The effect of neuraxial morphine on postoperative pain in dogs after extrahepatic portosystemic shunt attenuation

Opioid‐free anaesthesia for surgical attenuation of a congenital extrahepatic portosystemic shunt in a dog

“…12 Certain drugs with a termination of action highly dependent on hepatic metabolism, such as ketamine, acepromazine, benzodiazepines, were also not employed. 9,13 In order to optimise analgesia without incurring additional side effects, it may be advisable to employ regional nerve blocks. 14,15 The QL block is one such technique, although its mechanism has not yet been fully clarified, it provides analgesia of the ventral branches of caudal thoracic and lumbar spinal nerve roots, responsible for somatic innervation.…”

“…Owing to a decreased ability to process and inactivate drugs, care should be taken to employ appropriate doses of short‐acting anaesthetics and analgesics, avoiding such agents as opioids, whose termination of action is dependent on hepatic metabolism 3 . Most opioids are also highly protein bound, potentially leading to an increased risk of side effects in dogs with portosystemic shunts 9 due to delayed clearance and drug accumulation. An exception to the metabolic pathways that characterise most opioids is remifentanil, which undergoes extrahepatic metabolism by non‐specific blood and tissue esterases 10,11 and is excreted by the kidneys, rendering it a viable option in these cases 12 .…”

“…An exception to the metabolic pathways that characterise most opioids is remifentanil, which undergoes extrahepatic metabolism by non‐specific blood and tissue esterases 10,11 and is excreted by the kidneys, rendering it a viable option in these cases 12 . Certain drugs with a termination of action highly dependent on hepatic metabolism, such as ketamine, acepromazine, benzodiazepines, were also not employed 9,13 …”

“…The postoperative period was uneventful, and the patient exhibited a rapid recovery, an additional benefit from an opioid‐free anaesthesia. The surgical occlusion of the shunt vessel allows for eventual redirection of blood flow into the liver, which will ideally lead to development of normal hepatic blood flow 9 …”