Post-operative analgesic effects of butorphanol or firocoxib administered to dogs undergoing elective ovariohysterectomy

2022 ISFM Consensus Guidelines on the Management of Acute Pain in Cats

PRACTICAL RELEVANCE

Increases in cat ownership worldwide mean more cats are requiring veterinary care. Illness, trauma and surgery can result in acute pain, and effective management of pain is required for optimal feline welfare (ie, physical health and mental wellbeing). Validated pain assessment tools are available and pain management plans for the individual patient should incorporate pharmacological and non-pharmacological therapy. Preventive and multimodal analgesia, including local anaesthesia, are important principles of pain management, and the choice of analgesic drugs should take into account the type, severity and duration of pain, presence of comorbidities and avoidance of adverse effects. Nursing care, environmental modifications and cat friendly handling are likewise pivotal to the pain management plan, as is a team approach, involving the cat carer.

CLINICAL CHALLENGES

Pain has traditionally been under-recognised in cats. Pain assessment tools are not widely implemented, and signs of pain in this species may be subtle. The unique challenges of feline metabolism and comorbidities may lead to undertreatment of pain and the development of peripheral and central sensitisation. Lack of availability or experience with various analgesic drugs may compromise effective pain management.

EVIDENCE BASE

These Guidelines have been created by a panel of experts and the International Society of Feline Medicine (ISFM) based on the available literature and the authors' experience. They are aimed at general practitioners to assist in the assessment, prevention and management of acute pain in feline patients, and to provide a practical guide to selection and dosing of effective analgesic agents.

Pharmacokinetics and analgesic effects of intravenous, intramuscular or subcutaneous buprenorphine in dogs undergoing ovariohysterectomy: a randomized, prospective, masked, clinical trial

BACKGROUND

Buprenorphine is used for canine postoperative pain management. This study aimed to describe the pharmacokinetics and evaluate the analgesic efficacy of buprenorphine (Simbadol, 1.8 mg/mL) administered by different routes in dogs undergoing ovariohysterectomy. Twenty-four dogs were included in a randomized, prospective, masked, clinical trial. Buprenorphine (0.02 mg/kg) was administered intravenously (IV), intramuscularly (IM) or subcutaneously (SC) (n = 8/group) 0.5 h before general anesthesia with propofol-isoflurane. Carprofen (4.4 mg/kg SC) was administered after anesthetic induction and before ovariohysterectomy. Pain was scored using the short-form Glasgow composite pain scale for dogs (SF-GCPS). Dogs were administered morphine (0.25 mg/kg IV) when SF-GCPS scores were ≥ 5/20. Blood sampling was performed up to 720 min after drug administration. Plasma buprenorphine and norbuprenorphine concentrations were analyzed using liquid chromatography mass spectrometry. Pharmacokinetics of buprenorphine was described using a non-compartmental model (PK Solver 2.0). Statistical analysis was performed using linear mixed models and Fisher's exact test (p < 0.05).

RESULTS

Pain scores were significantly higher than baseline after IV (0.5-2 h), IM (0.5-3 h) and SC (0.5-4 h) but not among groups. Prevalence of rescue analgesia was significantly higher in SC (7/8 dogs) than IV (2/8) but not different between IV and IM (3/8) or IM and SC. The frequency of rescue analgesia was not significantly different among groups (IV = 2, IM = 5 and SC = 9). Norbuprenorphine was not detected. For IV, IM and SC administration, clearance was 1.29, 1.65 and 1.40 L/hour/kg, volume of distribution was 6.8, 14.2 and 40.1 L/kg, the elimination half-life was 3.7, 5.7, 22 h, and the area under the plasma concentration-time curved extrapolated to infinity was 15.7, 12.4 and 16.4 ng/mL/hour, respectively. Bioavailability for IM and SC was 62.6 and 40%, respectively. Maximum plasma concentrations of buprenorphine were 6.2 and 1.3 ng/mL at 0.14 and 0.33 h after IM and SC administration, respectively.

CONCLUSIONS

The route of administration influences the analgesic efficacy of buprenorphine in dogs. SC administration of buprenorphine failed to provide clinical analgesia due to erratic drug absorption. At the doses administered, the IV and IM routes are preferred for postoperative analgesia.

A systematic review of analgesia practices in dogs undergoing ovariohysterectomy

Aim

This was a systematic review conducted to evaluate the analgesic drugs and techniques used in the management of pain in dogs undergoing ovariohysterectomy.

Materials and Methods

Systematic searches in PubMed, Google Scholar, and ScienceDirect were conducted for peer-reviewed articles written in English and published from 1995 to 2015. The key search words were dogs, ovariohysterectomy, pain, and analgesics. This was followed by a manual search of the references within the primary data sources. Inclusion and exclusion of studies and data extraction were performed independently by two reviewers. All randomized studies evaluating the effects of analgesics during ovariohysterectomy in dogs were included.

Results

A total of 31 trials met the criteria and were, therefore, included in the study. Data on the type of analgesic drugs used, the technique of administration, and the need for rescue analgesia were extracted from the papers. Individual analgesic protocols were used in 83.9% of the studies compared to multimodal drug therapy, which was used in 16.1% of the studies. Opioids were used in 39.0% of studies, nonsteroidal anti-inflammatory drugs (NSAIDs) in 19.4%, a combination of NSAIDs and opioids in 19.4%, local analgesics in 6.5%, and acupuncture in 3.2% of the studies. Drug administration was done using three approaches that included pre-operative (64.5%), post-operative (22.6%) as well as combined pre- and post-operative approach (12.9%). In 77.4% of the studies, administration of analgesics was done once, while in 12.9%, it was done as a 72-h post-operative course. 24-h and 48-h courses of post-operative pain therapy were done in 6.5% and 3.2% of the studies, respectively. About 57% of the dogs in the control groups required rescue analgesia as compared to 21.6% in the single and 11.3% in multimodal drug therapy groups. The requirement for rescue analgesics was highest in dogs treated using acupuncture (43.8%) and lowest in dogs treated using NSAID-opioid combination (8.6%). Fewer dogs among those that received pain medication preoperatively and postoperatively required rescue analgesia compared to those in groups given drugs before and after surgery only. More dogs (26.4%) among those given analgesics only once postoperatively required rescue analgesia as compared to those that received analgesics daily for 72 h (4.4%).

Conclusions

This study provides evidence that opioids are the mainstream analgesic drugs used in managing acute post-operative pain in dogs' post-ovariohysterectomy. In addition, multimodal drug therapy, particularly, NSAID-opioids combination is more effective for pain management than single drug administration. Administering analgesics both before and after surgery is associated with better outcomes and so is a protracted course of post-operative pain therapy. Although these practices should be encouraged, controlled studies should be conducted to conclusively determine the best practices for pain management in dogs undergoing ovariohysterectomy.

The analgesic effects of buprenorphine (Vetergesic or Simbadol) in combination with carprofen in dogs undergoing ovariohysterectomy: a randomized, blinded, clinical trial

Background

Buprenorphine is a potent lipophilic opioid analgesic that is largely used in the multimodal treatment of acute pain. Simbadol (buprenorphine hydrochloride) is the first and only FDA-approved high-concentration formulation of buprenorphine for use in cats. The aim of this study was to evaluate the analgesic efficacy of carprofen in combination with one of two commercial formulations of buprenorphine (Simbadol and Vetergesic, 1.8 mg/mL and 0.3 mg/mL, respectively) in dogs undergoing ovariohysterectomy. Twenty-four dogs were included in a randomized, prospective, controlled, clinical trial. Patients were randomly divided into 2 groups as follows. Dogs were premedicated with acepromazine (0.02 mg/kg) and either 0.02 mg/kg of Vetergesic or Simbadol intramuscularly (Vetergesic group – VG; Simbadol group – SG, respectively; n = 12/group). General anesthesia was induced with propofol and maintained with isoflurane in 100% oxygen. Carprofen (4.4 mg/kg SC) was administered after induction of anesthesia. Heart rate, respiratory rate, blood pressure, pulse oximetry, pain scores using the Glasgow Composite Pain Scale Short Form (CMPS-SF), sedation scores using a dynamic interactive visual analogue scale and adverse events were evaluated before and after ovariohysterectomy by an observer who was unaware of treatment administration. If CMPS-SF scores were ≥ 5/20, dogs were administered rescue analgesia (morphine 0.5 mg/kg IM). Statistical analysis was performed using linear mixed models and Fisher’s exact test (p < 0.05).

Results

Pain and sedation scores and physiological parameters were not significantly different between treatments. Three dogs in VG (25%) and none in SG (0%) required rescue analgesia (p = 0.109). Adverse effects (i.e. vomiting and melena) were observed in two dogs in SG and were thought to be related to stress and/or nonsteroidal anti-inflammatory drug toxicity.

Conclusions

The administration of buprenorphine with carprofen preoperatively provided adequate postoperative analgesia for the majority of dogs undergoing OVH without serious adverse events. Prevalence of rescue analgesia was not significantly different between groups; however, it could be clinically relevant and explained by a type II error (i.e. small sample size). Future studies are necessary to determine if analgesic efficacy after Simbadol and Vetergesic is related to individual variability or pharmacokinetic differences.

Analgesic efficacy of oral firocoxib in ovariohysterectomized cats

The postoperative analgesic effects of firocoxib in ovariohysterectomized cats were observed. Twenty-four cats were divided into 3 groups: control (no medicine), firocoxib-1 (1 mg/kg/day) and firocoxib-3 (3 mg/kg/day). Colorado pain scale scores (CPSS), composite pain scores (CPS), and buccal mucosal bleeding times (BMBT) were recorded in blinded fashion before induction and 2, 5, 8, 24, 30, and 48 h post-operation. The average CPSS (mean ± SEM) over 2 to 48 h post-operation in firocoxib-3 (0.4 ± 0.1) was significantly lower than that of the control (0.7 ± 0.2; p = 0.004), but that of firocoxib-1 (0.5 ± 0.2) was not different from that of the control (p = 0.40). The mean CPS of firocoxib-3 was significantly lower than that of the control at 24 h post-operation (p = 0.04); nonetheless, there was no significant difference in mean CPS between firocoxib-1 and control groups at all intervals. BMBT and body temperature were within normal limits in all groups. However, reversible azotemia was identified in two firocoxib-3 cats at 72 h post-operation. One firocoxib-3 cat vomited once at 48 h post-operation. In conclusion, firocoxib-3 is helpful for postoperative pain control in cats; however, gastrointestinal irritation and renal function side effects may occur.

Postoperative comparison of four perioperative analgesia protocols in dogs undergoing stifle joint surgery

OBJECTIVE

To compare 4 analgesic protocols in dogs undergoing stifle joint surgery.

DESIGN

Randomized, blinded, prospective clinical trial. Animals-48 client-owned dogs that underwent stifle joint surgery.

PROCEDURES

Dogs undergoing tibial plateau leveling osteotomy were randomly assigned to receive a constant rate infusion of a combination of morphine, lidocaine, and ketamine; a lumbosacral epidural with morphine and ropivacaine; both treatments (ie, constant rate infusion and lumbosacral epidural); or only IM premedication with morphine. Indices of cardiorespiratory function and isoflurane requirement were recorded at 5-minute intervals during anesthesia. A validated sedation scoring system and the modified Glasgow composite measure pain score were used to assess comfort and sedation after surgery and anesthesia once the swallowing reflex returned and a body temperature of ≥ 36.7°C (98.1°F) was attained. Pain and sedation scores were acquired at 60-minute intervals for 4 hours, then at 4-hour intervals for 24 hours. Dogs with a postoperative pain score > 5 of 24 were given morphine as rescue analgesia.

RESULTS

No differences in heart rate, respiratory rate, systolic arterial blood pressure, end-tidal Pco2, end-tidal isoflurane concentration, and vaporizer setting were detected among groups. No differences in pain score, sedation score, rescue analgesia requirement, or time to first rescue analgesia after surgery were detected.

CONCLUSIONS AND CLINICAL RELEVANCE

Pain scores were similar among groups, and all 4 groups had similar rescue analgesia requirements and similar times to first administration of rescue analgesia. All 4 analgesic protocols provided acceptable analgesia for 24 hours after stifle joint surgery.

Evaluation of the isoflurane-sparing effects of fentanyl, lidocaine, ketamine, dexmedetomidine, or the combination lidocaine-ketamine-dexmedetomidine during ovariohysterectomy in dogs

OBJECTIVE

To evaluate the isoflurane-sparing effects of an intravenous (IV) constant rate infusion (CRI) of fentanyl, lidocaine, ketamine, dexmedetomidine, or lidocaine-ketamine-dexmedetomidine (LKD) in dogs undergoing ovariohysterectomy.

STUDY DESIGN

Randomized, prospective, blinded, clinical study.

ANIMALS

Fifty four dogs.

METHODS

Anesthesia was induced with propofol and maintained with isoflurane with one of the following IV treatments: butorphanol/saline (butorphanol 0.4 mg kg(-1), saline 0.9% CRI, CONTROL/BUT); fentanyl (5 μg kg(-1), 10 μg kg(-1) hour(-1), FENT); ketamine (1 mg kg(-1), 40 μg kg(-1) minute(-1), KET), lidocaine (2 mg kg(-1), 100 μg kg(-1) minute(-1), LIDO); dexmedetomidine (1 μg kg(-1), 3 μg kg(-1) hour(-1), DEX); or a LKD combination. Positive pressure ventilation maintained eucapnia. An anesthetist unaware of treatment and end-tidal isoflurane concentration (Fe'Iso) adjusted vaporizer settings to maintain surgical anesthetic depth. Cardiopulmonary variables and Fe'Iso concentrations were monitored. Data were analyzed using anova (p < 0.05).

RESULTS

At most time points, heart rate (HR) was lower in FENT than in other groups, except for DEX and LKD. Mean arterial blood pressure (MAP) was lower in FENT and CONTROL/BUT than in DEX. Overall mean ± SD Fe'Iso and % reduced isoflurane requirements were 1.01 ± 0.31/41.6% (range, 0.75 ± 0.31/56.6% to 1.12 ± 0.80/35.3%, FENT), 1.37 ± 0.19/20.8% (1.23 ± 0.14/28.9% to 1.51 ± 0.22/12.7%, KET), 1.34 ± 0.19/22.5% (1.24 ± 0.19/28.3% to 1.44 ± 0.21/16.8%, LIDO), 1.30 ± 0.28/24.8% (1.16 ± 0.18/32.9% to 1.43 ± 0.32/17.3%, DEX), 0.95 ± 0.19/54.9% (0.7 ± 0.16/59.5% to 1.12 ± 0.16/35.3%, LKD) and 1.73 ± 0.18/0.0% (1.64 ± 0.21 to 1.82 ± 0.14, CONTROL/BUT) during surgery. FENT and LKD significantly reduced Fe'Iso.

CONCLUSIONS AND CLINICAL RELEVANCE

At the doses administered, FENT and LKD had greater isoflurane-sparing effect than LIDO, KET or CONTROL/BUT, but not at all times. Low HR during FENT may limit improvement in MAP expected with reduced Fe'Iso.

Endogenous opiates and behavior: 2011

This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 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 (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).