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Intranasal (IN) drug delivery has increasingly considered as an easy, practical and non-invasive alternative to parenteral administration in veterinary medicine, offering rapid systemic and potential nose-to-brain effects. The first part of this review systematically collected and synthesized published evidence on IN administration across animal species, while the second part critically analysed the anatomical, pharmacological and technical factors that determine its success and limitations. Part I consisted a total of 110 eligible studies published between 1991 and 2025, encompassing dogs, cats, rabbits, pigs, ruminants, birds and reptiles. IN delivery has been investigated for a range of purposes and produced clinically meaningful sedation, analgesia and drug reversal, often comparable to intramuscular administration but generally characterized by slower onset and greater variability among species. Despite encouraging and favourable results, IN delivery was not without limitations. Its effectiveness can be strongly influenced by species-specific nasal anatomy and physiology, formulation characteristics and dosing volume. Defensive reactions, poor tolerability, sneezing, nasopharyngeal irritations, hypersalivation or swallowing of the drug are frequently reported. Future progress requires species-specific case selection guidelines and dosing standards, pharmacokinetic validation and developing safe concentrated formulations. Transparent reporting and balanced assessment of both benefits and drawbacks are essential to ensure the safe, effective and ethically responsible integration of IN administration into veterinary anaesthesia and critical care practice.
To identify anaesthesia-related risk between common domestic species and humans by analysing peer-reviewed and other literature on anaesthesia in great apes in both human care and free-ranging settings and thereby to identify knowledge gaps. We conducted literature searches in the CAB Abstracts, MEDLINE and Zoological Record databases, as well as conference proceedings of the American Association of Zoo Veterinarians, the British Veterinary Zoological Society and the European Association of Zoo and Wildlife Veterinarians. Of the 142 studies reviewed, 51 were conference abstracts and 91 were peer-reviewed journal articles. There was a steady increase in the number of published papers since 1960, surpassing 30 papers per decade since 2000. Case studies and series made up 79% of included studies, and 91-94% for all species except chimpanzees. Although data for chimpanzees appeared extensive, data for bonobos, eastern gorillas, and Sumatran orangutans were notably lacking. Infant great ape anaesthesia and anaesthesia in free-ranging settings were underrepresented in the literature. Over 50 anaesthetic drugs were reported in the literature, with ketamine, tiletamine/zolazepam, midazolam, medetomidine and isoflurane being most frequently reported. There is a notable lack of reporting of anaesthesia-related adverse events (AEs), and many studies failed to report key details, which limits reproducibility. Respiratory and cardiovascular AEs were reported most frequently. The incidence of prolonged recoveries and excitation on recovery was higher than in other domestic species, and there was a notable lack of hypothermia reported as an AEs. This is the first evidence synthesis on general anaesthesia in great apes, and findings highlight the need for targeted research on underrepresented species and improved reporting of anaesthesia practices and AEs.
To survey current veterinary anaesthesia practice during computed tomography (CT) scanning in UK referral hospitals and explore the factors influencing anaesthetists' decision-making. Anonymous online voluntary survey. A group of 93 veterinarians working as anaesthetists, from 189 eligible individuals. An email containing a link to a 26 question online survey was sent to 189 UK small-animal referral veterinarians with advanced anaesthesia training and access to CT scanners. Questions addressed training level, practice settings, and approaches to intravenous fluid therapy (IVFT) and anaesthesia during CT scans, including standard operating procedure (SOP) use. There were 93 responses (49.2%). An SOP was absent for selecting general anaesthesia (GA) versus sedation in 65% of cases, for pre-contrast blood testing in 71%, and for IVFT in 42%. Among respondents who routinely chose GA, reasons included requiring apnoea (51.6%), chest inflation requests (38.7%), and safety during anaphylactic reactions (10.7%). Creatinine and urea were commonly measured (52.7%) to assess kidney function and estimate the risk of contrast-induced acute kidney injury (CI-AKI). The initiation of IVFT and rates used varied, often adjusted according to animal condition, with 34.4% of respondents citing concerns about CI-AKI as the main reason for giving fluids. This study highlights variability in veterinary CT anaesthesia practices in UK referral hospitals. Although CI-AKI concerns were common, reported pre-contrast blood and urine analysis and IVFT practices varied considerably among respondents. More research is needed to establish evidence-based guidelines.
To assess interobserver agreement and predictive value of the Combined Horse Anaesthetic Risk Identification and Optimisation Tool (CHARIOT) compared with the American Society of Anesthesiologists Physical Status (ASA-PS) classification system among five groups of evaluators with different levels of expertise, and to explore the association between risk scores and 7-day postoperative mortality. Prospective, observational, single-centre pilot study. A group of 50 client-owned horses. Each horse was assessed (ASA-PS and CHARIOT) before general anaesthesia by one evaluator from each of five groups: equine rotating intern, resident of the European College of Veterinary Anaesthesia and Analgesia (ECVAA), anaesthetist expert (ECVAA Diplomate/residency-trained), equine resident [European College of Veterinary Surgeons (ECVS) or European College of Equine Internal Medicine (ECEIM)] and European Board of Veterinary Specialisation (EBVS) Specialist (ECVS or ECEIM Diplomate). Mixed-effects Poisson regression analysed adjusted mean scores by evaluator type and scoring system, with pairwise comparisons to identify significant differences. Logistic regression and receiver operating characteristic curve analysis assessed associations between scores and 7-day postoperative mortality. Adjusted mean scores (95% confidence interval) for ASA-PS and CHARIOT: anaesthesia experts 2 (1.8-2.2), 13.9 (13.4-14.3); anaesthesia residents 1.9 (1.7-2.2), 13.6 (13.1-14.1); interns 1.9 (1.7-2.1), 13.2 (12.8-13.7); equine residents 1.9 (1.7-2.1), 13.2 (12.8-13.6) and EBVS Specialists 1.8 (1.6-2), 12.7 (12.3-13.1). Pairwise differences existed between ECVAA evaluators (resident and experts) and every other group (p < 0.05). Higher scores for CHARIOT and ASA-PS were associated with increased odds of 7-day postoperative mortality (p < 0.001). Anaesthesia experts assigned higher risk scores with both scales. Higher scores on both scales were associated with increased mortality risk. Multicentre studies are warranted to confirm CHARIOT's predictive performance and to refine its clinical application.
To evaluate the evidence of the pharmacodynamic benefits of total intravenous anaesthesia (TIVA) compared with inhalant anaesthesia in dogs. PubMed, Embase, CABI and ScienceDirect databases were searched from 1 January 1990 to 30 August 2025. Search criteria: TIVA AND DOG AND INHALANT; ANAESTHESIA AND PROPOFOL OR ALFAXALONE AND TIVA AND DOG; PROPOFOL AND ISOFLURANE OR SEVOFLURANE AND DOG. Published research papers comparing TIVA and inhalant anaesthesia in dogs were evaluated. Studies were assessed for their level of evidence (LoE) based on categorization as clinical studies or experimental and the risk of bias (RoB). RoB was assigned by two independent assessors using five domains: selection bias, performance bias, attrition bias, reporting bias and other sources of bias. Assessments were then categorized as low, moderate or high RoB. This review identified 24 studies comparing TIVA with inhalant anaesthesia for maintenance of anaesthesia in dogs. All studies were categorized as LoE II-III. Of the 24 studies, 18 studies used isoflurane as the inhalant anaesthetic, whereas five studies used sevoflurane and one study used both. Propofol TIVA was used in 20 studies, whereas two studies used alfaxalone TIVA, and both were investigated in two studies. Cardiovascular outcomes were assessed in nine studies, whereas four studies focused on pulmonary outcomes. Neurological outcome, neuromuscular blockade, postoperative analgesia, immunological effects, urethral closing pressures and ease of duodenal endoscopy were also assessed. Of the 24 studies, three also included recovery quality characteristics. In all the evaluated studies, elements of bias were identified; five studies were assigned an overall moderate risk, 19 studies with an overall high RoB and none were low RoB. There is currently limited evidence supporting the use of TIVA in preference to inhalant anaesthesia in dogs.
To compare cardiopulmonary variables and recovery scores in isoflurane-anesthetized horses undergoing arthroscopy using two different intravenous (IV) lidocaine constant rate infusions (CRIs; 50 or 100 μg kg-1 minute-1) under intermittent positive pressure ventilation (IPPV) or spontaneous ventilation (SV). Prospective, randomized, clinical study. A group of 30 client-owned horses, 8-156 months old (range), with body masses of 280-550 kg. Anesthesia protocol consisted of xylazine, ketamine and diazepam, and maintenance with isoflurane and a CRI of dexmedetomidine. All groups were given an IV bolus of lidocaine (2 mg kg-1) 15 minutes after induction and were randomized to CRI 50 or 100 μg kg-1 minute-1 under IPPV or SV (groups IPPV50, IPPV100, SV50 and SV100). Lidocaine was stopped before recovery. Cardiopulmonary variables, plasma lidocaine concentrations during anesthesia and recovery, and a numerical and descriptive score for quality of recovery were compared between groups. Data were analyzed using one- or two-way ANOVA or Kruskal-Wallis tests when appropriate. SV groups had significantly higher arterial and end-tidal CO2 tensions and lower pH (p < 0.0001). Mean arterial blood pressure differed by ≤ 7 mmHg between groups, was significantly higher in SV100 (p < 0.0001) and IPPV100 (p = 0.0001) than SV50, and was higher in SV100 than IPPV50 (p = 0.044). Intraoperative lidocaine concentrations were significantly higher (p = 0.0005-0.049) with the higher CRI, and in all groups decreased significantly by 20 minutes in recovery (p < 0.0001-0.002). All groups had similar numerical (p = 0.529) and similar descriptive recovery scores [p = 0.413; IPPV50: 2 (1,2), IPPV100: 1 (1,3), SV50: 2 (1,2), SV100: 2 (2,3), median (range)], and of good quality. Low and high CRI lidocaine resulted in similar cardiopulmonary function and quality of recovery in healthy horses undergoing arthroscopy. SV resulted in hypercapnia.
To assess the reliability of a published rabbit sedation scale when used by inexperienced raters compared with experienced raters. Experimental, randomised and blinded study. A group of 16 rabbits, 3-4 months old and 1.9 ± 0.5 kg (mean ± standard deviation). Rabbits were premedicated intramuscularly with midazolam 1 mg kg-1 and butorphanol 0.5 mg kg-1 (n = 8) or midazolam 1 mg kg-1 and methadone 1 mg kg-1 (n = 8). After a short explanation of the sedation scale, two experienced raters (one Diplomate of the European College of Veterinary Anaesthesia and Analgesia, and one Diplomate of the European College of Zoological Medicine) and four inexperienced raters (veterinary students) applied the sedation scale before sedation and at 10 and 20 minutes after sedation. Weighted kappa (κw) with linear weights and Gwet's agreement coefficient AC2 (Gwet's AC2) were used to determine inter-observer agreement between the two Diplomates, and Gwet's AC2 and Krippendorff's α (αk) coefficients were used to evaluate inter-observer agreement between the four students for each of the eight items. Agreement was considered when κw = 0.81-1.000. Lin's concordance correlation coefficient was used to evaluate the concordance. A paired t-test and Gwet's AC2 coefficient were used to compare the groups. There was agreement within experienced [κw = 0.981 (0.970-0.992), p = 0.001; Gwet's AC2 = 0.973 (0.943-1.000), p = 0.001] and inexperienced raters [αk = 0.658 (0.618-0.699), p = 0.001; Gwet's AC2 = 0.741 (0.705-0.778), p = 0.001]. There were statistically significant differences depending on the experience of the rater (p = 0.001). The sedation protocol did not affect the agreement between raters (p = 0.084). The rabbit sedation scale was reliable when used by experienced or inexperienced raters.
To describe and compare a retrobulbar (RBA) and two peribulbar (PBA-1 and PBA-2) injection techniques in rabbit cadavers. Prospective experimental cadaveric study. A total of 30 New Zealand White Rabbit cadavers. Computed tomography (CT) was performed to evaluate the needle position and the distribution of contrast agent. A total of 60 retrobulbar spaces underwent one of the three techniques (20 each) with a mixture of 1:2:2 iodinated contrast medium, methylene blue, and 0.9% saline solution with 0.7 mL for RBA, 1 mL for ventrolateral PBA-1 and 1 mL twice for dorsomedial and ventrolateral PBA-2. Intra-versus extraconal contrast distribution were compared. p < 0.05. In 13/20 RBA cases, the contrast distribution was intra- and extraconal, in 6/20 purely extraconal, and in 1/20 intraocular (into the globe). RBA showed a statistically significant extraconal distribution (p < 0.001). In group PBA-1, intra- and extraconal contrast distribution were present in 7/20 orbits, in 11/20 extraconal, and in 2/20 intraocular. There was a statistically significant extraconal distribution in the PBA-1 (p < 0.001). PBA-2 showed a mixed intra- and extraconal contrast accumulation in 7/20 orbits, extraconal in 5/20, and intraocular in 8/20. The dorsally placed needle resulted in a statistically significant intraocular location compared with the ventral needle. The injection resulted in a change in the needle position in one orbit in the PBA-2 group compared with the pre-injection scan. In all other cases with an intraocular contrast distribution, no change in needle position could be detected. The lowest number of complications (intraocular contrast accumulation) was with RBA, but there was no pure intraconal distribution of contrast medium. This technique may be suitable if extraconal anesthesia is desired. Due to the high intraocular distribution, PBA-2 does not appear to be a suitable technique.
To compare the effects of haemorrhage and subsequent fluid resuscitation with Plasma-Lyte A (PA) or Ringer's Lactate (RL) on buccal microcirculation. Single-centre, randomised, blinded, experimental study. A group of 12 adult, healthy, intact, purpose-bred Beagle dogs. In sevoflurane anaesthetised Beagle dogs, a sidestream dark field (SDF) imaging device was positioned on the buccal mucosa to evaluate microcirculatory variables, which included perfused De Backer density (pDBD) and proportion of perfused vessels. Videos were recorded at baseline, following the removal of 30 mL kg-1 of blood to induce hypovolaemia (HV), and after each 10 mL kg-1 intravenous fluid bolus (B1 and B2) according to the assigned treatment group. Data were compared between groups and over time using a linear mixed model with group and time point as fixed and dogs as random factors. Post hoc multiple comparisons were performed with Sidak's corrections. A p value < 0.05 was considered significant. The haemorrhage resuscitation model resulted in significant changes in microcirculation over time. In group RL, pDBD was significantly more reduced compared with group PA at HV [RL: 1.3 (0.9-1.8) n mm-1 (median ± 95% confidence interval), PA: 2.3 (1.6-2.7) n mm-1, p = 0.004] and B2 [RL: 2 (1.7-2.7), PA: 3.3 (2.7- 4.2), p < 0.001]. Proportion of perfused vessels was also more reduced in group RL compared with group PA at HV [RL: 57 (53-77)%, PA: 78 (69-93)%, p < 0.001] and B2 [RL: 72 (65-96)%, PA: 85 (77-99)%, p = 0.012]. Dogs administered PA showed fewer changes in pDBD and proportion of perfused vessels values after haemorrhage and resuscitation with 20 mL kg-1 PA compared with those administered RL. Due to the small sample size these preliminary findings warrant further research.
To evaluate the nociceptive, motor and proprioceptive response after ultrasound-guided perineural sciatic nerve injections of bupivacaine 0.25% and 0.5% in Wistar rats. Prospective, randomized, blinded crossover study. A group of eight healthy adult female Wistar rats. Rats underwent isoflurane anesthesia and were given ultrasound-guided sciatic nerve injections of 0.1 mL of 0.25% or 0.5% bupivacaine, with a 1 week recovery period between injections. Nociceptive function [electronic von Frey (grams, response)], motor function [grip test, gait response (1-3 scale)] and proprioceptive function [tactile placing (0-3 scale) and paw positioning (clubbed digits/normal splaying)] were evaluated at baseline and at 5, 10, 20, 30, 40, 60, 90, 120, 180, 240, 300 and 360 minutes after anesthesia. Data were analyzed using mixed models with significance set at p < 0.05. Sciatic nerve blockade was effective from 20 minutes into recovery, with treatment, time and interaction on nociceptive function being significant from 20 to 240 minutes (p < 0.05). In Group 0.25%, sensory function peaked at 60 minutes [111.2 g, 95% confidence interval (CI) 100.8-121.5] and returned to a baseline response at 240 minutes (55.5 g, 95% CI: 45.2-65.9). Significant differences between treatment groups were observed from 5 to 240 minutes. Motor and proprioceptive functions were reduced at 20 minutes [median score: 1, interquartile range (IQR: 1)] and returned to baseline at 240 minutes. In Group 0.5%, sensory function peaked at 90 minutes (133.7 g, 95% CI: 123.3-144.1) and returned to baseline (52.0 g, 95% CI: 41.6-62.4) in 300 minutes. Motor and proprioceptive functions were reduced at 10 minutes [1 (IQR: 0.25)] and returned to baseline by 300 minutes. Both 0.25% and 0.5% bupivacaine concentrations produced effective sciatic nerve blockade in all rats, demonstrating a concentration-dependent effect on the duration and magnitude of nociceptive, motor and proprioceptive block.
To evaluate the pharmacokinetics of two doses of intraperitoneal ropivacaine in anaesthetized dogs. Randomized clinical trial. A total of 20 dogs undergoing ovariectomy/ovariohysterectomy. Dogs were anaesthetized and randomized to be given 1 (group R1) or 3 (group R3) mg kg-1 of ropivacaine intraperitoneally, diluted with 0.9% NaCl to a total volume of 0.8 mL kg-1. Before abdominal wall closure, solution aliquots were instilled over the ovarian pedicles and, if applicable, the uterine stump. Venous blood was sampled 2 minutes before and 5, 10, 15, 30, 45, 60, 120 and 240 minutes after instillation. Cardiovascular signs of toxicity were noted. Plasma concentrations of free and total ropivacaine were measured using ultrahigh-performance liquid chromatography-mass spectrometry. Plasma protein binding (PPB) was determined by rapid equilibrium dialysis. Pharmacokinetic parameters were derived by a noncompartmental analysis, and the maximum total and free ropivacaine plasma concentrations (Cmax) were compared between groups using an independent samples t-test. Data are presented as mean or median (95% confidence intervals). Significance was set at p < 0.05. One dog in R3 was excluded. Total ropivacaine Cmax values were 0.27 (0.21-0.33) and 0.67 (0.43-0.92) mg L-1 at 15 (8.64-30.35) and 5 (1.77-8.23) minutes (Tmax) for R1 and R3, respectively, and different between groups (p = 0.005). Free ropivacaine Cmax values were 0.02 (0.02-0.03) and 0.06 (0.03-0.09) mg L-1 at 10 (4.67-15.32) and 5 (0-19.13) minutes (Tmax) for R1 and R3, respectively, and Cmax was different between groups (p = 0.015). Median ropivacaine PPB for all dogs was 92.5% (89.7-95.2%). No signs of cardiovascular toxicity were noted. Although R3 had a greater total and free ropivacaine Cmax than R1, Cmax remained below toxic levels in all dogs.
To evaluate the accuracy, agreement, and trending ability of the pulse contour cardiac output (PulseCO) system calibrated with echocardiography-derived cardiac output (CO) in sevoflurane-anesthetized healthy dogs during 8 hours of general anesthetic. Prospective, randomized, blinded experimental study. A total of five healthy Beagle dogs, three intact females and two intact males. Dogs were anesthetized using intravenous alfaxalone for induction and sevoflurane in 100% oxygen for maintenance for 8 hours. CO was estimated using three methods: pulmonary artery catheter thermodilution (PAC-TD)-derived CO (COPAC-TD), Doppler-based echocardiography-derived CO (COEcho), and PulseCO-derived CO (COPulseCO). The PulseCO monitor was calibrated at baseline using COEcho and not recalibrated during the anesthetic. Measurements were taken at baseline and at intervals up to 8 hours. All CO values were converted to cardiac index (CI) by indexing to body surface area. Statistical analysis included Bland-Altman and linear regression analyses for agreement assessment and Critchley's four-quadrant and polar plots for trending analysis. A total of 100 paired CI measurements were obtained. Bland-Altman analysis revealed a mean bias of -0.1 L minute-1 m-2 and percentage error of 28.3% for CIPAC-TDversus CIPulseCO, and a mean bias of 0.01 L minute-1 m-2 with a percentage error of 24.9% for CIPAC-TDversus CIEcho. Trending analysis between CIPAC-TD and CIPulseCO showed a concordance rate of 98.2% in the four-quadrant plot and a mean angular bias of 2.6 ° with radial limits of agreement ranging from -21.47 ° to 26.67 ° in the polar plot. The results indicate that the PulseCO system has acceptable accuracy, agreement, and trending ability compared with the traditional reference method of PAC-TD. This highlights the potential of the PulseCO system as a minimally invasive and practical monitoring tool in sevoflurane-anesthetized dogs.
To evaluate the cardiac changes in healthy dogs sedated with medetomidine-vatinoxan and methadone, underdoing echocardiographic and radiographic evaluation. A prospective, clinical study. A group of 18 dogs. Dogs were administered intramuscularly methadone (0.1 mg kg-1) with medetomidine-vatinoxan (0.015-0.3 mg kg-1 in dogs < 20 kg or 0.01-0.2 mg kg-1 in dogs > 20 kg). Cardiovascular variables and sedation were recorded at baseline (T0) and at 5, 10 and 15 minutes after injection (T5, T10 and T15, respectively). Echocardiography and thoracic radiographs for vertebral heart score (VHS) were assessed before (T0), and 15 (T15) and 20 (20) minutes later, respectively. Left ventricular (LV) end-systolic diameter and volume, LV fractional shortening, ejection fraction, aortic and pulmonary blood flow were measured amongst other variables. Data are shown as the mean ± standard deviation p < 0.05. Sedation was achieved by T5. Heart rate decreased from T0. The blood pressure increased at T5 and thereafter was < baseline. After sedation, VHS increased (from 10.6 ± 0.9 to 11.0 ± 1.1) and the LV end-systolic diameter (from 2.5 ± 0.5 cm to 2.8 ± 0.6 cm) and volume (from 23.6 ± 8.2 mL m-2 to 31.5 ± 11.1 mL m-2) increased (overall p < 0.001). A decrease of LV fractional shortening (from 34.1 ± 7.2% to 27.0 ± 7.0%; p < 0.001), ejection fraction (from 63.3 ± 7.8% to 53.8 ± 10.1%; p < 0.001), aortic flow (from 144.9 ± 37.6 cm second-1 to 121.1 ± 36.9 cm second-1; p < 0.001), pulmonary flow (from 93.2 ± 19.8 cm second-1 to 76.9 ± 17.8 cm second-1; p < 0.001) were observed. Medetomidine-vatinoxan and methadone induced significant radiographic and echocardiographic changes, which were of limited clinical concern in this population of dogs. However, they should be considered when this drug combination is used.
To describe an ultrasound-guided in-plane technique for maxillary nerve block in dogs and its clinical analgesic application. Descriptive anatomical study and retrospective case series. A group of 12 canine cadavers and six client-owned dogs. Cadavers were placed in lateral recumbency, and the ultrasound transducer was positioned transversely across the head, ventral to the zygomatic arch and cranial to the mandible to visualize the pterygopalatine fossa. The fascial plane between the zygomatic gland and medial pterygoid muscle was identified, and a 22 gauge, 50 mm insulated needle was advanced in-plane to inject 0.1 mL of a 1:1 dye-saline per hemimaxilla. Injection success was assessed by staining of the maxillary nerve or its perineural fascia during dissection. Clinical anaesthesia records from six dogs undergoing maxillofacial procedures were reviewed retrospectively. Blocks were performed using the pulsation of the maxillary artery as a sonographic landmark. Block success was defined as absence of nociceptive response to upper lip pinching postoperatively. Staining success is presented as numbers and percentages (n/n, %). In the cadavers, 14/24 injections (58.3%) resulted in maxillary nerve or perineural fascia staining. In the clinical series, median body mass was 26.6 (range: 4.4-34.8 kg). A total of nine blocks were performed in six dogs using 0.5% bupivacaine (0.06-0.2 mL kg-1): bilateral blocks in three dogs and unilateral blocks in three dogs. All dogs (9/9, 100%) demonstrated postoperative sensory blockade; however, two dogs required intraoperative fentanyl. This ultrasound-guided in-plane approach achieved a moderate success rate in cadavers. In vivo, the pulsatile maxillary artery served as a reliable landmark for injection with consistent postoperative sensory blockade. The technique appears feasible and may represent a clinically effective alternative to traditional blind approaches.
To compare the length of nerve staining of two volumes of bupivacaine-dye solution following ultrasound-guided injections of sciatic and femoral nerves using a lateral approach in chicken cadavers. Prospective, randomized, blinded, crossover design. A group of eight Ross 708 breeder hen cadavers weighing 1.7 ± 0.5 kg. Chicken cadavers were placed in lateral recumbency, and an ultrasound transducer was positioned perpendicular to the femur, on the proximolateral aspect of the thigh, allowing visualization of the sciatic nerve and femoral neurovascular sheath in the same acoustic window. Each chicken leg (n = 16) was assigned to one of two treatments: low-volume (0.2 mL per nerve; LV) or high-volume (0.8 mL per nerve; HV) bupivacaine-dye solution. Perineural injections in the sciatic and femoral nerves were performed by advancing an insulated needle in-plane in a caudal-to-cranial direction. The coelomic cavities were inspected for dye solution. Gross dissections were conducted to assess distribution of the dye in both phases. Length of nerve staining between LV and HV groups was compared using a two-tailed t test. All sciatic nerves for both groups were stained. One femoral nerve in the LV group and two in the HV group were not stained. The mean ± standard deviation length of nerve staining for LV and HV was 2.3 ± 0.7 and 4.7 ± 1.0 cm (p = 0.001) for the sciatic nerve, and 1.5 ± 0.5 and 2.8 ± 0.7 cm (p = 0.002) for the femoral nerve, respectively. Dye was detected in the coelomic musculature of one chicken and coelomic cavity of another after femoral nerve injections. Both low- and high-injection volumes effectively stained all sciatic and most femoral nerves using an ultrasound-guided lateral approach. However, coelomic cavity injection may occur with this approach to the femoral nerve.
To assess the physiological effects and efficacy of immobilisation with low-dose thiafentanil in combination with medetomidine and azaperone in African buffalo. Observational prospective cohort study. A group of 41 African buffalo selected opportunistically during immobilisation events at nine game ranches and reserves. Buffalo (12 males, 29 females; 9 calves, 32 adults) were immobilised with thiafentanil, medetomidine and azaperone. Recumbency and recovery times were recorded. Immobilisation quality was scored (0-4; poor to excellent). Physiological data were recorded using a stethoscope, digital thermometer and pulse oximetry. Arterial blood samples were collected in 21 animals. Venous blood was collected for biochemical analyses. Oxygen (4-6 L minute-1) was delivered via nasal insufflation in 13 buffalo, with paired arterial blood samples from eight animals to explore effects on oxygenation. Naltrexone (20-25 mg per animal) was administered intravenously following procedure completion. Data are presented as median (interquartile range). Doses were 0.0038 (0.0033-0.0043) mg kg-1 thiafentanil, 0.0042 (0.0038-0.0050) mg kg-1 medetomidine and 0.050 (0.044-0.057) mg kg-1 azaperone, based on estimated body weights. Immobilisation and recovery times were 7.5 (6-9) and 2.0 (1.1-2.0) minutes, respectively. Immobilisation quality was good to excellent in 36 buffalo. Heart rate was 64 (55-76) beats minute-1, respiratory rate 24 (20-32) breaths minute-1, peripheral haemoglobin oxygen saturation 82 (72-85) % and rectal temperature 39.6 (38.3-40.5) °C. All 41 buffalo were hypoxemic, based on pulse oximetry and/or arterial blood gas analysis, and 17 were hyperthermic. For the eight buffalo with paired arterial blood samples, oxygen supplementation improved PaO2, with six becoming normoxaemic. This protocol resulted in rapid immobilisation, good to excellent immobilisation quality, and rapid recovery. However, hyperthermia and hypoxaemia were major concerns. Nasal insufflation of oxygen was a simple and effective method to improve arterial oxygenation.
To determine the antinausea and antiemetic effects of dimenhydrinate and maropitant in dogs when administered 60 minutes before hydromorphone and dexmedetomidine. Prospective, randomized, blinded, placebo-controlled clinical trial. A total of 87 healthy client-owned dogs undergoing ovariectomy/castration. Dogs were randomly assigned to be administered maropitant (1 mg kg-1; group M) subcutaneously (SC), dimenhydrinate (4 mg kg-1; group D) intramuscularly (IM), or 0.9% NaCl (0.1 mL kg-1; group C) SC 60 minutes before anesthetic premedication with hydromorphone (0.1 mg kg-1) and dexmedetomidine (5-15 μg kg-1) IM. Incidences of discomfort after injection of the treatment drug, nausea (ptyalism, lip licking, and swallowing), and vomiting/retching were documented. Scores for nausea and sedation were assigned immediately before premedication and for 20 minutes after premedication. Data were analyzed using Fisher's Exact test and Kruskal-Wallis test, with statistical significance set at p< 0.05. Discomfort to injection was significantly higher in group M (20/31, 64.5%) than in groups D (6/28, 21.4%) and C (2/28, 7.1%) (p< 0.0001). Incidence of nausea was not significantly different between treatment groups [group M; 23/31 (74.2%) versus group D; 27/28 (96%) versus group C; 23/28 (82.1%), p= 0.050]. The incidence of vomiting/retching was significantly lower in group M (0/31, 0%) compared to groups D (15/28, 53.6%) and C (9/28, 32.1%) (p< 0.0001). Dimenhydrinate produced no measurable antinausea and antiemetic effect when administered 60 minutes before hydromorphone and dexmedetomidine. Maropitant SC prevented hydromorphone-induced emesis but was ineffective in reducing nausea.
To evaluate the effects of intraoperative intravenous lidocaine continuous rate infusion (CRI) on postoperative pain and interleukin-6 (IL-6) concentrations in dogs undergoing thoracolumbar hemilaminectomy for intervertebral disc extrusion. Prospective, randomized, blinded, controlled clinical trial. A group of 40 client-owned dogs. Dogs were anesthetized with a standardized protocol that included fentanyl CRI for intra- and postoperative analgesia. Dogs received either lidocaine CRI at 100 μg kg-1 minute-1 or NaCl 0.9% (control) intraoperatively. Pain was assessed at presentation, 0, 2, 6, 12, and 24 hours postanesthesia using the Glasgow Composite Measure Pain Scale-Short Form (CMPS-SF). IL-6 plasma concentrations were measured on presentation, 0, 6, and 48 hours postanesthesia. A generalized linear mixed model was used to compare IL-6 and end-tidal isoflurane concentration values between groups and over time. A binary mixed model was used to model rescue analgesic required over time and between groups. Wilcoxon rank sum tests were used to compare recovery scores, total hospitalized days, maximum dose of fentanyl used postoperatively, and CMPS-SF scores between groups. Spearman's correlation coefficient was used to assess correlation between IL-6 and CMPS-SF scores. Data are median (interquartile range). Lidocaine was associated with lower pain scores (1, 1-6) compared to control (2, 1-11) at 0 hours (p = 0.023) with no significant differences between groups at other times. Lidocaine resulted in a lower anesthesia recovery score (1, 0-2) compared to control group (2, 1-3) (p = 0.041). IL-6 concentrations increased over time for both groups (p < 0.0001), with no significant differences between groups and no correlation between IL-6 values and postoperative pain scores. Intraoperative lidocaine CRI was associated with a lower CMPS-SF score during the immediate postoperative period, provided smoother anesthesia recoveries, and may be considered for dogs undergoing thoracolumbar hemilaminectomy.
To compare postoperative analgesic efficacy between ropivacaine and liposomal bupivacaine when used for an erector spinae plane (ESP) block as part of analgesic management for hemilaminectomy surgery caudal to the eleventh thoracic vertebrae. Randomized, blinded, single-center study. A total of 112 dogs. Following diagnosis of intervertebral disc extrusion caudal to the eleventh thoracic vertebra with magnetic resonance imaging, dogs were randomly assigned to either liposomal bupivacaine or ropivacaine (0.4 mL kg-1) for an ESP block. All dogs were anesthetized using the same anesthetic protocol. Rescue opioid analgesia was administered if physiological variables increased ≥ 10% from baseline following surgical stimulation. Pain was assessed using the short-form Glasgow Composite Measure Pain Scale (CMPS-SF) at initial presentation and 1, 4, 6, 12, and 24 hours postoperatively. Postoperative fentanyl (constant rate infusion) was administered to all dogs for 24 hours postoperatively. Postoperative ketamine was administered if the CMPS-SF score exceeded 6/24. Data were analyzed with a generalized linear mixed-effect model with a beta distribution and logit link function fitted, using the GLIMMIX procedure. Data are median (range). Of the 112 dogs, 56 were administered liposomal bupivacaine and 56 ropivacaine. No significant difference in pain score was found between treatment groups [bupivacaine 3 (2-4), ropivacaine 3 (2-4); p = 0.540] across all time points. Pain scores at 1 [bupivacaine 3 (2-4), ropivacaine 3 (2-4); p < 0.0001)] and 4 [bupivacaine 3 (2-4), ropivacaine 3 (2-4); p = 0.004] hours postoperatively were significantly higher than at 24 hours [bupivacaine 2 (2-3), ropivacaine 2 (1-2)]. These results indicate there is no significant difference in pain scores following use of ropivacaine or liposomal bupivacaine for an ESP block for hemilaminectomy surgery.
A 5-month-old English Bulldog with a history of clinically resolved bronchopneumonia was admitted for a computed tomography scan and corrective surgery for brachycephalic obstructive airway syndrome. The day of imaging and surgery, the dog did not show any signs of cardiovascular abnormalities. The dog was premedicated intravenously (IV) with maropitant (1 mg kg-1), pantoprazole (1 mg kg-1) and acepromazine (20 μg kg-1). Anaesthesia was induced with alfaxalone (2 mg kg-1) IV after 5 minutes of preoxygenation, and anaesthesia was maintained with isoflurane in oxygen [inspired fraction (FIO2) =1]. After induction, physiological variables were unremarkable. Metoclopramide (1 mg kg-1) was injected slowly IV, and the dog immediately developed a severe sinus bradycardia (4 beats minute-1) followed by asystole. Cardiopulmonary resuscitation was started along with atropine (40 μg kg-1 IV), and isoflurane discontinued. Within 1 minute, spontaneous circulation with stable haemodynamic variables was restored. Both the diagnostic and the surgical procedures were completed without further complications. The dog recovered and was discharged the same day. Rare but serious cardiac effects have been described following metoclopramide administration in humans, including bradycardia, asystole and arrhythmia. Cardiotoxicity may be linked to its clinical ability to inhibit sodium channels. To our knowledge, no metoclopramide-induced asystole has previously been reported in veterinary patients. The link between cardiac arrest and metoclopramide administration and possible predisposing factors in this case are discussed.