1. Investigación

This study compared four methods to provide intraoperative analgesia during canine ovariohysterectomy in a veterinary teaching hospital. A retrospective study was designed to assess the nociceptive response, cardiorespiratory stability, quality of recovery and complications of four analgesic protocols: epidural analgesia (EPIDURAL group), Quadratus Lumborum block (QLB group), Transversus Abdominis Plane block (TAP group), and just systemic analgesia (GENERAL group). Undergraduate students carried out all the loco-regional techniques under the direct supervision of a qualified anaesthetist. A total of 120 cases met the inclusion criteria and were included in the study and were distributed as follows: 22, 27, 32 and 39 cases with EPIDURAL, GENERAL, QLB and TAP groups, respectively. Data were analysed with statistical software R using different statistical methods. Significant differences among groups were defined as p < 0.05. Based on our results, all the groups needed the same number of rescue analgesia during the intra-operative period. The use of loco-regional techniques anticipated a better quality of recovery compared with the general group. The EPIDURAL group showed a statistically lower expired fraction of sevoflurane. No differences were found regarding complications. In conclusion, these four analgesic methods are suitable and safe to be performed for canine ovariohysterectomy, although loco-regional techniques might have some advantages.

Quadratus lumborum block (QLB) is used to provide analgesia for abdominal surgery in humans. The aim of this study was to assess an anaesthetic protocol involving the QLB for canine ovariohysterectomy. Ten dogs were included. Anaesthetic protocol consisted of premedication with IM medetomidine (20 g kg􀀀1) and SC meloxicam (0.1 mg kg􀀀1), induction with propofol to effect, and maintenance with sevoflurane in oxygen/medical air. QLB was performed injecting 0.4 mL kg􀀀1 of 0.25% bupivacaine/iohexol per side. Computed Tomography (CT) was performed before and after surgery. Fentanyl was administered as rescue analgesia during surgery. The Short Form of The Glasgow Composite Pain Scale and thermal threshold (TT) at the level of the elbow, T10, T13 and L3 were assessed before premedication and every hour postoperatively. Methadone was given as rescue analgesia postoperatively when pain score was >3. A Yuen’s test on trimmed means for dependent samples was used to analyse the data (p < 0.05). CT images showed spreading of the contrast/block for a median (range) of 3 (2–5) vertebrae, without differences between preoperative and postoperative images. One dog needed rescue analgesia during surgery. Pain score was less than 4/24 in all the animals during the first 4 h after surgery. TT showed a significant increased signal in all the areas tested, apart from the humerus, 30 min after surgery. The QLB may provide additional analgesia for canine ovariohysterectomy. Further studies are needed to assess the specific contribution of the QLB in abdominal analgesia.

Ultrasound-guided quadratus lumborum block (QLB) is a locoregional technique described in canine cadavers. The aim of this study was to assess a modified approach to QLB to minimise potential complications such as abdominal organ puncture. Nine canine cadavers were included and were positioned in lateral recumbency. An ultrasound-guided QLB was performed on each side. The probe was placed in the transverse position over the lumbar muscles just caudal to the last rib, and a needle was advanced in-plane from a dorso-lateral to a ventro-medial. A volume of 0.2 mL kg􀀀1 of a mixture of iomeprol and methylene blue was injected. Computed tomography (CT) and dissection were performed to evaluate the spreading. Success was defined as staining of the nerve with a length of more than 0.6 cm. Potential complications such as intra-abdominal, epidural, or intravascular spreading of the mixture were also assessed. The CT images showed a T13 to L7 vertebra distribution, with a median of 5 (3–6). Dissection showed staining of the nerves from T13 to L4, with a median of 3 (2–5). No complications were found. This modified approach to QLB is safe and shows similar results to the previous studies in canine carcass.

Background: The caudal thoracic paravertebral (CTPV) block is a regional anesthesia technique currently used in human medicine to provide analgesia in abdominal surgical procedures.Aim: The objectives of this study are to describe an ultrasound-guided technique to place catheters in CTPV space in canine cadavers and evaluate the distribution of a 50:50 contrast-dye solution administered through them.Methods: Eight thawed adult beagle cadavers (9.2 ± 2.0 kg body total weight) were used. Thirteen catheters were placed. In the first phase, a volume of 0.3 ml kg−1 of the contrast-dye was administered in all cases. After the injections, computed tomography (CT) scans were carried out to assess the distribution of the contrast-dye. In the second phase, an extra 0.2 ml kg−1 of the contrast-dye was administered through eight catheters, followed by a second CT scan. Two cadavers were dissected to assess the distribution of the contrast-dye.The injection site varied between T8-9 and T12-13. Results: The evaluation of the CT scans showed contrast-dye within the paravertebral space in 92% (12/13) of the injections. The distribution pattern observed after the injections performed within the TPV space was linear and intercostal in all cases. The median (range) linear spread of the contrast was 7 (5–10) spinal nerves and involved 3 (2–8) intercostal spaces. The contrast-dye reached lumbar regions in 42% of the injections (5/12). A larger spread of the contrast-dye was not observed after the administration of a second dose of the injectate. No signs of epidural, intrapleural/intrapulmonary, intravascular, or intraabdominal spread were observed. The dissection of the two cadavers confirmed the spread of the contrast-dye along the sympathetic trunk and intercostal spaces.Conclusion: The administration of 0.3 ml kg−1 of the contrast-dye in the CTPV space resulted in a distribution compatible with the block of nerves responsible for the innervation of the majority of the abdominal viscera and cranial abdominal wall.