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The purpose of this study was to investigate the hepatic effects of halothane in anesthetized goats and to compare them with those of isoflurane. [ABSTRACT FROM AUTHOR]

Our purpose was to assess the accuracy and precision of a point of care hemoglobinometer (HemoCue-B hemoglobin photometer) for measuring hemoglobin concentration in horse blood. Samples of jugular venous blood from 12 healthy adult horses were collected in EDTA. In order to test the device over a wide range of values, each sample was divided into nine aliquots, and autologous plasma was added or removed from the aliquots to produce blood with PCV values that approximated 5, 10, 20, 30, 40, 50, 60, 70, and 80%, respectively. The aliquots were rocked to ensure mixing of plasma and cells. Then hemoglobin by HemoCue-B (HbHQ ) and hemoglobin by the cyanmethemoglobin method (HbCY ) were measured on each aliquot. The PCV of each aliquot was also measured and this value was used for subsequent analyses. To test repeatability, hemoglobin was measured twice by the HemoCue-B on approximately 40% samples. Samples with HbHQ >25.4 g dL-1 required dilution prior to analysis. HbCY ranged from 1.6 to 33.4 g dL-1 . After regression, HbCY = -0.16 + 1.04 HbHQ (n = 101; r 2 = 99.6%). By inspection of a modified Bland-Altman plot, HbHQ values <16 g dL-1 closely approximated HbCY ; however, at greater values, HbHQ underestimated HbCY by as much as 3.2 g dL-1 . The difference between repeated measurements with the HemoCue-B was 0.02 ± 0.16 g dL-1 (mean ± SD; n = 10) and nonsignificant. After regression, PCV = -0.76 + 2.78 HbHQ (n = 101; r 2 = 99.4%). We conclude that HemoCue-B can be used to measure hemoglobin concentration in horse blood, and that it is accurate when hemoglobin is <16 g dL-1 . PCV can be estimated by multiplying HbHQ by 2.8 and then subtracting 0.8. [ABSTRACT FROM AUTHOR]

The purpose of this study was to find out if an LMA (#1 LMA-Classic) would provide a better airway than a face mask in spontaneously breathing anesthetized rabbits, and to test if it could be used for mechanically controlled ventilation. Sixteen rabbits (4.1 ± 0.8 kg, mean ± SD) were assigned randomly to three treatment groups; face mask with spontaneous ventilation (FM-SV; n = 5), LMA with spontaneous ventilation (LMA-SV; n = 5), and LMA with controlled ventilation (LMA-CV; n = 6). Rabbits were anesthetized in dorsal recumbency using a circle circuit at constant ET isoflurane (2.3%, Datex airway gas monitor) and constant rectal temperature (38.85 °C) for 2 hours. PaCO2 , PaO2 , minute volume, tidal volume (Wright's respirometer), and PeCO2 were measured at 15 minute intervals. Two individuals in the FM-SV group had PaCO2 >100 mm Hg (>13.3 kPa). One rabbit in the FM-SV had PaO2 <80 mm Hg (<10.7 kPa). All FM-SV rabbits showed signs of airway obstruction and two were withdrawn from the study at 45 and 90 minutes, respectively, because of cyanosis. Tidal volume could not be measured in the FM-SV group. No signs of airway obstructions were observed in either of the LMA groups. Four rabbits in the LMA-CV group developed gastric tympany, and one of these refluxed after 110 minutes. The significance of differences between the two spontaneously breathing groups and between the two LMA groups were measured using Wilcoxon's rank sum test (with significance assumed at p < 0.05). There were no statistical differences between FM-SV and LMA-SV in any variable tested. PaCO2 and Pe′CO2 were less in the LMA-CV group than in the LMA-SV group, while PaO2 , tidal volume, and minute volume were all more. We conclude that biologically, the LMA provides a better airway than the face mask during spontaneous breathing and that it can be used for IPPV, but that gastric tympany is likely to occur during IPPV. [ABSTRACT FROM AUTHOR]

The pre-medicant chosen may influence the ease with which gastroduodenoscopy (GD) is performed. The purpose of this study was to evaluate the relative ease of GD in cats under ketamine and isoflurane anesthesia after IM injection of hydromorphone (H, 0.1 mg kg-1 ), hydromorphone plus glycopyrrolate (HG, 0.1 mg kg-1 (H), 0.01 mg kg-1 (G)), medetomidine (M, 0.03 mg kg-1 ), or butorphanol (B, 0.4 mg kg-1 ). Eight cats were assigned randomly to receive each treatment in a cross-over design with at least 7 days between treatments. Twenty minutes after pre-medication, medetomidine produced greater (p = 0.001) sedation than the other treatments when assessed, using a subjective ordinal scale. The cats were injected with ketamine (10 mg kg-1 IM), orotracheally intubated, connected to a pediatric circle breathing system, and allowed to spontaneously breathe isoflurane in oxygen. Once end-tidal isoflurane concentration was stable at 1.4% for 15 minutes, endoscopy was started. A single endoscopist (REG), who was unaware of the treatment used, performed all endoscopies. The endoscopist scored the difficulty of endoscopy subjectively (0–3). The significance of differences between treatments was evaluated using Friedman's test. Time for entering the stomach was 9.4 (4.7–15.9) (median (minimum–maximum)), 6.6 (5.2–11.7), 8.4 (6.3–16.5), and 7.7 (5.1–14.7) seconds and for entering the duodenum from the stomach was 20.5 (13.8–40.9), 18.2 (10.3–39.8), 20.2 (16.2–119.5), and 22.2 (11.8–83.8) seconds for H, HG, M, and B treatments, respectively. There were no significant differences in the time for, or difficulty of, endoscopy. We conclude that any of these drugs can be used satisfactorily at the doses and combinations tested to pre-medicate cats prior to general anesthesia for GD. [ABSTRACT FROM AUTHOR]

The use of spring-loaded mouth gags in cats can be associated with the development of central neurological deficits, including blindness. In this species, the maxillary arteries are the main source of blood supply to the retinae and brain. Spring-loaded gags generate constant force after placement that could contribute to bulging of the soft tissues between the mandible and the tympanic bulla. Under these circumstances, the maxillary arteries can become compressed as they course between these osseous structures. Smaller gags that might apply less force to the mouth were investigated to determine if they preserved maxillary artery blood flow. Six healthy adult cats were anesthetized. Electroretinography (ERG) and magnetic resonance angiography (MRA) were performed without the use of a mouth gag and during submaximal (plastic mouth gags of 20, 30 and 42 mm in length between canine teeth) and maximal mouth opening. Maximal mouth opening produced alterations in ERG waveforms consistent with circulatory compromise in 1/6 cats and reductions in signal intensity during MRA in 4/6 cats. Placement of a 42 mm plastic gag produced a reduction in MRA signal in 1/6 cats. No changes were observed with smaller gags. The force applied against the mouth was significantly higher with the spring-loaded gag than with any other gags. The use of a smaller mouth gags was associated with fewer alterations of indicators of maxillary artery blood flow. Nevertheless, a 42 mm plastic gag, equivalent to the size of a needle cap, resulted in an abnormal MRA in one cat., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The mouth-gag is a common tool used in veterinary medicine during oral and transoral procedures in cats but its use has recently been associated with the development of blindness. The goal of this study was to investigate whether maximal opening of the mouth affects maxillary artery blood flow in six anesthetized cats. To assess blood flow, the electroretinogram (ERG), brainstem auditory evoked response (BAER) and magnetic resonance angiography (MRA) were evaluated qualitatively with the mouth closed and open. During dynamic computer tomography (CT) examinations, detection of contrast medium in the maxillary artery was quantified by measuring the Hounsfield units (HUs). The peak HU, time to peak and mean HU were determined. Changes ⩾10% of these parameters were considered indicative of altered blood flow. ERG and BAER were normal with the mouth closed in all cats, but was abnormal with the mouth opened maximally in two cats and one cat, respectively. During MRA, blood flow was undetected in either maxillary artery in one cat and reduced in the right maxillary artery in two cats, when the mouth was open. During CT, the peak HU decreased ⩾10% in three cats, the time to peak was ⩾10% longer in two cats, and the mean HU was ⩾10% lower in one cat when the mouth was open. No cat developed apparent blindness or deafness. Maximal opening of the mouth caused alterations in several indicators of blood flow in some individual cats., (Copyright © 2013. Published by Elsevier Ltd.)

Objective: To test whether partial pressure of CO2 in expired gas (PĒCO2) predicts the partial pressure of CO2 in arterial blood (PaCO2) in apneic chickens during air sac insufflation anesthesia at three different ventilation states., Secondary Objective: To determine the PĒCO2 at which apnea occurs during air sac insufflation anesthesia., Study Design: Randomized cross-over study., Animals: Twenty-three healthy male white leghorn chickens., Methods: Chickens were anesthetized via mask with isoflurane in oxygen and an air sac cannula was placed in the right abdominal air sac. Delivery of isoflurane in O2 was transferred from the mask to the air sac cannula. The birds were maintained at a surgical plane of anesthesia and apnea was induced by adjusting gas flow; the PĒCO2 at apnea was recorded. The birds were then paralyzed and gas flow was adjusted to achieve three different PĒCO2 s in random order: 43 mmHg (5.6 kPa) [hypoventilation]; 33 mmHg (4.3 kPa) [normoventilation]; and 23 mmHg (3.0 kPa) [hyperventilation]. After maintaining the target expired isoflurane concentration (EIso; 1.85 or 1.90%) and PĒCO2 for 15 minutes, arterial blood gas analysis was performed to determine the PaCO2 . The chickens were euthanized at the end of the experiment., Results: Based on Bland-Altman comparisons, PĒCO2 was not strongly associated with PaCO2 during the three ventilation states. The PĒCO2 at which apnea occurred varied {median (minimum, maximum): 35 (30, 48) mmHg [4.6 (3.9, 6.2) kPa]}., Conclusions: Measured PĒCO2 cannot be used in a simple linear fashion to predict PaCO2 in birds during air sac insufflation anesthesia. The PĒCO2 at which apnea occurs during air sac insufflation anesthesia is not predictable., Clinical Relevance: Arterial blood gases should be used to monitor CO2 during air sac insufflation anesthesia to verify appropriate patient ventilation., (© 2013 The Authors. Veterinary Anaesthesia and Analgesia © 2013 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.)

History: Ten dogs weighing 36 (21.4-75) kg [median (min-max)] and aged 3 (1-9) years scheduled for orthopedic surgery involving the stifle and structures distal to it., Physical Examination: Patients were classified as ASA I or II based on physical examination and basic hematology and biochemistry., Management: Each dog was managed using combined femoral and sciatic nerve blocks and procedural sedation with an intravenous infusion of propofol (0.07-0.15 mg kg(-1) minute(-1)) and dexmedetomidine (1 μg kg(-1) hour(-1)). None of the patients required conversion to general anesthesia as a result of response to surgical stimulation. The level of sedation was considered adequate in all patients and was characterized by occasional head lifting, thoracic limb stretching, yawning, lingual movements and swallowing. The eye position ranged from central to partial ventromedial rotation and was accompanied by spontaneous blinking. Intra-operative cardiovascular and ventilatory variables were considered within acceptable limits. Muscle relaxation at the surgical field was adequate and surgical conditions were indistinguishable from those produced by general anesthesia. Intraoperatively, no additional analgesics were considered necessary. The quality of the recoveries was considered excellent in all cases., Follow Up: No additional pain relief was required in any of the dogs within the 10 hours following blockade. All dogs ate 5.5 (3.5-12) hours after recovery. Ambulation occurred at 4 (2-6) hours. No evidence of esophagitis or aspiration pneumonitis has been reported during a period of 1 year after the procedures in any of the dogs., Conclusion: When combined with femoral and sciatic nerve blocks, procedural sedation has the potential of being an alternative to general anesthesia for orthopedic surgery involving the stifle and structures distal to it in the dog., (© 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.)

Objective: To evaluate the efficacy of combined femoral and sciatic nerve blocks as an alternative to epidural anesthesia and analgesia in dogs undergoing stifle surgery under general anesthesia., Study Design: Prospective, blinded, randomized, clinical comparison., Animals: Twenty dogs weighing 37 ± 11 (mean ± SD) kg, aged 3 (1-8) [median (minimum-maximum)] years undergoing elective unilateral tibial-plateau leveling osteotomy., Methods: Dogs were assigned randomly to receive either epidural anesthesia (bupivacaine 0.5%, 0.5 mg kg(-1) + morphine 0.1%, 0.1 mg kg(-1), in 0.2 mL kg(-1); EPID) or femoral and sciatic nerve blocks (Bupivacaine 0.5%, 0.1 mL kg(-1), was administered at each site; F + S) guided by electrolocation. All patients received a standard general anesthesia technique. Pain and sedation were scored (on scales of 0-10 and 0-3, respectively) pre-operatively, at extubation, and at 1, 4 and then every 4 hours thereafter up to 24 hours. Postoperatively, hydromorphone was administered to any patient with a pain score of >5 or whenever the blinded caregiver determined that more hydromorphone was necessary. Intraoperative heart rate (HR), mean arterial pressure (MAP), end tidal isoflurane (FE'ISO), body temperature, post-operative pain scores, time to first hydromorphone dose after surgery, time to first feeding, time to first drinking, time to first urination, time to first ambulation (walk on a lead) and cumulative dose of hydromorphone were recorded., Results: Intra-operatively, FE'ISO and MAP were significantly lower in the EPID group (p = 0.05 and p = 0.04, respectively). Postoperatively, the cumulative hydromorphone consumption (p = 0.04) and the incidence of urinary retention (p = 0.03) were higher in the EPID group., Conclusion and Clinical Relevance: F + S is a practical alternative to EPID that produces less urine retention and reduces opioid consumption in the 24 hours after surgery. EPID might be associated with a lower isoflurane requirement and lower systemic blood pressure., (© 2011 The Authors. Veterinary Anaesthesia and Analgesia. © 2011 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.)

Objective: To determine the effect of ondansetron on the incidence of vomiting in cats pre-medicated with dexmedetomidine and buprenorphine., Study Design: Randomized, blinded, controlled trial., Animals: Eighty-nine female domestic shorthair cats, aged 3-60 months (median, 12 months) and weighing 1.2-5.1 kg., Methods: Each cat received dexmedetomidine (40 μg kg(-1)) plus buprenorphine (20 μg kg(-1)), intramuscularly as pre-anesthetic medication. Cats were assigned to three treatment groups: ondansetron (0.22 mg kg(-1), intramuscular [IM]), either 30 minutes before the pre-anesthetic medication (ONDA group, n = 31) or with the pre-anesthetic medication (OPM group, n = 30) mixed with the pre-anesthetic medications in the same syringe, or not to receive the antiemetic (control group, n = 28). Emesis was recorded as an all-or-none response. The number of episodes of emesis and the time until onset of the first emetic episode were recorded for each cat. Clinical signs of nausea were recorded whenever they occurred, and a numerical rating scale was used to quantify these signs. Data were analyzed using Kruskal-Wallis and Chi-square test; a Bonferroni correction was made for six comparisons; thus, the two-sided p for significance was 0.05/6 = 0.008., Results: There was a significant reduction in the number of cats vomiting, in the episodes of vomiting/cat, the time elapsed between the premedication and the first vomiting and the severity of nausea in the OPM group compared to the ONDA and control groups., Conclusions and Clinical Relevance: In cats, the administration of ondansetron (0.22 mg kg(-1)) ameliorates and reduced the severity of dexmedetomidine-induced nausea and vomiting only when it was administered in association with this drug., (© 2011 The Authors. Veterinary Anaesthesia and Analgesia. © 2011 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.)

The objective of this prospective observational cohort study in free-ranging female white-tailed deer (Odocoileus virginianus) was to compare the physiologic effects of two methods of anesthetic drug administration: hand-injection in Clover traps and remote injection by dart after ground-stalking. Six trapped and 14 darted female deer were injected with a median (minimum, maximum) of 590 microg/kg butorphanol (401, 1070 microg/kg), plus 235 microg/kg medetomidine (160, 429 microg/kg) intramuscularly. In the trap, the deer struggled when approached and were restrained for injection. Darted deer sprinted away after injection. Once immobilized, deer were transported to a veterinary hospital where blood was collected and vital signs were measured on admission. Admission data from a subset of deer in which measurements were taken within 40 min of trapping (n = 6) or darting (n = 5) were analyzed. After salpingectomy under isoflurane and while still anesthetized, another blood sample was collected from all 20 deer. Body weight and immobilization drug doses were not different between groups. On admission, most deer from both groups were hypoxemic, although the darted deer were significantly more hypoxemic. The median rectal temperature in trapped deer was higher than in darted deer, and temperatures higher than 39 degrees C only occurred in trapped deer. The median heart rate in trapped deer was more than twice that in darted deer. Trapped deer had lower median pH and base excess; in trapped deer, the median plasma lactate concentration was more than fivefold higher than in darted deer. After surgery, the median serum creatine kinase concentration was nearly 10-fold higher in trapped deer, and the median cardiac troponin I concentration was higher in trapped deer but undetectable in 10 of 14 darted deer. The white-tailed deer immobilized by hand-injection in Clover traps experienced more severe physiologic perturbations than deer remotely injected by dart after ground-stalking. These perturbations might be sufficient to cause myocardial damage.

Objective: To determine whether dogs that received eyedrops containing phenylephrine and scopolamine would have a higher mean arterial blood pressure (MAP) when anesthetized than would dogs that did not receive the eyedrops., Animals: 37 nondiabetic and 29 diabetic dogs anesthetized for phacoemulsification and 15 nondiabetic dogs anesthetized for corneal ulcer repair (control dogs)., Procedures: Medical records were reviewed to identify study dogs. Dogs undergoing phacoemulsification received 2 types of eyedrops (10% phenylephrine hydrochloride and 0.3% scopolamine hydrobromide) 4 times during a 2-hour period prior to the procedure. Control dogs did not receive these eyedrops. Heart rate and MAP were measured before surgery in all dogs 10 and 5 minutes before, at the time of (t0), and 5 (t5) and 10 (t10) minutes after atracurium administration., Results: MAP was greater in the 2 groups that received the eyedrops than in the control group at t0 and t5; at t10, it was greater only for the nondiabetic dogs that received eyedrops. Nine nondiabetic dogs and 1 diabetic dog anesthetized for phacoemulsification had at least 1 MAP value>131 mm Hg; 73% of MAP values>131 mm Hg were detected within 10 minutes after atracurium administration. At no time did a control dog have an MAP value>131 mm Hg., Conclusions and Clinical Relevance: Anesthetized dogs pretreated with eyedrops containing phenylephrine and scopolamine had higher MAP values than dogs that did not receive the eyedrops, suggesting the drops caused hypertension. Atracurium may interact with the eyedrops and contribute to the hypertension.

Objective: To determine if buprenorphine plus dexmedetomidine administered via the oral transmucosal route produces sufficient sedation in cats so that students can insert intravenous catheters., Study Design: Prospective, randomized, blinded, clinical trial., Animals: Eighty-seven shelter-owned female cats aged 4-48 months, weighing 1.1-4.9 kg., Methods: Cats were randomly allocated to two treatment groups based on route of drug administration: oral transmucosal (OTM), or intramuscular (IM). Buprenorphine (20 microg kg(-1)) plus dexmedetomidine (20 microg kg(-1)) were administered as pre-medicants via one of these two routes. Prior to and 20 minutes after drug administration, heart and respiratory rates, systolic arterial pressure, and posture were measured and recorded. Twenty minutes after drug administration the same variables plus each cat's response to clipper sound, clipping, and restraint were recorded; higher scores indicated more sedation., Results: There were no significant differences between the two groups prior to pre-medication. Within each treatment group heart rate was significantly lower 20 minutes after treatment, but it did not differ significantly between the two groups. Twenty minutes after treatment, respiratory rate was significantly less in the OTM group, but did not differ significantly between the two groups. Systolic arterial pressure did not differ within or between the two groups at either time. Scores for posture increased significantly within both groups, and cats in the IM group had higher scores after treatment. Twenty minutes after treatment, cats in the IM group had higher scores for clipping and restraint than OTM cats. Ketamine (IM) was necessary to facilitate catheterization in 25% and 16% of cats in the OTM and IM groups, respectively, but this was not significantly different., Conclusions and Clinical Relevance: Administration of dexmedetomidine plus buprenorphine by the OTM route is easy to perform, but produces less sedation than the IM route for IV catheterization in cats.

Objective: To determine if horses before undergoing anesthesia for surgical correction of colic would have lower plasma arginine vasopressin (AVP) concentrations than healthy horses undergoing anesthesia for arthroscopic surgery, and would not increase their plasma AVP concentrations in response to anesthesia and surgery., Design: Prospective clinical study., Setting: University teaching hospital., Animals: Fourteen horses with colic and 8 healthy horses., Interventions: Horses with colic underwent anesthesia and surgery for alleviation of colic, and healthy horses underwent anesthesia and surgery for arthroscopy., Measurements and Main Results: Plasma AVP was measured perioperatively in horses with colic and in healthy horses. Before anesthesia, and 30 and 60 minutes after induction, horses with colic had greater median plasma AVP concentrations than control horses (P

Objective: To describe the pharmacokinetics of pregabalin in normal dogs after a single oral dose., Study Design: Prospective experiment., Animals: Six adult Labrador/Greyhound dogs (four females and two males) aged 2.6 (2.6-5.6) years old (median and range) weighing 33.4 (26.8-42.1) kg., Methods: After jugular vein catheterization, the dogs received a single oral dose of pregabalin ( approximately 4 mg kg(-1)). Blood samples were collected at: 0 (before drug administration), 15 and 30 minutes and at 1, 1.5, 2, 3, 4, 6, 8, 12, 24 and 36 hours after drug administration. Plasma pregabalin concentration was measured by HPLC. Noncompartmental analysis was used to estimate pharmacokinetic variables., Results: No adverse effects were observed. The median (range) pharmacokinetic parameters were: Area under the curve from time 0 to 36 hours = 81.8 (56.5-92.1) microg hour mL(-1); absorption half-life = 0.38 (0.25-1.11) hours; elimination half-life = 6.90 (6.21-7.40) hours; time over 2.8 microg mL(-1) (the presumed minimal effective concentration) = 11.11 (6.97-14.47) hours; maximal plasma concentration (C(max)) = 7.15 (4.6-7.9) microg mL(-1); time for C(max) to occur = 1.5 (1.0-4.0) hours. Assuming an 8-hour dosing interval, predicted minimal, average, and maximal steady state plasma concentrations were 6.5 (4.8-8.1), 8.8 (7.3-10.9), and 13.0 (8.8-15.2) microg mL(-1). The corresponding values assuming a 12-hour interval were 3.8 (2.4-4.8), 6.8 (4.9-7.9), and 10.1 (6.6-11.6) microg mL(-1)., Conclusions and Clinical Relevance: Pregabalin 4 mg kg(-1) PO produces plasma concentrations within the extrapolated therapeutic range from humans for sufficient time to suggest that a twice daily dosing regime would be adequate. Further study of the drug's safety and efficacy for the treatment of neuropathic pain and seizures in dogs is warranted.

Objective: To compare the analgesic efficacy of buprenorphine plus detomidine with that of morphine plus detomidine when administered epidurally in horses undergoing bilateral stifle arthroscopy., Study Design: Prospective, randomized, blinded clinical trial., Animals: Twelve healthy adult horses participating in an orthopedic research study. Group M (n = 6) received morphine (0.2 mg kg(-1)) and detomidine (0.15 mg kg(-1)) epidurally; group B (n = 6) received buprenorphine (0.005 mg kg(-1)) and detomidine (0.15 mg kg(-1)) epidurally., Methods: Horses received one of two epidural treatments following induction of general anesthesia for bilateral stifle arthroscopy. Heart rate (HR), mean arterial blood pressure (MAP), end-tidal CO(2) (Pe'CO(2)), and end-tidal isoflurane concentrations (E'Iso%) were recorded every 15 minutes following epidural administration. Post-operative assessment was performed at 1, 2, 3, 6, 9, 12, and 24 hours after standing; variables recorded included HR, respiratory rate (f(R)), abdominal borborygmi, defecation, and the presence of undesirable side effects. At the same times post-operatively, each horse was videotaped at a walk and subsequently assigned a lameness score (0-4) by three ACVS diplomates blinded to treatment and who followed previously published guidelines. Nonparametric data were analyzed using Wilcoxon's rank-sum test. Inter- and intra-rater agreement were determined using weighted kappa coefficients. Statistical significance was set at p

Objective: To determine the influence on the distribution of the volume of a local anaesthetic-methylene blue solution at three different nerve block sites in the dog., Study Design: Randomized, controlled, blinded experimental trial., Animals: 23 hound-cross dogs weighing 16-40 kg and aged 2 +/- 0 years (mean +/- SD)., Methods: Dogs were anaesthetized and randomly assigned to three groups of seven or eight dogs each, based on volume administered: low, medium and high volume (L, M and H). Using electrolocation, the injection was performed after a positive response was elicited (flexion of the elbow for the brachial plexus block, quadriceps contractions for the lumbar plexus and dorsiflexion/plantar extension of the foot for the sciatic nerve block). At the brachial plexus site, groups L, M and H received 0.075, 0.15 and 0.3 mL kg(-1), respectively. At the lumbar plexus site, groups L, M and H received 0.1, 0.2 and 0.4 mL kg(-1), respectively. At the proximal sciatic nerve site, groups L, M and H received 0.05, 0.1 and 0.25 mL kg(-1), respectively. Necropsies were performed immediately following euthanasia. Staining of > or =2 cm along the nerve was considered sufficient; the proportions sufficient were compared with Fisher's exact test. The volume was recommended when all the relevant nerves were stained sufficiently in all or all but one of the dogs within the group., Results: In the brachial plexus, only in group H were all the nerves stained sufficiently. In the lumbar plexus site, no statistical difference was found, but we suggest the H group volume to balance sufficient and excessive staining. At the sciatic nerve site, all volumes tested produced sufficient staining in all (or all but one) dogs., Conclusions and Clinical Relevance: Volumes of 0.3 and 0.05 mL kg(-1) produced sufficient distribution for performing brachial plexus, and sciatic nerve blocks, respectively. Additionally, a volume of 0.4 mL kg(-1) might also be adequate for a lumbar plexus block (no statistical significance was reached).

Objective: To compare acceleromyography (AMG) with visual assessment of train-of-four (TOF) for monitoring neuromuscular blockade and detecting residual muscle paralysis in horses receiving atracurium., Study Design: Prospective, controlled clinical study., Animals: Nine adult, client-owned horses weighing 577 (436, 727) kg (median, minimum, maximum) and ASA physical status I-II, admitted for surgery., Methods: An electrical nerve stimulator was used to stimulate the peroneal nerve with TOFs at 1 minute intervals. Before and after atracurium administration (0.15 mg kg(-1), IV), the number of twitches observed (TOF count, or TOFc) was assessed visually. When four twitches were seen (i.e., TOFc = 4) presence or absence of fade by visual assessment was recorded. Simultaneously, the response to each TOF was assessed by AMG; this measured TOFc, and twitch fade using TOF ratio (TOFR; ratio of fourth to first twitch). The anesthetist performing the visual evaluation was blinded to the AMG readings. Recovery from neuromuscular blockade was defined as the absence of fade by visual inspection or a TOFR > or =90% by AMG., Results: During onset of action of the drug, fade was first detected 4 (1, 8) minutes earlier by AMG (p = 0.008). Maximal blockade started at 6 (3, 17) minutes by visual assessment and 9 (3, 25) minutes by AMG (not significantly different). Only four horses achieved complete neuromuscular blockade (TOFc of zero by both methods); in those four horses AMG did not detect the start of the return of neuromuscular transmission before visual assessment. Visual assessment indicated the return of four twitches with no fade 12 (8, 42) minutes before AMG gave a TOFR of > or =90% (p = 0.004)., Conclusion and Clinical Relevance: There was no substantial advantage for AMG in detecting the onset of atracurium-induced neuromuscular blockade. However, AMG detected residual blockade when visual assessment of TOF did not. Application of AMG is likely to reduce the incidence of residual blockade.

Objective: To determine the effects of adenosine infusion on the minimum alveolar concentration (MAC) of isoflurane in dogs., Study Design: Prospective, randomized crossover study., Animals: Seven adult male and female Beagles weighing 10.9 (7.5, 13.6) kg [median (minimum, maximum)]., Methods: Each dog was anesthetized with isoflurane in oxygen and randomly assigned to receive either an intravenous (IV) adenosine (0.3 mg kg(-1) minute(-1)) or saline (6 mL kg(-1) hour(-1) IV) infusion. After an interval of 7 days or more, each dog was re-anesthetized and treated with the alternative infusion. Using a tail-clamp technique, MAC was determined before (pre-infusion), during (infusion), and 2 hours after the infusions (post-infusion)., Results: The pre-infusion MAC of isoflurane was 1.25 (1.15, 1.35) [median (minimum, maximum)] vol.% for the saline treatment group and 1.25 (1.05, 1.45) vol.% for the adenosine treatment group, and did not differ significantly between the two treatments. The infusion MAC values were not significantly different (p = 0.16) and were 1.25 (0.95, 1.35) vol.% and 1.05 (1.00, 1.25) vol.%, respectively. The post-infusion MAC values differed significantly (p = 0.016); MAC was 1.15 (1.15, 1.35) vol.% and 1.05 (1.05, 1.25) vol.% for the saline and adenosine treatment groups, respectively. During infusion, mean arterial blood pressure decreased significantly (p = 0.008) during adenosine treatment compared with the saline 66 mmHg (52, 72) and 91 mmHg (68, 110), respectively. End-tidal CO2 (Pe'CO2), urine production, hematocrit, and plasma total solids did not differ significantly between the two treatments at any time (all p > 0.05)., Conclusion: Although the MAC of isoflurane in dogs was not decreased significantly during infusion with adenosine (0.3 mg kg(-1) minute(-1)), it was significantly decreased post-infusion, but only by 0.1 vol.%, an amount not considered clinically important. Adenosine infusion decreased mean arterial pressure by 27% and did not adversely affect renal function.

Objective: To assess whether administration of hydromorphone and, or ketamine are associated with post-anesthetic hyperthermia in cats undergoing routine surgery., Study Design: Prospective clinical study., Animals: Forty healthy, adult cats undergoing ovariohysterectomy (OVH), castration, or declaw surgery., Materials and Methods: Each cat was assigned randomly to one of four groups (n = 10). For pre-anesthetic medication, all cats received subcutaneous (SC) glycopyrrolate (0.01 mg kg(-1)) and acepromazine (0.02 mg kg(-1)) and either hydromorphone (0.1 mg kg(-1) SC) or medetomidine (7.5 microg kg(-1) SC). Anesthesia was induced with either diazepam (0.1 mg kg(-1)) and ketamine (5 mg kg(-1)) or propofol (6 mg kg(-1) injected to effect). Group 1 (HDK) received hydromorphone and diazepam-ketamine. Group 2 (HP) received hydromorphone and propofol. Group 3 (MDK) received medetomidine and diazepam-ketamine. Group 4 (MP) received medetomidine and propofol. Rectal temperature was measured before drugs were given, at tracheal extubation and at hourly intervals for 5 hours thereafter., Results: During the 5 hours after anesthesia and surgery, at least one cat in every group had a rectal temperature >39.2 degrees C (102.5 degrees F). The percentage of observations for which a cat's temperature exceeded its pre-anesthetic temperature in groups HDK, HP, MDK, and MP were 86%, 80%, 25%, and 34%, respectively. Maximum temperatures in groups HDK, HP, MDK, and MP were 41.6 degrees C (107.0 degrees F), 40.3 degrees C (104.2 degrees F), 39.2 degrees C (102.6 degrees F), and 40.1 degrees C (104.1 degrees F), respectively. By 5 hours after tracheal extubation there were no differences in temperature between the treatment groups., Conclusion: For up to 5 hours following anesthesia and surgery, cats might have body temperatures that exceed their pre-anesthesia body temperatures. The use of hydromorphone is associated with post-anesthetic hyperthermia. However, hyperthermia may occur when other drugs are used., Clinical Relevance: Cats given hydromorphone should be closely monitored for hyperthermia following anesthesia and surgery.

Objective: To evaluate whether a synthetic analogue of feline facial pheromone (FFP) calms cats before, and reduces struggling during intravenous catheterization., Design: Block-randomized, 'blinded' clinical trial., Animals: Seventy-seven healthy cats presented for elective surgery., Procedure: Cats given glycopyrrolate and oxymorphone were assigned to one of four treatments: acepromazine and exposure to FFP (aceFFP); acepromazine and exposure to a placebo (acePlac); exposure to FFP only (FFP) and exposure to placebo only (Plac). The behaviour of cats was recorded on videotape for evaluation by assessors unaware of treatment group. Cats' veins were then catheterized by veterinary students unaware of the study protocol. Based on each cat's response to catheterization, the student independently decided whether intramuscular ketamine was required., Results: Cats in the aceFFP group appeared to be calmer than acePlac cats on the basis of head position and their location in the cage (suggesting benefit from FFP among cats receiving acepromazine) but appeared to be less sedated. Cats in the aceFFP group also appeared to be calmer than FFP cats on the basis of head position and location in the cage. Feline facial pheromone cats were also calmer than Plac cats when compared using body and leg position. Exposure to FFP did not significantly reduce struggling at catheterization, nevertheless, the students were able to catheterize the veins in all cats., Conclusion and Clinical Relevance: There were no detrimental behavioural effects associated with either FFP or acepromazine. The FFP had additional calming effects in cats given acepromazine and, to a lesser degree, helped to calm cats that were not given acepromazine. Feline facial pheromone helps to calm cats in unfamiliar surroundings.

Objective: To determine whether a laryngeal mask airway (LMA) provides a better airway than a facemask in spontaneously breathing anesthetized rabbits, and to test if it can be used for mechanically controlled ventilation., Study Design: Randomized prospective experimental trial., Animals: Sixteen young, healthy, specific pathogen-free Giant Flemish cross Chinchilla rabbits (10 females and 6 males) weighing 4.1 +/- 0.8 kg., Methods: Rabbits were assigned randomly to one of three treatment groups: facemask with spontaneous ventilation (FM-SV; n = 5), LMA with spontaneous ventilation (LMA-SV; n = 5), and LMA with controlled ventilation (LMA-CV; n = 6). In dorsal recumbency, and at 2.3% end-tidal isoflurane concentration, Fé isoflurane, Fi isoflurane, partial pressure of expired isoflurane (PECO(2)), partial pressure of inspired carbon dioxide (PiCO(2)), heart rate, respiratory rate, minute volume, arterial oxygen tensions (PaO(2)), arterial carbon dioxide tensions (PaCO(2)), arterial pH (pH(a)), arterial standard base excess (SBE(a)) values were measured for 120 minutes. Results Two individuals in the FM-SV group had PaCO(2) > 100 mm Hg. One rabbit in the FM-SV had PaO(2) < 80 mm Hg. All FM-SV rabbits showed signs of airway obstruction, and two were withdrawn from the study at 45 and 90 minutes, respectively, because cyanosis was observed. No signs of airway obstruction were observed in either LMA group. Four rabbits in the LMA-CV group developed gastric tympanism, one of which refluxed gastric contents after 110 minutes. There were no differences between FM-SV and LMA-SV in any variable tested. PaCO(2) and PECO(2) were decreased, while PaO(2) and minute volume were increased in the LMA-CV group compared to the LMA-SV group., Conclusions: An LMA provided a better airway than a facemask during spontaneous breathing in rabbits, as the use of a facemask was associated with hypercapnia and low partial pressures of oxygen. Although an LMA can be used for intermittent positive pressure ventilation (IPPV), gastric tympanism may develop, especially at a peak inspiratory pressure of 14 cm H(2)O., Clinical Relevance: The LMA can be used in rabbits but further work is needed before it is applied routinely.

Objective: To evaluate the effects of hydromorphone, hydromorphone and glycopyrrolate, medetomidine, and butorphanol premedication on the difficulty and time required to pass an endoscope into the stomach and duodenum of cats anesthetized with ketamine and isoflurane., Design: Randomized complete block crossover study., Animals: 8 purpose-bred adult female cats., Procedures: Each cat was premedicated and anesthetized 4 times with an interval of at least 7 days between procedures. Cats were premedicated with hydromorphone, hydromorphone and glycopyrrolate, medetomidine, or butorphanol administered IM. Twenty minutes after premedication, sedation was assessed by use of a subjective ordinal scale. Cats received ketamine administered IM, and 10 minutes later a cuffed orotracheal tube was placed and anesthesia maintained with isoflurane. Cats breathed spontaneously throughout the procedure. When end-tidal isoflurane concentration was stable at 1.4% for 15 minutes, endoscopy was begun. The times required to pass the endoscope through the cardiac and pyloric sphincters were recorded, and the difficulty of endoscope passage was scored by use of a subjective ordinal scale., Results: No significant differences in difficulty or time required to pass the endoscope through the cardiac and pyloric sphincters were found among premedicant groups. Premedication with medetomidine resulted in the greatest degree of sedation and longest time to return to sternal recumbency., Conclusions and Clinical Relevance: Results suggest that hydromorphone, hydromorphone and glycopyrrolate, medetomidine, and butorphanol at the doses tested can be used satisfactorily to premedicate cats prior to general anesthesia for gastroduodenoscopy.

Objective: To determine accuracy and precision of a point-of-care hemoglobinometer for measuring hemoglobin concentration and estimating PCV in horses., Design: Prospective trial., Animals: 55 horses., Procedure: Blood samples were obtained from 43 horses examined at a veterinary teaching hospital. Hemoglobin concentration was measured with the hemoglobinometer and by means of the standard cyanmethemoglobin method; PCV was measured by centrifugation. Blood samples were also obtained from 12 healthy horses, and PCV of aliquots of these samples was altered to approximately 5 to 80% by removing or adding plasma. Hemoglobin concentration and PCV were then measured., Results: For samples from the clinic patients, hemoglobin concentrations obtained with the hemoglobinometer were less than concentrations obtained with the cyanmethemoglobin method; however, there was a linear relationship between concentrations obtained with the 2 methods. Breed, sex, body weight, and duration of sample storage did not significantly affect the difference between hemoglobin concentrations obtained with the 2 methods. There was a significant linear relationship between PCV and hemoglobinometer hemoglobin concentration (PCV = [2.83 x hemoglobin concentration] - 0.62). For samples from the healthy horses, a substantial negative bias was evident with the hemoglobinometer when hemoglobin concentration exceeded 16 g/dL., Conclusions and Clinical Relevance: Results suggest that this hemoglobinometer is reasonably accurate and precise when used to measure hemoglobin concentration in blood samples from horses with a hemoglobin concentration < 16 g/dL.

Objective: To determine whether preoperative epidural administration of morphine and detomidine would decrease postoperative lameness after bilateral stifle arthroscopy in horses., Study Design: Prospective clinical controlled study., Animals: Eight adult horses that had bilateral arthroscopic procedures, including drilling of cartilage and subchondral bone within the femoropatellar joints., Methods: Horses were randomly separated into 2 groups. Preoperatively, 4 horses were administered a combination of epidural morphine (0.2 mg/kg) and detomidine (30 microg/kg), and 4 horses were administered an equivalent volume of epidural saline (0.9% NaCl) solution. Postoperative pain was assessed using 6 video recordings made at hourly intervals of each horse at a walk. Assessments began 1 hour after recovery from anesthesia. The recordings were scrambled out of sequence and evaluated by 3 observers, unaware of treatment groups, who scored lameness from 0 to 4. Lameness scores of the 2 groups of horses were compared using a Wilcoxon's rank sum test. Heart and respiratory rates were also measured at each hourly interval and compared between groups using a repeated-measures ANOVA; statistical significance was set at P <.05., Results: Preoperative administration of epidural morphine and detomidine significantly decreased lameness and heart rates after bilateral stifle arthroscopy. The greatest decrease was detected at hours 1 and 2 after recovery from anesthesia., Conclusion: We conclude that horses undergoing a painful arthroscopic procedure of the stifle joint benefit from the administration of preoperative epidural morphine and detomidine., Clinical Relevance: Preoperative epidural administration of detomidine and morphine may be useful in decreasing postoperative pain after stifle arthroscopy as well as pain associated with other painful disorders involving the stifle joint, such as septic arthritis and trauma., (Copyright 2002 by The American College of Veterinary Surgeons)

Florida sandhill cranes (Grus canadensis pratensis) were conditioned to confinement 6 hr/day for 7 days. On day 8, each bird's jugular vein was catheterized, blood samples were drawn, and each crane was confined for 6 hr. Using a randomized, restricted cross-over design, cranes were injected intravenously with either 0.9% NaCl solution or ACTH (cosyntropin; Cortrosyn; 0.25 mg). During the 6 hr of confinement, fecal samples (feces and urine) were collected from each of five cranes immediately after defecation. Individual fecal samples were collected approximately at hourly intervals and assayed for corticosterone. We showed previously that serum corticosterone did not vary significantly following saline injection, but peaked significantly 60 min after ACTH injection. Maximal fecal corticosterone concentrations (ng/g) were greater (P < 0.10; median 1087 ng/g) following ACTH stimulation compared to maximal fecal corticosterone concentrations at the end of acclimation (day 7; median 176) and following saline treatment (median 541). In cranes under controlled conditions, fecal corticosterone concentration reflects serum corticosterone levels, fecal corticosterone, Grus canadensis pratensis, sandhill cranes, serum corticosterone levels.

Understanding behavioral indicators of pain and other assessment techniques can help one to recognize pain in birds and prompt us to treat birds with analgesics. An analgesic plan needs to include several modalities to help reduce pain in the avian patient. Analgesic therapy should be directed at treating the disease/injury in the periphery, and the changes that occur in the central nervous system (CNS). Both opioid and nonsteroidal anti-inflammatory drug (NSAID) therapeutics can be selected to provide analgesia for the avian patient.

Objective: To determine hepatic effects of halothane and isoflurane anesthesia in young healthy goats., Design: Randomized prospective clinical trial., Animals: 24 healthy 9-month-old female goats., Procedure: Goats were sedated with xylazine hydrochloride and ketamine hydrochloride and anesthetized with halothane (n = 12) or isoflurane (12) while undergoing tendon surgery. End-tidal halothane and isoflurane concentrations were maintained at 0.9 and 1.2 times the minimal alveolar concentrations, respectively, and ventilation was controlled. Venous blood samples were collected approximately 15 minutes after xylazine was administered and 24 and 48 hours after anesthesia, and serum aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), alkaline phosphatase (ALP), and gamma-glutamyltransferase (GGT) activities and bilirubin concentration were measured. Goats were euthanatized 25 or 62 days after anesthesia, and postmortem liver specimens were submitted for histologic examination., Results: All goats recovered from anesthesia and survived until euthanasia. Serum SDH, GGT, and ALP activities and bilirubin concentration did not increase after anesthesia, but serum AST activity was significantly increased. However, serum hepatic enzyme activities were within reference limits at all times in all except 1 goat in which serum AST activity was high 24 and 48 hours after anesthesia. This goat had been anesthetized with halothane and had the longest duration of anesthesia. No clinically important abnormalities were seen on histologic examination of liver specimens., Conclusions and Clinical Relevance: Results suggest that use of halothane or isoflurane for anesthesia in young healthy goats is unlikely to cause hepatic injury.

Florida sandhill cranes (Grus canadensis pratensis) were conditioned to confinement in an enclosure for 7 days, 6 hr a day. On day 8, cranes were catheterized and then confined in an enclosure. Venous blood (2 ml) was collected through the catheter and an attached IV line immediately before (-60 min) and 60 min after (0 min) confinement. Using a randomization table and a restricted cross-over experimental design, cranes were injected intravenously with either saline (control) or adrenocorticotropic hormone (ACTH; cosyntropin, Cortrosyn; 0.25 mg). At 30, 60, 120, 180, 240 and 300 min after injection, blood samples were collected and assayed for corticosterone. The cranes receiving ACTH increased their serum corticosterone concentrations as much as fivefold above baseline concentrations. Serum corticosterone concentrations remained significantly elevated for approximately 60 min after ACTH stimulation. Physical restraint and catheterization caused an increase in serum corticosterone almost comparable to that induced by ACTH stimulation. In cranes injected with saline, serum corticosterone decreased within 1 hr after physical restraint and catheterization, and remained at lower levels throughout the remaining 5 hr of confinement.

Objective: To describe dogs undergoing cesarean section in the United States and Canada, to determine perioperative management, and to calculate survival proportions., Design: Multicenter prospective case series., Animals: 3,908 puppies from 808 dams., Results: Survival rates immediately, 2 hours, and 7 days after delivery were 92, 87, and 80%, respectively, for puppies delivered by cesarean section (n = 3,410) and 86, 83, and 75%, respectively, for puppies born naturally (498). For 614 of 807 (76%) litters, all puppies delivered by cesarean section were born alive. Maternal mortality rate was 1% (n = 9). Of 776 surgeries, 453 (58%) were done on an emergency basis. The most common breeds of dogs that underwent emergency surgery were Bulldog, Labrador Retriever, Boxer, Corgis, and Chihuahua. The most common breeds of dogs that underwent elective surgery were Bulldog, Labrador Retriever, Mastiff, Golden Retriever, and Yorkshire Terrier. The most common methods of inducing and maintaining anesthesia were administration of isoflurane for induction and maintenance (n = 266; 34%) and administration of propofol for induction followed by administration of isoflurane for maintenance (237; 30%)., Clinical Implications: Mortality rates of dams and puppies undergoing cesarean section in the United States and Canada are low. Knowledge of mortality rates should be useful to veterinarians when advising clients on the likelihood of puppy and dam survival associated with cesarean section.

Objective: To describe the effects of tromethamine, a putative treatment for metabolic acidosis, and to compare its biochemical effects with those of sodium bicarbonate., Design: Randomized intervention study with repeated measures., Animals: 16 healthy horses, 3 to 17 years old, weighing 391 to 684 kg., Methods: Ten horses received 3 mEq/kg tromethamine and six received 3 mEq/kg sodium bicarbonate. Samples of venous blood and cerebrospinal fluid (CSF) were collected at intervals before and after drug administration. Heart rate and breathing rate were also recorded at intervals., Results: Median standard base excess increased significantly (P < .05) from baseline immediately after both bicarbonate and tromethamine. These increases were not significantly different between treatments. Standard base excess returned toward baseline but remained significantly increased 3 hours after infusion of either treatment. After tromethamine, there was a significant decrease in plasma sodium concentration that lasted for at least 90 minutes. After sodium bicarbonate, no change in plasma sodium concentration was detected. Both sodium bicarbonate and tromethamine increased carbon dioxide tension in venous blood and CSF. Despite venous alkalemia, the pH of CSF decreased after both treatments., Conclusions: Tromethamine and sodium bicarbonate have similar alkalinizing ability. Tromethamine causes hyponatremia, whereas both tromethamine and sodium bicarbonate increase carbon dioxide tension in venous blood and CSF., Clinical Relevance: If hyponatremia, hypercarbia, and acidosis of the CSF occur after tromethamine is given to horses with existing metabolic acidosis, some of the potential advantages of tromethamine may prove theoretical rather than practical.

Background: Fentanyl is used in anesthetic protocols for swine, but there are no reports on its potency in this species. This study measured the extent to which fentanyl reduces the minimum alveolar concentration of isoflurane (MACISO) in swine., Methods: Sixteen swine were randomly assigned to four groups. For each group, baseline MACISO was determined, and three groups received two of three fentanyl infusions as follows: 50 micrograms.kg-1.h-1 intravenously followed by 100 micrograms.kg-1.h-1, 50 micrograms.kg-1.h-1 followed by 200 micrograms.kg-1.h-1, or 100 micrograms.kg-1.h-1 followed by 200 micrograms.kg-1.h-1 (n = 8 for each dosage). A loading dose of fentanyl preceded each infusion. Each infusion was maintained for 60 min before initiating minimum alveolar concentration determination. The infusions were maintained throughout the period of minimum alveolar concentration determination. Plasma fentanyl samples were obtained after 30 min of each infusion, and plasma fentanyl and hemodynamic parameters were obtained immediately before stimulating swine for the final isoflurane concentration used in determining minimum alveolar concentration. A fourth group, control animals, received saline infusions. After each infusion, the MACISO was redetermined. Minimum alveolar concentration was determined using incremental changes in isoflurane concentrations until gross purposeful movement resulted when using a hemostat stimulus applied for 1 min to a rear dewclaw., Results: MACISO for controls was 2.19 +/- 0.17% (mean +/- SEM) and changed minimally over time (-0.13 +/- 4.77%). MACISO decreased significantly (P < or = 0.01) 24.5 +/- 3.2%, 29.9 +/- 4.8%, and 45.9 +/- 5.5% with fentanyl dosages of 50, 100, and 200 micrograms.kg-1.h-1, respectively. Corresponding plasma fentanyl concentrations were 14 +/- 1 ng/ml, 26 +/- 3 ng/ml, and 59 +/- 5 ng/ml, respectively. A ceiling effect on reduction of MACISO was not observed. Changes over time or between groups were not observed for arterial blood gas tensions, blood pressure, heart and respiratory rate, or body temperature., Conclusions: These fentanyl dosages are larger than those commonly used in humans and other species. Anesthetic protocols using fentanyl for swine should be designed with the knowledge that a fentanyl infusion of 200 micrograms.kg-1.h-1 contributes approximately a 50% MACISO equivalent.

The haemodynamic effects of hyoscine-N-butylbromide (0.30 mg/kg, intravenously) were studied in eight adult ponies in a blinded two-period crossover experiment with repeated measures. Values for heart rate were 63%, 48% and 13% greater than control values at 1, 16 and 46 min, respectively, after administration of hyoscine-N-butylbromide. Cardiac output increased by 16% at 16 min after drug injection. Mean right atrial pressure was decreased by 79%, 63%, 45% and 52% at 1, 16, 46 and 61 min, respectively, after drug administration. Stroke volume was decreased by 32% at 1 min and pulmonary arterial wedge pressure was decreased by 44% at 16 min. We detected no significant difference in mean systemic arterial pressure, mean pulmonary arterial pressure, systemic vascular resistance or pulmonary vascular resistance at any time.

High fractions of inspired oxygen are commonly used during general anesthesia in birds. Observations in ducks anesthetized with halothane or pentobarbital indicated that high fractions of inspired oxygen depress ventilation. The purpose of this study was to test the hypothesis that ducks hypoventilate when breathing high fractions of inspired oxygen, compared with the same ducks breathing low fractions of inspired oxygen. Respiratory variables were recorded in 7 ducks anesthetized with 1.4% isoflurane in oxygen. Four concentrations of oxygen (21, 40, 70, and > 90%) were used for each duck. Respiratory rate decreased as the fraction of inspired oxygen increased, but not significantly. There was a significant decrease in tidal volume as PaCO2 increased. Hyperoxia was observed to contribute to hypoventilation in ducks anesthetized with isoflurane in oxygen.