The aim of this study was to evaluate the effect of the transverse quadratus lumborum block (QLB_LQL-T) on time to the first postoperative rescue analgesia in dogs submitted to laparoscopic ovariectomy. A total of twenty-three female dogs were included. Dogs were randomly assigned to receive a bilateral QLB_LQL-T, performed either with 0.3 mL kg⁻¹ ropivacaine 0.5% [group QLB_0.5% (n = 8)] or with ropivacaine 0.33% [group QLB_0.33% (n = 8)] or a fentanyl-based protocol [group No-QLB (n = 7)]. Dogs were premedicated intravenously (IV) with fentanyl 5 mcg kg⁻¹, general anesthesia was induced IV with propofol and maintained with sevoflurane. Invasive mean arterial pressure (MAP) values were recorded five minutes before and five minutes after performing the QLB_LQL-T. The short-form of the Glasgow composite measure pain scale was used every hour after extubation, and methadone 0.2 mg kg⁻¹ was administered IV when pain score was ≥5/24. Kolmogorov–Smirnov test, ANOVA test combined with Tukey post hoc test, Student’s T-test and Chi-square test were used to analyze data; p < 0.05. Time from QLB_LQL-T to the first rescue analgesia was significantly longer in QLB_0.5% than in group QLB_0.33% and No-QLB. MAP pre- and post-block decreased significantly only in group QLB_0.33%.

A prospective, randomized clinical trial was designed to compare four epidural treatments in dogs undergoing total unilateral mastectomy. The epidural volume of injectate was based on the individual occipito-coccygeal length (OCL) aiming to reach the first thoracic vertebra (T₁). The first ten dogs were allocated in a control group (C) and did not receive epidural treatment. Subsequently, forty dogs were randomly allocated in four groups of ten: epidural ropivacaine 0.5% (R_0.5%); morphine 0.1 mg kg⁻¹ plus ropivacaine 0.5% (MR_0.5%); morphine 0.1 mg kg⁻¹ plus ropivacaine 0.35% (MR_0.35%); morphine 0.1 mg kg⁻¹ plus ropivacaine 0.25% (MR_0.25%). Intraoperatively, isoflurane requirement (1.3% vs. <1.1% FE’Iso) and fentanyl requirement (9.8 vs. <1.1 µg kg⁻¹ h⁻¹) were significantly higher in C group compared to all epidural groups. Postoperatively, methadone requirement was higher (1.8 mg kg⁻¹ vs. <0.8 mg kg⁻¹) for C group compared to all epidural treatment groups. The ability to walk and to urinate returned 4 h earlier in MR_0.35% and MR_0.25%. The mean epidural volume of ropivacaine, using a dose regimen based on OCL, to reach T₁ was about 0.15 mL cm⁻¹. The addition of morphine further reduced the methadone requirement, without affecting urinary and motor functions.