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Background: We evaluated the use of lumbosacral epidural anaesthesia (LEA) in dogs undergoing caesarean section over 10 years., Methods: Anaesthetic records were reviewed and divided into two treatment groups: LEA and control. Outcome variables identified a priori as potentially affected by LEA were compared between groups. Results are frequency or median (minimum-maximum)., Results: Ninety-five dogs received LEA and 87 did not. LEA consisted of 0.2 (0.1-0.3) ml/kg containing bupivacaine (n = 63), ropivacaine (n = 15), or lidocaine (n = 12) at concentrations ranging between 0.06% and 2%. Morphine, fentanyl, or buprenorphine were used as part of LEA. Groups were similar for demographic variables (all p > 0.06). Intravenous opioids were used more often in control than in LEA (p < 0.0005). Incidence of hypotension (MAP < 60 mm Hg) was LEA 68% and control 56% (p = 0.12). Duration of hypotension was longer in LEA (p = 0.03). Use of crystalloids and vasoactive drugs did not differ (all p > 0.1). Time from induction to operating room was 30 (8-75) min for control and 35 (18-65) min for LEA (p = 0.003)., Discussion: LEA during caesarean section in dogs was associated with lower rates of opioid administration and did not exacerbate the incidence of hypotension., (© 2021 British Veterinary Association.)

Objective: To evaluate arterial oxygenation during the first 4 postoperative hours in dogs administered different fractions of inspired oxygen (FiO 2 ) during general anesthesia with mechanical ventilation., Study Design: Prospective, randomized clinical trial., Animals: A total of 20 healthy female dogs, weighing >15 kg and body condition scores 3-7/9, admitted for ovariohysterectomy., Methods: Dogs were randomized to breathe an FiO 2 >0.9 or 0.4 during isoflurane anesthesia with intermittent positive pressure ventilation. The intraoperative PaO 2 :FiO 2 ratio was recorded during closure of the linea alba. Arterial blood was obtained 5, 60 and 240 minutes after extubation for measurement of PaO 2 and PaCO 2 (FiO 2  = 0.21). Demographic characteristics, duration of anesthesia, PaO 2 :FiO 2 ratio and anesthetic agents were compared between groups with Wilcoxon tests. The postoperative PaO 2 , PaCO 2 , rectal temperature, a visual sedation score and events of hypoxemia (PaO 2 < 80 mmHg) were compared between groups with mixed-effects models or generalized linear mixed models., Results: Groups were indistinguishable by demographic characteristics, duration of anesthesia, anesthetic agents administered and intraoperative PaO 2 :FiO 2 ratio (all p > 0.08). Postoperative PaO 2 , PaCO 2 , rectal temperature or sedation score were not different between groups (all p > 0.07). During the first 4 postoperative hours, hypoxemia occurred in three and seven dogs that breathed FiO 2 >0.9 or 0.4 during anesthesia, respectively (p = 0.04)., Conclusions and Clinical Relevance: The results identified no advantage to decreasing FiO 2 to 0.4 during anesthesia with mechanical ventilation with respect to postoperative oxygenation. Moreover, the incidence of hypoxemia in the first 4 hours after anesthesia was higher in these dogs than in dogs breathing FiO 2 >0.9., (Copyright © 2020 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Objective: To assess the ability to visually detect fade during train-of-four (TOF) or double burst stimulation (DBS) in anesthetized dogs recovering from nondepolarizing neuromuscular block., Study Design: Online anonymous survey., Population: Data from 112 participants., Methods: A web-based survey containing 12 videos of the response to ulnar nerve stimulation with TOF and 12 with DBS obtained at different levels of recovery from rocuronium-induced block was distributed to participants of the American College of Veterinary Anesthesia and Analgesia and the Academy of Veterinary Technicians in Anesthesia and Analgesia e-mail lists. Participants were asked to provide their highest training degree in anesthesiology, watch each video no more than twice, and determine whether fade was present. The probability to correctly recognize fade was calculated using binomial general linear models. General linear models and Tukey's tests were used to assess the effects of level of neuromuscular block, pattern of stimulation, and observers' training on the probability to detect fade., Results: The survey was completed by 53 diplomates, 29 licensed veterinary technicians, 24 residents and six doctors of veterinary medicine (DVMs). The probability to detect fade decreased as partial neuromuscular block became more shallow (p < 0.0001). A TOF or DBS ratio of 0.7 had a 50% chance of being detected. DBS was superior to TOF for detecting fade when the ratio was 0.3-0.69. TOF was superior to DBS when the ratio was 0.7-0.9 (p < 0.0001). There were no differences among groups of observers when assessing fade with TOF or DBS., Conclusions and Clinical Relevance: Detection of fade from observations of the response to TOF in dogs is unreliable. Advance training in anesthesiology or the use of DBS confers little to no advantage for this subjective test., (Copyright © 2019 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

OBJECTIVE To evaluate the effects of 2 fractions of inspired oxygen (Fio 2 s) during anesthesia on postanesthesia Pao 2 and other measures of oxygen exchange. ANIMALS 22 healthy adult sexually intact female dogs undergoing ovariohysterectomy by ventral midline celiotomy. PROCEDURES Dogs were randomly assigned to receive either oxygen (Fio 2 > 0.9 [100% oxygen]; n = 11; control group) or a mixture of nitrogen and oxygen (Fio 2 = 0.4; 11; 40% oxygen group) as the carrier gas for isoflurane while anesthetized. All dogs were allowed to breathe spontaneously while anesthetized. For each dog, the Pao 2 , Paco 2 , other indices of oxygenation, and extent of sedation were monitored at predetermined times during and for 1 hour after anesthesia. Measured variables were compared between the 2 treatment groups and over time within each treatment group. RESULTS None of the measured variables differed significantly between the control and 40% oxygen groups at any time during the postanesthesia period. Within each treatment group, the Paco 2 and extent of sedation decreased over time during the postanesthesia period. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that indices of oxygenation did not differ significantly between healthy dogs in which the Fio 2 was maintained at > 0.9 and those in which the Fio 2 was maintained at 0.4 while anesthetized for ovariohysterectomy. Thus, the addition of nitrogen to the carrier gas for an inhalant anesthetic conferred neither an advantage nor disadvantage in regard to oxygenation during the first hour of anesthesia recovery.

Objective: Quantitative neuromuscular monitoring is essential for studies of potency and duration of neuromuscular blocking agents, and for detecting residual paralysis in anesthetized patients. This investigation evaluates whether there are systematic differences between acceleromyography (AMG) and electromyography (EMG); two quantitative methods for monitoring neuromuscular block., Study Design: Prospective., Animals: Ten healthy Beagle dogs., Methods: Dogs were anesthetized with isoflurane and dexmedetomidine. Both ulnar nerves were stimulated with a train-of-four (TOF) pattern every 15 seconds. The magnitude of the first twitch (T1) and the TOF ratio (magnitude of T4/T1; TOFR) were quantified simultaneously with AMG and EMG, applied randomly to each extremity. The extent of maximal block (T1 depression) and onset time were measured by AMG and EMG during TOF monitoring after the administration of cisatracurium (0.05 mg kg(-1)). In addition, recovery of T1 to 25% and 75%, the recovery index (time between T1 of 25% and 75%), and recovery of the TOFR to 0.9 were used to characterize recovery from cisatracurium and were compared between monitors. Regression and Bland-Altman plots for T1 and TOFR were also created., Results: Maximal block and onset time were not different between monitors. Time to recovery of T1 to 25% and 75%, and time to TOF ratio 0.9 was significantly shorter with AMG. The recovery index was not different between monitors. When the TOFR returned to 0.9 with AMG, EMG still measured considerable residual block (TOFR 0.47)., Conclusions and Clinical Relevance: Electromyography consistently detected residual NMB when recovery from NMB was complete as assessed by AMG., (© 2014 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.)

Objective: To measure twitch potentiation (the staircase phenomenon) in anesthetized dogs, and assess its relevance during neuromuscular monitoring with acceleromyography (AMG)., Study Design: Randomized, prospective clinical trial., Animals: Sixteen dogs undergoing ovariohysterectomy., Methods: Under isoflurane anesthesia, neuromuscular function was monitored with train-of-four (TOF) stimuli every 15 seconds and quantified by AMG. Neuromuscular blockade (NMB) was produced with 0.15 mg kg(-1) atracurium IV. Dogs were randomly divided into two groups; a potentiation group (PG) in which TOF stimulation was applied for 20 minutes before atracurium was administered; and a control group (CG) where no such time was allowed. In both groups, the AMG was calibrated (at tCAL) just before atracurium was administered. TOF stimulation continued throughout the experiment in all dogs. The height of the first twitch (T(1)) (expressed as a fraction of T(1) at tCAL) and train-of-four ratio (TOFR) were recorded until TOFR returned to ≥90%., Results: In PG, T(1) increased significantly (p = 0.0078) from a median of 102% (range, 95, 109) at baseline to 118% (100, 142) at 20 minutes. In PG, no difference was found between T(1) at tCAL (immediately before atracurium administration) and T(1) when neuromuscular transmission returned (p = 0.42). In the CG, T(1) increased significantly between tCAL and the time neuromuscular transmission returned (p = 0.027). TOFR did not increase during twitch potentiation (all p = 0.32)., Conclusions and Clinical Relevance: T(1) increased significantly during 20 minutes of uninterrupted TOF stimulation in the absence of NMB, establishing that twitch potentiation occurs in anesthetized dogs. With no time for potentiation, T(1) increased during the course of recovery from NMB; this phenomenon introduces a bias in T(1) measurements and could affect studies reporting potency and duration of NMB based on T(1) or single twitches. TOFR was unaltered by potentiation emphasizing its clinical usefulness for excluding post-operative residual NMB., (© 2011 The Authors. Veterinary Anaesthesia and Analgesia. © 2011 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.)

A case of prolonged muscle relaxation after vecuronium in an anesthetized dog is presented. After using peripheral nerve stimulation to confirm partial recovery of neuromuscular transmission, administration of 0.5 mg/kg IV of intravenous edrophonium failed to complete the reversal process. Subsequent administration of neostigmine resulted in complete recovery from blockade. Without monitoring neuromuscular function with a peripheral nerve stimulator until reversal was complete, it was very likely this patient would have been extubated with incomplete neuromuscular transmission. Several factors affecting the duration of neuromuscular blockade and its reversal are addressed.

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 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 the variability in the duration of action of a single dose of rocuronium or cisatracurium, and duration of subsequent top‐up doses in anesthetized dogs. Animals: Thirty dogs requiring ophthalmic surgery with neuromuscular block. Procedures: Neuromuscular function was monitored with train‐of‐four (TOF) and acceleromyography. Dogs received an initial dose of rocuronium 0.6 mg/kg, or cisatracurium 0.15 mg/kg IV, which produced complete neuromuscular block. Upon return of the first response (T1) of TOF, a third of the initial dose was repeated. The duration of the initial dose and its variability were compared between agents. Duration of subsequent top‐up doses was assessed with mixed effect models. Spontaneous (from last return of T1) or neostigmine‐enhanced (from administration to complete recovery) recovery times were measured for each agent. Results: Duration of action of the initial dose was [median (range)] 25 (10–60) min with rocuronium and 35 (15–45) min with cisatracurium (p =.231). The variability of rocuronium was 3.25 times larger than cisatracurium (p =.034). Duration of top‐up doses did not vary for either agent. Spontaneous recovery was shorter for rocuronium [15 (10–20) min] than cisatracurium [25 (15–45) min] (p =.02). Neostigmine‐enhanced recovery times were 5 (5–25) for rocuronium and 10 (5–10) for cisatracurium (p =.491). Conclusions: Duration of action for a single dose is significantly more variable with rocuronium than cisatracurium. Time to spontaneous recovery was longer for cisatracurium, and cases of unexpectedly long recovery times were observed with both agents. Objective monitoring is recommended. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To describe the acquisition and pitfalls of a 3-view transesophageal echocardiography (TEE) protocol in anesthetized, dorsally recumbent dogs. ANIMALS: 8 beagles, 1 to 2 years old, 7.4 to 11.2 kg. METHODS: Dogs were anesthetized, mechanically ventilated, and placed in dorsal recumbency. A TEE probe was advanced, and 3 views were performed: midesophageal 4-chamber and long axis (ME 4C and ME LAX) and caudal esophageal short axis (CE SAX) at the level of the papillary muscles. Probe insertion depth, flexion, omniplane angle, and image acquisition time were recorded. Two observers assessed 24 video clips each and identified anatomical structures. RESULTS: The ME 4C and ME LAX were obtained at 35 (30 to 40) cm insertion depth, omniplane at 0° and 103° (90 to 116), respectively. Views were obtained in ≥30 seconds once the TEE was in the cervical esophagus. Left-sided structures were identified in all cases, whereas right-sided structures were not always simultaneously obtained in the ME 4C, requiring further probe manipulation. All structures were identified on ME LAX. CE SAX was obtained at 40 (35 to 45) cm, omniplane at 0°, and in 15 (10 to 90) seconds. A true SAX view (circular left ventricle at the level of papillary muscles) could not be obtained in all dogs. CLINICAL RELEVANCE: A 3-view TEE protocol using core views as those described in humans may be applicable to dogs under general anesthesia and in dorsal recumbency. The CE SAX view at the level of the papillary muscles appears more difficult to obtain with consistency than midesophageal views. [ABSTRACT FROM AUTHOR]

OBJECTIVE To evaluate the duration and analgesic quality of bupivacaine mixed with dexmedetomidine (BUP-DEX) or bupivacaine liposome suspension (BLS) administered as a transverse abdominis plane (TAP) block, compared with a negative control (no TAP block; CTRL) in dogs. ANIMALS 26 mixed-breed shelter dogs undergoing elective ovariohysterectomy between January 28 and December 8, 2020. PROCEDURES Each dog was randomly assigned to receive either an ultrasound-guided TAP block with either BUP-DEX or BLS or to receive no TAP block at time 0 after induction of general anesthesia. Superficial and abdominal wall pain scores were evaluated before time 0 and at 4, 6, 12, 24, 48, 72, and 96 hours later. Additionally, sedation scores and time to return of various behaviors, such as eating or drinking, were compared. RESULTS The CTRL group had significantly greater pain scores than the BUP-DEX and BLS groups, but no differences were found between the BUP-DEX and BLS groups. Postoperatively, significantly more dogs needed rescue analgesia and the time to need it was shorter for the CTRL group, compared with the BUP-DEX or BLS groups. Additionally, the CTRL group had greater sedation scores than the other 2 groups. No significant differences were observed in any of the evaluated outcome variables such as eating or drinking. CLINICAL RELEVANCE A TAP block appeared to provide adequate postoperative analgesia for abdominal surgery in the dogs of the present study undergoing elective ovariohysterectomy. The BLS TAP block did not appear to provide any extra benefit beyond what BUP-DEX TAP block added under these specific conditions. [ABSTRACT FROM AUTHOR]

Objective To describe an ultrasound-guided technique and the anatomical basis for three clinically useful nerve blocks in dogs. Study design Prospective experimental trial. Animals Four hound-cross dogs aged 2 ± 0 years (mean ± SD) weighing 30 ± 5 kg and four Beagles aged 2 ± 0 years and weighing 8.5 ± 0.5 kg. Methods Axillary brachial plexus, femoral, and sciatic combined ultrasound/electrolocation-guided nerve blocks were performed sequentially and bilaterally using a lidocaine solution mixed with methylene blue. Sciatic nerve blocks were not performed in the hounds. After the blocks, the dogs were euthanatized and each relevant site dissected. Results Axillary brachial plexus block Landmark blood vessels and the roots of the brachial plexus were identified by ultrasound in all eight dogs. Anatomical examination confirmed the relationship between the four ventral nerve roots (C6, C7, C8, and T1) and the axillary vessels. Three roots (C7, C8, and T1) were adequately stained bilaterally in all dogs. Femoral nerve block Landmark blood vessels (femoral artery and femoral vein), the femoral and saphenous nerves and the medial portion of the rectus femoris muscle were identified by ultrasound in all dogs. Anatomical examination confirmed the relationship between the femoral vessels, femoral nerve, and the rectus femoris muscle. The femoral nerves were adequately stained bilaterally in all dogs. Sciatic nerve block. Ultrasound landmarks (semimembranosus muscle, the fascia of the biceps femoris muscle and the sciatic nerve) could be identified in all of the dogs. In the four Beagles, anatomical examination confirmed the relationship between the biceps femoris muscle, the semimembranosus muscle, and the sciatic nerve. In the Beagles, all but one of the sciatic nerves were stained adequately. Conclusions and clinical relevance Ultrasound-guided needle insertion is an accurate method for depositing local anesthetic for axillary brachial plexus, femoral, and sciatic nerve blocks. [ABSTRACT FROM AUTHOR]

Thermal radiofrequency (TRF) of the saphenous nerve (a sensory nerve) combined with pulsed radiofrequency (PRF) of the sciatic nerve (a sensory and motor nerve) might relieve intractable stifle osteoarthritis (OA) pain in dogs. The objective was to determine if saphenous nerve TRF induces Wallerian degeneration and if sciatic nerve PRF induces degeneration or dysfunction. Blinded, controlled, randomized, preclinical study. A group of six intact, female Beagle dogs aged 14–16 months. In each dog, one pelvic limb was assigned randomly to the control group and the other to the treatment group. Dogs were anesthetized and, using ultrasonography, radiofrequency electrodes were positioned adjacent to saphenous and sciatic nerves bilaterally; TRF and PRF were performed only in the treatment limb. Motor nerve conduction velocity (MNCV) was measured in both sciatic nerves 2 weeks later, and the dogs were euthanized. Hematoxylin and eosin-stained sections of saphenous and sciatic nerves were examined using light microscopy. Degeneration and inflammation were scored 0 (none) to 3 (severe). A one-tailed, paired Wilcoxon signed-rank test was used to test for differences in scores and MNCV between control and treatment nerves. Degeneration and inflammation scores were higher in treatment saphenous nerves in 5/6 dogs [83%; 95% confidence interval (CI), 36%, 99%]; however, after Bonferroni correction only degeneration score was higher (p = 0.0313). Degeneration, inflammation or decreased MNCV were not observed in sciatic nerves (each outcome: 0/6 nerves, 0%; 95% CI, 0%, 48%). No dogs experienced postprocedural pain or neurological deficits. The degeneration in TRF-treated saphenous nerves appears sufficient to impair transmission. Sciatic nerve PRF did not cause degeneration with attendant motor deficits, consistent with a proposed neuromodulatory mechanism. A clinical trial is needed to confirm the combined techniques produce analgesia without motor deficits in dogs with stifle OA. [ABSTRACT FROM AUTHOR]

Objective To analyze practice habits associated with the use, reversal and monitoring of nondepolarizing neuromuscular blocking agents (NMBAs) in dogs by different groups of veterinarians. Study design Online anonymous survey to veterinarians. Population Data from 390 answered surveys. Methods A questionnaire was sent to e-mail list servers of the American College of Veterinary Anesthesia and Analgesia (ACVAA-list), Sociedad Española de Anestesia y Analgesia Veterinaria (SEEAV-list), Colégio Brasileiro de Anestesiologia Veterinária (Brazilian College of Veterinary Anesthesiology; CBAV-list) and American College of Veterinary Ophthalmologists (ACVO-list) to elicit information regarding use of NMBAs and reversal agents, monitoring techniques, criteria for redosing, reversing and assessing adequacy of recovery of neuromuscular function. Binomial logistic regression was used to test for association between responses and group of veterinarians in selected questions. Results Veterinarians of the ACVO-list use NMBAs on a higher fraction of their caseload than other groups (all p < 0.0001). Subjective assessment (observation) of spontaneous movement, including spontaneous breathing, is the most common method for assessing neuromuscular function (43% of pooled responses); 18% of participants always reverse NMBAs, whereas 16% never reverse them. Restoration of neuromuscular function is assessed subjectively by 35% of respondents. Residual neuromuscular block is the most common concern regarding the use of NMBAs for all groups of veterinarians. Side effects of reversal agents (anticholinesterases) were of least concern for all groups. Conclusions and clinical relevance While most veterinarians are concerned about residual neuromuscular block, relatively few steps are implemented to reduce the risks of this complication, such as routine use of quantitative neuromuscular monitoring or routine reversal of NMBAs. These results suggest a limitation in transferring information among groups of veterinarians, or in implementing techniques suggested by scientific research. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objective To evaluate the non-depolarizing neuromuscular blocking drug cis-atracurium in dogs with porto-systemic shunts, and to compare it in clinically normal animals. Animals Thirteen dogs of mixed breed and sex, aged between 3 and 31 months old, weighing 2.2–25.5 kg, with ASA physical status II–IV, and undergoing surgical attenuation of porto-systemic shunt. A control group of 11 bitches of mixed breed, between 8 and 60 months old, and weighing 4.5–41.0 kg, all ASA physical status I, undergoing routine ovarohysterectomy were also studied. Materials and methods Pre-anaesthetic medication was an opioid analgesic, given either alone or in combination with acepromazine. Following induction of general anaesthesia with intravenous (IV) propofol and oro-tracheal intubation, anaesthesia was maintained using isoflurane in either oxygen or oxygen and nitrous oxide. Ventilation was controlled. The train of four (TOF) technique was used to monitor neuromuscular blockade. An initial dose of 0.1 mg kg−1 cis-atracurium was given IV and additional doses of 0.03 mg kg−1 cis-atracurium were administered when at least one twitch of the TOF was present. Results Except for one dog that was killed during surgery because its anomaly was inoperable, all animals recovered satisfactorily from anaesthesia and surgery. In dogs with porto-systemic shunt, onset of neuromuscular blockade was 3.1 ± 1.1 minutes (mean ± SD) and in control dogs was 3.4 ± 0.7 minutes (not significantly different). Neuromuscular blockade lasted 34 ± 13 minutes in dogs with porto-systemic shunt and 29 ± 17 minutes in control dogs (not significantly different). Conclusions The presence of porto-systemic shunt did not affect the rate of onset or duration of action of cis-atracurium. Clinical relevance cis-Atracurium may have a use in veterinary anaesthesia for producing neuromuscular blockade in dogs with hepatic insufficiency, including those with porto-systemic shunt. [ABSTRACT FROM AUTHOR]