiss' kappa showed agreement ranging from 0.54 to 0.71 and from 0.13 to 0.49 for the first and second session, respectively. Of the 12 Wilcoxon tests run, seven found significantly different scores between the two scoring sessions. The recoveries given an overall good or bad were the same on both occasions that they were reviewed. CONCLUSIONS AND CLINICAL RELEVANCE: The use of a video to evaluate recovery in dogs should be used with caution. Individual raters' agreement for specific scores was poor, but evaluating recovery overall had perfect agreement.

Agreement between veterinary students and anesthesiologists regarding postoperative pain assessment in dogs.

OBJECTIVE: To determine the levels of agreement among first- and second-year veterinary students and experienced anesthesiologists in assessing postoperative pain in dogs from video-recordings. STUDY DESIGN: Cross-sectional study. SUBJECTS: Twenty-seven veterinary students, five anesthesiologists and 13 canine clinical patients. METHODS: Prior to their enrolment in a core anesthesia course, veterinary students volunteered to watch 13 90 second videos of dogs. Dogs were hospitalized in an intensive care unit after a variety of surgical procedures. Students were asked to score the level of the dogs' pain using the Dynamic Interactive Visual Analog Scale and the Short Form of the Glasgow Composite-Measure Pain Scale. The same videotapes were scored by five board-certified anesthesiologists. The differences and agreement between the ratings of anesthesiologists and students, and first- and second-year students were determined with Mann-Whitney U-tests and Fleiss' or Cohen's kappa, respectively. RESULTS: Pain scores assigned by students and anesthesiologists differed significantly (p < 0.01). Students assigned higher pain scores to dogs that were given low pain scores by anesthesiologists, and lower pain scores to dogs deemed to be in more pain by anesthesiologists. On average, students assigned higher scores on both scales. CONCLUSIONS AND CLINICAL RELEVANCE: Veterinary students early in their training assigned pain scores to dogs that differed from scores assigned by experienced anesthesiologists.

The use of equine surfactant and positive pressure ventilation to treat a premature alpaca cria with severe hypoventilation and hypercapnia.

A 5-hour-old, premature alpaca cria was presented with failure to nurse, weakness, hypoglycemia, hypercapnia, and respiratory distress. The cria was treated with 3 doses of fresh, crude equine surfactant, positive pressure ventilation, and supplemental intranasal oxygen. Recovery to discharge was uneventful, and the cria regained apparently normal respiratory function. Three years after hospital discharge, the alpaca was a healthy adult.

Utilisation du surfactant équin et de la ventilation à pression positive pour traiter un jeune alpaga atteint d'hypoventilation grave et d'hypercapnie. Un jeune alpaga né prématurément et âgé de 5 heures a été présenté pour une absence d'allaitement, une faiblesse, l'hypoglycémie, l'hypercapnie et la détresse respiratoire. Le jeune a été traité à l'aide de 3 doses de surfactant équin frais et brut, une ventilation à pression positive et de l'oxygène intranasal supplémentaire. Le rétablissement et le congé se sont bien passés et la fonction respiratoire normale du jeune s'est apparemment rétablie. Trois ans après le congé de l'hôpital, l'alpaga était un adulte en santé.(Traduit par Isabelle Vallières).

Evaluation of serial venous and arterial lactate concentrations in healthy anesthetized sheep undergoing ovariectomy.

OBJECTIVE: To determine if lactate concentrations in jugular venous and auricular arterial blood differ in anesthetized sheep. STUDY DESIGN: Prospective, controlled experimental study. ANIMALS: Twelve healthy adult ewes, 4-7 years and weighing 62-77 kg. METHODS: Jugular venous blood was collected before anesthesia (PreOv ) for measurement of lactate concentration, packed cell volume and total protein. Ewes were administered a standard anesthesia protocol. Jugular venous (IntraOv ) and auricular arterial (IntraOa ) blood samples were obtained 40 minutes after induction of anesthesia, and again in recovery (PostOv and PostOa ). An additional blood sample was drawn 6 weeks post-operatively from non-fasted sheep (NF_Lact). Lactate concentrations were compared among PreOv , IntraOv and IntraOa , PostOv and PostOa , and between PreOv and NF_Lact with paired t-test and repeated measure analyses of variance (anova) with PreOv as a covariate (p ≤ 0.05). RESULTS: IntraOv lactate concentration had decreased from PreOv There were significant differences between arterial and venous IntraO and PostO lactate concentrations. There was no significant difference between IntraO and PostO, or PreOv and NF_Lact. CONCLUSIONS AND CLINICAL RELEVANCE: Lactate concentrations were significantly lower in anesthetized sheep compared to non-anesthetized sheep. Lactate concentrations in venous blood were higher than in arterial blood. Therefore, anesthetic status and sampling site should be considered when interpreting lactate concentrations, and the sampling site should be consistent for repeated measurements.

Retrospective assessment of general anesthesia-related challenges, morbidity, and death in snakes: 139 cases (2000-2022).

OBJECTIVE: To summarize the anesthetic events of snakes seen at a large university hospital, identify challenges with record keeping, and assess patient and anesthesia-related morbidity and death. SAMPLE: 139 anesthetic events were performed; only 106 cases had detailed anesthetic reports available for further analyses. PROCEDURES: Medical records of snakes that underwent general anesthesia between October 2000 and January 2022 were retrospectively reviewed. Only cases with complete anesthesia records were used to assess anesthetic parameters. Collected data included general patient details, diagnoses, procedures, premedication, induction, maintenance, monitoring, and recovery. RESULTS: A thorough review of the records identified issues or scenarios that resulted in poor record management as well as highlighted the most frequently used anesthetics in snakes. For premedication this was alfaxalone, butorphanol, and hydromorphone, whereas isoflurane, alfaxalone, or propofol were the most common with induction. Lastly, with maintenance, isoflurane was the most popular choice. Of the 139 cases performed, 127 animals recovered, 8 were euthanatized due to poor prognosis, and 4 failed to recover. All snakes that failed to recover had preexisting disease identified pre-, peri-, or postoperatively at necropsy. CLINICAL RELEVANCE: General anesthesia can be reliably and safely undertaken in snakes without severe preexisting disease. Efforts should be directed at identifying preexisting disease and maintaining and completing anesthesia records, and we recommend an auditing system to identify and correct issues as they arise.

The effect of adding a heated humidified breathing circuit on body temperature in healthy anesthetized dogs.

OBJECTIVE: To compare the effect of a circulating warm water blanket (WWB) in combination with a heated humidified breathing circuit (HHBC) heated to 45 °C on rectal temperature (RT) in dogs undergoing general anesthesia for elective ovariohysterectomies. ANIMALS: 29 healthy dogs. PROCEDURES: Dogs in the experimental group (n = 8) and dogs in the control group (21) were connected to an HHBC and a conventional rebreathing circuit, respectively. All dogs were placed on a WWB in the operating room (OR). The RT was recorded at baseline, premedication, induction, transfer to OR, every 15 minutes during maintenance of anesthesia, and extubation. Incidence of hypothermia (RT < 37 °C) at extubation was recorded. Data were analyzed using unpaired t tests, the Fisher exact test, and mixed-effect ANOVA. Statistical significance was defined as P < .05. RESULTS: There was no difference in RT during baseline, premedication, induction, and transfer to OR. The overall RT was higher for the HHBC group during anesthesia (P = .005) and at extubation (37.7 ± 0.6 °C) compared with the control group (36.6 ± 1.0 °C; P = .006). The incidence of hypothermia at extubation was 12.5% for the HHBC group and 66.7% for the control group (P = .014). CLINICAL RELEVANCE: The combination of HHBC and WWB can reduce the incidence of postanesthetic hypothermia in dogs. Use of an HHBC should be considered in veterinary patients.

Post-anesthetic CPS and EQUUS-FAP scores in surgical and non-surgical equine patients: an observational study.

Background: Equine pain scoring may be affected by the residual effect of anesthetic drugs. Objectives: To compare pain scores in the hours immediately following anesthetic recovery to baseline pre-anesthetic scores in equine patients undergoing surgical and non-surgical procedures. Study design: Clinical observational study. Methods: Fifty adult horses undergoing anesthesia for surgical or non-surgical procedures were enrolled. Horses underwent pain scoring using the Composite Pain Score (CPS) and Equine Utrecht University Scale for Facial Assessment of Pain (EQUUS-FAP) prior to anesthesia (T0) and following anesthetic recovery to standing, every hour for 5 h (T1-T5). Data were analyzed using a generalized linear mixed effects model. A post-hoc Dunnett's test for multiple comparisons was performed for variables where an effect was detected. Results: Mean (95% confidence interval) CPS scores for T0-T5 were 1.6 (1.2-2.0), 6.8 (6.0-7.6), 5.1 (4.3-5.9), 4.3 (3.4-5.2), 3.7 (2.8-4.6), and 2.8 (2.0-3.6) and EQUUS-FAP scores were 0.6 (0.3-0.9), 3.0 (2.5-3.5), 1.9 (1.6-2.2), 1.1 (0.8-1.4), 0.6 (0.4-0.8), and 0.7 (0.4-1.0), respectively. For the CPS, scores greater than 5, and for the EQUUS-FAP scores greater than 3, are consistent with minor pain. There was no effect of type of procedure (surgical vs non-surgical) on CPS or EQUUS-FAP scores. There was an effect of time with CPS scores significantly greater than baseline at T1-T5 and EQUUS-FAP scores significantly greater than baseline at T1 and T2. Main limitations: Discomfort caused by hoisting was not quantified and it was difficult to ascertain if this affected the results. Conclusions: Post-anesthetic pain scores may be influenced by the residual effect of anesthetic agents for as long as 5 h and 2 h for the CPS and EQUUS-FAP, respectively.

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

OBJECTIVE: To compare isoflurane, sevoflurane and desflurane for inhalant anesthesia in red-tailed hawks (Buteo jamaicensis) in terms of the speed and characteristics of induction; cardiovascular and respiratory parameters while anesthetized; and speed and quality of recovery. STUDY DESIGN: Prospective, cross over, randomized experimental study. ANIMALS: 12 healthy adult red-tailed hawks. METHODS: Anesthesia was induced with isoflurane, sevoflurane or desflurane in oxygen via face mask in a crossover, randomized design with a 1 week washout period between each treatment. Hawks were tracheally intubated, allowed to breathe spontaneously, and instrumented for cardiopulmonary monitoring. Data collected included heart rate, respiratory rate, end-tidal CO(2) , inspired and expired agent, SpO(2,) temperature, systolic blood pressure, time to intubation and time to recovery (tracking). Recovery was subjectively scored on a 4 point scale as well as a summary evaluation, by a single blinded observer. RESULTS: No significant difference in time to induction and time to extubation was noted with the administration of isoflurane, sevoflurane or desflurane. Time to the ability of the bird to follow a moving object with its eyes (tracking) was significantly faster with the administration of sevoflurane and desflurane. All recoveries were scored 1 or 2 and were assessed as good to excellent. No significant difference was noted in heart rate, blood pressure and temperature among the three inhalants. Administration of isoflurane resulted in lower respiratory rates. CONCLUSIONS AND CLINICAL RELEVANCE: Overall, although isoflurane remains the most common inhaled anesthetic in avian practice, sevoflurane and desflurane both offer faster time to tracking, while similar changes in cardiopulmonary function were observed with each agent during anesthesia of healthy red-tailed hawks.

The effect of a ketamine constant rate infusion on cardiovascular variables in sheep anesthetized at the minimum alveolar concentration of sevoflurane that blunts adrenergic responses.

OBJECTIVE: To evaluate the effect of a constant rate infusion of ketamine on cardiac index (CI) in sheep, as estimated using noninvasive cardiac output (NICO) monitoring by partial carbon dioxide rebreathing, when anesthetized with sevoflurane at the previously determined minimum alveolar concentration that blunts adrenergic responses (MACBAR). ANIMALS: 12 healthy Dorset-crossbred adult sheep. PROCEDURES: Sheep were anesthetized 2 times in a balanced placebo-controlled crossover design. Anesthesia was induced with sevoflurane delivered via a tight-fitting face mask and maintained at MACBAR. Following induction, sheep received either ketamine (1.5 mg/kg IV, followed by a constant rate infusion of 1.5 mg/kg/h) or an equivalent volume of saline (0.9% NaCl) solution (placebo). After an 8-day washout period, each sheep received the alternate treatment. NICO measurements were performed in triplicate 20 minutes after treatment administration and were converted to CI. Blood samples were collected prior to the start of NICO measurements for analysis of ketamine plasma concentrations. The paired t test was used to compare CI values between groups and the ketamine plasma concentrations with those achieved during the previous study. RESULTS: Mean ± SD CI of the ketamine and placebo treatments were 2.69 ± 0.65 and 2.57 ± 0.53 L/min/m2, respectively. No significant difference was found between the 2 treatments. Mean ketamine plasma concentration achieved prior to the NICO measurement was 1.37 ± 0.58 µg/mL, with no significant difference observed between the current and prior study. CLINICAL RELEVANCE: Ketamine, at the dose administered, did not significantly increase the CI in sheep when determined by partial carbon dioxide rebreathing.

Pharmacokinetics and pharmacodynamics of methadone administered intravenously and intramuscularly to isoflurane-anesthetized chickens.

OBJECTIVE: To determine the pharmacokinetics and pharmacodynamics of methadone after IV or IM administration to isoflurane-anesthetized chickens. ANIMALS: 6 healthy adult Hy-Line hens. PROCEDURES: In a randomized crossover-design study, methadone (6 mg/kg) was administered IV and IM to isoflurane-anesthetized chickens with a 1-week washout period between experiments. Blood samples were collected immediately before and at predetermined time points up to 480 minutes after methadone administration. Plasma concentrations were determined by liquid chromatography-mass spectrometry, and appropriate compartmental models were fit to the plasma concentration-versus-time data. Cardiorespiratory variables were compared between treatments and over time with mixed-effect repeated-measures analysis. RESULTS: A 3-compartment model best described the changes in plasma methadone concentration after IV or IM administration. Estimated typical values for volumes of distribution were 692 mL/kg for the central compartment and 2,439 and 2,293 mL/kg for the first and second peripheral compartments, respectively, with metabolic clearance of 23.3 mL/kg/min and first and second distributional clearances of 556.4 and 51.8 mL/kg/min, respectively. Typical bioavailability after IM administration was 79%. Elimination half-life was 177 minutes, and maximum plasma concentration after IM administration was 950 ng/mL. Heart rate was mildly decreased at most time points beginning 5 minutes after IV or IM drug administration. CONCLUSIONS AND CLINICAL RELEVANCE: Disposition of methadone in isoflurane-anesthetized chickens was characterized by a large volume of distribution and moderate clearance, with high bioavailability after IM administration. Additional studies are warranted to assess pharmacokinetics and pharmacodynamics of methadone in awake chickens.

Arterial oxygenation in anesthetized horses placed in a 5-degree reverse Trendelenburg position.

Low arterial oxygen is a common complication in anesthetized horses and placing the animal in reverse Trendelenburg (RT) position may treat hypoxemia. The objective of this study was to assess the arterial partial pressure of oxygen (PaO2) in horses placed in a 5-degree RT compared to horizontal (H) position. Client-owned healthy horses (n = 60) undergoing elective surgeries were enrolled in a randomized controlled clinical study. Horses were sedated with butorphanol, an α2-adrenoceptor agonist, ± acepromazine and induced with ketamine combined with a benzodiazepine, propofol, or guaifenesin. Anesthesia was maintained with isoflurane in oxygen with mechanical ventilation. Each group (RT and H) included 30 horses, 10 in each recumbency (dorsal, right and left lateral). Arterial blood gas analyses (aBG) were performed following arterial catheter placement then hourly. Time first-to-last aBG, changes in PaO2, dynamic compliance (Cdyn), estimated pulmonary shunt fraction (F-shunt), and alveolar dead space to tidal volume ratio (VD/VT) were evaluated with a 2-way analysis of variance. Statistical significance was set at p < .05. Overall, PaO2 increased in all groups; however no significant difference was found between recumbencies (dorsal, right and left lateral) and RT versus H in changes over time for PaO2 (p = .064 and p = .070, respectively), Cdyn (p = .721 and p = .672, respectively), F-shunt (p = .055 and p = .054, respectively), or VD/VT (p = .616 and p = .064, respectively). In healthy anesthetized horses, 5-degree RT did not affect changes in PaO2 as compared to H position.

Determination of the minimum alveolar concentration of sevoflurane that blunts adrenergic responses and the effect of a constant rate infusion of ketamine in sheep.

Minimizing sympathetic stimulation under anesthesia prevents activation of the neuroendocrine stress response. The minimum alveolar concentration blunting adrenergic responses in 50% of the population when exposed to a noxious stimulus is defined as MAC-BAR. The purpose of this study was to determine the MAC-BAR of sevoflurane (MAC-BARsevo) in sheep and the MAC-BAR sparing effects of ketamine. Thirteen healthy Dorset-cross adult ewes, 4 ± 1 year old and weighing 74 ± 9 kg, were enrolled in a randomized blinded crossover study design. Ewes were anesthetized twice for MAC-BARsevo determination. After face mask induction with sevoflurane, sheep received intravenous ketamine at 1.5 mg/kg and a constant rate infusion of 1.5 mg/kg/h or an equivalent volume of saline (placebo). After 8 day washout, the other treatment was administered. A bracketing technique was used for MAC-BARsevo determination and values were collected in duplicate. The mechanical stimulus (sponge forceps) was applied at the coronary band for 1 min and blood was collected for ketamine plasma concentrations. The MAC-BARsevo values of each treatment were compared using a paired t-test. Mean MAC-BARsevo of the ketamine and placebo were 2.73 ± 0.23% and 2.77 ± 0.31%, respectively and no significant difference was found (p = .638). Average ketamine plasma concentrations was 1.54 ± 0.18 µg/mL maintained through the study. Ketamine at 1.5 mg/kg, followed by 1.5 mg/kg/h, did not decrease the MAC-BARsevo in sheep. Further studies to determine the effect of higher doses of ketamine on inhalational anesthetic agents and their potential adverse effects are warranted.

Effect of Meperidine on Equine Blood Histamine, Tryptase, and Immunoglobulin-E Concentrations.

Objectives: To evaluate changes in immunological parameters following subcutaneous (SC) and intramuscular (IM) administration of meperidine in horses through quantitative analysis of plasma tryptase, histamine, and IgE levels. Methods: Six adult horses were enrolled in a prospective randomized crossover design. Horses were administered one treatment per day, with a seven day washout period: (a) meperidine 1 mg/kg IM, saline 6 mL SC; (b) saline 6 mL IM, meperidine 1 mg/kg SC; (c) saline 6 mL SC, saline 6 mL IM. Blood samples were obtained for plasmatic histamine (baseline, 5, 10, 15, 30, and 60 min) via LC-MS/MS and plasmatic tryptase (baseline, 15, 30, 60, 120, and 240 min) quantification with enzyme-linked immunoabsorbent assays. Serum immunoglobulin E (IgE) concentrations prior to any meperidine treatment and 7-14 days following the first meperidine treatment were evaluated with enzyme-linked immunoabsorbent assays. Histamine and tryptase concentrations were evaluated with a mixed-effect analysis of variance. The levels of IgE at baseline (before the administration of the first dose of meperidine) were compared with the IgE values at 60 min following the second meperidine administration with the Paired t test. Biopsies of localized injection site reactions from subcutaneous meperidine administration were collected from two horses. Results: No statistically significant elevations from baseline in histamine (p = 0.595), tryptase (p = 0.836), or IgE (p = 0.844) were found in any of the horses in this study. There were no differences between treatment groups. Administration of SC meperidine caused a localized vasculitis and thrombosis with regional edema and hemorrhage. Conclusion: No evidence of anaphylactoid or anaphylactic type reactions occurred following IM or SC meperidine administration.

Use of a wireless system to measure invasive arterial blood pressure in ponies - preliminary study.

OBJECTIVE: To evaluate the feasibility and functionality of intra-carotid wireless device implantation in ponies, and to investigate its short-term complications. STUDY DESIGN: Prospective preliminary study. ANIMALS: Five mixed breed, adult, intact male ponies weighing 104 +/- 28.8 kg (mean +/- SD) underwent surgery. Arterial blood pressure data were continuously collected from four animals. METHODS: General anesthesia was induced on two consecutive days. On the first day, an intra-arterial wireless device was implanted in the right carotid artery. On the next day, a transcutaneous intra-arterial catheter was placed in the left facial artery. Data from both sources were collected. Post-mortem examination was performed. RESULTS: Surgical time was 27.1 +/- 11.85 minutes. All catheters remained in place with some extra vascular migration. Complications included mild seroma and hematoma. CONCLUSION: The wireless system allowed continuous monitoring in ponies throughout anesthesia and at rest and may allow for the recording of arterial blood pressure and heart rate when it would be difficult to achieve with a conventional system (e.g. during recovery from anesthesia). CLINICAL RELEVANCE: The wireless invasive blood pressure monitor may allow continuous measurements when only intermittent measurements would be feasible with a wired system.

Evaluation of a point-of-care blood glucose monitor in healthy goats.

OBJECTIVE: To assess agreement between a point-of-care glucometer (POCG) and a laboratory chemistry analyzer for blood glucose measurements in goats. DESIGN: Prospective study. SETTING: University teaching hospital. ANIMALS: Eighteen healthy adult goats. INVESTIGATIONS: Whole blood samples were obtained via jugular venipuncture prior to premedication with xylazine and butorphanol (T0), following premedication (T20), and after 1 hour of inhalant anesthesia (T60). Each sample was tested with a POCG and a laboratory analyzer (HITA). Agreement was assessed using concordance correlation coefficients and calculation of bias and 95% limits of agreement. MEASUREMENTS AND MAIN RESULTS: Mean blood glucose concentration at T0 was 3.9 ± 0.6 mmol/L (70 ± 10 mg/dL; POCG) and 2.9 ± 0.4 mmol/dL (53 ± 8 mg/dL; HITA). Glucose concentrations at T20 were 6.7 ± 2.4 mmol/L (121 ± 43 mg/dL) and 5.4 ± 2.1 mmol/L (97 ± 37 mg/dL) and at T60 were 5.7 ± 1.7 mmol/L (102 ± 31 mg/dL) and 4.7 ± 1.3 mmol/L (85 ± 24 mg/dL) when measured with the POCG and HITA, respectively. The POCG overestimated blood glucose compared to the HITA. The bias ± SD was 1.08 ± 0.53 mmol/L (19.4 ± 9.5 mg/dL) (95% LOA 0.04 to 2.11 mmol/L [0.7 to 38.0 mg/dL]) and the concordance correlation coefficient was 0.82. After correcting the results of the POCG using a mixed-effects linear model, the bias was 0.0 ± 0.38 mmol/L (0.0 ± 6.8 mg/dL) (95% LOA ± 0.74 mmol/L [± 13.4 mg/dL]) and the concordance correlation coefficient was 0.98. CONCLUSIONS: The POCG overestimated blood glucose concentrations in goats, compared to the HITA, but when the POCG concentrations were corrected, the agreement was excellent.

Influence of sedation on onset and quality of euthanasia in sheep.

The purpose of this study was to determine if dexmedetomidine administered IV prior to euthanasia in sheep affected the speed or quality of euthanasia. Twenty clinically healthy Dorset-cross adult ewes between 1 and 3years of age were enrolled in a randomized blinded experimental trial. The subjects were randomly assigned to receive dexmedetomidine 5µg/kg IV or an equivalent volume of saline. Five minutes later, euthanasia was accomplished with a pentobarbital/phenytoin overdose given IV. The time to apnea, asystole, cessation of audible heartbeat, and absence of corneal reflex were recorded by two blinded investigators. If any muscle spasms, contractions, vocalization, and/or dysrhythmias were noted, the time was recorded and type of ECG abnormality was described. An overall score of the euthanasia event was assigned using a numeric rating scale (NRS) after the animal was declared dead. The time to loss of corneal reflex was significantly longer in sheep given dexmedetomidine compared with those who received saline (P=0.03). Although vocalization was observed only in some animals premedicated with dexmedetomidine, no significance was found for this event and no other significant differences between groups were noted. Dexmedetomidine at 5µg/kg IV 5min prior to injection of pentobarbital/phenytoin for euthanasia did not substantially affect the progress of euthanasia. Dexmedetomidine may be given to sedate sheep prior to euthanasia without concern for it adversely affecting the progress of euthanasia, however vocalization may occur.

A survey of the use of arterial catheters in anesthetized dogs and cats: 267 cases.

OBJECTIVES: To describe the clinical practice of insertion of arterial catheters in anesthetized dogs and cats, to document complications of arterial catheterization, and to determine risk factors associated with the complications. DESIGN: Prospective clinical study and retrospective evaluation of medical records. SETTING: University teaching hospital. ANIMALS: Dogs (n = 251) and 13 cats anesthetized for clinical procedures with arterial catheters inserted for blood pressure monitoring. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Details of the animal and catheter were collected at the time of anesthesia. On the following day, the catheter site was palpated and observed for abnormalities and the medical records of all animals were reviewed retrospectively for complications. Details of catheter placement were available for 216 catheters: 158 catheters in a dorsal pedal artery, 50 catheters in the median caudal (coccygeal) artery, 6 in the median artery, and 1 each in a cranial tibial and lingual artery. Blood pressure was obtained from 200 catheters, and 12 catheters failed before the end of anesthesia. Postoperative observational data obtained from 112 catheters described a palpable arterial pulse at 73 sites and no pulse at 21 sites. No risk factor for arterial occlusion was identified. No complications resulting from arterial catheterization were noted in the medical records. CONCLUSIONS: Arterial catheterization resulted in loss of a peripheral pulse postoperatively in 21/94 (22.3%) of animals examined, although no evidence of tissue ischemia was noted in the medical records of any of the patients in this study. These results suggest that insertion of a catheter in the dorsal pedal or coccygeal arteries was not associated with a high risk for complications. However, the course of arterial occlusion postoperatively warrants further investigation.