Postoperative Analgesic Effects of Epidural Administration of Methadone, Tramadol, or Nalbuphine in Ovariohysterectomized Dogs

Abstract

The objective of this study was to evaluate the effectiveness of epidural methadone, tramadol or nalbuphine for postoperative analgesia in dogs. Thirty two healthy female dogs (ASA grade 1) undergoing ovariohysterectomy were randomly allocated into 4 treatments of 8 each: treatment 1 (control group) received 2% lidocaine (LD; 4 mg kgG 1), treatment 2 lidocaine and methadone (LDMT; 4 and 0.3 mg kgG 1 , respectively), treatment 3 lidocaine and tramadol (LDTR; 4 and 2 mg kgG 1 , respectively) and treatment 4 lidocaine and nalbuphine (LDNB; 4 and 0.3 mg kgG 1 , respectively). The drugs were administered into the lumbosacral space, diluted in saline solution to a total volume of 0.36 mL kgG 1. Heart and respiratory rates, arterial pressures and peripheral SpO 2 were evaluated during the peri-operative period until 240 min. Postoperative pain and sedation were measured after extubation until the first rescue analgesic and thereafter regularly for 18 h. The time to first rescue analgesia was significantly (p<0.05) prolonged in dogs in the LDMT group as compared to the control and LDTR or LDNB groups. Although all 3 drug combinations administered epidurally in dogs allowed ovariohysterectomy to be performed with sufficient analgesia, the analgesia was maintained longer with the combination of lidocaine and methadone.

Different Volumes and Concentrations in Fixed Doses of Bupivacaine in Lumbosacral Epidural in Relation to Cranial Spread in Live Dogs

“…The volume required for analgesia after lumbosacral epidural in dogs has been evaluated by several authors [7,8,22,27]. The volume per kg of dosage produces a narrow linear correlation with the dermatome level of the blockade [28].…”

“…HR was measured using electrocardiography, RR was determined as the number of chest movements counted over 1 min, and RT was obtained with a digital thermometer at baseline. Post-operative pain was assessed using a score composed of physiologic and behavioral parameters based on previous studies that evaluated post-operative pain in small animals [19][20][21][22]; the usual precautions were taken by the same blinded researcher. The bitches were evaluated for motor blockade by the presence or absence of pelvic limb weakness.…”

A Comparison of Nalbuphine and Pentazocine in Controlling Postoperative Pain in Dogs

“…Similar to pentazocine, nalbuphine is also a synthetic opiate which is chemically related to oxymorphone [9]. Nalbuphine exerts its effects by binding to specific opiate receptors present in the central nervous system.…”