Local and regional anaesthesia in dogs and cats: Overview of concepts and drugs (Part 1)

Ultrasound-guided ventral approach to the brachial plexus block in barred owls (Strix varia): a cadaveric study

OBJECTIVE

To develop an ultrasound (US)-guided ventral approach to the brachial plexus (BP) and evaluate nerve anatomy and staining in barred owl cadavers.

STUDY DESIGN

Prospective, cadaveric study.

ANIMALS

Eleven adult male and female barred owl cadavers with a body mass of 0.43-0.98 kg.

METHODS

Eleven frozen cadavers were thawed for 48 hours, weighed and assigned a body condition score. Ten cadavers were placed in dorsal recumbency with wings abducted. US-guided visualization of the BP was achieved by placing a 13-6 MHz linear probe over the ventral aspect of the scapulohumeral joint, parallel to the sternum. A 22 gauge, 50 mm insulated needle was advanced in-plane in a caudal-to-cranial direction. In each owl, injection targeting one BP was performed with 0.4 mL kg-1 of a 1:1 0.5% ropivacaine and 1% methylene blue solution. Dissection was performed 15 minutes postinjection. Nerve staining was deemed successful if ≥ 1 cm of circumferential staining was achieved. The eleventh owl cadaver was injected with a 1:1 solution of 1% methylene blue and 74% ioversol contrast into both wings, and computed tomography (CT) was performed just before and 15 minutes after injection.

RESULTS

The BP was clearly identified ultrasonographically in cadavers weighing > 0.5 kg. An injectate volume of 0.4 mL kg-1 provided complete staining of the BP branches in all cadavers. CT scan revealed no contrast within the coelomic cavity.

CONCLUSIONS AND CLINICAL RELEVANCE

The US-guided BP injection using a ventral approach was easily performed in barred owl cadavers weighing > 0.5 kg. The injection of 0.4 mL kg-1 of a ropivacaine-dye solution resulted in complete staining of the BP branches in all wings, suggesting that this technique could provide analgesia for structures distal to the scapulohumeral joint. Clinical studies are necessary to confirm the safety and efficacy of this technique in barred owls and other bird species.

Evaluation of preoperative intraperitoneal injection of bupivacaine for intraoperative antinociception in cats undergoing ovariohysterectomy: A randomized clinical trial

OBJECTIVE

To determine if preoperative intraperitoneal bupivacaine can minimize intra- and postoperative nociception/pain in cats undergoing ovariohysterectomy.

STUDY DESIGN

Prospective, randomized, investigator-blinded, placebo-controlled clinical trial.

ANIMALS

Forty-seven, intact female cats.

METHODS

Cats were anesthetized using a standard protocol and randomized to receive ultrasound-guided intraperitoneal 0.9 % saline (US-S) or 0.25 % bupivacaine (US-IPLA) before ovariohysterectomy. On recovery, US-S cats received 2 mg/kg robenacoxib subcutaneously and US-IPLA cats received equivalent volume of 0.9 % saline subcutaneously. Intraoperative outcome variables included heart rate (HR), respiratory rate (fR), systolic arterial pressure (SAP), and vaporizer setting associated with relevant surgical events characterized by manipulation of each ovarian pedicle (OP1, OP2) and the uterine body (UB). The postoperative outcome variable was need for rescue analgesia, determined using the Glasgow Composite Measure Pain Scale during 6 h after tracheal extubation. Intraoperative data were analyzed using two-way ANOVA and Šidák's multiple comparisons test. The probability of postoperative rescue analgesia was analyzed using the Gehan-Breslow-Wilcoxon test. Significance was p < 0.05.

RESULTS

Compared to baseline, all surgical events caused significant increases in HR and SAP in both groups, fR increased in US-IPLA but not in US-S, vaporizer settings remained unchanged during OP1, OP2 and UB in group US-IPLA, and were significantly higher only during OP1 in group US-S. There were no significant between-group differences in intraoperative variables and postoperative need for rescue analgesia.

CONCLUSIONS AND CLINICAL RELEVANCE

Preoperative intraperitoneal bupivacaine had minimal effects on intraoperative indicators of nociception. The need for rescue analgesia was not significantly different between groups.

Ultrasound-Guided Deep Serratus Plane Block in Cat Cadavers (Felis catus): A Description of Dye and Contrast Media Distribution

The serratus plane block is an ultrasound-guided anaesthetic technique that aims to provide analgesia to the lateral thoracic wall cranial to the 8th rib. This block can be performed in a superficial (between the latissimus dorsi and the serratus ventralis thoracis (SVT) muscles) or deep plane (between the intercostales externi and the SVT muscles). This study aimed to assess the distribution and nerve staining of a mixture of 0.4 mL kg-1 of methylene blue and iopromide 50:50 performing a deep serratus plane (DSP) block at the level of the 5th rib. We hypothesise that this technique would be feasible and could stain the rami cutanei laterales (RCL) of the intercostales nerves cranial to the 8th rib in cat cadavers. This study was divided into two phases. Phase 1 consisted of an anatomical study of the thoracic wall (2 cadavers). Phase 2 consisted of the ultrasound-guided injection of the aforementioned mixture and the assessment of its distribution by computed tomography and anatomical dissection (12 cadavers). Contrast media spread a median of 5.5 (2.5-7.5) intercostal spaces. The dye stained a median of 3 (0-5) RCL, affecting RCL 2 (17.39%), RCL 3 (57.17%), RCL 4 (78.26%), RCL 5 (91.30%), RCL 6 (78.26%), and RCL 7 (8.70%) within the DSP. Occasionally, the rami dorsales laterales and the thoracicus longus nerve were stained. Based on these findings, the DSP block performed with a volume of 0.4 mL kg-1 of an anaesthetic could provide analgesia in the area innervated from T4 to T6.

Non-surgical nursing care for tumor patients: an overview of sedation, analgesia, and recent innovations

With the increasing prevalence of tumors, effective symptom management has emerged as a cornerstone of patient care. While surgical interventions remain pivotal, non-surgical nursing methods have gained prominence in providing relief from pain, discomfort, and other tumor-related symptoms. This review delves into the various non-surgical approaches employed, emphasizing tumor sedation and analgesia. We discuss the array of non-pharmacological and pharmacological strategies, shedding light on their indications, contraindications, and potential side effects. Furthermore, the importance of addressing individual differences in pain perception and the ethical considerations in symptom management are highlighted. We conclude by providing insights into the recent innovations in the field, emphasizing the need for personalized and comprehensive care to enhance patients' quality of life. Tumor sedation, Tumor analgesia, Non-surgical nursing care, Pain management, Non-pharmacological interventions, Palliative care, Recent innovations, Symptom management.

Pharmacokinetics of single dose levobupivacaine after peri-incisional subcutaneous infiltration in anaesthetized domestic pigs

Increasing use of pigs as models in translational research, and growing focus on animal welfare are leading to better use of effective analgesics and anaesthetics when painful procedures are performed. However, there is a gap in basic knowledge such as pharmacokinetics of different anaesthetics in these species. The main objective of our study was to determine the pharmacokinetics of levobupivacaine in domestic pigs. Twelve female grower pigs weighing 31.17 ± 4.6 kg were subjected to general anaesthesia and experimental surgery, at the end of which they received 1 mg/kg levobupivacaine via peri-incisional subcutaneous infiltration. Plasma samples were collected before administration of levobupivacaine and at 0.5, 1, 2, 4, 8, 12, 24 and 48 h thereafter. Concentrations of levobupivacaine were determined by liquid chromatography coupled with tandem mass spectrometry. Following single dose of levobupivacaine, all animals had measurable plasma concentrations 0.5 h after drug administration, with most peak concentrations observed at the 1-h time point. In all 12 animals, levobupivacaine was below the limit of quantification 48 h after drug administration. The mean maximum plasma concentration, area under the curve and half-life were determined to be 809.98 μg/l, 6552.46 μg/l h and 6.25 h, respectively. Plasma clearance, volume of distribution and weight-normalized volume of distribution were 4.41 l/h, 35.57 l and 1.23 l/kg, respectively. Peak plasma concentrations in our study were well below concentrations that were found to produce toxicity in pigs.

Immobilisation and Epidural Anaesthesia in a Eurasian Lynx (Lynx lynx) Undergoing Pelvic Limb Orthopaedic Surgery

Immobilisation and anaesthesia of wild felids may be complex and potentially dangerous events, making it difficult to implement more advanced anaesthetic techniques such as neuraxial anaesthesia. A Eurasian lynx was referred for femur fracture repair after it was seen with lameness of the left pelvic limb sustained in its natural environment. The animal was remotely darted using a combination of ketamine (5 mg/kg) and xylazine (5 mg/kg) intramuscularly. Once immobilised, the lynx was transported to the veterinary hospital in a restraining cage. After induction and endotracheal intubation, pelvic limb radiographs confirmed a closed, comminuted fracture of the left femur that required open reduction and internal stabilisation. A sacrococcygeal epidural was performed before surgery using lidocaine (2 mg/kg) and morphine (0.1 mg/kg) to complement the ketamine-xylazine-isoflurane anaesthesia, which allows a low-end-tidal isoflurane concentration. Clinical signs were continuously monitored and remained stable during the entire procedure, with the exception of a temperature that decreased to 35.8°C. No intraoperative analgesic rescues were necessary. Recovery was smooth and uneventful. The lynx showed no signs of motor weakness after surgery or other side effects related to the anaesthetic procedure. The successful management of this surgical case suggests that the described anaesthetic protocol could be recommended in orthopaedic procedures of the pelvic limbs in wild Felidae.

Retrospective case-control non-inferiority analysis of ultrasound-guided erector spinae plane block in dogs undergoing mini-hemilaminectomy for intervertebral disc disease

BACKGROUND

Veterinary medicine has seen significant advancements in locoregional anaesthesia and pain management, including the emergence of the erector spinae plane (ESP) block. However, limited clinical evidence exists on its efficacy and safety.

OBJECTIVES

This study compares ultrasound-guided ESP block (ESP group) with an intraoperative intravenous ketamine infusion analgesic protocol (CRI group) in dogs undergoing thoracolumbar mini-hemilaminectomy, focusing on intraoperative opioid consumption, cardiovascular response to surgical stimulation (CR), postoperative pain scores (PS), and postoperative opioid consumption.

METHODS

Retrospective, case-control, non-inferiority study conducted in a single centre. Data collected included demographics, bupivacaine dose, ESP block operator, intraoperative recorded variables (haemodynamic variables, CR, complications, rescue analgesia), pre- and postoperative analgesia, 24-hour PS and opioid administration, first food intake post-extubation and postoperative complications. Univariate and multiple regression analyses were applied.

RESULTS

One-hundred dogs were included, 75 in the ESP group and 25 in the CRI group. Univariate analysis revealed no significant differences between treatment groups in terms of CR, PS, postoperative rescue analgesia, intraoperative and postoperative opioid consumption, or time to first meal intake. However, the multivariate regression analysis indicated that dogs receiving ketamine infusion had higher CR suspected to be nociception-related (p = 0.036), and higher postoperative opioid consumption (p = 0.013).

CONCLUSION

Our study suggests that ultrasound-guided ESP block is as effective as intraoperative ketamine infusion providing perioperative analgesia in dogs undergoing thoracolumbar mini-hemilaminectomy for intervertebral disc disease. ESP group showed significantly lower CR suspected to be nociception-related intraoperatively and lower postoperative opioid consumption within the initial 24 hours.

Use of Caudal Quadratus Lumborum Block with Ropivacaine as Part of an Opioid-Free Analgesic Protocol in Dogs Undergoing Orchiectomy: A Randomized Trial

In veterinary medicine, the use of loco-regional anesthesia techniques is increasing. The Quadratus Lumborum block (QL) is an interfascial loco-regional technique that involves the release of local anesthetic (LA) between the Quadratus Lumborum and the Small Psoas (Pm) muscle. The study aims to evaluate the effect of the QL block on reducing the total amount of opioids in dogs undergoing pre-scrotal orchiectomy. A group of 36 dogs was enrolled in a randomized blinded study. The animals were divided into two groups: 18 in the experimental group (QL) and 18 in the control group (C). The QL group received 0.4 mL kg-1 of ropivacaine 0.5% for each hemiabdomen (total amount of 3 mg kg-1 of ropivacaine, 1.5 mg kg-1 per side). The C group was brought into the operating room (OR) after receiving the same clipping as the QL group. In the intraoperative period, opioid consumption in the QL group was significantly lower than in the C group. No differences were found in the post-operative phase. No side effects were reported when performing the QL technique. The QL block performed at the level of L6 appears to be a valid approach to reducing opioid use in dogs undergoing orchidectomy with a pre-scrotal surgical approach.

Description and Evaluation of Dye and Contrast Media Distribution of Ultrasound-Guided Rectus Sheath Block in Cat Cadavers

The rectus sheath block is an ultrasound-guided anaesthetic technique which aims to provide analgesia to the abdominal midline. This study aimed to assess the distribution of 0.4 mL kg-1 of a mixture of methylene blue and iopromide injected into each hemiabdomen in the internal rectus sheath in cat cadavers. We hypothesise that this technique would be feasible and would cover the rami ventrales of the last thoracic and the first lumbar spinal nerves. The study was divided into two phases. Phase 1 aimed to study the anatomical structures of the ventral abdominal wall (four cats were dissected). Phase 2 (ten cadavers) consisted of an ultrasound-guided injection of the mixture mentioned above and the assessment of its distribution by computed tomography and anatomical dissection. The results showed the staining of the cranioventral abdominal wall with a craniocaudal spread of four (three to eight) vertebral bodies. Methylene blue stained three (one to four) rami ventrales, affecting T10 (60%), T11 (100%), T12 (90%), T13 (50%) and L1 (5%). Based on these results, it could be stated that this technique could supply anaesthesia to the midline of the abdominal midline cranial to the umbilicus in clinical patients, but it may not be able to provide anaesthesia to the middle and caudal midline abdominal region.

To Compare the Effects of Post-tonsillectomy Intra-operative Infiltration of Ropivacaine Versus Bupivacaine in Tonsillar Fossa

Tonsillectomy is one of the most common surgical procedures practiced in Otorhinolaryngology. A significant obstacle for the speedy and smooth recovery is early post- operative pain. Pain leads to negative outcomes such as poor intake, tachycardia, anxiety, delayed wound healing and insomnia. Aim to assess and compare the effect of post-incisional infiltration of 0.75% Ropivacaine v/s 0.5% Bupivacaine on post tonsillectomy pain, the on start of oral intake and stay in hospital and to investigate any complications that can arise due to infiltration of the said drugs. 60 Patients above the age of 5 years were posted for tonsillectomy or adenotonsillectomy under general anesthesia. Patients were blinded about the group in which they will be enrolled. Group A received Inj. ropivacaine (0.75%) 2 ml and Group B: received Inj. Bupivacaine (0.50%) 2 ml in each fossa. After surgery, no analgesics were given & patients were observed for the intensity of post-operative pain in the immediate post-operative period, at 2, 4, 6, 12, 24, 48 h and further if not discharged using VISUAL ANALOGUE SCORE (VAS) and VERBAL RATING SCALE(VRS). Post-operative pain assessment was done using VAS and VRS at 2nd, 4th, 6th, 12th, 24th and 48th hour which was found to be lower in Group 'A'. Patients in Group 'A' also started their oral intake sooner, had lesser hospitalization days than group 'B' patients. Longer time for Rescue analgesic and reduced total dose of analgesic required was seen in Group A compared to Group B. This comparative study on Post-incisional infiltration of 2 ml 0.75% Ropivacaine v/s 2 ml 0.5% Bupivacaine has shown that Ropivacaine is a more effective drug in reducing post-operative pain in comparison to Bupivacaine, proven statistically.

Perioperative analgesic efficacy of lumbar erector spinae plane block in dogs undergoing hemilaminectomy: a randomized blinded clinical trial

OBJECTIVE

To evaluate the perioperative analgesic effect of the unilateral lumbar erector spinae plane block (ESPBL) in dogs undergoing hemilaminectomy.

STUDY DESIGN

Randomized, blinded clinical study.

ANIMALS

A total of 30 client-owned dogs undergoing thoracolumbar or lumbar hemilaminectomy for intervertebral disc extrusion (IVDE).

METHODS

Dogs were randomly assigned to receive a unilateral ESPBL, performed either with 0.4 mL kg-1 ropivacaine 0.5% [group ROPI (n = 15)] or with saline solution [CNT group (n = 15)]. Dogs were premedicated intravenously (IV) with acepromazine 5 μg kg-1 and methadone 0.2 mg kg-1, general anaesthesia was induced by administering IV midazolam 0.2 mg kg-1 and propofol to effect and maintained with isoflurane. Fentanyl was administered as rescue analgesia. Bradycardia [heart rate (HR) < 60 beats minute-1] with hypotension was treated with atropine IV. The Short-Form of the Glasgow Composite Pain Scale was used pre- and postoperatively at 1, 2, 4, 8, 12, 16, 20 and 24 hours after extubation, and methadone 0.2 mg kg-1 was administered IV when pain score was ≥ 5/20. HR and end-tidal concentration of isoflurane (Fe'Iso) were compared between groups with anova combined with a Dunnet's post hoc test. Time to the first rescue methadone and total dose of fentanyl (FENtot, μg kg-1 hour-1) and methadone (METtot, mg kg-1) in the first 24 postoperative hours were compared using unpaired Student's t test. Postoperative pain scores were compared with the Mann-Whitney test and atropine administration with a Fisher's exact test; p < 0.05.

RESULTS

HR, Fe'Iso, FENtot, METtot and atropine administration were significantly lower in group ROPI compared to CNT. Postoperative analgesic effect was significantly longer, and pain scores were significantly lower in group ROPI for all time points.

CONCLUSIONS AND CLINICAL RELEVANCE

Unilateral ESPBL with ropivacaine reduced perioperative opioid consumption and the occurrence of bradycardia in dogs undergoing hemilaminectomy.

Evaluation of the technique of localization of the epidural space with the aid of a peripheral nerve stimulator and epidurographic, comparing two techniques for determining the infused volume, in rabbits (Oryctolagus Cuniculus)

Veterinary care for rabbits has been growing, and, consequently, the anesthetic and analgesic management of this species must be improved. The aim of the present study was to evaluate the technique of localization of the epidural space with the aid of a peripheral nerve stimulator and epidurographic, comparing two techniques for determining the infused volume in rabbits (Oryctolagus Cuniculus). In a prospective, randomized blinded study, six healthy New Zealand rabbits, adults, and weighing from 2.2 kg to 3.8 kg received two treatments, at 1 week intervals: 0.33 mL/kg (treatment I) or 0.05 mL per centimeter of the spine (treatment II) of ioexol epidurally. In both treatments, a peripheral nerve stimulator (2 Hz, 0.25 mA and 0.1 milliseconds) was used to determine the location of the epidural space. Latero-lateral and ventro-dorsal radiographs were taken after five (T5) and twenty-five minutes (T25) of iohexol administration. The epidural space was correctly accessed in 92% of attempts. Treatment I received a smaller volume of contrast than treatment II, 1.0 ± 0.2 mL versus 2.1 ± 0.1 mL (mean ± standard deviation), respectively (p = 0.007). At T5, the cranial progression of the contrast varied between L4 and L5 in treatment I, and L5 and T10 in treatment II. At T25, no contrast was observed in any rabbit. In conclusion, peripheral nerve stimulator aided in accessing the lumbosacral epidural space, and the administration of 0.05 mL per centimeter of the spine resulted in greater cranial progression of contrast.

Effects of Intratesticular Lidocaine in Pet Rabbits Undergoing Orchiectomy

The use of local anesthetics for castration is both simple and cost-effective, and it may contribute to reducing the anesthetic requirements. Despite its common use in clinical practice, the literature regarding the effects of intratesticular lidocaine in rabbits is limited. In this study, nine rabbits per group were assigned to intratesticularly receive either 2% lidocaine (0.05 mL/kg into each testicle) or an equivalent volume of saline prior to elective orchiectomy. Anesthesia was induced by intranasal administration of ketamine, medetomidine, and butorphanol. During intraoperative assessment, no significant differences in vital parameters (heart rate, respiratory rate, and peripheral saturation of oxygen) were observed between the groups. However, rabbits receiving intratesticular saline displayed a higher incidence of responses to surgical stimuli. Postoperative pain was evaluated using the composite Centro Animali Non Convenzionali Rabbit Scale (CANCRS), revealing a significantly lower score at the initial post-surgery assessment in rabbits treated with intratesticular lidocaine. All subjects exhibited rapid resumption of food intake and fecal output. While all rabbits demonstrated satisfactory perioperative performances, the use of intratesticular lidocaine was associated with a diminished response to surgical stimuli. Consequently, this practice has the potential to reduce the requirement for additional anesthetics or analgesics, promoting faster recovery.

Evaluation of lidocaine administration into the ovarian pedicle for the control of intraoperative and early postoperative pain during ovariohysterectomy in dogs

OBJECTIVE

To evaluate effects of lidocaine 2% administration into the ovarian pedicle on intraoperative nociception and early postoperative pain in dogs undergoing ovariohysterectomy.

STUDY DESIGN

Prospective, randomized, blinded clinical study.

ANIMALS

A total of 20 healthy adult female dogs of different breeds.

METHODS

Dogs were premedicated with acepromazine (0.02 mg kg-1) and morphine (0.5 mg kg-1) intramuscularly, anesthesia induced with propofol and maintained with isoflurane. Dogs were randomly assigned to be administered 2 mL of saline (group S) or lidocaine 2% (group L) into the mesovarium (1 mL each side). Heart rate (HR) and noninvasive systemic arterial pressure were recorded before surgery (T0), before (T1) and during ligation of the right ovarian pedicle (T2), before (T3) and during ligation of the left ovarian pedicle (T4). Rescue treatment (propofol) was administered if HR or systolic arterial pressure (SAP) increased by 20% compared with the previous time point. Pain, assessed with the Glasgow Composite Measure Pain Scale-Short Form (CMPS-SF) was recorded before premedication (baseline) and after extubation. Administration of postoperative rescue analgesia was recorded.

RESULTS

In group S, HR was higher at T2 than T1 (112 ± 18 versus 89 ± 21 beats minute-1, p = 0.001) There were no significant differences between treatments at any time. SAP was higher at T2 than T1 in group S (110 ± 12 versus 100 ± 10 mmHg, p = 0.031). SAP was higher in group S than group L at T3 (113 ± 12 and 91 ± 10 mmHg, respectively, p = 0.001). No dogs required propofol intraoperatively. All dogs required postoperative rescue analgesia. Compared with baseline, CMPS-SF increased 60 minutes after extubation (group S; p = 0.019, group L; p = 0.043).

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of lidocaine 2% into the mesovarium did not reduce intraoperative nociception and did not improve postoperative analgesia.

A dose characterization study evaluating the pharmacodynamics and safety of a concentrated alfaxalone solution (4%) as an intramuscular sedative in dogs

Alfaxalone is a commonly employed veterinary anaesthetic induction and sedation agent. A 4% w/v preserved, aqueous formulation of alfaxalone 'RD0387' (A4%) has recently been developed. To evaluate the sedative effects of A4%, three doses, 5 mg kg-1 (A5); 7.5 mg kg-1 (A7.5) and 10 mg kg-1 (A10) were administered intramuscularly into the epaxial musculature of six healthy adult mixed-breed dogs in an experimental, randomized, blinded, crossover study. Sedation time variables, quality of sedation (including onset of sedation and recovery), physiological variables, response to cephalic vein catheterization and frequency of undesirable events were recorded. Continuous variables were analysed between treatments (one-way ANOVA or restricted maximum likelihood modelling) and within treatments compared with baseline (Tukey's test). Categorical data were analysed between treatments (Kruskal-Wallis' test) and within treatments from baseline (Dunn's test). Significance was set at p < .05. All dogs became sedated (laterally recumbent) and sedation onset was significantly faster in groups A7.5 (9.8 ± 5.3 min) and A10 (9.1 ± 5.6 min) compared to A5 (25.6 ± 16.1 min) (p = .033, p = .027, respectively). Duration of sedation was significantly longer in A10 (168.5 ± 70.6 min) and A7.5 (143.8 ± 58 min) compared to A5 (63.8 ± 28.2 min) (p = .005 and p = .003, respectively). Dogs in A10 had a superior quality of onset of sedation compared to A5 (p = .028). Sedation scores and quality of recovery from sedation were not significantly different between doses. Two dogs (2/6) in A5 were insufficiently sedated for cephalic catheterization. Ataxia was the most frequently observed undesirable event with an overall frequency of 78% (14/18) and 89% (16/18) during sedation onset and recovery, respectively. Overall, A4% administered IM in dogs at 7.5 and 10 mg kg-1 resulted in sufficient sedation for IV catheterization in dogs. To improve the speed and quality of the sedation, it is recommended that future research focuses on combining A4% with other sedative or analgesic drugs.

Modified Ultrasound-Guided Dorsal Quadratus Lumborum Block in Cat Cadavers

The quadratus lumborum (QL) block is an ultrasound-guided locoregional anesthesia technique which aims to provide analgesia to the abdomen. The main objective of this study was to assess a modified ultrasound-guided dorsal QL block in cat cadavers. For this purpose, a volume of 0.4 mL kg-1 of a mixture of iopromide and methylene blue was administered between the psoas minor muscle and the vertebral body (VB) of the first lumbar vertebra, and its distribution was assessed in thirteen cat cadavers. We hypothesized that this injection point would be feasible, offering a more cranial distribution of the injectate and a more consistent staining of the truncus sympathicus. The study was divided into two phases. Phase 1 consisted of an anatomical study (three cadavers were dissected). Phase 2 consisted of the ultrasound-guided administration of the injectate and the assessment of its distribution by computed tomography and anatomical dissection. The results showed a consistent distribution of contrast media within five (4-8) VBs from T10 to L5. Methylene blue stained three (2-6) rami ventrales, affecting T11 (10%), T12 (20%), T13 (60%), L1 (85%), L2 (95%) and L3 (65%). The truncus sympathicus was dyed in all cadavers with a spread of five (3-7) VBs. Finally, the splanchnicus major nerve was stained in all cadavers (100%). These results suggest that this technique could provide analgesia to the abdominal viscera and the abdominal wall, probably with the exception of the cranial aspects of the abdominal wall.

A comparison of intra and postoperative analgesic effects of sacrococcygeal and lumbosacral epidural levobupivacaine in cats undergoing ovariohysterectomy

The aim of this study was to compare the intra and postoperative analgesic effects of sacrococcygeal epidural levobupivacaine with those of lumbosacral levobupivacaine in feline ovariohysterectomy. Thirty-six cats were premedicated with intramuscular acepromazine (0.05 mg/kg) and meperidine (6 mg/kg). Anesthesia was induced with intravenous propofol and maintained with isoflurane in oxygen. The cats were randomly assigned one of the three treatments receiving 0.33% levobupivacaine (0.3 mL/kg) into the sacrococcygeal (S-C group, n=12) or lumbosacral (L-S group, n=12) epidural space, or the same volume of 0.9% saline solution into one of the epidural approaches (Control group, n=12). Intraoperatively, cardiorespiratory variables, end-tidal isoflurane concentration (FE´ISO), and fentanyl requirements were recorded. Postoperative pain was assessed by the UNESP (Universidade Estadual Paulista)-Botucatu multidimensional composite pain scale and the Glasgow feline composite measure pain scale up to 8 hr post-extubation. Morphine was administered as rescue analgesia. Overall FE´ISO and fentanyl requirements were lower in the L-S and S-C compared to the Control (P=0.002-0.048, respectively). There was no significant difference in the cardiorespiratory variables during anesthesia, postoperative pain and rescue analgesia among groups. The time to standing after anesthesia was prolonged in the L-S and S-C groups than in the Control (P<0.001). Lumbosacral and sacrococcygeal epidural levobupivacaine resulted in similar decreases in isoflurane requirements and intraoperative fentanyl supplementation in the cats, with no postoperative benefits.

Anaesthesia in Veterinary Oncology: The Effects of Surgery, Volatile and Intravenous Anaesthetics on the Immune System and Tumour Spread

Throughout the course of oncological disease, the majority of patients require surgical, anaesthetic and analgesic intervention. However, during the perioperative period, anaesthetic agents and techniques, surgical tissue trauma, adjuvant drugs for local pain and inflammation and other non-pharmacological factors, such as blood transfusions, hydration, temperature and nutrition, may influence the prognosis of the disease. These factors significantly impact the oncologic patient's immune response, which is the primary barrier to tumour progress, promoting a window of vulnerability for its dissemination and recurrence. More research is required to ascertain which anaesthetics and techniques have immunoprotective and anti-tumour effects, which will contribute to developing novel anaesthetic strategies in veterinary medicine.

Comparison between the Effect of Lidocaine or Ropivacaine Hematoma Block and of Different Timings of Administration on Post-Operative Pain in Dogs Undergoing Osteosynthesis of Long-Bone Fractures

OBJECTIVE

We aimed to compare the efficacy of intra-operative lidocaine hematoma block (HB) to ropivacaine HB and to compare the efficacy of different timings of ropivacaine HB in controlling post-operative pain in dogs undergoing the osteosynthesis of long-bone fractures.

STUDY DESIGN

We conducted a randomized, blinded, prospective clinical study.

ANIMALS

Forty-eight dogs with long-bone fractures were included and were randomly allocated to four groups: lidocaine (L), ropivacaine (Rmid), ropivacaine pre- (Rpre) and ropivacaine post- (Rpost) groups.

METHODS

The dogs in group L (n = 14) and in group Rmid (n = 11) received a lidocaine or ropivacaine HB, respectively, after fracture reduction and before osteosynthesis material placement. Rpre dogs (n = 11) received ropivacaine HB before fracture reduction, and Rpost dogs (n = 12) received ropivacaine HB after osteosynthesis material placement. Eight post-operative pain assessments were performed using the University of Melbourne Pain Scale (UMPS) and an algometer. Rescue analgesia was administered based on UMPS scoring. For data analysis, the Shapiro-Wilk test of normality, chi-square, Student t test and Split Plot analysis were used. The level of significance was set at α = 0.05.

RESULTS

Rescue analgesia was administered to one dog in group L, one in group Rmid and one in group Rpost, with no significant differences detected. Compared to group Rmid, group L dogs exhibited significantly higher mean mechanical pain thresholds (p = 0.049) and lower mean UMPS scores (p = 0.001). Group Rpost dogs had statistically significantly higher mean pain thresholds compared to group Rmid (p = 0.009).

CLINICAL IMPLICATIONS

When performed after fracture reduction and before osteosynthesis material placement, lidocaine HB seems to be more effective than ropivacaine HB in controlling post-operative pain in dogs undergoing osteosynthesis of long-bone fractures. The administration of ropivacaine HB after osteosynthesis material placement seems to be more effective than administration after fracture reduction and before osteosynthesis material placement or administration before fracture reduction in controlling post-operative pain in dogs undergoing osteosynthesis of long-bone fractures.

Use of wound infusion catheters for postoperative local anaesthetic administration in cats

OBJECTIVES

The present study aimed to document the use of the wound infusion catheter (WIC) following a variety of surgical procedures in cats, investigating complications and risk factors associated with catheter placement or local anaesthetic (LA) administration.

METHODS

A retrospective, multicentric study was performed. Medical databases of eight veterinary referral hospitals from 2010 to 2021 were searched to identify records of cats where WICs were used. Information regarding signalment, type of surgery, size and type of WIC placed, and LA protocol used, as well as postoperative complications, were retrieved.

RESULTS

One hundred and sixty-six cases fulfilled the inclusion criteria. Feline injection site sarcoma resection was the most common surgery. Overall complications were identified in 22/166 cats (13.2%). Thirteen cats (7.8%) experienced wound-related complications, whereas nine cats (5.4%) experienced drug-delivery complications. The only factor associated with an increased risk of complications was the amount of a single dose of LA delivered through the catheter (P <0.001). An amount higher than 2.5 ml of LA delivered at each administration was associated with an increased risk of complications. All complications were minor and self-limiting.

CONCLUSIONS AND RELEVANCE

WICs were used for a large variety of surgical procedures with different protocols of LA administration as part of a multimodal analgesic plan in cats. The risk of complications was relatively low and self-limiting, suggesting its safe use in cats. Further prospective studies are required to evaluate efficacy of postoperative analgesia and to determine the suitable protocol for WIC handling and maintenance.

Ultrasound-Guided Dorsolateral Approach for Quadratus Lumborum Block in Rabbits (Oryctolagus cuniculus): A Prospective, Randomized, Blinded, Cadaveric Study Comparing Four Different Injectate Volumes

Ultrasound-guided (US-guided) loco-regional anesthesia can provide significant analgesia and anesthetic-sparing effects when used in rabbits. The aims of this study were to investigate the thoraco-lumbar anatomy of the rabbits, particularly the quadratus lumborum (QL) muscle, to design an appropriate US-guided quadratus lumborum block (QLB) specific for rabbits, and to define the most adequate volume of injectate required to consistently cover the ventral branches of T11 to L3 without affecting the pelvic limb innervation (L4, L5 and L6). Sixteen adult rabbit cadavers were included in the study. After randomization, four different volumes of injectate (0.1 mL/kg, 0.2 mL/kg, 0.3 mL/kg and 0.4 mL/kg) were tested, with these volumes additionally randomized to two sites of injection (right or left QL fascia). An ultrasound-guided QLB was performed with a solution of lidocaine, iodinated contrast and tissue dye (in a proportion of 3:1:1 volume, respectively), with subsequent computed tomography (CT) and anatomical dissection, to evaluate the spread of the injectate. In all but one case, the US-guided QLB performed with a dorsolateral approach using 0.3 mL/kg was adequate, while a dose of 0.4 mL/kg consistently reached the targeted nerves but also extended to L4 and caudally. This may suggest that an injectate volume of 0.3 mL/kg may be the most appropriate to produce adequate spread while not affecting pelvic limb innervation.

Contribution to the Study of Perioperative Factors Affecting the Restoration of Dog's Mobility after Femoral Head and Neck Excision: A Clinical Study in 30 Dogs

This study aimed to compare postoperative analgesia and the time of limb weight bearing induced by the intraoperative administration of a local anesthetic at the site of the femoral head and neck excision (FHNE) in dogs, with and without the administration of preoperative epidural anesthesia. Additionally, the impact of postoperative opioid drug administration on weight-bearing time was examined. This randomized, blinded, prospective clinical study included 30 client-owned dogs. The dogs were randomly divided into three groups (A, B, C), each further divided into two subgroups (A1, A2, B1, B2, C1, C2). Group A received epidural anesthesia and ropivacaine at the ostectomy site, Group B received only ropivacaine, and Group C served as the control group. Subgroup 1 received a non-steroidal anti-inflammatory drug postoperatively, while Subgroup 2 had tramadol added to their regimen. Pain assessment was conducted using the University of Melbourne Pain Scale (UMPS) and an algometer. The study concluded that multimodal analgesia, utilizing all the aforementioned analgesic techniques, resulted in faster limb weight bearing for dogs undergoing FHNE.

Antinociceptive effects of bupivacaine injected within the internal abdominis rectus sheath in standing healthy horses

OBJECTIVE

To evaluate a regional anesthetic technique for blocking the abdominal midline in horses.

STUDY DESIGN

Anatomical description and prospective, crossover, placebo-controlled, blinded study.

ANIMALS

Adult horses; two cadavers, six healthy animals.

METHODS

In stage 1, 0.5% methylene blue with 0.25% bupivacaine (0.5 mL kg-1) was injected using ultrasonography into the internal rectus abdominis sheath (RAS) of two cadavers with a one-point or two-point technique. The dye spread was described after the dissection of the abdomens. In stage 2, each horse was injected with 1 mL kg-1 of 0.9% NaCl (treatment PT) or 0.2% bupivacaine (treatment BT) using a two-point technique. The abdominal midline mechanical nociceptive threshold (MNT) was measured with a 1 mm blunted probe tip and results analyzed with mixed-effect anova. Signs of pelvic limb weakness were recorded.

RESULTS

The cadaver dissections showed staining of the ventral branches from the eleventh thoracic (T11) to the second lumbar (L2) nerve with the one-point technique and T9-L2 with the two-point technique. Baseline MNTs were, mean ± standard deviation, 12.6 ± 1.6 N and 12.4 ± 2.4 N in treatments PT and BT, respectively. MNT increased to 18.9 ± 5.8 N (p = 0.010) at 30 minutes, and MNT was between 9.4 ± 2.0 and 15.3 ± 3.4 N from 1 to 8 hours (p > 0.521) in treatment PT. MNTs in treatment BT were 21.1 ± 5.9 to 25.0 ± 0.1 N from 30 minutes to 8 hours (p < 0.001). MNTs after the RAS injections were higher in treatment BT than PT (p = 0.007). No pelvic limb weakness was observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Antinociception of at least 8 hours without pelvic limb weakness was observed in the abdominal midline in standing horses after the RAS block. Further investigations are necessary to evaluate suitability for ventral celiotomies.

Post-operative Pain Assessment Following Tooth Extraction Using Liposomal Encapsulated Bupivacaine as a Local Anesthetic in Dogs

The objective of this study was to evaluate owner assessment of appetite, demeanor, and mouth soreness following dental extractions in dogs receiving either bupivacaine hydrochloride (BH) or liposomal encapsulated bupivacaine (LEB) for dental blocks. Thirty healthy, adult dogs requiring dental extractions were enrolled in the study. All procedures were completed with dogs under general anesthesia. A non-steroidal anti-inflammatory drug was administered subcutaneously in the preoperative period. Dogs were randomly assigned to receive BH or LEB. An owner assessment to evaluate appetite, demeanor, and soreness of mouth was completed at the end of both the first and second day after discharge from the hospital. The total of the owner assessments for day 1 and both days combined was significantly lower for dogs receiving LEB (P = .007). There were no differences in the number of extractions (P = .21), time from block to evaluations (P = .07), in-hospital pain assessments (P = .99), or number of dogs requiring rescue analgesia (P = .99). This study concluded, dogs that received LEB for dental blocks had improved appetite and demeanor, and reduced soreness of mouth, as evaluated by the owner two days postoperatively, when compared to dogs who received BH.

Liposomal Bupivacaine in Dentistry and Oral and Maxillofacial Surgery. A Review of Human and Veterinary Literature

This article reviews the human and veterinary literature regarding liposome encapsulated bupivacaine use in dentistry and oral and maxillofacial surgery. The purpose of this review is to present available information on this local anesthetic in a manner that will allow veterinary dentists and oral and maxillofacial surgeons to use evidence-based information when considering incorporating liposomal bupivacaine into their practice. The twelve human clinical studies and three veterinary reports that met the literature search criteria do not support the use of liposomal bupivacaine in veterinary dentistry and oral and maxillofacial surgery.

Possible Brainstem Anaesthesia in a Cat after Ultrasound-Guided Retrobulbar Block

A 13-year-old neutered, blue-eyed female Siamese cat with a bodyweight of 4.8 kg was admitted for enucleation of the right eye. An ultrasound guided retrobulbar block with 1 mL of ropivacaine was performed under general anaesthesia. When the tip of the needle was visualised inside the intraconal space, negative aspiration of the syringe before injection and no obvious resistance during injection were confirmed. Instantly, after ropivacaine was administered, the cat became apnoeic, and its heart rate and the blood pressure increased significantly for a short period of time. During surgery, the cat needed cardiovascular support to maintain blood pressure and was under continuous mechanical ventilation. Spontaneous breathing returned 20 min after the end of anaesthesia. Brainstem anaesthesia was suspected, and after recovery, the contralateral eye was examined. A reduced menace response, horizontal nystagmus, mydriasis, and absence of the pupillary light reflex were present. The following day, mydriasis was still present, but the cat was visual and was discharged. The inadvertent intra-arterial injection of ropivacaine was suspected to be the cause of the spread into the brainstem. To the current authors' knowledge, possible brainstem anaesthesia has only been reported in a cat 5 min after a retrobulbar block but never instantly.

Evaluation of a constant rate intravenous infusion of dexmedetomidine on the duration of a femoral and sciatic nerve block using lidocaine in dogs

Objectives

This study investigated the effects of 1 μg/kg/h intravenous constant rate infusion (CRI) of dexmedetomidine on the sensory and motor blockade for femoral and sciatic nerve blocks in dogs undergoing stifle surgery.

Materials and methods

Client-owned dogs referred for stifle surgery were enrolled in this prospective, randomized, blinded study. Dogs were pre-medicated with acepromazine (0.005-0.01 mg/kg intramuscularly, IM); anesthesia was induced with propofol intravenously and maintained with isoflurane in a mixture of air and oxygen. Electrolocation-guided sciatic and femoral nerve blocks with lidocaine 2% (0.15 mL/kg) were performed using the parasacral and lateral pre-iliac approaches, respectively. After performing local block, a systemic infusion of saline solution (group C) or dexmedetomidine (group D) was started at a CRI at 1 ml/kg/h and continued until the end of surgery. Dexmedetomidine was infused at a dose of 1 μg/kg/h. Respiratory and hemodynamic variables were recorded during surgery. Sensory and motor blockade was evaluated by response to pinching the skin innervated by the sciatic/femoral nerves, with forceps and by observing the dogs' ability to walk and testing proprioception at 30, 60, 120, 180, and 240 min after extubation. Analgesia was monitored with SF-GCPS. Methadone IM was administered as rescue analgesia. Intraoperative data were analyzed by analysis of variance, while postoperative data were analyzed by the independent two-tailed t-test and a Kaplan-Meier test (p < 0.05).

Results

Twenty dogs were included in this study (10/group). A significant difference in the recovery of sensory nerve function was observed between the groups. The mean durations of the sensory blockade for femoral and sciatic nerves, respectively, was longer (p < 0.001) for group D [168 (146-191, 95% CI), 161 (143-179, 95% CI) min] than in group C [120 (96.1-144, 95% CI), 116 (90.9-142, 95% CI]. No differences in the recovery of patellar and tibial reflexes, proprioceptive function, and ability to walk were found among groups. The overall postoperative rescue analgesia requirement was significantly different (p = 0.019) between groups, with an incidence of 5/10 (50%) dogs in group D and 10/10 (100%) dogs in group C.

Conclusion

Dexmedetomidine administered as a CRI (1 μg/kg/h) combined with local lidocaine increases the duration of the sensory component of the sciatic and femoral nerve blocks and reduces the requirement for additional analgesia during the immediate postoperative hours.

Evaluation of lidocaine for brachial plexus blockade in eastern box turtles (Terrapene carolina carolina)

OBJECTIVE

To evaluate latency and duration of a brachial plexus block technique in eastern box turtles performed with 2% lidocaine at three dose rates.

STUDY DESIGN

Prospective, randomized, blinded crossover study.

ANIMALS

Adult eastern box turtles, two for drug dose evaluation and a group of six (three male, three female) weighing 432 ± 40 g (mean ± standard deviation) for the main study.

METHODS

Animals were randomly assigned to four brachial plexus blocks with lidocaine at 5, 10 and 20 mg kg^-1 or 0.9% saline (treatments LID5, LID10, LID20 and CON, respectively), separated by 1 week. Treatment side was randomized and blocks were performed unilaterally. Baseline observations of mentation, heart rate (HR), respiratory rate (f_R), skin temperature and limb response to manipulation or toe pinch were evaluated. Assessments were made every 10 minutes until 1 hour of normal sensory and motor function to the treated thoracic limb, or for a total of 2 hours if no block was evident.

RESULTS

Motor and sensory blockade was achieved in treatments LID10 and LID20 in one turtle, with a latency of 10 minutes and duration of 50 minutes for both doses. Raising of the ipsilateral lower palpebra occurred with both blocks. Turtles administered lidocaine experienced higher HR compared with CON, and HR decreased over time for all individuals. Mentation and f_R were not changed with any lidocaine dose.

CONCLUSIONS

The technique was unreliable in producing brachial plexus motor and sensory blockade at the lidocaine doses evaluated in this study. HR was higher in lidocaine-administered turtles but remained within normal limits for the species. No change in mentation or f_R was observed among treatments.

CLINICAL RELEVANCE

General anesthesia with systemic analgesia is recommended for surgical procedures involving the chelonian thoracic limb. Further studies are needed to optimize a brachial plexus block in this species.

Efficacy of dexmedetomidine as adjuvant to bupivacaine in femoral-sciatic nerve blocks in dogs undergoing tibial plateau levelling osteotomy (TPLO)

The aim of this randomized, prospective clinical study was to evaluate the efficacy of dexmedetomidine combined with bupivacaine on sciatic and femoral nerve blocks in dogs. Thirty dogs were selected for elective unilateral tibial plateau levelling osteotomy, and each subject was assigned randomly to receive perineural bupivacaine 0.5% (0.1 mL/kg) and intramuscular dexmedetomidine (0.5 μg/kg) in the BDs group, perineural bupivacaine 0.5% (0.1 mL/kg) plus dexmedetomidine (0.5 μg/kg) in the BDloc group, and perineural bupivacaine 0.5% (0.1 mL/kg) plus intramuscular administration of saline solution the in Bupi group. Nerve blocks were guided by electrolocation. The main intraoperative parameters were registered 10 min before the start of surgery (BASE) and during the skin incision (SKIN), the osteotomy (BONE) and the suture (SUTURE). At 2, 4, 6, 8, 10, 15, 20 and 24 h after blocks, the Glasgow Composite Pain scale (GPCs) was used to identify the degree of pain during the postoperative period. Patients with scores ≥5/20 received rescue analgesia and were excluded. Furthermore, heart rate, mean arterial pressure, footstep capacity, reaction to wound touch and femoral and sciatic skin sensitivity were registered. Parametric data were compared at each time point of the study with the one-way ANOVA for repeated measures and Fisher's test for yes/no variables analysis (p < 0.05). No subject required intraoperative rescue analgesia. In BDloc group, the GCPs score was <5/20 for all dogs at all times of the study, and 70% of dogs did not need systemic analgesia. In the Bupi and BDs groups, 100% of subjects achieved a score ≥ 5/20 between 8 and 10 h after the blocks, and 100% of subjects showed femoral and sciatic skin sensitivity and required rescue analgesia within 10 h. Our results showed that the addition of dexmedetomidine as an adjuvant to bupivacaine in SF blocks may prolong the sensory block and ensure sufficient analgesia for up to 24 h in dogs undergoing TPLO surgery.

Bupivacaine as a euthanasia agent for African Clawed Frogs (Xenopus laevis)

Immersion in tricaine methanesulfonate (i.e. TMS) has been used for euthanasia of Xenopus laevis (African Clawed frogs). However, the time for preparation and potential human health hazards may pose as a barrier for large group culls. Here, we aimed to investigate whether immersion in bupivacaine is an effective means to euthanize this species. In experiment one, frogs (n = 10/group) were randomly assigned to 1-h immersion in 1 of 3 treatment groups: 1) TMS-5 (MS-222, 5g/L); 2) TMS-10 (MS-222, 10 g/L); or 3) Bupi-1.5 (0.5% Bupivacaine, 1.5 g/L). Frogs were then removed from solutions, rinsed with system water, and placed into a recovery cage. Heart rate was evaluated audibly via doppler ultrasound flow over 1 min at immediate removal (T1h), at 2 (T2h), and 3 (T3h) h in the recovery cage. In experiment two, frogs (n = 7/group) underwent 5-h & 19-h immersion in either TMS-5 or Bupi-1.5, with heart rate assessment at 5 and 19 hrs. Righting reflex and withdrawal reflex of the hindlimb were tested during the experiments. Experiment one-after the 1-h immersion, Bupi-1.5 treated animals had decreased heart rates compared to TMS-5 and TMS-10 treated animals by T2h. Neither TMS-5, TMS-10, nor Bupi-1.5 ceased heart rate after the 1-h immersion. Experiment two-after the 5-h immersion, Bupi-1.5 and TMS-5 treated animals were comparable in heart rates. 43% of TMS-5 animals and 14% of the Bupi-1.5 animals had completely ceased heart rates at T5h. At 19 h all remaining animals exhibited rigor mortis and had ceased heart rate. We recommend 19-h of immersion using either TMS-5 or Bupi-1.5 for cessation of heart rate in African Clawed frogs. These data are strong support for the use of secondary physical methods for euthanasia in African Clawed frogs when euthanasia by immersion is performed.

Safety and accuracy of blind vs. ultrasound‐guided dorsal retrobulbar nerve blocks in horses—A cadaveric study

OBJECTIVE

There is limited knowledge regarding the safety and accuracy of ultrasound-guided retrobulbar nerve blocks in horses. The aim of this study was to compare these parameters between blind and ultrasound-guided injection techniques for the dorsal retrobulbar nerve block in horses.

METHODS

Equine cadaver heads were used to inject the retrobulbar space with contrast medium (CM). Injections were performed either blindly based on anatomic landmarks (blind group, n = 44) or under ultrasonographic guidance (US-group, n = 44), equally divided between an experienced and unexperienced operator. Needle position and distribution of CM were assessed with computed tomography imaging and evaluated by a board-certified veterinary diagnostic imager blinded to the technique. Safety and accuracy of both techniques were compared.

RESULTS

Ocular penetration was observed in two cases (n = 2/44) in the blind group but not in the US group (n = 0/44). No intrathecal, intraneural, or intravascular injections were seen in either group. Safety was significantly improved in the US group (p = .026). There was no statistically significant difference between the groups regarding the accuracy of the injection. Excellent accuracy was achieved more often with the ultrasound-guided technique (n = 11/22) than with the blind technique (n = 7/22) when performed by the unexperienced operator, but this difference was not statistically significant.

CONCLUSION

To prevent globe-threatening complications and improve the safety of the injection, we recommend using the ultrasound-guided injection technique for the dorsal retrobulbar nerve block.

Effect of temperature-responsive hydrogel on femoral and sciatic nerve blocks using bupivacaine in Beagle dogs

OBJECTIVES

To compare the duration of regional anesthesia of the pelvic limb using bupivacaine with and without a temperature-responsive hydrogel (TRH) in dogs.

METHODS

Under anesthesia using medetomidine (10 μg·kg^-1 ), alfaxalone (2 mg·kg^-1 ), and isoflurane, seven healthy male Beagles received four injections of 0.5% bupivacaine (1 mg·kg^-1 with 5 μg·ml^-1 epinephrine) to block the femoral and sciatic nerves bilaterally via ultrasound with nerve stimulation guidance. Bupivacaine was used on one pelvic limb (Bup treatment), and bupivacaine with TRH was used on the contralateral limb (Bup-TRH treatment). The nerve block was considered successful upon the absence of responses to pinching the digital pads and mid-tibial skin of both pelvic limbs with mosquito forceps; the pinch, proprioception, and locomotion tests were performed before (baseline) and at each hour after the nerve block until sensory and motor functions returned to baseline. The effect of TRH on nerve blocks was analyzed using a linear mixed model.

RESULTS

The duration of the sensory nerve block at the digital pads and mid-tibial skin was longer with Bup-TRH (8.0 ± 1.6 h and 10.9 ± 1.6 h, respectively) than with Bup treatment (3.7 ± 2.0 h and 8.0 ± 1.6 h, respectively). Motor block times of proprioception and locomotion were longer with Bup-TRH (9.3 ± 1.6 and 12.7 ± 1.5 h, respectively) than with Bup treatment (4.6 ± 1.9 and 9.6 ± 1.5 h, respectively). No complications were observed.

CLINICAL SIGNIFICANCE

TRH extended the duration of regional anesthesia of the pelvic limb using bupivacaine.

Use of Transversus Abdominis Plane and Intercostal Blocks in Bitches Undergoing Laparoscopic Ovariectomy: A Randomized Controlled Trial

In humans and dogs, loco-regional anesthesia is associated with lower peri-operative opioid consumption and less related side effects. The combination of transversus abdominis plane (TAP) and intercostal blocks can be used to desensitize the entire abdominal wall in dogs. The aim of this study was to evaluate the effectiveness of TAP and intercostal blocks in bitches undergoing laparoscopic ovariectomy. Twenty client-owned bitches were enrolled in this double-blinded randomized controlled trial. After premedication with dexmedetomidine, methadone and ketamine, the animals were randomized into two groups. Dogs in the TAP group received intercostal blocks from T8 to T10 and a TAP block with ropivacaine. Dogs in the FEN group received a fentanyl bolus and a constant rate infusion for the entire duration of the procedure. Intra-operative cardiovascular stability, post-operative pain scores, rescue opioid requirement, dysphoria during recovery, time to attain sternal recumbency and interest in food at 6 h post-extubation were compared. Bitches in the TAP group received a statistically significant lower amount of rescue fentanyl intra-operatively and methadone post-operatively. Pain scores were lower in the TAP group until 6 h post-extubation. No difference was found for dysphoric recoveries, time to attain sternal recumbency and appetite at 6 h post-extubation. No adverse event was recorded for any of the dogs. The combination of TAP and intercostal blocks can be part of an effective multi-modal analgesic strategy in bitches undergoing laparoscopic ovariectomy.

An Anatomical, Sonographic, and Computed Tomography Study of the Transversus Abdominis Plane Block in Cat Cadavers

This study compared the distribution of a bupivacaine-iopamidol-dye solution following ultrasound-guided in-plane TAP injection using a 1-point (TAP-L) or 2-point (TAP-SL) approach in cat cadavers. Two cadavers were used to study the TAP sonoanatomy while eight cadavers were enrolled in a randomized, prospective, blinded investigation. Each cat randomly received a TAP-L with 0.5 mL/kg in one hemiabdomen and a TAP-SL with 0.25 mL/kg/point in the contralateral hemiabdomen. After injection, computed tomography and dissection were performed to assess contrast distribution and number of stained target nerves. TAP-SL resulted in a wider contrast spread (mm) compared with TAP-L (87 ± 7 versus 71 ± 9; p = 0.002). The prevalence of nerve staining was higher using TAP-SL than TAP-L (p = 0.001). The ventral branches of T10, T11, T12, T13, L1 and L2 were stained in 2/8, 2/8, 5/8, 7/8, 4/8 and 1/8, and in 7/8, 7/8, 8/8, 8/8, 8/8 and 1/8 using TAP-L and TAP-SL approaches, respectively. Computed tomography and dissection identified minimal injectate intraperitoneally or within the falciform ligament fat following 1 TAP-L and 2 TAP-SL. Ultrasound-guided TAP-SL provided better injectate distribution around the thoracolumbar spinal nerve branches than TAP-L.

Thoracolumbar retrolaminar block in seven dogs undergoing spinal surgery

Background

Thoracolumbar intervertebral disc extrusion is a common neurologic complaint in dogs and is associated with debilitating pain that requires careful analgesic management to avoid the transition to a chronic pain state. Recently, there has been an increased effort to incorporate regional anaesthetic techniques whenever possible, both for perioperative analgesia management and for prevention of chronic pain. A novel regional anaesthetic technique named retrolaminar block is a fascial plane block where the local anaesthetic is injected directly on top of the dorsal aspect of the vertebral lamina, in the fascial plane between the lamina and the epaxial muscles. The technique was recently described in humans and it is claimed to provide analgesia in patients undergoing thoracic and lumbar procedures. To the authors’ knowledge, the retrolaminar block has not been previously reported in live dogs.

Case presentation

Seven dogs presented to our hospital for suspected thoracolumbar intervertebral disc extrusion were anaesthetised using an anaesthetic premedication and induction protocol tailored for each individual animal. Once the suspected diagnosis was confirmed, all seven dogs were placed in sternal recumbency, and the target thoracolumbar vertebral spinous process was identified with palpation. A unilateral retrolaminar block was performed in all dogs with 2 mg/kg of 0.25% bupivacaine. Physiologic parameters, as well as responses to nociceptive stimuli, were monitored throughout the anaesthetic event.

Intraoperatively, one dog required a bolus of fentanyl to control nociceptive stimulation while the epaxial muscles were retracted. No further intraoperative rescue analgesia was required in any of the cases. The postoperative pain was assessed using the Short Form of Glasgow Composite Measure Pain Scale for dogs every four hours for the duration of the dogs’ hospitalization. The retrolaminar block reduced the intraoperative requirement for systemic opioids and other adjunct analgesic agents and all dogs were comfortable throughout their hospitalization and up until the time of their discharge.

Conclusions

This case report presents the performance of the retrolaminar block technique as part of multimodal analgesia management in seven dogs undergoing thoracolumbar spinal surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13620-022-00224-7.

Local and Regional Anaesthetic Techniques in Canine Ovariectomy: A Review of the Literature and Technique Description

Simple Summary

This review stems from a general trend of increasing attention toward surgical nociception in the veterinary field. Indeed, veterinarian anaesthetists are becoming more careful in relieving perioperative nociception, improving the analgesic protocols and therefore optimising surgical outcomes. Canine ovariectomy is a common surgical procedure with a moderate level of pain. Therefore, intraoperative analgesia is very important because pain causes various systemic inflammatory effects that slow patient recovery. This review aims to collect all recent information about local and regional anaesthetic/analgesic techniques in a review of the literature describing the technique utilised. In addition, the present review aims to provide practical guidelines for veterinary practitioners to improve the anaesthetic techniques in canine neutering through an overview of the available literature. In fact, the methods described, considering the relative simplicity of execution, can be used in daily routine practice.

Abstract

Canine ovariectomy is an elective surgery with a moderate level of pain. Despite its relative simplicity, it requires surgical pain management. This study aimed to collect all recent information about local and regional anaesthetic/analgesic techniques in a review of the literature describing the technique utilised. The various procedures described in this review use local anaesthetics to improve analgesia in the routine systemic anaesthetic protocol. The approach described in this paper is called multimodal analgesia and is used in addition to the normal standard anaesthetic protocol. These techniques proved effective in minimising responses to the surgical stimulus and ensured adequate intraoperative and postoperative analgesia. The routine use of multimodal analgesia is considered a useful alternative for pain management in canine ovariectomy, in that it minimises patient suffering, improves the recovery of rescue analgesia, increases drug savings, and improves animal outcomes. In addition, the use of these local and regional techniques ensures satisfactory analgesic coverage that lasts for the first hours postoperatively.

An Observational Survey Study on the Use of Locoregional Anaesthesia in Non-Conventional Species: Current Practice and Potential Future Developments

The objectives of this study were to investigate the current attitudes of veterinarians towards the use of locoregional anaesthesia in non-conventional animal species and to identify areas for future useful research on this topic. A questionnaire was circulated online. A total of 417 veterinarians, including American and European specialists/specialists-in-training in both zoological medicine and anaesthesia/analgesia (ACZM/ECZM and ACVAA/ECVAA), participated in the study. Fifty-nine percent of respondents performed locoregional anaesthesia in rabbits, with intratesticular injections and local infiltration being the most commonly-reported techniques. ACZM/ECZM specialists reportedly performed dental blocks in rabbits more frequently than ACVAA/ECVAA specialists (p = 0.030). Forty percent of respondents performed locoregional anaesthesia in rodents, with intratesticular injections, topical/splash blocks and local infiltration being the most commonly reported techniques. The proportions of respondents who reportedly used locoregional anaesthesia in ferrets, birds and reptiles were 37.9%, 34.5% and 31.2%, respectively. The use of Tuohy (p < 0.001) and spinal needles (p < 0.001), as well as of ultrasonography (p = 0.009) and nerve-stimulators (p < 0.001), was more common among ACVAA/ECVAA compared to ACZM/ECZM specialists. Major topic areas for future research were identified as dental block techniques for rabbits and rodents and blocks for the wings of birds.

The ultrasound-guided funicular block in cats undergoing orchiectomy: ropivacaine injection into the spermatic cord to improve intra and postoperative analgesia

BACKGROUND

The orchiectomy in cats is a common surgical procedure with medium level of pain and for this reason requires intra and postoperative analgesia management. The aim of this study was to compare intra and postoperative pain in two groups of cats undergoing orchiectomy. Sixty healthy cats were randomly assigned in two groups (n = 30) to receive pre surgery ropivacaine hydrochloride (0.2 mL/kg at 0.5%) (R Group) or NaCl 0.9% (C group) into the spermatic cord. The intraoperative evaluation was carried out using the cardiorespiratory stability parameters and eventually administration of rescue analgesia. A rescue analgesia (fentanyl 2 µg/kg) was administered during orchiectomy in case of considerable increase of blood pressure, heart rate or respiratory rate. The postoperative evaluation was been done using scores following a UNESP-Botucatu multimodal scale for 6 h post-surgery.

RESULTS

As result, cats in R group responded better to surgical procedure, maintaining lower postoperative pain scores than C group.

CONCLUSIONS

The ultrasound-guided funicular block used in this study, as already demonstrated in dogs, is a good method to protect the cats from surgical pain and ensure a good level of surgical analgesia.

2022 AAHA Pain Management Guidelines for Dogs and Cats

These updated guidelines present a practical and logical approach to the assessment and management of acute and chronic pain in canine and feline patients. Recognizing pain is fundamental to successful treatment, and diagnostic guides and algorithms are included for assessment of both acute and chronic pain. Particularly for chronic pain, capturing owner evaluation is important, and pain-assessment instruments for pet owners are described. Expert consensus emphasizes proactive, preemptive pain management rather than a reactive, "damage control" approach. The guidelines discuss treatment options centered on preemptive, multimodal analgesic therapies. There is an extensive variety of pharmacologic and nonpharmacologic therapeutic options for the management of acute and chronic pain in cats and dogs. The guidelines include a tiered decision tree that prioritizes the use of the most efficacious therapeutic modalities for the treatment of acute and chronic pain.