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

OBJECTIVE

To investigate the analgesic effect of epidural morphine after surgical extrahepatic portosystemic shunt (EHPSS) attenuation.

STUDY DESIGN

Randomized clinical trial.

ANIMALS

A total of 20 dogs with a congenital EHPSS.

METHODS

Dogs were randomly allocated to be given either a single epidural dose of 0.2 mg kg^-1 preservative-free morphine (group M) or not (group C) before surgery. All dogs were administered 0.3 mg kg^-1 methadone intravenously (IV) as preanaesthetic medication. Pain scores were determined every 2 hours for the first 24 hours postoperatively using the short-form Glasgow Composite Measure Pain Scale (GCMPS-SF). Dogs with a GCMPS-SF pain score >4/20 or >5/24 received 0.1 mg kg^-1 methadone IV as rescue analgesia and were reassessed 30 minutes later. If more than three doses of methadone were administered in a 2 hour period, alternative pain relief was provided and a treatment failure recorded. The GCMPS-SF pain scores and number of rescue analgesia injections were analysed over 24 hours. The last observation carried forward method was applied in case of treatment failure. Food consumption and time to first urination were recorded. Data were analysed using a Mann-Whitney U test and presented as median (minimum-maximum range), with significance set at p < 0.05.

RESULTS

Group M showed lower GCMPS-SF pain scores [15 (11-41) versus 31 (11-86); p = 0.023] and lower postoperative methadone requirements [0 (0-0.2) versus 0.25 (0-0.5) mg kg^-1; p = 0.029] than group C. There were three treatment failures in group C only. Food consumption and time to first urination did not differ between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Epidural morphine reduced the requirement for postoperative analgesia in this study population.

An Update on Drugs Used for Lumbosacral Epidural Anesthesia and Analgesia in Dogs

This review aims to report an update on drugs administered into the epidural space for anesthesia and analgesia in dogs, describing their potential advantages and disadvantages in the clinical setting. Databases searched include Pubmed, Google scholar, and CAB abstracts. Benefits of administering local anesthetics, opioids, and alpha₂ agonists into the epidural space include the use of lower doses of general anesthetics (anesthetic “sparing” effect), perioperative analgesia, and reduced side effects associated with systemic administration of drugs. However, the potential for cardiorespiratory compromise, neurotoxicity, and other adverse effects should be considered when using the epidural route of administration. When these variables are considered, the epidural technique is useful as a complementary method of anesthesia for preventive and postoperative analgesia and/or as part of a balanced anesthesia technique.

Endogenous Opiates and Behavior: 2015

This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Epidural analgesia in cattle, buffalo, and camels

Epidural analgesia is commonly used in large animals. It is an easy, cheap, and effective technique used to prevent or control pain during surgeries involving the tail, anus, vulva, perineum, caudal udder, scrotum, and upper hind limbs. The objectives of this article were to comprehensively review and summarize all scientific data available in the literature on new techniques and drugs or drug combinations used for epidural anesthesia in cattle, camel, and buffalo. Only articles published between 2006 and 2016 were included in the review. The most common sites for epidural administration in cattle, camels, and buffalos were the sacrococcygeal intervertebral space (S5-Co1) and first intercoccygeal intervertebral space (Co1-Co2). The most frequently used drugs and dosages were lidocaine (0.22-0.5 mg/kg), bupivacaine (0.125 mg/kg), ropivacaine (0.11 mg/kg), xylazine (0.05 mg/kg), medetomidine (15 µg/kg), romifidine (30-50 µg/kg), ketamine (0.3-2.5 mg/kg), tramadol (1 mg/kg), and neostigmine (10 µg/kg), and the clinical applications, clinical effects, recommendations, and side effects were discussed.