EFFICACY OF TOLAZOLINE AND VATINOXAN IN REDUCING ADVERSE EFFECTS OF BUTORPHANOL-AZAPERONE-MEDETOMIDINE IMMOBILIZATION IN ROCKY MOUNTAIN ELK (CERVUS CANADENSIS).

A mixture of butorphanol, azaperone, and medetomidine (BAM) is frequently used for immobilization of North American hoofstock. Common adverse effects include respiratory depression, hypoxemia, and bradycardia. In this nonblinded crossover study the efficacy of two a-2 adrenergic antagonists, tolazoline and vatinoxan, were evaluated in alleviating adverse effects of BAM in Rocky Mountain elk (Cervus canadensis). Early administration of these antagonists was hypothesized to cause an increase in heart rate, respiratory rate, partial pressure of oxygen (PaO2) and hemoglobin oxygen saturation (SpO2), as well as reduction in mean arterial blood pressure without affecting sedation levels. Eight captive adult female elk were immobilized on three separate occasions at least 14 d apart with 0.15 mg/kg butorphanol, 0.05 mg/kg azaperone, and 0.06 mg/kg medetomidine. Tolazoline (2 mg/kg IM), vatinoxan (3 mg/mg medetomidine IV) or sterile saline (2 ml IM) were administered 20 min postinduction. The BAM caused hypoxemia, bradycardia, and moderate hypertension, and because of the severe hypoxemia observed, all animals received intratracheal oxygen throughout immobilization. Heart rate, respiratory rate, rectal temperature, SpO2, PaO2, and systolic, diastolic, and mean arterial blood pressure were monitored every 5 min throughout the immobilization. Intramuscular tolazoline caused a brief but significant drop in mean arterial pressure compared with controls and a brief but nonsignificant increase in heart rate. Vatinoxan caused a significant drop in blood pressure and a brief significant increase in heart rate. Changes in respiratory rates and PaO2 were not observed with either antagonist; however, all animals received oxygen, which may have influenced this result. The depth of sedation was unchanged after administration of either drug.

Effect of butorphanol-soaked nasal packing after endoscopic nasal surgery: a double-blind, randomized, placebo-controlled trial.

OBJECTIVE: This study was designed to investigate the effect of butorphanol-soaked nasal packing on analgesia and sleep quality in patients undergoing bilateral endoscopic nasal surgery. METHODS: Sixty-six patients were enrolled and randomly allocated into three groups: group B1 (butorphanol 0.03mg/kg), group B2 (butorphanol 0.04mg/kg) and group N (control group). The primary outcome was postoperative pain scores evaluated by a Visual Analogue Scale (VAS) at 2h (T1), 8h (T2), 24h (T3) and 48h (T4) after surgery. Secondary outcome was postoperative sleep quality measured using Subjective Sleep Quality Value (SSQV). RESULTS: Postoperative VAS scores of butorphanol groups were significantly lower than the control group at T2, T3 and T4. VAS scores at each time point did not differ between groups B1 and B2. On the first and second nights after surgery, SSQV was higher in butorphanol groups than in the control group. There were no significant differences in SSQV1 and SSQV2 between group B1 and group B2. The incidence of respiratory depression, dizziness, agitation and rescue analgesic use did not show difference among three groups. CONCLUSIONS: Butorphanol-soaked nasal packing can reduce pain and improve sleep quality after bilateral endoscopic nasal surgery without increasing adverse effects. A concentration of 0.03mg/kg may be appropriate for clinical application. LEVEL OF EVIDENCE: Level 1B.

The effects of fentanyl, oxycodone, and butorphanol on gastrointestinal function in patients undergoing laparoscopic hysterectomy: a prospective, double-blind, randomized controlled trial.

BACKGROUND: Perioperative opioid use is associated with postoperative bowel dysfunction, which causes longer hospital stay and higher healthcare costs. This study aimed to investigate the effect of the equivalent doses of fentanyl, oxycodone, and butorphanol on bowel function in patients undergoing laparoscopic hysterectomy. METHODS: In this randomized controlled trial, 135 patients undergoing laparoscopic hysterectomy received postoperative intravenous patient-controlled analgesia (IV-PCA) with fentanyl 8.3 µg/kg, butorphanol 0.16 mg/kg, and oxycodone 0.5 mg/kg (1: 20: 60), respectively. The primary outcome measure was the recovery of bowel function. We also evaluated and recorded the following nine indicators: pain score, sedation level, leukocyte count, percentage of neutrophils, plasma potassium levels, time to first ambulation, postoperative side effects, patients' satisfaction, and postoperative hospital length of stay. RESULTS: The mean time to flatus was significantly prolonged in Group B (45.2 ± 11.6 h) compared with Group F (33.1 ± 11.2 h, P < 0.001) and Group O (36.2 ± 10.9 h, P = 0.001). The incidence of somnolence and dizziness prove higher in Group B (P < 0.001). No statistical difference was observed in the mean time to tolerate oral diet, time to defecation, analgesic outcome, satisfaction score, time to first ambulation, and postoperative hospital length of stay. CONCLUSIONS: Compared with fentanyl and oxycodone, butorphanol prolonged the recovery of bowel function with more severe somnolence and dizziness, suggesting that butorphanol is not well suitable for IV-PCA in patients undergoing laparoscopic hysterectomy. TRIAL REGISTRATION: ClinicalTrials.gov- NCT04295109 . Date of registration: March, 2020.

Use of Butorphanol as Treatment for Cholestatic Itch.

BACKGROUND: Pruritus is a debilitating symptom of cholestatic diseases such as primary biliary cholangitis and primary sclerosing cholangitis and often results in major reduction in quality of life for afflicted patients. Classic treatment options for the treatment of cholestatic pruritus include antihistamines, bile acid resins, serotonin reuptake inhibitors, and mu-opioid antagonists. Unfortunately, these drugs are not always successful in treating pruritus of cholestasis and may be associated with adverse effects. Recent advances in our understanding of itch pathophysiology have led to the use of butorphanol, a kappa-opioid agonist and mu-opioid antagonist, for the treatment of various forms of pruritus. Reports of butorphanol to treat cholestatic itch specifically are rare. AIMS: To better understand the role of butorphanol in the treatment of cholestatic pruritus, including characterization of its side effect profile. METHODS: We present a case series of eight adult patients with cholestatic disease who were treated with butorphanol in hopes of alleviating intractable pruritus. Patients were identified through a clinical data request form serviced by University of Miami Information Technology. RESULTS: Five out of eight patients (62.5%) reported successful reductions in itch severity after treatment with butorphanol, two patients reported no (or transient) change in itch severity, and one patient reported a paradoxical increase in itching. Side effects included somnolence, sedation, nausea, vomiting, and dizziness. CONCLUSIONS: Butorphanol was safe and leads to clinically significant symptomatic improvement. Clinicians should be aware of butorphanol as an off-label treatment option for pruritus of cholestasis. Further studies are needed to better characterize the effect of butorphanol on cholestatic itch.

Cats undergoing spay with medetomidine, ketamine and butorphanol develop arterial oxygen desaturation independent of surgical positioning and increased intraocular pressure in Trendelenburg position.

INTRODUCTION: This study observed the effects of three different surgical positions on arterial blood oxygenation measured noninvasively by pulse oximetry (SpO2) and on intraocular pressure (IOP) in anaesthetised cats undergoing spay. A total of 222 female feral cats were anaesthetised for a large-scale trap-neuter-return program with an intramuscular combination of medetomidine (0.03 - 0.05 mg/kg), ketamine (7 - 10 mg/kg) and butorphanol (0.4 mg/kg). Cats were randomly allocated to undergo spay in either Trendelenburg (70° downward head tilt), lateral or dorsal recumbency. SpO2 and pulse rate were measured at baseline, prior to surgical positioning, after one minute in surgical position and in one-minute intervals after surgical incision. Intraocular pressure was measured before positioning and at the end of surgery. At the end of surgery, all cats were placed into left lateral recumbency and all parameters were revaluated after five minutes. No significant differences between the three positions were found regarding SpO2, but an increase over time was observed. In total, 52 ± 10% (mean ± SD) of cats were hypoxaemic (SpO2 < 90%) at baseline. SpO2 improved over time, but 27 ± 3% (mean ± SD) of the cats remained hypoxaemic at the end of surgery. Trendelenburg position increased IOP during surgery (mean 31 ± 6 mmHg, individual max. 48 mmHg, versus 17 ± 4 mmHg in dorsal/lateral recumbency) but normalised after 5 mins in lateral recumbence. All cats recovered well from surgery and were released within 24 hours post-anaesthesia. Surgical position was shown to have no notable influence on SpO2 during anaesthesia in cats not receiving oxygen supplementation, whereas Trendelenburg position led to increased IOP. Oxygen supplementation is recommended with this anaesthetic protocol, as hypoxaemia is frequently observed.

INTRODUCTION: Dans cette étude, on a observé les effets de trois positions chirurgicales différentes sur l'oxygénation du sang artériel mesurée de manière non invasive par oxymétrie de pouls (SpO2) et sur la pression intraoculaire (PIO) chez des chattes anesthésiées subissant une stérilisation. Un total de 222 chattes sauvages ont été, dans le cadre d'un large programme de piégeage-castration-libération, anesthésiées avec une combinaison de médétomidine (0,03 à 0,05 mg/kg), de kétamine (7 à 10 mg/kg) et de butorphanol (0,4 mg/kg) par voie intramusculaire. Les chattes ont été réparties au hasard pour subir une stérilisation en Trendelenburg (inclinaison de la tête à 70 ° vers le bas), en décubitus latéral ou dorsal. La SpO2 et la fréquence du pouls ont été mesurées au départ, avant le positionnement chirurgical, après une minute en position chirurgicale et à des intervalles d'une minute après l'incision chirurgicale. La pression intraoculaire a été mesurée avant le positionnement et à la fin de la chirurgie. À la fin de la chirurgie, toutes les chattes ont été placées en décubitus latéral gauche et tous les paramètres ont été réévalués après cinq minutes. Aucune différence significative entre les trois positions n'a été constatée concernant la SpO2, mais une augmentation au fil du temps a été observée. Au total, 52 ± 10% (moyenne ± SD) des chattes étaient hypoxémiques (SpO2.

EVALUATION OF TWO ANESTHETIC COMBINATIONS IN LOWLAND NYALA (TRAGELAPHUS ANGASII).

Fourteen lowland nyala (Tragelaphus angasii) in managed care were successfully anesthetized for a total of 17 anesthetic events using either a combination of butorphanol (0.75 ± 0.15 mg/kg), azaperone (0.25 ± 0.05 mg/kg), and medetomidine (0.30 ± 0.06 mg/kg) (BAM) or medetomidine (0.17 ± 0.01 mg/kg), azaperone (0.22 ± 0.02 mg/kg), and alfaxalone (0.52 ± 0.08 mg/kg) (MAA) delivered intramuscularly via dart. Mean time to initial effect, sternal recumbency, lateral recumbency, handling, and intubation were recorded. The nyala were maintained in sternal recumbency with supplemental oxygenation until 60 min after initial injection. Cardiopulmonary effects were recorded every 5 min after handling until reversal. Arterial blood samples were collected every 15 min for analysis. Level of sedation and quality of recovery were scored. Anesthesia was antagonized with atipamezole (at 5 mg per mg of medetomidine) for both protocols and naltrexone (at 2 mg per mg of butorphanol) for the BAM protocol delivered intramuscularly via hand injection. Mean time to extubation, head control, and standing post reversal were recorded. No hyperthermia, acidemia, apnea, or tachycardia occurred; however, animals did display hypoxemia. Two animals in the BAM cohort required supplementation to facilitate handling. These drug combinations provided satisfactory levels of sedation in most cases for safe handling and minor procedures in lowland nyala under managed care.

Anesthetic efficacy of propofol combined butorphanol in laparoscopic surgery for ectopic pregnancy: A protocol of systematic review and meta-analysis.

BACKGROUND: Recent studies have suggested that propofol combined butorphanol (PB) has anesthetic effect in laparoscopic surgery (LS) for ectopic pregnancy (EP). But investigations of its potential effects are inconsistent. We will explore the current literature examining PB in LS for EP. METHODS: We will perform a comprehensive search from MEDLINE, Embase, Cochrane Library, PsycINFO, Global Health, Web of Science, Allied and Complementary Medicine Database, and China National Knowledge Infrastructure from inception to the present. Other literatures, such as conference abstracts, references to the relevant reviews will also be checked. Two authors will check the titles, abstracts, and full texts independently. They will also independently carry out data collection and study quality assessment. We will conduct statistical analysis using RevMan 5.3 software. RESULTS: This study will provide accurate results on the anesthetic effect and safety of PB in LS for EP. CONCLUSION: This study will establish high-quality evidence of the anesthetic effect and safety of PB in LS for EP to facilitate the clinical practice and guideline development. STUDY REGISTRATION NUMBER: INPLASY202040044.

ASPIRATION PNEUMONIA IN TWO TIBETAN YAK BULLS ( BOS GRUNNIENS) AS A COMPLICATION OF KETAMINE-XYLAZINE-BUTORPHANOL ANESTHESIA FOR RECUMBENT CASTRATION.

Among members of the genus Bos, aspiration pneumonia has been described in domestic cattle ( Bos taurus and Bos indicus). In these species, aspiration pneumonia is most commonly a sequelae to oral administration of fluids or medications, as well as aspiration during procedures under anesthesia. Management of aspiration pneumonia secondary to complications from anesthesia for short duration surgical procedures is minimally reported in the Tibetan yak ( Bos grunniens). Although regurgitation under anesthesia has been reported in the yak, there are no reports of aspiration pneumonia treatment. This case report describes the diagnosis and management of aspiration pneumonia in two Tibetan yaks undergoing castration under injectable ketamine-xylazine-butorphanol anesthesia. This case report also describes the gross and pathologic characteristics of anesthesia-induced aspiration pneumonia in one Tibetan yak, as well as successful treatment in another.

Pharmacological properties of various anesthetic protocols in 10-day-old neonatal rats.

In general, the anesthesia in neonates involves high risk. Although hypothermic anesthesia is recommended in rats up to the age of 7 days, neonatal anesthesia for later periods has not been standardized. The present study investigated the pharmacological properties of conventional anesthetic protocols in 10-day-old SD rats. The rats were anesthetized with four anesthetics: a combination of ketamine and xylazine (K/X); a combination of medetomidine, midazolam, and butorphanol (M/M/B); isoflurane; and sevoflurane. Anesthetic depth was scored by reflex response to noxious stimuli. Induction and recovery times were recorded. Vital signs and mortality rate were evaluated for safety assessment. All rats died after administration of K/X at a dose of 60/6 mg/kg, whereas K/X at 40/4 mg/kg resulted in insufficient anesthetic depth, indicating inappropriate for neonatal anesthesia. Although M/M/B at the adult rat dose (0.15/2/2.5 mg/kg) did not provide surgical anesthetic depth, the mouse dose (0.3/4/5 mg/kg) showed sufficient anesthetic depth with relatively stable vital signs. Isoflurane required a long induction period, and caused remarkable respiratory depression and hypothermia, resulted in a 25% mortality rate. In contrast, sevoflurane provided consistent surgical anesthetic depth with rapid induction. Although respiratory rate decrease was markedly observed, all rats survived. Among the anesthetic protocols investigated in the present study, sevoflurane and M/M/B at the mouse dose were recommended for the neonatal anesthesia. Compared with adult rats, the required dose of both anesthetics in neonates was higher, possibly associated with their lower anesthetic sensitivity.

CARDIORESPIRATORY EFFECTS OF DEXMEDETOMIDINE-BUTORPHANOL-MIDAZOLAM (DBM): A FULLY REVERSIBLE ANESTHETIC PROTOCOL IN CAPTIVE AND SEMI-FREE-RANGING CHEETAHS (ACINONYX JUBATUS).

Multiple anesthesia protocols have been used in the cheetah ( Acinonyx jubatus ). Twenty healthy, captive cheetahs were immobilized with dexmedetomidine (15.8 ± 1.9 µg/kg), butorphanol (0.22 ± 0.03 mg/kg), and midazolam (0.18 ± 0.03 mg/kg) by intramuscular injection. Induction, recumbency, and recovery times were recorded, and physiologic parameters were monitored. Anesthesia was antagonized with atipamezole (0.125 ± 0.02 mg/kg) and naltrexone (0.1 ± 0.014 mg/kg) intramuscularly. All cheetahs were safely anesthetized with this protocol. Cheetahs were laterally recumbent by 8 ± 3.5 min. Cardiorespiratory values were stable throughout the length of anesthesia. Moderate hypertension, with systolic blood pressure ranging from 178 ± 19.8 mm Hg, was initially observed but decreased over time. There was a statistical decreasing trend in temperature; SpO2; and systolic, mean, and diastolic blood pressure, but not in heart rate and end-tidal CO2. Recoveries were rapid, with cheetahs standing by 11.3 ± 5.7 min postreversal administration. This is the first report of a dexmedetomidine-butorphanol-midazolam anesthetic combination in cheetahs. Overall, this anesthetic protocol proved to be safe and effective.

Combining isoflurane anesthesia with midazolam and butorphanol in rats.

Representative inhalant anesthetic agent, isoflurane is commonly used during surgery in rats. However, isoflurane mediates relatively strong respiratory depression. In human and veterinary medicine, sedatives and analgesics are co-administered to complement the anesthetic action of inhalant anesthesia. The present study aimed to establish the novel balanced anesthesia that combines midazolam and butorphanol with isoflurane (MBI) in rats. Male Sprague Dawley rats were divided into 2 groups, and administered either isoflurane monoanesthesia or isoflurane with midazolam (2.5 mg/kg, ip) and butorphanol (2.0 mg/kg, ip). The minimum alveolar concentration (MAC) in each group was evaluated. Induction and recovery times were measured in each group. Adverse reactions during induction were also recorded. In each group, vital signs were assessed for 1 h under 1.5×MAC of isoflurane. Instability of vital signs was assessed under each anesthesia by calculating coefficient of variance. Compared with isoflurane monoanesthesia, MBI anesthesia caused 32% MAC reduction (isoflurane monoanesthesia: 1.30 ± 0.09%, MBI 0.87 ± 0.08%, P<0.05). MB premedication mediated smooth sedating action with low incidence of adverse reactions such as urination and defecation. Isoflurane monoanesthsesia remarkably decreased respiratory rate and saturation O2 (SPO2). In contrast, MBI anesthesia resulted in a relatively stable respiratory rate without decreases in SPO2 during the anesthetic period. In summary, MB premedication is effective for attenuating respiratory depression induced by isoflurane, and achieving smooth induction. This anesthetic protocol serves as a novel option for appropriate anesthesia in rats.

Alfaxalone-butorphanol versus alfaxalone-morphine combination for immersion anaesthesia in oriental fire-bellied toads (Bombina orientalis).

Oriental fire-bellied toads (Bombina orientalis) are small semi-aquatic anuran species popular as both pets and laboratory animals. Although they are commonly anaesthetized to undergo clinical and experimental procedures, very little is known about their anaesthetic management. The aims of this prospective, randomized, cross-over experimental trial were to establish effective butorphanol and morphine concentrations to be added to alfaxalone for immersion anaesthesia (pilot study), and to compare the anaesthetic and antinociceptive effects of the two drug mixtures (alfaxalone-butorphanol and alfaxalone-morphine), in Bombina orientalis toads. For the actual trial, the toads were randomly assigned to one of two treatment groups: AB and AM, with seven animals in each group, which received alfaxalone-butorphanol and alfaxalone-morphine combinations, respectively, at the concentrations established during the pilot study. Heart rate, respiratory rate, von Frey filament threshold and response to nociceptive withdrawal (NWR), righting and myotactic reflexes were measured at 5 min intervals until return of righting reflex was observed. The investigator who carried out all the measurements was blinded to the treatment. Any undesired effect or complication was noted and recorded. The two treatments were found to be comparable in terms of onset and duration of anaesthesia, and occurrence of undesired effects. However, group AM resulted in lower NWR scores and higher von Frey filament thresholds than group AB. It is concluded that, at the investigated concentrations and in combination with alfaxalone by immersion, morphine provides better antinociception than butorphanol in oriental fire-bellied toads.

Contamination of multidose butorphanol vials in small animal general practices.

OBJECTIVES: To assess and quantify medetomidine contamination of butorphanol multidose vials in small animal general practices and determine if practice policies and procedures regarding drug handling, as determined by questionnaire, impact upon contamination level. METHODS: Samples of butorphanol were withdrawn from in-use vials in participating practices in June and July 2013. Samples were analysed using high-performance liquid chromatography and mass spectrometry. RESULTS: Forty-one samples were obtained from 31 practices. Contamination was detected in 29 samples from 10 mL vials. The mean (αsd) contamination was 0 · 275 (α0 · 393) µg/mL; maximum contamination in any vial was 2 · 034 µg/mL. There was no correlation between volume of the vial used and the level of contamination. None of the survey factors predicted contamination levels of the vials. CLINICAL SIGNIFICANCE: Contamination of butorphanol multidose vials with medetomidine was common but the level of contamination was insufficient to cause detrimental effects in dogs if butorphanol were to be administered alone. The potential for sporadic higher levels of contamination must be taken into account, especially when using 50 mL vials when sedating critically ill cases, because there is a risk of clinical side effects.

Effects of intravenous analgesia with combined dezocine and butorphanol on postoperative cognitive function in elderly patients.

The aim of this study was to observe the analgesic effects of the combination of dezocine and butorphanol on postoperative cognitive function in elderly patients. Forty elderly patients undergoing upper abdominal surgeries or thoracotomies with general anesthesia were randomly divided into the dezocine and butorphanol group or the butorphanol group (20 patients per group). A visual analog scale was used to evaluate analgesia and the degree of malignant vomiting. The Ramsay scoring method was used to evaluate sedation. The Mini-Mental State Examination (MMSE) was used to evaluate cognitive function. Forty-eight hours after the operation, the pain score of the dezocine and butorphanol group (means ± SD, 1.75 ± 0.44) was lower than that of the butorphanol group (2.25 ± 0.79; P < 0.05), and the nausea and vomiting score of the dezocine and butorphanol group (0) was lower than that of the butorphanol group (0.70 ± 1.30; P < 0.05). Six hours after the operation, the sedative score of the butorphanol group (3.75 ± 0.79) was higher than that of the dezocine and butorphanol group (2.15 ± 0.75; P < 0.05). Compared to 1 day before the operation, the MMSE scores of both groups decreased 6 h after the operation, and the MMSE score of the butorphanol group (15.00 ± 2.00) was lower than that of the dezocine and butorphanol group (20.95 ± 1.54; P < 0.05). Dezocine and butorphanol analgesia had transient effects on postoperative cognitive function in elderly patients, and the effect of the combination was superior than butorphanol only.

Comparison of epidural butorphanol versus epidural morphine in postoperative pain relief.

INTRODUCTION: Epidural route is preferable for postoperative pain relief in thoraco-abdominal and lower limb surgeries. We aimed to compare epidural butorphanol versus morphine for postoperative analgesia up to 24 hours in open nephrectomy surgery. METHODS: 80 ASA physical status I and II adult patients were selected for this randomized double blind prospective study. A standard balanced general anesthesia technique was applied for all patients. Epidural catheter was placed in lower thoracic inter-vertebral space before the start of surgery. Injection butorphanol 0.04 mg/kg in group B (n = 40) or morphine 0.06 mg/kg in group M (n = 40) was given in a double blind manner after completion of surgery and before extubation through the epidural catheter. Patients were observed for pain relief by Visual Analogue Scale (VAS) for the next 24 hours. Dose was repeated when VAS was > 4. The onset and peak effect of pain relief, duration of analgesia of 1st dose, frequency of drug administration and side effects if any were observed. RESULTS: The average onset of analgesia was 26.5 +/- 7.61 minutes with butorphanol and 62.5 +/- 13.4 minutes with morphine group which was statistically significant (p < 0.05). The mean peak effect of pain relief following 1st dose was 173 +/- 51.25 minutes with butorphanol and 251 +/- 52.32 minutes with morphine group. The duration of pain relief after 1st dose was statistically significant and was 339.13 +/- 79.57 minutes in group B and 709.75 +/- 72.12 minutes in group M which was gradually increased on repeated dosing in group B while it was almost same in Group M. Number of doses required in 24 hours was significantly higher (p < 0.05) in butorphanol group than morphine group. Somnolence was the main side effect in group B while pruritus was the main side effect with group M. CONCLUSION: Epidural butorphanol appears to provide safer and faster postoperative analgesia without much untoward effects but its analgesic action is short so more repeated doses are required than morphine via epidural catheter up to 24 hours.

Comparative analgesic efficacy of morphine sulfate and butorphanol tartrate in koi (Cyprinus carpio) undergoing unilateral gonadectomy.

OBJECTIVE: To identify pain-related behaviors and assess the effects of butorphanol tartrate and morphine sulfate in koi (Cyprinus carpio) undergoing unilateral gonadectomy. Design-Prospective study. ANIMALS: 90 adult male and female koi. PROCEDURES: Each fish received saline (0.9% NaCl) solution (which is physiologically compatible with fish) IM, butorphanol (10 mg/kg [4.5 mg/lb], IM), or morphine (5 mg/kg [2.3 mg/lb], IM) as an injection only (6 fish/treatment); an injection with anesthesia and surgery (12 fish/treatment); or an injection with anesthesia but without surgery (12 fish/treatment). Physiologic and behavioral data were recorded 12 hours before and at intervals after treatment. RESULTS: Compared with baseline values, the saline solution-surgery group had significantly decreased respiratory rates (at 12 to 24 hours), food consumption assessed as a percentage of floating pellets consumed (at 0 to 36 hours), and activity score (at 0 to 48 hours). Respiratory rate decreased in all butorphanol-treated fish; significant decreases were detected at fewer time points following morphine administration. In the butorphanol-surgery group, the value for food consumption initially decreased but returned to baseline values within 3 hours after treatment; food consumption did not change in the morphine-surgery group. Surgery resulted in decreased activity, regardless of treatment, with the most pronounced effect in the saline solution-surgery group. Changes in location in water column, interactive behavior, and hiding behavior were not significantly different among groups. Butorphanol and morphine administration was associated with temporary buoyancy problems and temporary bouts of excessive activity, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Butorphanol and morphine appeared to have an analgesic effect in koi, but morphine administration caused fewer deleterious adverse effects. Food consumption appeared to be a reliable indicator of pain in koi.