Pulmonary artery dissection following pulmonary balloon valvuloplasty in dogs

Introduction/objectivesPulmonary artery dissection is a rare complication following balloon valvuloplasty for pulmonic stenosis. We sought to report the rate of this complication in dogs and describe the demographic, clinical, procedural, and outcome data in affected dogs.Animals, materials and methodsMedical records at a single academic institution between 2002 and 2021 were reviewed for dogs with pulmonic stenosis treated by a balloon valvuloplasty. Dogs were included for evaluation if there was evidence of pulmonary artery dissection on echocardiography or necropsy following balloon valvuloplasty. The demographic, clinical, surgical, and follow-up information were then recorded.ResultsSix dogs were included from 210 balloon valvuloplasty procedures for pulmonic stenosis giving a 3.9% rate of pulmonary dissection. There was a variety of signalment, pulmonary valve morphologies, and balloon catheter types used in each dog. All dogs had severe pulmonic stenosis (median pressure gradient of 208 mmHg, range 94–220 mmHg) with 5/6 dogs having a pressure gradient >144 mmHg. The median balloon to pulmonary valve annulus ratio was 1.35 (range 1.25–1.5). Three dogs died perioperatively, and three dogs were alive at follow up 3.3, 4.0, and 4.1 years postoperatively.ConclusionPulmonary artery dissection is a rare complication following balloon valvuloplasty for pulmonic stenosis. Extreme elevations in preoperative pulmonary valve flow velocity were common. Prognosis is variable, with a potential 50% perioperative survival rate, but extended survival times were noted in those patients discharged from hospital.     

Effects of fentanyl–lidocaine–ketamine versus sufentanil–lidocaine–ketamine on the isoflurane requirements in dogs undergoing total ear canal ablation and lateral bulla osteotomy

ObjectiveTo compare the isoflurane-sparing effects of sufentanil–lidocaine–ketamine (SLK) and fentanyl–lidocaine–ketamine (FLK) infusions in dogs undergoing total ear canal ablation and lateral bulla osteotomy (TECA–LBO).Study designRandomized blinded clinical study.AnimalsA group of 20 client-owned dogs undergoing TECA–LBO.MethodsIntravenous (IV) administration of lidocaine (3 mg kg^–1) and ketamine (0.6 mg kg^–1) with fentanyl (5.4 μg kg^–1; n = 10; FLK group) or sufentanil (0.72 μg kg^–1; n = 10; SLK group) was immediately followed by the corresponding constant rate infusion (CRI) (lidocaine 3 mg kg^–1 hour^–1; ketamine 0.6 mg kg^–1 hour^–1; either fentanyl 5.4 μg kg^–1 hour^–1 or sufentanil 0.72 μg kg^–1 hour^–1). Anaesthesia was induced with propofol 3–5 mg kg^–1 IV and was maintained with isoflurane. End-tidal isoflurane concentration (Fe′Iso) was decreased in 0.2% steps every 15 minutes until spontaneous movements were observed (treated with propofol 1 mg kg^–1 IV) or an increase of > 30% in heart rate or mean arterial pressure from baseline occurred (treated with rescue fentanyl or sufentanil). Quality of recovery and pain were assessed at extubation using the short-form Glasgow Composite Pain Scale (SF-GCPS), Colorado State University Canine Acute Pain scale (CSU-CAP), and visual analogue scale (VAS). Data were analysed with analysis of variance, t tests, Fisher test and Spearman coefficient (p < 0.05).ResultsFe′Iso decreased significantly in SLK group (45%; p = 0.0006) but not in FLK (15%; p = 0.1135) (p = 0.0136). SLK group had lower scores for recovery quality (p = 0.0204), SF-GCPS (p = 0.0071) and CSU-CAP (p = 0.0273) than FLK at extubation. Intraoperative rescue analgesia and VAS were not significantly different between groups.Conclusions and clinical relevanceCompared with FLK infusion, CRI of SLK at these doses decreased isoflurane requirements, decreased pain scores and improved recovery quality at extubation in dogs undergoing TECA–LBO.     

Transthoracic echocardiographically-guided interventional cardiac procedures in the dog

ObjectivesInterventional cardiac procedures are traditionally performed using fluoroscopy, or, more recently, transesophageal echocardiography (TEE). Neither modality is widely available to practicing cardiologists worldwide. We examined whether balloon valvuloplasty of pulmonic stenosis (PS) and transarterial occlusion of patent ductus arteriosus (PDA) in dogs could be performed safely with transthoracic echocardiography (TTE).AnimalsA prospective consecutive case series of 26 client-owned dogs with PS (n = 10) and PDA (n = 16).MethodsThe cardiovascular procedures were performed using TTE. Each dog was positioned on a standard echocardiography table in right lateral recumbency (dogs with PS) or left lateral recumbency (dogs with PDA). Guide wires, balloon catheters, Amplatz^® Canine Ductal Occluder (ACDO) delivery sheaths, and ACDO were imaged by standard echocardiographic views optimized to allow visualization of the defects and devices.ResultsProcedures were performed successfully without major complications in 20 dogs. In 2 dogs (German shepherds) with Type III PDA, ACDO placement was unsuccessful; 2 other German Shepherds were excluded from the procedure because their ductal diameters, measured echocardiographically, exceeded the limits of the maximal ACDO size. Two dogs weighing ≤3.5 kg had suboptimal echocardiographic visualization of the PDA and were considered too small for safe ACDO deployment. All intravascular devices at the level of the heart and great vessels appeared hyperechoic on TTE image and could be clearly monitored and guided in real-time.ConclusionsWe have demonstrated that TTE monitoring can guide each step of pulmonic balloon valvuloplasty and PDA occlusion without fluoroscopy.     

Effects of intravenous lidocaine, ketamine, and the combination on the minimum alveolar concentration of sevoflurane in dogs

ObjectiveTo evaluate the effects of intravenous lidocaine (L) and ketamine (K) alone and their combination (LK) on the minimum alveolar concentration (MAC) of sevoflurane (SEVO) in dogs.Study designProspective randomized, Latin-square experimental study.AnimalsSix, healthy, adult Beagles, 2 males, 4 females, weighing 7.8 – 12.8 kg.MethodsAnesthesia was induced with SEVO in oxygen delivered by face mask. The tracheas were intubated and the lungs ventilated to maintain normocapnia. Baseline minimum alveolar concentration of SEVO (MAC_B) was determined in duplicate for each dog using an electrical stimulus and then the treatment was initiated. Each dog received each of the following treatments, intravenously as a loading dose (LD) followed by a constant rate infusion (CRI): lidocaine (LD 2 mg kg⁻¹, CRI 50 μg kg⁻¹minute⁻¹), lidocaine (LD 2 mg kg⁻¹, CRI 100 μgkg⁻¹ minute⁻¹), lidocaine (LD 2 mg kg⁻¹, CRI 200 μg kg⁻¹ minute⁻¹), ketamine (LD 3 mg kg⁻¹, CRI 50 μg kg⁻¹ minute⁻¹), ketamine (LD 3 mgkg⁻¹, CRI 100 μg kg⁻¹ minute⁻¹), or lidocaine (LD 2 mg kg⁻¹, CRI 100 μg kg⁻¹ minute⁻¹) + ketamine (LD 3 mg kg⁻¹, CRI 100 μg kg⁻¹ minute⁻¹) in combination. Post-treatment MAC (MAC_T) determination started 30 minutes after initiation of treatment.ResultsLeast squares mean ± SEM MAC_B of all groups was 1.9 ± 0.2%. Lidocaine infusions of 50, 100, and 200 μg kg⁻¹ minute⁻¹ significantly reduced MAC_B by 22.6%, 29.0%, and 39.6%, respectively. Ketamine infusions of 50 and 100 μg kg⁻¹ minute⁻¹ significantly reduced MAC_B by 40.0% and 44.7%, respectively. The combination of K and L significantly reduced MAC_B by 62.8%.Conclusions and clinical relevanceLidocaine and K, alone and in combination, decrease SEVO MAC in dogs. Their use, at the doses studied, provides a clinically important reduction in the concentration of SEVO during anesthesia in dogs.     

Opioid-sparing effect of a medetomidine constant rate infusion during thoraco-lumbar hemilaminectomy in dogs administered a ketamine infusion

ObjectiveTo evaluate the perioperative opioid-sparing effect of a medetomidine (MED) infusion compared to a saline (SAL) infusion in otherwise healthy dogs undergoing thoraco-lumbar hemilaminectomy surgery.Study designRandomized, partially blinded, clinical study.AnimalsA total of 44 client-owned adult dogs.MethodsAll dogs were administered a 1 μg kg^–1 MED loading dose, followed by a 1.7 μg kg^–1 hour^–1 constant rate infusion (CRI) intravenously or equivalent volumes of SAL. Infusions were started 10–15 minutes before surgical incision and continued throughout the surgical procedure. All dogs were administered a standardized anaesthetic and analgesic protocol (including a ketamine CRI). Multiparametric monitoring, including invasive arterial blood pressure, was performed. A trained investigator, unaware of the treatment, performed pain scores for 4 hours postoperatively. Rescue analgesia consisted of fentanyl administered intraoperatively and methadone postoperatively. Data were tested for normality and analysed with Fisher’s exact test, Mann–Whitney U-test, analysis of variance and Kaplan–Meier survival analysis. Data are shown as median (interquartile range) and p-value was set at < 0.05.ResultsThe total dose of fentanyl was significantly lower with MED 0 (0–0.8) μg kg^–1 hour^–1 compared to SAL 3 (1.8–5.3) μg kg^–1 hour^–1 (p = 0.004). In the MED group, one dog compared to 12 dogs in the SAL group required a fentanyl CRI (p = 0.001). There were no statistically significant differences between groups regarding the total dose of methadone administered.Conclusions and clinical relevanceThe addition of a low-dose medetomidine CRI to the anaesthetic protocol decreased the need for a fentanyl CRI in otherwise healthy dogs undergoing thoraco-lumbar hemilaminectomy surgery during administration of a ketamine CRI.     

Minimum infusion rate and hemodynamic effects of propofol, propofol-lidocaine and propofol-lidocaine-ketamine in dogs

ObjectiveTo evaluate the effects of a constant rate infusion (CRI) of lidocaine alone or in combination with ketamine on the minimum infusion rate (MIR) of propofol in dogs and to compare the hemodynamic effects produced by propofol, propofol-lidocaine or propofol-lidocaine-ketamine anesthesia.Study designProspective, randomized cross-over experimental design.AnimalsFourteen adult mixed-breed dogs weighing 15.8 ± 3.5 kg.MethodsEight dogs were anesthetized on different occasions to determine the MIR of propofol alone and propofol in combination with lidocaine (loading dose [LD] 1.5 mg kg^?1, CRI 0.25 mg kg^?1 minute^?1) or lidocaine (LD 1.5 mg kg^?1, CRI 0.25 mg kg^?1 minute^?1) and ketamine (LD 1 mg kg^?1, CRI 0.1 mg kg^?1 minute^?1). In six other dogs, the hemodynamic effects and bispectral index (BIS) were investigated. Each animal received each treatment (propofol, propofol-lidocaine or propofol-lidocaine-ketamine) on the basis of the MIR of propofol determined in the first set of experiments.ResultsMean ± SD MIR of propofol was 0.51 ± 0.08 mg kg^?1 minute^?1. Lidocaine-ketamine significantly decreased the MIR of propofol to 0.31 ± 0.07 mg kg^?1 minute^?1 (37 ± 18% reduction), although lidocaine alone did not (0.42 ± 0.08 mg kg^?1 minute^?1, 18 ± 7% reduction). Hemodynamic effects were similar in all treatments. Compared with the conscious state, in all treatments, heart rate, cardiac index, mean arterial blood pressure, stroke index and oxygen delivery index decreased significantly, whereas systemic vascular resistance index increased. Stroke index was lower in dogs treated with propofol-lidocaine-ketamine at 30 minutes compared with propofol alone. The BIS was lower during anesthesia with propofol-lidocaine-ketamine compared to propofol alone.Conclusions and clinical relevanceLidocaine-ketamine, but not lidocaine alone, reduced the MIR of propofol in dogs. Neither lidocaine nor lidocaine in combination with ketamine attenuated cardiovascular depression produced by a continuous rate infusion of propofol.     

Comparison between intravenous lidocaine and fentanyl on cough reflex and sympathetic response during endotracheal intubation in dogs

ObjectiveTo compare the effects of intravenous (IV) lidocaine and fentanyl on the cough reflex and autonomic response during endotracheal intubation in dogs.Study designRandomized, blinded, superiority clinical trial.AnimalsA total of 46 client-owned dogs undergoing magnetic resonance imaging.MethodsAfter intramuscular methadone (0.2 mg kg^–1), dogs were randomized to be administered either IV lidocaine (2 mg kg^–1; group L) or fentanyl (7 μg kg^–1; group F). After 5 minutes, alfaxalone was administered until endotracheal intubation was possible (1 mg kg^–1 IV over 40 seconds followed by 0.4 mg kg^–1 increments to effect). Total dose of alfaxalone was recorded and cough reflex at endotracheal intubation was scored. Heart rate (HR) was continuously recorded, Doppler systolic arterial blood pressure (SAP) was measured every 20 seconds. Vasovagal tonus index (VVTI) and changes (Δ) in HR, SAP and VVTI between pre-intubation and intubation were calculated. Groups were compared using univariate and multivariate analysis. Statistical significance was set as p < 0.05.ResultsGroup F included 22 dogs and group L 24 dogs. The mean (± standard deviation) alfaxalone dose was 1.1 (± 0.2) and 1.35 (± 0.3) mg kg^–1 in groups F and L, respectively (p = 0.0008). At intubation, cough was more likely in group L (odds ratio = 11.3; 95% confidence intervals, 2.1 – 94.2; p = 0.01) and HR increased in 87.5% and 54.5% of groups L and F, respectively (p = 0.02). The median (range) ΔHR between pre-intubation and intubation was higher (13.1%; – 4.3 to + 55.1) in group L (p = 0.0021). Between groups, SAP and VVTI were similar.Conclusion and clinical relevanceAt the stated doses, whilst reducing the alfaxalone dose, fentanyl is superior to lidocaine in suppressing the cough reflex and blunting the increase in HR at endotracheal intubation in dogs premedicated with methadone.     

Clinical efficacy of dexmedetomidine combined with lidocaine for femoral and sciatic nerve blocks in dogs undergoing stifle surgery

ObjectiveTo evaluate the effects of dexmedetomidine administered perineurally or intramuscularly (IM) on sensory, motor function and postoperative analgesia produced by lidocaine for sciatic and femoral nerve blocks in dogs undergoing unilateral tibial tuberosity advancement surgery.Study designProspective, blinded, clinical study.AnimalsA group of 30 dogs.MethodsDogs were anaesthetized with acepromazine, propofol and isoflurane in oxygen/air. Electrolocation-guided femoral and sciatic nerve blocks were performed: group L, 0.15 mL kg^–1 2% lidocaine (n = 10); group LD_loc, lidocaine and 0.15 μg kg^–1 dexmedetomidine perineurally (n = 10); group LD_sys, lidocaine and 0.3 μg kg^–1 dexmedetomidine IM (n = 10). After anaesthesia, sensory blockade was evaluated by response to forceps pinch on skin innervated by the saphenous/femoral, common fibular and tibial nerves. Motor blockade was evaluated by observing the ability to walk and proprioception. Analgesia was monitored with Short Form of Glasgow Composite Pain Scale for up to 4 hours after extubation. Methadone IM was administered as rescue analgesia. Data were analysed by linear mixed effect models and Kaplan-Meier test (p < 0.05).ResultsMedian duration of the sensory blockade for all nerves was longer (p < 0.001) for group LD_loc than for groups L and LD_sys and was longer (p = 0.0011) for group LD_sys than for group L. Proprioception returned later (p < 0.001) for group LD_loc [285 (221–328) minutes] compared with group L [160 (134–179) minutes] or LD_sys [195 (162–257) minutes]. Return of the ability to walk was similar among all groups. Dogs in group LD_loc required postoperative rescue analgesia later (p = 0.001) than dogs in groups LD_sys and L.Conclusions and clinical relevanceDexmedetomidine administered perineurally with lidocaine prolonged sensory blockade and analgesia during the immediate postoperative period. Systemic dexmedetomidine also prolonged the sensory blockade of perineural lidocaine.     

Comparison of postoperative effects between lidocaine infusion,meloxicam, and their combination in dogs undergoing ovariohysterectomy

ObjectiveTo compare the postoperative analgesic effects of intravenous (IV) lidocaine, meloxicam, and their combination in dogs undergoing ovariohysterectomy.Study designProspective, randomized, double‐blind, controlled clinical trial.AnimalsTwenty‐seven dogs aged (mean ± SD) 16.1 ± 7.5 months and weighing 22.4 ± 17.9 kg scheduled for ovariohysterectomy.MethodsAnaesthesia was induced with propofol and maintained with isoflurane. Dogs (n = 9 in each group) were allocated to receive just prior to and during surgery one of the following regimens: M group, 0.2 mg kg^?1 IV meloxicam then a continuous rate infusion (CRI) of lactated Ringer's at 10 mL kg^?1 hour^?1; L group, a bolus of lidocaine (1 mg kg^?1 IV) then a CRI of lidocaine at 0.025 mg kg^?1 minute^?1; and M + L group, both the above meloxicam and lidocaine treatments. Pain and sedation were scored, and venous samples taken for serum cortisol and glucose measurement before and at intervals for 12 hours after anaesthesia. Pain scores were assessed using a multi‐parameter subjective scoring scale (cumulative scale 0–21) by three observers. The protocol stated that dogs with a total score exceeding 9 or a sub‐score above 3 in any one category would receive rescue analgesia. Sedation was scored on a scale of 0–4.ResultsThere were no significant differences in subjective pain scores, serum cortisol, and glucose concentrations between the three groups. The highest pain score at any time was 5, and no dog required rescue analgesia. None of the three regimens caused any observable side effects during or after anaesthesia. At 1 and 2 hours after extubation dogs in group L were significantly more sedated than in the other two groups.Conclusions and Clinical relevanceThis study suggests that, with the scoring system used, IV lidocaine and meloxicam provide similar and adequate post‐operative analgesia in healthy dogs undergoing ovariohysterectomy.     

Comparison between continuous rate infusion and target-controlled infusion of propofol in dogs: a randomized clinical trial

ObjectiveTo compare a propofol continuous rate infusion (CRI) with a target-controlled infusion (TCI) in dogs.Study designRandomized prospective double-blinded clinical study.AnimalsA total of 38 healthy client-owned dogs.MethodsDogs premedicated intramuscularly with acepromazine (0.03 mg kg^–1) and an opioid (pethidine 3 mg kg^–1, morphine 0.2 mg kg^–1 or methadone 0.2 mg kg^–1) were allocated to P-CRI group (propofol 4 mg kg^–1 intravenously followed by CRI at 0.2 mg kg^–1 minute^–1), or P-TCI group [propofol predicted plasma concentration (Cp) of 3.5 μg mL^–1 for induction and maintenance of anaesthesia via TCI]. Plane of anaesthesia, heart rate, respiratory rate, invasive blood pressure, oxygen haemoglobin saturation, end-tidal carbon dioxide and body temperature were monitored by an anaesthetist blinded to the group. Numerical data were analysed by unpaired t test or Mann–Whitney U test, one-way analysis of variance and Dunnett’s post hoc test. Categorical data were analysed with Fisher’s exact test. Significance was set for p < 0.005.ResultsOverall, propofol induced a significant incidence of relative hypotension (mean arterial pressure 20% below baseline, 45%), apnoea (71%) and haemoglobin desaturation (65%) at induction of anaesthesia, with a higher incidence of hypotension and apnoea in the P-CRI than P-TCI group (68% versus 21%, p = 0.008; 84% versus 58%, p = 0.0151, respectively). Propofol Cp was significantly higher at intubation in the P-CRI than P-TCI group (4.83 versus 3.5 μg mL^–1, p < 0.0001), but decreased during infusion, while Cp remained steady in the P-TCI group. Total propofol administered was similar between groups.Conclusions and clinical relevanceBoth techniques provided a smooth induction of anaesthesia but caused a high incidence of side effects. Titration of anaesthesia with TCI caused fewer fluctuations in Cp and lower risk of hypotension compared with CRI.     

Evaluation of perfusion index as a noninvasive tool to determine epidural anesthesia effectiveness in dogs

ObjectiveTo evaluate perfusion index (PI) as a noninvasive tool to determine effectiveness and onset of epidural anesthesia in dogs.Study designProspective clinical trial.AnimalsA total of 21 adult dogs, aged 6.5 ± 3 years and weighing 34.9 ± 6.4 kg, undergoing a tibial plateau leveling osteotomy.MethodsDogs were premedicated intramuscularly with acepromazine (0.03 mg kg^–1) and hydromorphone (0.1 mg kg^–1) and anesthetized with intravenous propofol (to effect) and isoflurane in oxygen. A surface transflectance probe was secured to the tail base to monitor PI and a dorsal pedal artery catheter was placed for invasive blood pressure monitoring. A lumbosacral epidural was performed with the dog in sternal recumbency. Dogs were randomly assigned for inclusion of epidural morphine (0.1 mg kg^–1) or morphine (0.1 mg kg^–1) and lidocaine (4 mg kg^–1). PI was recorded following instrumentation of each dog just prior to the epidural (baseline), at 10 minute intervals for 30 minutes, before and after the surgical skin incision and before and after completion of the osteotomy. Physiological variables and end-tidal isoflurane were recorded at the same time points.ResultsThere was no significant difference in PI between the groups at any time point. There was a significant change in end-tidal isoflurane before and after the skin incision in the epidural morphine and epidural morphine–lidocaine groups (p = 0.04, p = 0.05, respectively) and before and after the osteotomy in each group for heart rate (p = 0.001, p = 0.04), diastolic (p = 0.01, p = 0.01) and mean arterial blood pressure (p = 0.03, p = 0.05).Conclusions and clinical relevancePI did not provide an objective means for determining the onset or effectiveness of epidural anesthesia in anesthetized dogs and alternate methods of noninvasive assessment should be investigated.     

Evaluation of analgesic,sympathetic and motor effects of 1% and 2% lidocaine administered epidurally in dogs undergoing ovariohysterectomy

ObjectiveTo compare, versus a control, the sensory, sympathetic and motor blockade of lidocaine 1% and 2% administered epidurally in bitches undergoing ovariohysterectomy.Study designRandomized, blinded, controlled clinical trial.AnimalsA total of 24 mixed-breed intact female dogs.MethodsAll dogs were administered dexmedetomidine, tramadol and meloxicam prior to general anesthesia with midazolam–propofol and isoflurane. Animals were randomly assigned for an epidural injection of lidocaine 1% (0.4 mL kg⁻¹; group L1), lidocaine 2% (0.4 mL kg⁻¹; group L2) or no injection (group CONTROL). Heart rate (HR), respiratory rate (f_R), end-tidal partial pressure of carbon dioxide (Pe′CO₂), and invasive systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures were recorded every 5 minutes. Increases in physiological variables were treated with fentanyl (3 μg kg⁻¹) intravenously (IV). Phenylephrine (1 μg kg⁻¹) was administered IV when MAP was <60 mmHg. Postoperative pain [Glasgow Composite Pain Score – Short Form (GCPS–SF)] and return of normal ambulation were recorded at 1, 2, 3, 4 and 6 hours after extubation.ResultsThere were no differences over time or among groups for HR, f_R, Pe′CO₂ and SAP. MAP and DAP were lower in epidural groups than in CONTROL (p = 0.0146 and 0.0047, respectively). There was no difference in the use of phenylephrine boluses. More fentanyl was administered in CONTROL than in L1 and L2 (p = 0.011). GCPS–SF was lower for L2 than for CONTROL, and lower in L1 than in both other groups (p = 0.001). Time to ambulation was 2 (1–2) hours in L1 and 3 (2–4) hours in L2 (p = 0.004).Conclusions and clinical relevanceEpidural administration of lidocaine (0.4 mL kg⁻¹) reduced fentanyl requirements and lowered MAP and DAP. Time to ambulation decreased and postoperative pain scores were improved by use of 1% lidocaine compared with 2% lidocaine.     

Comparison between dexmedetomidine and acepromazine in combination with methadone for premedication in brachycephalic dogs undergoing surgery for brachycephalic obstructive airway syndrome

ObjectiveTo compare dexmedetomidine with acepromazine for premedication combined with methadone in dogs undergoing brachycephalic obstructive airway syndrome (BOAS) surgery.Study designRandomized, blinded clinical study.AnimalsA group of 40 dogs weighing mean (± standard deviation) 10.5 ± 6 kg, aged 2.6 ± 1.9 years.MethodsDogs received either acepromazine 20 μg kg^–1 (group A) or dexmedetomidine 2 μg kg^–1 (group D) intramuscularly with methadone 0.3 mg kg^–1. Anaesthesia was induced with propofol and maintained with sevoflurane. Sedation (0–18), induction (0–6) and recovery (0–5) qualities were scored. Propofol dose, hypotension incidence, mechanical ventilation requirement, extubation time, additional sedation, oxygen supplementation, regurgitation and emergency intubation following premedication or during recovery were recorded. Data were analysed using t tests, Mann-Whitney U or Chi-square tests.ResultsGroup A dogs were less sedated [median (range): 1.5 (0–12)] than group D [5 (1–18)] (p = 0.021) and required more propofol [3.5 (1–7) versus 2.4 (1–8) mg kg^–1; p = 0.018]. Induction scores [group A: 5 (4–5); group D 5 (3–5)] (p = 0.989), recovery scores [group A 5 (4–5); group D 5(3–5)](p = 0.738) and anaesthesia duration [group A:93 (50–170); group D 96 (54–263) minutes] (p = 0.758) were similar between groups. Time to extubation was longer in group A 12.5 (3-35) versus group D 5.5 (0–15) minutes; (p = 0.005). During recovery, two dogs required emergency intubation (p > 0.99) and five dogs required additional sedation (p > 0.99). Oxygen supplementation was required in 16 and 12 dogs in group A and D, respectively (p = 0.167); no dogs in group A and one dog in group D regurgitated (p = 0.311).Conclusions and clinical relevanceDexmedetomidine 2 μg kg^–1 produces more sedation but similar recovery quality to acepromazine 20 μg kg^–1 combined with methadone in dogs undergoing BOAS surgery.     

The effect of midazolam or lidocaine administration prior to etomidate induction of anesthesia on heart rate,arterial pressure,intraocular pressure and serum cortisol concentration in healthy dogs

ObjectiveTo evaluate selected effects of midazolam or lidocaine administered prior to etomidate for co-induction of anesthesia in healthy dogs.Study designProspective crossover experimental study.AnimalsA group of 12 healthy adult female Beagle dogs.MethodsDogs were premedicated with intravenous (IV) butorphanol (0.3 mg kg^–1), and anesthesia was induced with etomidate following midazolam (0.3 mg kg^–1), lidocaine (2 mg kg^–1) or physiologic saline (1 mL) IV. Heart rate (HR), arterial blood pressure, respiratory rate (f_R) and intraocular pressure (IOP) were recorded following butorphanol, after co-induction administration, after etomidate administration and immediately following intubation. Baseline IOP values were also obtained prior to sedation. Etomidate dose requirements and the presence of myoclonus, as well as coughing or gagging during intubation were recorded. Serum cortisol concentrations were measured prior to premedication and 6 hours following etomidate administration.ResultsBlood pressure, f_R and IOP were similar among treatments. Blood pressure decreased in all treatments following etomidate administration and generally returned to sedated values following intubation. HR increased following intubation with midazolam and lidocaine but remained stable in the saline treatment. The dose of etomidate (median, interquartile range, range) required for intubation was lower following midazolam (2.2, 2.1–2.6, 1.7–4.1 mg kg⁻¹) compared with lidocaine (2.7, 2.4–3.6, 2.2–5.1 mg kg⁻¹, p = 0.012) or saline (3.0, 2.8–3.8, 1.9–5.1 mg kg⁻¹, p = 0.015). Coughing or gagging was less frequent with midazolam compared with saline. Myoclonus was not observed. Changes in serum cortisol concentrations were not different among treatments.Conclusions and clinical relevanceMidazolam administration reduced etomidate dose requirements and improved intubation conditions compared with lidocaine or saline treatments. Neither co-induction agent caused clinically relevant differences in measured cardiopulmonary function, IOP or cortisol concentrations compared with saline in healthy dogs. Apnea was noted in all treatments following the induction of anesthesia and preoxygenation is recommended.     

Evaluation of the isoflurane-sparing effects of lidocaine infusion during umbilical surgery in calves

ObjectiveTo evaluate the isoflurane-sparing effects of lidocaine administered by constant rate infusion (CRI) during umbilical surgery in calves.Study designRandomized ‘blinded’ prospective clinical study.AnimalsThirty calves (mean 4.7 ± SD 2.5 weeks old) undergoing umbilical surgery.MethodsAfter premedication with xylazine (0.1 mg kg^?1, IM), anaesthesia was induced with ketamine (4 mg kg^?1, IV) and maintained with isoflurane in O₂ administered through a circle breathing system. The calves were assigned randomly to receive a bolus of 2 mg kg^?1 lidocaine IV after induction of anaesthesia, followed by CRI of 50 μg kg^?1 minute^?1 (group L, n = 15) or a bolus and CRI of 0.9% sodium chloride (NaCl, group S, n = 15). End-tidal isoflurane was adjusted to achieve adequate depth of anaesthesia. Heart rate, direct arterial blood pressure and body temperature were measured intraoperatively. Groups were compared by t- tests, anova or Mann–Whitney rank sum test as appropriate.ResultsThe end-tidal concentration of isoflurane (median, IQR) was significantly lower in group L [1.0% (0.94–1.1)] compared to group S [1.2% (1.1–1.5)], indicating a 16.7% reduction in anaesthetic requirement during lidocaine CRI. Cardiopulmonary parameters and recovery times did not differ significantly between groups.Conclusion and clinical relevanceLidocaine CRI may be used as a supplement to inhalation anaesthesia during umbilical surgery in calves in countries where such a protocol would be within the legal requirements for veterinary use in food animals. This study did not show any measurable benefit to the calves other than a reduction in isoflurane requirement.     

Evaluation of the analgesic effect of fentanyl–ketamine and fentanyl–lidocaine constant rate infusions in isoflurane-anesthetized dogs undergoing thoracolumbar hemilaminectomy

ObjectiveTo evaluate anesthetic conditions and postoperative analgesia with the use of intraoperative constant rate infusions (CRIs) of fentanyl–lidocaine or fentanyl–ketamine in dogs undergoing thoracolumbar hemilaminectomy.Study designProspective, randomized, blinded, clinical study.AnimalsA total of 32 client-owned dogs.MethodsDogs were premedicated with fentanyl (5 μg kg^–1) administered intravenously (IV), anesthesia was induced with IV alfaxalone and maintained with isoflurane. Fentanyl (0.083 μg kg^–1 minute^–1) was infused IV with either ketamine (0.5 mg kg^–1; then 40 μg kg^–1 minute^–1; group KF) or lidocaine (2 mg kg^–1; then 200 μg kg^–1 minute^–1; group LF) assigned randomly. Heart rate, noninvasive arterial pressures, respiratory rate, esophageal temperature, end-tidal partial pressure of carbon dioxide and isoflurane concentration were recorded throughout anesthesia. Maintenance of anesthesia, recovery and postoperative pain (Glasgow Composite Pain Scale) were scored. Cardiopulmonary data were analyzed using a two-way anova with repeated measures, demographics of the two groups with a t test, and scores with Mann–Whitney U test, with p < 0.05.ResultsAll dogs recovered from anesthesia without complications. No significant difference was found between groups for cardiopulmonary variables, total anesthesia time, sedation score and requirement for postoperative sedation or for rescue analgesia. Anesthetic maintenance score was of lower quality in KF than in LF [median (interquartile range): 0 (0–0.5) versus 0 (0–0); p = 0.032)], but still considered ideal. Recovery score was higher and indicative of less sedation in LF than in KF [1 (1–1.5) versus 0.5 (0–1); p < 0.0001]. Pain score was higher in KF than in LF [2 (1–3) versus 1 (1–2); p = 0.0009].Conclusions and clinical relevanceBoth CRIs of KF and LF provided adequate anesthetic conditions in dogs undergoing thoracolumbar hemilaminectomy. Based on requirement for rescue analgesia, postoperative analgesia was adequate in both groups.     

Primary pulmonic infundibular stenosis in 12 cats: Natural history and the effects of balloon valvuloplasty

ObjectivesTo evaluate the natural history of primary pulmonic infundibular stenosis in cats and the effects of balloon valvuloplasty.BackgroundPrimary pulmonic infundibular stenosis is an uncommon congenital defect in cats. The natural history of the disease has not been described. Information regarding balloon valvuloplasty in the cat is limited.AnimalsRecords between January 1, 1999 and December 31, 2005 were reviewed and cats with a confirmed echocardiographic diagnosis of primary pulmonic infundibular stenosis, a complete medical history, and no evidence of significant systemic disease were identified.MethodsEchocardiographic, electrocardiographic, and radiographic findings are described. The natural history of those with severe disease was compared to those with mild to moderate disease. Balloon valvuloplasty was performed in six of the cats. The technique used is described.ResultsA stenotic gradient ≥70 mmHg and a right ventricular outflow tract (measured at the level of the stenosis) to pulmonary valve annulus ratio of ≤0.25 were consistent with clinical and echocardiographic severe disease. Cats with severe disease had a very guarded prognosis with a high incidence of congestive heart failure (CHF). Balloon valvuloplasty was successfully performed in 4 of the cats and appeared to improve prognosis, especially if performed prior to the development of CHF. Concurrent hypertrophic cardiomyopathy complicated the outcome in some cats.ConclusionsSevere primary pulmonic infundibular stenosis carries a very guarded prognosis in the cat. Balloon valvuloplasty should be considered in the presence of severe disease and should be performed prior to the development of CHF if possible. The presence of concurrent hypertrophic cardiomyopathy may complicate the prognosis.     

Epidural administration of combinations of ropivacaine,morphine and xylazine in bitches undergoing total unilateral mastectomy: a randomized clinical trial

ObjectiveTo investigate the epidural administration of combinations of ropivacaine, morphine and xylazine in bitches undergoing unilateral mastectomy.Study designProspective, randomized, blinded, clinical study.AnimalsA total of 22 bitches scheduled to undergo unilateral mastectomy for mammary tumor excision.MethodsDogs were anesthetized with acepromazine (0.02 mg kg^–1) and morphine (0.3 mg kg^–1) intramuscularly, propofol intravenously (IV) and isoflurane. Prior to the beginning of surgery, dogs were randomly administered one of three epidural treatments: ropivacaine (0.75 mg kg^–1) with morphine (0.1 mg kg^–1) (group RM, n = 7); ropivacaine with xylazine (0.1 mg kg^–1) (group RX, n = 8); or ropivacaine with morphine and xylazine (group RMX, n = 7). Cardiopulmonary variables and the expired concentration of isoflurane (Fe′Iso) were recorded intraoperatively. Meloxicam (0.1 mg kg^–1) was administered IV during skin closure. Postoperative pain scores were evaluated with the Glasgow composite measure pain scale short form for 24 hours, and rescue analgesia with morphine (0.5 mg kg^–1) was administered intramuscularly when pain scores were ≥ 6/24.ResultsFe′Iso was significantly higher in group RM than in groups RX and RMX. Heart rate decreased significantly in groups RX and RMX, but blood pressure remained within acceptable values. The number of dogs administered rescue analgesia within 24 hours was significantly higher in group RX (seven dogs, 87.5%) than in groups RM (one dog, 14.3%; p = 0.01) and RMX (two dogs, 28.6%; p = 0.04). Time to standing was significantly longer in group RX than in group RM.Conclusions and clinical relevanceAll epidural treatments provided adequate antinociception with minimal cardiovascular adverse effects during mastectomy. The inclusion of morphine (groups RM and RMX) provided the best postoperative analgesia. Owing to the undesirable effect of xylazine on ambulation, the combination ropivacaine–morphine appeared to provide greater benefits in bitches undergoing unilateral mastectomy.     

Behavioural and cardiovascular effects of medetomidine constant rate infusion compared with detomidine for standing sedation in horses

ObjectiveTo compare the efficacy of a medetomidine constant rate infusion (CRI) with a detomidine CRI for standing sedation in horses undergoing high dose rate brachytherapy.Study designRandomized, controlled, crossover, blinded clinical trial.AnimalsA total of 50 horses with owner consent, excluding stallions.MethodsEach horse was sedated with intravenous acepromazine (0.02 mg kg^–1), followed by an α₂-adrenoceptor agonist 30 minutes later and then by butorphanol (0.1 mg kg^–1) 5 minutes later. A CRI of the same α₂-adrenoceptor agonist was started 10 minutes after butorphanol administration and maintained for the treatment duration. Treatments were given 1 week apart. Each horse was sedated with detomidine (bolus dose, 10 μg kg^–1; CRI, 6 μg kg^–1 hour^–1) or medetomidine (bolus dose, 5 μg kg^–1; CRI, 3.5 μg kg^–1 hour^–1). If sedation was inadequate, a quarter of the initial bolus of the α₂-adrenoceptor agonist was administered. Heart rate (HR) was measured via electrocardiography, and sedation and behaviour evaluated using a previously published scale. Between treatments, behaviour scores were compared using a Wilcoxon signed-rank test, frequencies of arrhythmias with chi-square tests, and HR with two-tailed paired t tests. A p value <0.05 indicated statistical significance.ResultsTotal treatment time for medetomidine was longer than that for detomidine (p = 0.04), and ear movements during medetomidine sedation were more numerous than those during detomidine sedation (p = 0.03), suggesting there may be a subtle difference in the depth of sedation. No significant differences in HR were found between treatments (p ≥ 0.09). Several horses had arrhythmias, with no difference in their frequency between the two infusions.Conclusions and clinical relevanceMedetomidine at this dose rate may produce less sedation than detomidine. Further studies are required to evaluate any clinical advantages to either drug, or whether a different CRI may be more appropriate.     

Evaluation of nalbuphine,butorphanol and morphine in dogs during ovariohysterectomy and on early postoperative pain

ObjectiveTo evaluate the effects of nalbuphine, butorphanol and morphine combined with acepromazine on intraoperative and early postoperative pain management in dogs anesthetized for ovariohysterectomy.Study designProspective, randomized blinded clinical study.AnimalsA total of 48 healthy female dogs of different breeds, aged 1–6 years, weighing (mean ± standard deviation) 14.5 ± 4.8 kg.MethodsDogs were randomly assigned into four groups to be intravenously administered nalbuphine (0.5 mg kg^–1; group N0.5), nalbuphine (1.0 mg kg^–1; group N1.0), butorphanol (0.4 mg kg^–1; group B0.4) or morphine (0.2 mg kg^–1; group M0.2) combined with acepromazine (0.02 mg kg^–1) prior to propofol and isoflurane for anesthesia. Heart rate (HR), respiratory rate, systolic arterial pressure and rectal temperature (RT) were recorded at time points during anesthesia. A dynamic interactive visual analog scale applied in three phases (DIVAS I, II and III) and the modified Glasgow composite measure pain scale were used to assess pain before premedication and 1, 2, 3, 4, 5 and 6 hours after extubation. Administration of rescue analgesia was recorded.ResultsAt the left ovarian pedicle ligation, HR was higher in N1.0 than in B0.4 (p = 0.020). RT decreased significantly by the end of surgery in N0.5 (p = 0.043) and B0.4 (p = 0.010). Rescue analgesia was administered postoperatively over 6 hours to eight, seven, nine and 10 dogs in N0.5, N1.0, B0.4 and M0.2, respectively (p = 0.57). DIVAS II was higher in B0.4 than in N1.0 at 2 and 3 hours (p = 0.038 and p = 0.002, respectively) and N0.5 at 3 hours (p = 0.003).Conclusions and clinical relevanceAt the doses used, all premedication protocols provided insufficient intraoperative analgesia, with minimal clinical differences between groups. No premedication provided satisfactory analgesia in the first 6 hours postoperatively.