Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) soil contamination in Lausanne, Switzerland: Combining pollution mapping and human exposure assessment for targeted risk management.

In December 2020, high soil concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were discovered across large parts of Lausanne, Switzerland. Concentrations reached up to 640 ng TEQWHO-2005/kg dry weight. The most likely source was a former municipal waste incinerator. A three-step, multidisciplinary approach to human health risk assessment was conducted to determine the potential population exposure to PCDD/Fs and identify appropriate preventive measures. First, exposure scenarios were developed based on contaminated land uses. Second, the toxicological risks of different scenarios were evaluated using a toxicokinetic model estimating increases in blood serum PCDD/F concentrations over background concentrations from the general population's food consumption. Third, a detailed geostatistical mapping of PCDD/F soil contamination was performed. Stochastic simulations with an external drift and an anisotropic model of the variogram were generated to incorporate the effects of distance from emission source, topography, and main wind directions on the spatial distribution of PCDD/Fs in topsoil. Three main scenarios were assessed: i) direct ingestion of soil by children in playgrounds; ii) consumption of vegetables from private gardens by children and adults; and iii) consumption of food from livestock and poultry raised on contaminated soil. The worst exposure scenario involved the consumption of eggs from private hen houses, resulting in PCDD/F concentrations in serum an order of magnitude higher than might normally be expected. No relevant increases in serum concentrations were calculated for direct soil ingestion and vegetable consumption, except for cucurbitaceous vegetables. Combining mapping and exposure scenario assessment resulted in targeted protective measures for land users, especially concerning food consumption. The results also raised concerns about the potential unsafe consumption of products derived from animals raised on land with PCDD/F concentrations only moderately over environmental background levels.

Effects of perineural dexmedetomidine combined with ropivacaine on postoperative methadone requirements in dogs after tibial plateau levelling osteotomy: a two-centre study.

OBJECTIVE: To evaluate the efficacy of a perineural injection of dexmedetomidine combined with ropivacaine for reducing postoperative methadone requirements in dogs after tibial plateau levelling osteotomy (TPLO). STUDY DESIGN: A prospective, clinical, randomized and blinded trial. ANIMALS: A total of 58 client-owned dogs. METHODS: Ultrasound-guided midfemoral sciatic and inguinal femoral nerve blocks with ropivacaine (1 mg kg-1 per nerve block) combined with either dexmedetomidine (0.5 µg kg-1 per nerve block; group DEX) or the same volume of saline (group CON) were performed in dogs undergoing TPLO. Pain was assessed 30 minutes, 2 hours and then every 4 hours for 24 hours after surgery with a validated pain scale (4AVet). Meloxicam (0.15 mg kg-1) was administered intravenously (IV) at recovery. Rescue methadone (0.2 mg kg-1 IV) was administered if a score ≥ 6 (maximal score 18) was recorded and the number of postoperative doses was analysed by Fisher exact tests. The study was performed in parallel at a Veterinary Teaching Hospital (VTH) and a private Veterinary Referral Centre (VRC). RESULTS: Dogs received a total of 22 and 31 postoperative doses of methadone in groups DEX (14 doses at VRC, eight doses at VTH) and CON (28 doses at VRC, three doses at VTH), respectively. Overall, there was no difference in the postoperative rescue analgesia requirements between groups (p = 0.244). At the VRC, dogs received less methadone (p = 0.026) in group DEX compared with group CON, whereas at the VTH, there was no difference between groups (p = 0.216). CONCLUSIONS AND CLINICAL RELEVANCE: Perineural dexmedetomidine combined with ropivacaine did not reduce postoperative methadone requirements in dogs after TPLO, but results may differ from one centre to another. This discrepancy might be linked to variations in clinical practices and questions the validity of results obtained from single-centre randomized controlled trials but applied to different clinical settings.

Effects of perineural administration of ropivacaine combined with perineural or intravenous administration of dexmedetomidine for sciatic and saphenous nerve blocks in dogs.

OBJECTIVE: To evaluate the effects of using ropivacaine combined with dexmedetomidine for sciatic and saphenous nerve blocks in dogs. ANIMALS: 7 healthy adult Beagles. PROCEDURES: In phase 1, dogs received each of the following 3 treatments in random order: perineural sciatic and saphenous nerve injections of 0.5% ropivacaine (0.4 mL/kg) mixed with saline (0.9% NaCl) solution (0.04 mL/kg; DEX0PN), 0.5% ropivacaine mixed with dexmedetomidine (1 µg/kg; DEX1PN), and 0.5% ropivacaine mixed with dexmedetomidine (2 µg/kg; DEX2PN). In phase 2, dogs received perineural sciatic and saphenous nerve injections of 0.5% ropivacaine and an IV injection of diluted dexmedetomidine (1 µg/kg; DEX1IV). For perineural injections, the dose was divided equally between the 2 sites. Duration of sensory blockade was evaluated, and plasma dexmedetomidine concentrations were measured. RESULTS: Duration of sensory blockade was significantly longer with DEX1PN and DEX2PN, compared with DEX0PN; DEX1IV did not prolong duration of sensory blockade, compared with DEX0PN. Peak plasma dexmedetomidine concentrations were reached after 15 minutes with DEX1PN (mean ± SD, 348 ± 200 pg/mL) and after 30 minutes DEX2PN (816 ± 607 pg/mL), and bioavailability was 54 ± 40% and 73 ± 43%, respectively. The highest plasma dexmedetomidine concentration was measured with DEX1IV (1,032 ± 415 pg/mL) 5 minutes after injection. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that perineural injection of 0.5% ropivacaine in combination with dexmedetomidine (1 µg/kg) for locoregional anesthesia in dogs seemed to balance the benefit of prolonging sensory nerve blockade while minimizing adverse effects.

Opioid requirements after locoregional anaesthesia in dogs undergoing tibial plateau levelling osteotomy: a pilot study.

OBJECTIVE: To determine the intraoperative and early postoperative opioid requirement after ultrasound-guided sciatic and/or femoral nerve block or epidural anaesthesia in dogs undergoing tibial plateau levelling osteotomy (TPLO). STUDY DESIGN: Prospective, masked, pilot, randomized, clinical trial. ANIMALS: A total of 40 client-owned dogs undergoing TPLO. METHODS: Each dog was randomly assigned to group SF (combined sciatic and femoral nerve block), group S (sciatic nerve block), group F (femoral nerve block) or group E (epidural anaesthesia). A total of 0.3 mL kg-1 of ropivacaine 0.5% was administered to each nerve or in the epidural space. Intraoperatively, fentanyl (2 µg kg-1) was administered intravenously when heart rate, mean arterial pressure or respiratory rate increased by >30% compared with baseline values. Postoperatively, a visual analogue scale (VAS) and a modified German version of the French pain scale (4AVet) were used to assess pain every 30 minutes for 150 minutes and again once the morning after surgery. Methadone (0.1 mg kg-1) was administered intravenously if the VAS was ≥ 4 cm [maximal value 10 cm; median (interquartile range)] or the composite pain score was ≥5 [maximal value 15; median (interquartile range)]. Significance was defined as p ≤ 0.05. RESULTS: Groups SF and E required less total intraoperative and early postoperative opioid doses compared with groups S and F (p = 0.031). No dogs in group SF had a block failure or required postoperative methadone. A reduced methadone requirement was found in group SF compared with all the other groups up to 150 minutes after recovery (p = 0.041). CONCLUSIONS AND CLINICAL RELEVANCE: Combined sciatic and femoral nerve block and epidural anaesthesia lead to less cumulative consumption of perioperative opioids than single nerve blockade. Sciatic or femoral nerve block alone might be insufficient to control nociception and early postoperative pain in dogs undergoing TPLO.

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

OBJECTIVE: To 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 DESIGN: Randomized blinded clinical study. ANIMALS: A group of 20 client-owned dogs undergoing TECA-LBO. METHODS: Intravenous (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). RESULTS: Fe'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 RELEVANCE: Compared 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.

Sciatic nerve block in dogs: description and evaluation of a modified ultrasound-guided parasacral approach.

OBJECTIVE: To develop a modified ultrasound-guided parasacral approach to the sciatic nerve and compare the effects of a volume of 0.2 mL kg-1 of 0.5% levobupivacaine with an equivalent volume of 0.9% saline injected near the sciatic nerve. STUDY DESIGN: Cadaveric and experimental, blinded, randomized study. ANIMALS: Seven canine cadavers and seven experimental Beagle dogs. METHODS: Both sciatic nerves of seven cadavers were identified using a modified in-plane ultrasound-guided approach. Methylene blue solution (0.2 mL) was injected perineurally, and success was evaluated through dissection. The same approach was repeated in seven Beagle dogs sedated with dexmedetomidine (50 µg kg-1) injected intramuscularly (IM). After randomization, 0.2 mL kg-1 of 0.5% levobupivacaine (limb L) and 0.2 mL kg-1 of 0.9% saline (limb C) were injected perineurally on either right or left limb. Block success was determined by sensory deficits every hour for 8 hours after an atipamezole injection (0.2 mg kg-1) IM. Reaction to pinprick (binary score) over the course of the sciatic nerve (four locations) and locomotion were assessed. RESULTS: The overall sciatic nerve block success was 93% in cadavers and 86% in sedated dogs. It was impossible to localize the sciatic nerves in one obese sedated dog. Significant differences between limb L and limb C were observed for pinprick at great trochanter, caudal thigh and lateral tarsal joint (p < 0.0001). Reaction to pinprick was absent in all dogs at great trochanter and caudal thigh up to at least 3 hours on limb L. Locomotion was impaired in all but one dog for 60 (30-210) minutes (median; interquartile range). No complications were observed. CONCLUSIONS AND CLINICAL RELEVANCE: A volume of ≥0.2 mL kg-1 and a concentration of 0.5% levobupivacaine can be recommended when using a modified ultrasound-guided parasacral approach to the sciatic nerve in dogs.

Advanced Atrio-Ventricular Blocks in a Foal Undergoing Surgical Bladder Repair: First Step to Cardiac Arrest?

A 3-day-old Swiss Warmblood colt was diagnosed with uroabdomen after urinary bladder rupture. The foal had classical electrolyte abnormalities (hyponatremia, hypochloremia and hyperkalemia) on presentation. The foal was supported prior to surgery with intravenous fluids and the electrolyte abnormalities were treated with physiologic saline, glucose and insulin. Urine could not be drained from the abdomen prior to surgery because the omentum was continuously occluding the drainage cannula and due to progressive abdominal distension, it was decided to pursue surgery without further correction of electrolyte abnormalities. After induction of anaesthesia, signs of hypoxemia were present. Controlled mandatory ventilation using a pressure-controlled ventilation mode with positive end-expiratory pressure was initiated. Urine was drained from the abdomen by free flow. Atrio-ventricular (AV) blocks unresponsive to intravenous antimuscarinic drugs developed. After low dose of epinephrine and cardiac massage, sinus rhythm was restored. Surgery was completed successfully and the foal recovered from anaesthesia. The postoperative period was uneventful and the foal was discharged from the hospital three days later. Based on a clinical case, the purpose of the manuscript is to provide the clinician with potential causes, prevention and treatment of this already known but rarely observed dysrhythmia which could lead to fatal consequences. Definitions of cardiac arrest and asystole are reappraised. We discuss the fact that advanced AV-blocks should be treated as a cardiovascular emergency with advanced life support. The early recognition of advanced AV blocks is the first step to reduce perioperative mortality and morbidity of foal suffering from uroabdomen.

Does systemic lidocaine reduce ketamine requirements for endotracheal intubation in calves?

OBJECTIVE: To investigate whether an intravenous (IV) lidocaine bolus in calves premedicated with xylazine-butorphanol reduces the amount of ketamine required to allow endotracheal intubation. STUDY DESIGN: Randomized, prospective clinical study. ANIMALS: In total, 41 calves scheduled for elective umbilical surgery. METHODS: Calves were randomly assigned to one of two groups (L: lidocaine or S: saline). The calves were administered xylazine (0.07 mg kg-1) and butorphanol (0.1 mg kg-1) intramuscularly and 10 minutes later lidocaine (2 mg kg-1; group L) or saline (group S) IV over 1 minute. After 2 minutes, ketamine (2.5 mg kg-1) was injected IV. If the depth of anaesthesia was insufficient for intubation, additional ketamine (1 mg kg-1) was administered every minute until intubation was successful. The amount of ketamine required for intubation, respiratory rate, pulse rate, arterial pressures, the depth of sedation and conditions of endotracheal intubation after induction of anaesthesia were compared between the two groups. RESULTS: The calves in group L were sedated more deeply than those in group S; however, neither the median (range) amount of ketamine required for intubation, 3.5 (2.5-4.5) mg kg-1 and 3.5 (2.5-3.5) mg kg-1, respectively, nor the induction quality differed significantly between the groups. CONCLUSION AND CLINICAL RELEVANCE: A bolus of lidocaine (2 mg kg-1) administered 10 minutes after xylazine-butorphanol in calves deepened the degree of sedation but did not decrease the requirement of ketamine for endotracheal intubation. No adverse effects were recorded in the physiological variables measured.

Use of a perineural coiled catheter at the sciatic nerve in dogs after tibial plateau levelling osteotomy - preliminary observations.

The analgesic effects of peripheral nerve blocks can be prolonged with the placement of perineural catheters allowing repeated injections of local anaesthetics in humans. The objectives of this study were to evaluate the clinical suitability of a perineural coiled catheter (PCC) at the sciatic nerve and to evaluate pain during the early post-operative period in dogs after tibial plateau levelling osteotomy. Pre-operatively, a combined block of the sciatic and the femoral nerves was performed under sonographic guidance (ropivacaine 0.5%; 0.3 mL kg-1 per nerve). Thereafter, a PCC was placed near the sciatic nerve. Carprofen (4 mg kg-1 intravenously) was administered at the end of anaesthesia. After surgery, all dogs were randomly assigned to receive four injections of ropivacaine (group R; 0.25%, 0.3 mL kg-1) or NaCl 0.9% (group C; 0.3 mL kg-1) every 6 h through the PCC. Pain was assessed by use of a visual analogue scale (VAS) and a multi-dimensional pain score (4Avet) before surgery (T-1), for 390 min (T0, T30, T60, T120, T180, T240, T300, T360 and T390) as well as 1 day after surgery (Day 1). Methadone (0.1 mg kg-1) was administered each time the VAS was ≥40 mm or the 4Avet was ≥5. At T390 dogs received buprenorphine (0.02 mg kg-1). Data were compared using Mann-Whitney rank sum tests and repeated measures analysis of variance. Regardless of group allocation, 55% of dogs required methadone. VAS was significantly lower at T390 (P = 0.003), and at Day 1 (P = 0.002) and so was 4Avet at Day 1 (P = 0.012) in group R than in group C. Bleeding occurred in one dog at PCC placement and PCC dislodged six times of 47 PCCs placed. Minor complications occurred with PCC but allowed four repeated administrations of ropivacaine or saline over 24 h in 91.5% of the cases.