Peripheral nerve blocks play a critical role in pain management; however, no technique has been described to specifically target the articular nerve branches of the elbow in dogs. This study aimed to develop and compare the success rate of an ultrasound-guided versus a blind pericapsular elbow desensitization (PED) technique in canine cadavers. Phase I involved gross and ultrasonographic evaluations of the elbow joint in four cadavers to identify landmarks for the PED technique. Phase II compared the ultrasound-guided and blind PED techniques using dye injections in eight cadavers, followed by the dissection and histological analysis of stained tissues to confirm nerve involvement. The results demonstrated that four quadrant injections are required to target the articular branches of the radial, ulnar, median, and musculocutaneous nerves. The ultrasound-guided technique achieved a significantly higher overall success rate (77.5%) than the blind technique (45%, p = 0.005). While both techniques showed similar success rates (50–62.5%) for the ulnar, median, and musculocutaneous branches, the ultrasound-guided technique (100%) outperformed the blind technique for the cranial (37%, p = 0.02) and caudal (12.5%, p = 0.001) articular branches of the radial nerve. These findings provide a foundation for future clinical studies evaluating the ultrasound-guided PED technique in live animals.

Regional anesthesia techniques targeting articular nerve branches offer promising avenues for managing articular pain. This study developed and compared the success rates of an ultrasound-guided versus a blind pericapsular knee desensitization (PKD) technique in canine cadavers. In Phase I, gross dissection and ultrasound evaluations were performed in eight limbs to characterize the anatomy of the medial (MAN), lateral (LAN), and posterior (PAN) articular branches of the saphenous, common fibular, and tibial nerves, respectively, and to identify suitable anatomical and ultrasonographic landmarks. In Phase II, ultrasound-guided and blind PKD injections of a dye solution were randomly performed in 10 cadavers (20 limbs), followed by dissection and histological assessment of staining accuracy. The ultrasound-guided technique achieved a significantly higher overall success rate (96.7%) than the blind technique (73.3%; p = 0.02). The MAN was successfully stained in 100% of ultrasound-guided and 50% of blind injections (p = 0.03), while the LAN and PAN were stained with high but comparable success. Parent nerve involvement was minimal for MAN and PAN but frequent for the common fibular nerve following LAN injections. Histological confirmation supported the anatomical findings, although PAN identification remained inconsistent. These results support the feasibility and increased precision of ultrasound-guided PKD, providing a foundation for further clinical evaluation.

Thoracolumbar and lumbar hemilaminectomy in dogs requires effective perioperative analgesia. The erector spinae plane (ESP) and retromammillary (RM) blocks are ultrasound-guided regional anesthesia techniques targeting the dorsal branches of spinal nerves, but comparative clinical data are lacking. This retrospective cohort study compared perioperative analgesic requirements and complication rates between ESP (n = 62) and RM (n = 207) blocks in client-owned dogs undergoing hemilaminectomy. The primary outcome was intraoperative opioid rescue analgesia; secondary outcomes included rescue analgesia using any analgesic agent, perioperative opioid consumption (expressed as morphine equivalents, mg kg⁻¹), pain scores, time to voluntary food intake, and complications. Multivariable logistic regression, with covariates selected using a directed acyclic graph, assessed independent predictors of intraoperative opioid rescue administration. Dogs receiving ESP blocks were more likely to require intraoperative opioid rescue than those receiving RM blocks (59.7% versus 38.7%; adjusted odds ratio (OR) 3.4, 95% confidence interval (CI) 1.7–6.6; p < 0.001). Rescue analgesia using any analgesic agent was also more frequent in the ESP group (64.5% versus 43.0%; p = 0.004). Postoperative pain scores, time to first voluntary food intake, and complications were similar between groups. The RM block was associated with reduced intraoperative rescue analgesia compared to the ESP block, though both techniques provided effective postoperative analgesia within multimodal protocols. Prospective randomized trials are warranted to confirm these findings.

Background: Perioperative fluid therapy can influence oxygen delivery and tissue oxygenation, but its effects in horses are poorly understood. Objectives: To compare two intraoperative fluid administration strategies on peripheral tissue oxygenation (StO ₂ ) and cardiorespiratory variables in isoflurane-anaesthetised horses. Study Design: In vivo, randomised experimental study. Methods: Sixteen euvolemic adult horses undergoing coeliotomy for intestinal sampling were anaesthetised with xylazine, ketamine, and midazolam, maintained on isoflurane with a constant-rate lidocaine infusion. Horses received lactated Ringer’s solution at either 2.5 mL/kg/hr (maintenance; MNT) or 40 mL/kg/hr (overhydration; OHD) for 120 minutes. Peripheral tissue oxygenation was measured at the extensor carpi radialis using near-infrared spectroscopy (NIRS). Heart rate, respiratory rate, mean arterial pressure (MAP), central venous pressure (CVP), cardiac output (CO), serum lactate, and urine output were recorded at baseline, 60, and 120 minutes. Data were analysed using mixed-effects linear regression and Bland–Altman repeated-measures correlation. Results: Over time, StO ₂ increased in both groups (P = 0.019) and it was weakly correlated with MAP and lactate (ρ = 0.36, P = 0.05). At 60 and 120 minutes, MAP, CVP, and lactate concentrations were significantly higher in the OHD group (P < 0.01). Cardiac output increased over time in the MNT group and slightly declined in the OHD group, indicating a significant interaction (LR χ ² = 8.27, P = 0.016). Urinary output was 0.72 (0.53–1.63) mL/kg/hr with OHD compared to 0.37 (0.20–0.58) mL/kg/hr with MNT (P < 0.05). Main limitations: Small sample size and short observation window may have influenced results. Conclusions: High-rate fluid therapy increased MAP, CVP, and urine output compared with MNT, but did not enhance StO ₂ or CO. Tissue oxygenation increased over time regardless of fluid rate, suggesting limited benefits of aggressive crystalloid administration for this purpose.

Dexmedetomidine improves pulmonary function in dogs and humans, but evidence in horses is scarce. This study evaluated dexmedetomidine infusion on oxygenation and respiratory mechanics in anesthetized horses. Twenty horses undergoing elective surgery were included in a prospective, non-randomized, observational study. Horses received either lidocaine alone (1.3 mg/kg over 15 min, then 3 mg/kg/hour; LIDO) or combined with dexmedetomidine (1.75 μg/kg over 15 min, then 1.75 μg/kg/hour; DL). Respiratory mechanics, gas exchange, and cardiovascular variables were recorded at baseline, post-loading, and after 30, 60, and 90 min. Data were analyzed using mixed-effects linear models with horse as a random effect and time and treatment and their interaction as fixed effects (p ≤ 0.05). Peak inspiratory pressure increased over time with both treatments but was lower with DL at 90 min (−1.26 mmHg, p = 0.046). There was no evidence that arterial oxygen pressure or oxygenation ratio improved over time with DL (p > 0.75). Shunt fraction did not significantly change over time or between treatments (Wald χ² = 4.77, p = 0.85). Heart rate with DL decreased from baseline (p ≤ 0.001) but remained higher than LIDO overall (p = 0.001). Dexmedetomidine infusion showed no benefit on oxygenation or respiratory mechanics in anesthetized horses.