Onset of Action of Bupivacaine Administered via Dural Puncture Epidural versus Spinal, Lumbosacral, and Sacrococcygeal Epidural Injections in Dogs: Randomised Clinical Trial

Efficacy of lumbosacral and sacrococcygeal epidural ropivacaine in dogs undergoing surgery for perineal hernia

Epidural anesthesia is commonly administered as part of balanced anesthesia for perioperative analgesia. The main goal of this randomized clinical trial was to compare the efficacy of two epidural approaches in dogs undergoing surgery for a perineal hernia. A secondary aim was to compare motor blockade. Intact ASA 1 and 2 male dogs, weighing ≤25 kg with no previous surgery for perineal hernia were enrolled. After premedication with IM acepromazine 0.02 mg/kg and butorphanol 0.3 mg/kg, general anesthesia was induced with propofol and maintained with sevoflurane in oxygen. Dogs were randomly allocated to receive either a lumbosacral (LS, n = 30) or a sacrococcygeal (SC, n = 26) epidural injection with ropivacaine 1% (0.2 mL/kg) under computed tomography guidance. Successful analgesia was defined as no need of intraoperative rescue analgesia (fentanyl 3 μg/kg IV). Clinical failure was defined as the need of more than two boluses of fentanyl/h each dog received meloxicam 0.2 mg/kg IV at the end of the surgery. The Glasgow Composite Pain Scale short form (GCPS-SF), tactile sensitivity, pressure pain thresholds and motor blockade were assessed at 4, 6, 8, and 24 h after the epidural injection. Methadone (0.2 mg/kg, IV) was administered if the GCPS-SF was ≥6/24 points. Differences between groups were analyzed with the Mann-Whitney U test, Student's t-test or Fisher's Exact test, as appropriate. Success rate was assessed for non-inferiority between groups. The non-inferiority margin was set at -10%. Epidural analgesia was successful in 24 dogs in group LS and 17 dogs in group SC (p = 0.243), resulting in success rates of 80 and 65% in LS and SC groups, respectively. The non-inferiority of group SC versus group LS was confirmed. Clinical failure was recorded in two dogs in group LS and one dog in group SC. No significant differences between groups were detected in the GCPS-SF score, tactile sensitivity, pressure pain thresholds, need of post-operative methadone, or motor blockade. Both epidural techniques are valuable analgesic options for perineal hernia repair in dogs.

Comparative Study of the Sedative and Anti-nociceptive Effects of Sacrococcygeal Epidural Administration of Romifidine, Lidocaine, and Romifidine/Lidocaine in the Dromedary Camel

In a randomized prospective study, comparative sedative and anti-nociceptive effects of epidural administration of romifidine (RO), lidocaine (LD), and a combination of romifidine-lidocaine (ROLD) in camel were evaluated. Eighteen healthy adult dromedary camels were assigned randomly to three treatment groups (n = 6), each receiving 50 μg/kg of RO, 0.30 mg/kg of LD, or a combination of both RO and LD. All treatments were expanded in 0.9% sterile normal saline solution to a final dose volume of 20 ml and administered directly into the sacrococcygeal space. After epidural injection of each treatment, the onset time, duration, anatomical extension of anti-nociception, and sedation were documented. Anti-nociception was tested at different areas using a pinprick test and artery forceps pinching at the perineum and inguinal area. RO and ROLD treatments resulted in mild to severe sedation and complete bilateral analgesia with loss of sensation in the tail, perineum, scrotum in males, vulva in females, the caudal aspect skin of the upper hind limb, and inguinal region (udder in females and the prepuce in males). The anatomic extent of anti-nociception reached the chest cranially and the footpad distally. Camels who received LD showed the shortest duration (P < 0.001) to the onset of perineal anti-nociception (3.67 ± 0.33 min) followed by those who received RO LD (4.00 ± 0.37 min) and RO (6.67 ± 0.33 min), respectively. RO and ROLD resulted in significantly (P < 0.001) longer periods of analgesia (158.33 ± 4.01 min and 165 ± 3.87 min, respectively) than LD (75.83 ± 3.27). An epidural RO and ROLD would appear to produce a very effective and acceptable anti-nociceptive effect in the perineal and inguinal regions of camels.

Cardiopulmonary Effects and Pharmacokinetics of Dexmedetomidine Used as an Adjunctive Analgesic to Regional Anesthesia of the Oral Cavity with Levobupivacaine in Dogs

This study investigated the cardiopulmonary effects and pharmacokinetics of dexmedetomidine (DEX) used as an adjunctive analgesic for regional anesthesia of the oral cavity with levobupivacaine in anesthetized dogs. Forty dogs were randomly assigned to four groups of 10 dogs. All dogs received levobupivacaine (4 blocks) with DEX IO (infraorbital block, n = 10) or IA (inferior alveolar block, n = 10) or placebo (PLC; n = 10) or DEX (n = 10) was injected intravenously (IV) after administration of levobupivacaine. The dose of DEX was always 0.5 µg/kg. Cardiopulmonary parameters were recorded, and blood was drawn for the quantification of DEX in plasma using LC-MS/MS. Heart rate was lower in all LB + DEX groups, while mean arterial pressure (MAP) was higher in the LB + DEX IV and LB + DEX IA groups compared to the LB + PLC IV group. Compared to DEX IV, IO and IA administration resulted in lower MAP up to 2 min after application. Absorption of DEX was faster at IO administration (Cmax and Tmax were 0.47 ± 0.08 ng/mL and 7.22 ± 1.28 min and 0.76 ± 0.09 ng/mL and 7.50 ± 1.63 min for the IO and IA block, respectively). The IA administration resulted in better bioavailability and faster elimination (t1/2 was 63.44 ± 24.15 min and 23.78 ± 3.78 min for the IO and IA block, respectively). Perineural administration of DEX may be preferable because of the less pronounced cardiovascular response compared to IV administration.