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Observations A 1-month-old Nubian goat presented for sialocyst resection. Physical examination and bloodwork were unremarkable. While pre-oxygenating, the goat was sedated with midazolam and morphine (0.1 mg kg−1 each) intravenously (IV). General anesthesia was induced 5 minutes later with 1.7 mg kg−1 propofol. Sevoflurane was administered in oxygen without assisted ventilation via a cuffed orotracheal tube. Throughout the first 85 minutes of anesthesia, the goat was well-oxygenated (SpO2, ≥97%), ventilating adequately (Pe′CO2, 36–48 mmHg), and had normal mean arterial blood pressure (MAP, 60–85 mmHg). Blood-gas values at 45 minutes were consistent with adequate ventilation on oxygen. At 75 minutes, the goat moved in response to surgical stimulation, requiring additional propofol (0.4 mg kg−1). After 10 minutes, MAP dropped precipitously to 40 mmHg and frequent multiform premature ventricular contractions (PVCs) were observed. Crystalloids, hetastarch, and dopamine (5 μg kg−1 minute−1) were administered to correct the hypotension. Arterial blood-gas analysis revealed that the goat had become hypoxemic (PaO2, 50 mmHg). Intermittent positive pressure ventilation (IPPV) was initiated. Subsequent blood-gas analysis did not show significant improvement in PaO2 (53 and 56 mmHg, respectively). Occasional PVCs were observed thereafter. Surgery ended, and sevoflurane and IPPV were discontinued. The goat was extubated within 7 minutes and received 100% oxygen by mask. Diffuse crackles were ausculted over both hemithoraces. Suspecting pulmonary edema, furosemide (1 mg kg−1) was administered IV. Radiographs taken immediately post-operatively revealed a severe, caudodorsal airspace (alveolar) pattern, confirming the diagnosis. Respiration improved considerably within an hour with nasal oxygen and two additional doses of furosemide. Conclusions The goat developed acute, drug-induced, noncardiogenic pulmonary edema in response to the second dose of propofol. [ABSTRACT FROM AUTHOR]

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 μg 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 °C (102.5 °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 °C (107.0 °F), 40.3 °C (104.2 °F), 39.2 °C (102.6 °F), and 40.1 °C (104.1 °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. [ABSTRACT FROM AUTHOR]

Purpose: The goals of this investigation were to evaluate the accuracy and reliability of the Angioflow meter system with use of in vitro and in vivo methods and to compare it to the standard Transonics HD01 system in a clinical setting.Materials and Methods: The Angioflow meter system consists of a 6-F endovascular catheter and a laptop computer containing proprietary software for this application. Bench-top testing with use of a flow model was performed to determine the accuracy of the Angioflow meter system. Initial in vivo studies were performed with use of an animal model to assess the endovascular performance of the Angioflow meter system. Subsequently, a human clinical trial was performed to compare the Angioflow meter to the standard Transonics HD01 system. Twenty-five patients with dysfunctional (<600 mL/min) hemodialysis grafts were referred for fistulography and angioplasty. Intragraft blood flow measurements were obtained before and after angioplasty with use of both the Angioflow meter system and the Transonics HD01 system. A comparison of the two systems was performed.Results: Bench-top testing and animal studies demonstrated an excellent (r =.98) correlation between the measurements of the Angioflow meter and volumetric flow measurements. In the clinical trial, there was reasonable correlation (r =.72) between the blood flow measurements obtained with use of the Angioflow meter and Transonics HD01 system. The reproducibility of consecutive measurements with the Angioflow meter was excellent (r =.98). The mean increase in intragraft blood flow after angioplasty was 320 mL/min.Conclusion: The Angioflow meter is an accurate and reliable endovascular device for measuring intragraft blood flow during interventional procedures. Use of this catheter-based system should prove beneficial for quantifying the success of endovascular interventions, the assessment of arterial inflow, and identification of inconspicuous lesions. [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]

Objective To assess whether recovery from general anesthesia, in an illuminated or a darkened stall, has an effect on time to first movement, time to standing, and recovery score. Study design Prospective randomized clinical study. Animals Twenty-nine healthy, 2- to 5-year-old horses undergoing surgical correction of dorsal displacement of the soft palate. Methods Each horse was assigned randomly to recover in either an illuminated ( n = 15) or a darkened stall ( n = 14). For pre-anesthetic medication, all horses received intravenous (IV) xylazine (0.4 mg kg−1) and butorphanol (0.02 mg kg−1). Anesthesia was induced with midazolam (0.1 mg kg−1) and ketamine (2.2 mg kg−1) IV and maintained on isoflurane in oxygen. Vital parameters, end-tidal CO2 and isoflurane were recorded at 5-minute intervals. At the conclusion of anesthesia, horses were placed in either an illuminated or a darkened stall and xylazine (0.2 mg kg−1) IV was administered at extubation. Video cameras were used to record the horses while they were allowed to recover undisturbed. Video recordings were later viewed and recoveries were evaluated on a 100-point scale by three graders. Results Horses in illuminated and darkened recovery stalls were evaluated on total anesthesia time, minimum alveolar concentration hours of isoflurane, time to first movement, time to standing, and total recovery score. There were no significant differences between the two groups in any of the measured parameters. Conclusion Recovering horses in a darkened versus an illuminated recovery stall may provide no benefit. Clinical relevance Darkening the recovery stalls for horses recovering from general anesthesia may be unnecessary. [ABSTRACT FROM AUTHOR]

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. Randomized prospective experimental trial. Sixteen young, healthy, specific pathogen-free Giant Flemish cross Chinchilla rabbits (10 females and 6 males) weighing 4.1 ± 0.8 kg. 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, F é isoflurane, F i isoflurane, partial pressure of expired isoflurane (P éCO2), partial pressure of inspired carbon dioxide (P iCO2), heart rate, respiratory rate, minute volume, arterial oxygen tensions (PaO2), arterial carbon dioxide tensions (PaCO2), arterial pH (pHa), arterial standard base excess (SBEa) values were measured for 120 minutes. Two individuals in the FM-SV group had PaCO2 > 100 mm Hg. One rabbit in the FM-SV had PaO2 < 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. PaCO2 and P éCO2 were decreased, while PaO2 and minute volume were increased in the LMA-CV group compared to the LMA-SV group. 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 H2O. The LMA can be used in rabbits but further work is needed before it is applied routinely. [ABSTRACT FROM AUTHOR]

Several factors affect the quality of recovery from general anesthesia in horses. These can increase the likelihood of injury. Body and limb position during recovery may correlate with successful standing. The objective of this study was to identify the prevalence of and the factors associated with successful standing at the first attempt in horses undergoing general anesthesia. Retrospective study. Video of recovery and anesthetic records from 221 equine patients were reviewed by six veterinary students. Cases with poor video quality or incomplete anesthetic records were excluded. Demographic variables, type of procedure, perioperative drugs administered, assistance during recovery and body and limb positions during the first attempt to stand were recorded. Association between putative variables (including specific descriptors for body and limb position) and success for standing were analyzed using backward logistic regression; significance was set at 0.05. A decision tree for a successful attempt was created to predict the outcome of a recovery attempt based on these variables. Extension of the carpal joints, head and neck alignment with the thoracic limbs, greater time in lateral recumbency, coordination during sternal recumbency, longer time to first attempt to stand and pelvic limb position were associated with successful standing at the first attempt. The association between extension of the carpal joints with wide base positioning of the pelvic limbs provided the best success rate for standing, whereas the association of flexed carpal joints and head and neck orientation different from the thoracic limbs resulted in a worse success rate. Results suggest that certain limb and body positions displayed by horses during recovery may be associated with the likelihood of successful standing at the first attempt. These variables may be useful for assessing recovery quality in future research. [ABSTRACT FROM AUTHOR]

To develop a scale to diagnose and assess the severity of postamputation pain (PAP) in dogs. Single-center retrospective study. A total of 66 dogs that underwent thoracic or pelvic limb amputation and 139 dogs that underwent tibial plateau leveling osteotomy (TPLO) at a veterinary teaching hospital. An online survey regarding postoperative behavioral changes was sent to owners. Categorical, multiple-choice responses were entered into a univariable logistic regression model and tested for association with amputation using the Wald test. If p < 0.2, variables were forwarded to a multivariable logistic regression model for manual build. Model simplicity and predictive ability were optimized using the area under the receiver operating curve (AUROC) characteristic, and model calibration was assessed using the Hosmer–Lemeshow test. The selected model was converted to an integer scale (0–10), the Canine Postamputation Pain (CAMPPAIN) scale. Univariable logistic regression related each dog's calculated score to the probability of PAP. Multivariable logistic regression identified four independent predictors of PAP (p < 0.05): 1) restlessness or difficulty sleeping, 2) episodes of panic or anxiety, 3) sudden vocalization, and 4) compulsive grooming of the residual limb. Score AUROC was 0.70 (95% confidence interval = 0.63–0.78) with good calibration (Hosmer–Lemeshow statistic p = 0.82). A score of 2 corresponded to a risk probability of 0.5. Taking a score ≥ 2 to indicate PAP, score specificity and sensitivity were 92.1% and 36.4%, respectively. When this score was used to diagnose PAP, prevalence was 36.4% (24/66) and 7.9% (11/139) in the amputation and TPLO groups, respectively. Postamputation pain is characterized by specific postoperative behaviors and appears to affect approximately one-third of canine amputees. The CAMPPAIN scale generated from these data could facilitate diagnosis, treatment and further study of PAP but requires external validation. [ABSTRACT FROM AUTHOR]

To collect data about the current practice of recovering horses from general anesthesia and recovery personnel safety. Online survey. An online questionnaire, including questions on general demographic data, recovery drugs, modality and characteristics of equine recovery and morbidity and mortality, was designed and distributed via e-mail to equine practitioners worldwide. Practitioners from 22 countries completed 373 questionnaires; 53% of the participants were board-certified equine surgeons, and the remainder were board-certified anesthesiologists (18%), large animal residents (8%), general practitioners (7%), large animal interns (6%), anesthesia residents (4.5%) and veterinary technicians (1.6%). Respondents were employed by academia (58%) or private practice (42%). Of the respondents employed at a university, 93% had a board-certified anesthesiologist on staff compared with 7% of respondents employed at a private practice. Most of the respondents assist horses during recovery, with 23% assisting every recovery and 44% assisting recovery in the majority of cases. Reasons for choosing to assist horses during recovery were: orthopedic procedures (57%), neurological deficits (49%), bad health (47%), history of poor recovery (44%), foals (42%), draft breeds (30%), magnetic resonance imaging (17%) and computed tomography (16%). Unacceptable recoveries were reported by 77% of participants. Commonly reported complications during recovery with any method were: orthopedic injury (66%), myopathy (54%), skin abrasion (53%) and airway obstruction (37%). The incidences of unacceptable quality of recovery (p = 0.09) or personnel injury (p = 0.56) were not different between assisted and nonassisted recoveries; however, more equine fatalities were reported for assisted recoveries (p < 0.006). Practitioners in academia reported more unacceptable recoveries (p < 0.0007) and personnel injuries (p < 0.002) compared with those in private practice. The method of recovery differs among hospitals. Recovery personnel injuries associated with assisting horses during recovery are an important and previously unreported finding. [ABSTRACT FROM AUTHOR]

To compare the duration of nociceptive and proprioceptive blockade from an experimental encapsulated lidocaine preparation with that of conventional lidocaine. Prospective, blinded, randomly assigned, crossover study. A total of six adult Dorset ewes, American Society of Anesthesiologists physical status I or II, weighing 60.4 ± 18.0 kg (mean ± standard deviation). Under general anesthesia and guided by electrolocation, the common peroneal nerve was blocked unilaterally with encapsulated lidocaine (0.1 mL kg–1, 200 mg mL–1) or conventional lidocaine hydrochloride (0.1 mL kg–1, 20 mg mL–1). Each sheep was administered both treatments with an interval of 2 weeks between treatments. Nociception and proprioception were scored (scales of 0–3) before anesthesia, at 0.5, 1, 2, 4, 8, 12, 16, 20 and 24 hours after completion of local anesthetic injection, and every 12 hours thereafter for 9 days. Nociceptive and proprioceptive blockade ended the first time each score reached '0'; maximum blockade duration was considered and recorded to be the time point immediately prior to this end point. Significance of differences between treatments for duration of blockade was tested with the Wilcoxon rank-sum test. Effects of time and treatment on nociceptive and proprioceptive blockade were evaluated with mixed-effect models. Significance was set at p < 0.05. Compared with conventional lidocaine, nociceptive blockade lasted 88 hours longer with encapsulated lidocaine (p = 0.008), and proprioceptive blockade lasted 6 hours longer (p = 0.03). Significant effects of time (p < 0.0001), treatment (p = 0.0435) and treatment∗time (p < 0.0001) were observed for nociception. Significant effects of time (p < 0.0001) and treatment∗time (p = 0.0058) were observed for proprioception. Encapsulated lidocaine produced nociceptive blockade with a duration substantially longer than conventional lidocaine. Sustained-release encapsulated lidocaine alleviates pain and may minimize systemic analgesic use. [ABSTRACT FROM AUTHOR]

To evaluate arterial oxygenation during the first 4 postoperative hours in dogs administered different fractions of inspired oxygen (F i O 2) during general anesthesia with mechanical ventilation. Prospective, randomized clinical trial. A total of 20 healthy female dogs, weighing >15 kg and body condition scores 3–7/9, admitted for ovariohysterectomy. Dogs were randomized to breathe an F i O 2 >0.9 or 0.4 during isoflurane anesthesia with intermittent positive pressure ventilation. The intraoperative PaO 2 :F i O 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 (F i O 2 = 0.21). Demographic characteristics, duration of anesthesia, PaO 2 :F i O 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. Groups were indistinguishable by demographic characteristics, duration of anesthesia, anesthetic agents administered and intraoperative PaO 2 :F i O 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 F i O 2 >0.9 or 0.4 during anesthesia, respectively (p = 0.04). The results identified no advantage to decreasing F i O 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 F i O 2 >0.9. [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]

Abstract 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. [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 Anticholinesterase drugs may produce paradoxical neuromuscular block when administered at shallow levels of neuromuscular block. The objective of this study was to evaluate the effects of neostigmine and edrophonium when administered at near-complete reversal from nondepolarizing block in anesthetized dogs. Study design Incomplete crossover, randomized, blinded experimental study. Animals A total of 12 Beagle dogs. Methods Each dog was anesthetized twice with propofol and maintained with isoflurane and dexmedetomidine. Intravenous (IV) vecuronium (0.1 mg kg-11) was administered. When the mechanographic train-of-four (TOF) ratio had spontaneously recovered to ≥0.9, either neostigmine (0.04 mg kg-11) or edrophonium (0.5 mg kg-11) was administered IV, preceeded by atropine. Changes in twitch height or TOF ratio were measured for the next 10 minutes. Recurarization was considered to be present if values decreased by ≥10%. Results Data from four dogs in each treatment were excluded from analysis, resulting in data from five dogs administered both treatments, three dogs administered neostigmine and three dogs administered edrophonium. There was no difference between groups for age, weight, T1 and T4 twitch heights or TOF ratio values, before or after anticholinesterase administration. The TOF ratio decreased by 17% and 18% in two of the eight dogs administered neostigmine, resulting from a larger increase in T1 relative to T4. No reductions in individual twitch amplitudes were recorded in those dogs. When edrophonium was used, no cases of recurarization were observed. Conclusions and clinical relevance The results support use of edrophonium for reversal of shallow neuromuscular block. The decreases in TOF ratio recorded after neostigmine does not necessarily indicate muscular weakness. Although the clinical implications are uncertain, the results suggest that, at these doses, edrophonium may be preferable to neostigmine for reversal of shallow neuromuscular block in dogs. [ABSTRACT FROM AUTHOR]

Objective To describe ultrasound-visualized anatomy and the spread characteristics of a dye injected in the thoracic paravertebral (TPV) space under ultrasound guidance. Study design Anatomic cadaver study. Animals Seven dog cadavers. Methods One cadaver was used to observe, identify, and describe the relevant TPV anatomy. In the remaining six, the left fifth TPV space was randomly assigned to be injected with either a low volume (LV; 0.05 mL kg-1) or high volume (HV; 0.15 mL kg-1) of dye. Subsequently, the contralateral side was injected with the alternative volume. Anatomic dissections were conducted to determine the incidence of complete spinal nerve staining (>1 cm circumferential coverage), number of contiguous spinal nerves dyed and the absence or presence of solution in particular locations. Results The ultrasound-visualized anatomy of the TPV space was defined as the intercostal space abaxial to the vertebral body, delimited by the parietal pleura ventrally and the internal intercostal membrane dorsally. The endothoracic fascia divides the paravertebral space into dorsal and ventral compartments. The target nerve was completely dyed in five of six and six of six injections in the LV and HV conditions, respectively. In one LV injection, the nerve was partially dyed. No multisegmental spread affecting contiguous spinal nerves was found in either treatment. Multisegmental spread was found in the ventral compartment of the TPV space, affecting the sympathetic trunk on 3 (0-3) and 3.5 (1-6) vertebral spinal levels in the LV and HV conditions, respectively, but differences between volumes were not significant. No intrapleural, ventral mediastinal or epidural migration was observed. Conclusions and clinical relevance Ultrasoundguided TPV block is a potentially reliable technique. The LV appeared sufficient to dye a single spinal nerve and multiple sympathetic trunk vertebral levels. Multiple TPV injections may be needed to provide adequate thoracic analgesia in dogs undergoing thoracic surgery. [ABSTRACT FROM AUTHOR]

Objective To determine if neuromuscular monitoring at the pelvic limb accurately reflects neuromuscular function in the larynx after administration of rocuronium in anesthetized dogs. Study design Prospective experimental study. Animals Six healthy Beagle dogs. Methods Anesthesia was maintained in dogs with isoflurane and a continuous infusion of dexmedetomidine. Rocuronium (0.6 mg kg-1) was administered intravenously to induce neuromuscular block. Train-of-four (TOF) impulses were applied to the left recurrent laryngeal nerve (RLn) and the peroneal nerve (Pn). The evoked TOF ratio (TOFR; T4:T1) was measured with electromyography (EMG) simultaneously at the larynx and at the pelvic limb. Spontaneous recoveries of T1 to 25% (T125%) and 75% (T175%) of twitch height, and to TOFR of 0.70 and 0.90 (TOFR0.90) at each EMG site were compared. Results Data from five dogs were analyzed. Times to T125% were similar at the pelvic limb and larynx when measured by EMG; time to T175% was slower at the larynx by 6 ± 4 minutes (p = 0.012). The larynx had a slower recovery to TOFR0.70 (41 ± 13 minutes) and TOFR0.90 (45 ± 13 minutes) than did the pelvic limb [29 ± 8 minutes (p = 0.011) and 33 ± 9 minutes (p = 0.003), respectively]. When the pelvic limb EMG returned to TOFR0.70 and TOFR0.90, the larynx EMG TOFR0.70 and TOFR0.90 values were 0.32 ± 0.12 (p = 0.001) and 0.38 ± 0.13 (p = 0.001), respectively. Conclusions and clinical relevance After administration of rocuronium, neuromuscular function assessed by EMG recovered approximately 36% slower at the larynx than at the pelvic limb. The results in these dogs suggest that quantitative neuromuscular monitoring instrumented at a pelvic limb may be unable to exclude residual block at the larynx in anesthetized dogs. [ABSTRACT FROM AUTHOR]

Objective To identify the dose of rocuronium that will prevent a laryngeal response to water spraying of the glottis in anesthetized cats. Study design Randomized crossover study. Animals Eight healthy, adult, short-haired cats, aged 1-4 years, weighing 3.2-6.0 kg. Methods Each cat was anesthetized four times and administered one of four doses of rocuronium (0.1, 0.2, 0.3 and 0.6 mg kg−1) in random order. The larynx was observed with a video-endoscope inserted through a laryngeal mask airway. Video-clips of the laryngeal response to a sterile water spray (0.2 mL) were obtained at baseline (without rocuronium) and at maximal effect of each treatment. Glottal closure score (0-2), duration of glottal closure, and number of adductive arytenoid movements were obtained from video-clips of laryngeal responses (reproduced in slow motion) at baseline and after treatment. Two observers blinded to treatment allocation scored the vigor of the laryngeal response on a visual analog scale ( VAS). The duration of apnea (up to 5 minutes) was recorded for each treatment. Results Compared with baseline, rocuronium 0.3 mg kg−1 and 0.6 mg kg−1 significantly decreased all glottal scores obtained from the videos (all p < 0.03). Both observers gave lower VAS scores after 0.3 mg kg−1 (both p = 0.015). Apnea lasting ≥ 5 minutes occurred in none, one, three and seven of eight cats administered doses of rocuronium 0.1, 0.2, 0.3 and 0.6 mg kg−1, respectively. Conclusions and clinical relevance Rocuronium 0.3 mg kg−1 and 0.6 mg kg−1 consistently decreased the completeness and duration of the laryngeal response to water spray, and reduced the number of arytenoid adductive movements in response to that stimulus. However, a laryngeal response was never completely prevented. Rocuronium 0.3 mg kg−1 may be useful for facilitating tracheal intubation. Positive pressure ventilation must be available for cats administered rocuronium. [ABSTRACT FROM AUTHOR]

Objective To compare the quality of anesthesia and analgesia from femoral and sciatic nerve blocks ( FS) with bupivacaine and dexmedetomidine with that from an epidural injection ( EPI) with bupivacaine and buprenorphine in dogs undergoing unilateral stifle arthroplasty. Study design Prospective, blinded, randomized, clinical comparison. Animals Twenty-six dogs weighing 36 ± 10 kg and aged 5 (1-11) years. Methods Dogs were randomly assigned to either FS [ n = 13; bupivacaine 0.5% (0.5 mg kg−1) plus dexmedetomidine (0.1 μg kg−1) for each nerve] or EPI [ n = 13; bupivacaine 0.5% (1 mg kg−1) plus buprenorphine (4 μg kg−1)]. Data collected included intraoperative cardiopulmonary variables and postoperative pain scores (Glasgow Composite Pain Scale), sedation scores, opioid consumption, time to urination and time to return of various behaviors. Rescue analgesia (hydromorphone 0.05 mg kg−1) was administered intravenously whenever pain scores were ≥ 6/24. Subsequent data from rescued dogs were excluded from further analysis. Results No differences were found for any of the variables evaluated during and after anesthesia. Over 60% (nine dogs in FS, eight dogs in EPI) of patients from either group did not need additional analgesia within the 24 hour observational period. Three and four patients in FS and EPI, respectively, that required rescue analgesia did so within the first 30 minutes after extubation; only one patient in EPI required supplemental analgesia more than 4 hours after extubation. One patient in each group did not urinate spontaneously for 24 hours. Conclusions and clinical relevance Both techniques have the potential to provide sufficient analgesia for up to 24 hours in approximately two-thirds of dogs. Careful observation for signs of pain and preparedness to intervene is still recommended. The incidence of urinary retention was low in both groups. These techniques show promise for providing high-quality analgesia for stifle arthroplasty. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objective To evaluate the hypothesis that epidural morphine (0.1 mg kg−1) decreases pain in horses after laparoscopic surgery without adversely affecting gastrointestinal ( GI) motility. Study design Randomized clinical trial. Animals Eighteen horses undergoing laparoscopic cryptorchidectomy under general anesthesia. Methods Horses were randomly assigned to receive either epidural morphine (0.1 mg kg−1) or no epidural before the start of surgery. Pain behaviors were assessed during the first two post-operative days using a numerical rating scale. Barium-filled spheres were administered through a nasogastric tube before anesthesia. GI motility was assessed by recording manure production, by quantitating the spheres in the manure, and by abdominal auscultation of intestinal sounds. Heart rates and cortisol concentrations were also measured during the post-operative period. Results Pain scores increased for 12 hours after surgery in the control group and were significantly higher than in the morphine group for the first 6 hours. Pain scores remained unaltered in the morphine group throughout the observation period. Heart rate and plasma cortisol concentrations did not differ between groups or with time. No signs of colic were observed in any horse. Conclusion and clinical relevance Epidural morphine (0.1 mg kg−1) did not adversely affect GI motility in horses after laparoscopic surgery under general anesthesia. [ABSTRACT FROM AUTHOR]

Objective To evaluate the potency and duration of three subparalyzing doses of vecuronium (VEC) in isoflurane-anesthetized horses. Study design Prospective experimental study. Animals Thirteen healthy adult horses undergoing arthroscopic surgery. Methods During isoflurane anesthesia, horses received one of three doses of vecuronium (25, 50, or 100 μg kg−1). Neuromuscular transmission was monitored with acceleromyography (AMG) with train-of-four (TOF) stimulation of the radial nerve. Maximal depression of the first twitch (T1), and onset time were recorded for each dose. Recovery time to a TOF ratio >90% was also evaluated. Results Vecuronium 25 μg kg−1 produced no observable T1 depression in four horses. VEC 50 μg kg−1 ( n = 5) produced a maximal T1 depression of [median (min, max)] 41 (20, 71) % in four horses, and no neuromuscular block was seen in the fifth. VEC 100 μg kg−1 was given to four horses and produced a T1 depression of 73 (64, 78) %. Of the four horses in which VEC 50 μg kg−1 produced a measurable neuromuscular block, three recovered spontaneously 43 (40, 52) minutes after VEC administration; a fourth subject received edrophonium to reverse residual block at the end of the surgery. Spontaneous recovery after VEC 100 μg kg−1 occurred by 112 minutes in one horse, and had to be facilitated by edrophonium in the remaining three horses, more than 2 hours after VEC had been given. Conclusions and clinical relevance A dose of 100 μg kg−1 VEC in isoflurane anesthetized horses failed to produce complete paralysis. The partial neuromuscular block lasted at least 2 hours after this dose had been administered. Edrophonium was required to reverse the neuromuscular block in three of four horses. It is likely that more than 100 μg kg−1 VEC would be necessary for complete neuromuscular blockade in horses, and that this dose will last >2 hours. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 (F E′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, F E′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. [ABSTRACT FROM AUTHOR]

To measure twitch potentiation (the staircase phenomenon) in anesthetized dogs, and assess its relevance during neuromuscular monitoring with acceleromyography (AMG). Randomized, prospective clinical trial. Sixteen dogs undergoing ovariohysterectomy. 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 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) (expressed as a fraction of T at tCAL) and train-of-four ratio (TOFR) were recorded until TOFR returned to ≥90%. In PG, T 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 at tCAL (immediately before atracurium administration) and T when neuromuscular transmission returned ( p = 0.42). In the CG, T increased significantly between tCAL and the time neuromuscular transmission returned ( p = 0.027). TOFR did not increase during twitch potentiation (all p = 0.32). T 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 increased during the course of recovery from NMB; this phenomenon introduces a bias in T measurements and could affect studies reporting potency and duration of NMB based on T or single twitches. TOFR was unaltered by potentiation emphasizing its clinical usefulness for excluding post-operative residual NMB. [ABSTRACT FROM AUTHOR]

To evaluate the effect of epidural morphine on gastrointestinal (GI) motility in horses. Randomly ordered crossover design. Six healthy adult horses weighing 585 ± 48 kg (mean ± SD). Horses were randomly assigned to receive either 0.2 mg kg morphine or an equal volume (0.04 mL kg) of saline epidurally (the first inter coccygeal space) with 2 weeks between treatments. The horses were stabled, fed a standardized diet and allowed water ad libitum throughout the duration of the study. Radiopaque spheres were administered by stomach tube. Xylazine 0.2 mg kg intravenously was administered prior to epidural injection. Heart rate, respiratory rate, GI sounds score and behavior score were recorded before drug administration and after epidural injection at 4, 8, 12, 18, 24 hours and every 12 hours thereafter for 6 days. Feces were weighed, radiographed and the number of spheres counted. Data were analyzed using a mixed effect model. At no time did horses exhibit signs of colic or show significant differences between treatments regarding heart rate, respiratory rate, GI sounds score, behavior score, or cumulative number of spheres. The concentration of spheres per kg of feces was significantly lower ( p < 0.05) for the morphine group at 18 and 24 hours. Using the centroid of the curves (spheres kg plotted versus time) the average transit time after saline epidural was 38 hours and after morphine it was 43 hours. The weight of feces hour was significantly lower ( p < 0.05) at only 4 and 8 hours after morphine. Epidural morphine, at a dose of 0.2 mg kg, temporarily reduced GI motility but did not cause ileus or colic in this small group of healthy unfasted horses. Care should be taken when extrapolating these data to situations in which other factors may also affect GI motility. [ABSTRACT FROM AUTHOR]

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 μg kg−1) plus dexmedetomidine (20 μg 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. [ABSTRACT FROM AUTHOR]

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 (∼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) μg 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 μg mL−1 (the presumed minimal effective concentration) = 11.11 (6.97–14.47) hours; maximal plasma concentration ( Cmax) = 7.15 (4.6–7.9) μg mL−1; time for Cmax 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) μg 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) μg 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. [ABSTRACT FROM AUTHOR]

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 ≥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). [ABSTRACT FROM AUTHOR]

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 ≥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 ≥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. [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 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. [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]

Abstract Objective To compare plasma colloid osmotic pressure (COP) of both maternal and fetal blood, before and after hemorrhage, and replenishment with Oxyglobin Solution (Biopure Corporation, Cambridge, MA, USA), hetastarch or whole blood in pregnant ewes. Study design Prospective, randomized study. Animals A total of 17 adult Rambouillet ewes at 131 (128–133) [median (minimum, maximum)] days gestation, weighing 56 (46, 63) kg. Methods Ewes and fetuses were chronically instrumented with catheters in a maternal jugular vein, maternal carotid artery and fetal femoral artery. Twenty milliliters per kilograms of blood were removed from each ewe over 1 hour. The ewes were then given 20 mL kg-1 of either Oxyglobin Solution (n = 5), hetastarch (n = 6), or autologous whole blood (n = 6) IV. Maternal plasma COP was measured before hemorrhage, after hemorrhage, after replenishment, and 1 and 2 hours later. Fetal plasma COP was measured after maternal hemorrhage and 2 hours after maternal volume replenishment. Results Median COP of all ewes before hemorrhage was 20 (16, 24) mm Hg and after hemorrhage (p < 0.05), decreased to 16 (11, 19) mm Hg. After volume replenishment, the COP of the Oxyglobin Solution group was 22 (21, 25) mm Hg, the autologous whole blood group was 17 (16, 22) mm Hg and the hetastarch group was 20 (17, 21) mm Hg. The COP of the Oxyglobin Solution group was significantly greater (p < 0.05) than the COP of the hetastarch group immediately and 60 minutes after volume replenishment, and greater (p < 0.05) than that of the autologous whole blood group at 60 minutes after volume replenishment. The COP of all the fetuses after maternal hemorrhage was 16 (12, 19) mm Hg and at 120 minutes after maternal volume replenishment was 15 (11, 18) mm Hg. There were no differences in COP between or within any of the fetal groups. Conclusions When used to treat blood loss, Oxyglobin Solution increases plasma COP more than an equal volume of... [ABSTRACT FROM AUTHOR]