Pharmacokinetics of intra‐articular morphine in horses with lipopolysaccharide‐induced synovitis

ObjectiveTo describe the pharmacokinetics of intra-articularly (IA) administered morphine.Study designExperimental randomized, cross-over study.AnimalsEight adult healthy mixed breed horses aged 6.5 ± 2.3 (mean ± SD) years and weighing 535 ± 86 kg.MethodsUnilateral radiocarpal synovitis was induced by IA injection of 3 μg lipopolysaccharide (LPS) on two occasions (right and left radiocarpal joint, respectively) separated by a 3-week wash-out period. Treatments were administered 4 hours post-LPS-injection: Treatment IA; preservative free morphine IA (0.05 mg kg^?1) plus saline intravenous (IV) and treatment IV; saline IA plus preservative free morphine IV (0.05 mg kg^?1). Concentrations of morphine, morphine-3-glucuronide and morphine-6-glucuronide (M6G) were determined repeatedly in serum and synovial fluid (SF) by high-performance liquid chromatography mass spectrometry, at 2 and 4 hours and then at 4 hours intervals until 28 hours post-treatment.ResultsInjection of LPS elicited a marked and comparable synovitis in all LPS-injected radiocarpal joints. IA administered morphine was detectable in SF of all eight joints 24 hours post-treatment and in 6/8 joints 28 hours post-treatment. The terminal half-life of morphine in SF was estimated to be 2.6 hours. IA administration of morphine resulted in mean serum concentrations of morphine below 5 ng mL^?1 from 2 to 28 hours after treatment.Conclusions and clinical relevanceIntra-articularly administered morphine remained within the joint for at least 24 hours. At the same time only very low serum concentrations of morphine and M6G were detected. The present results suggest that IA morphine at 0.05 mg kg^?1 may be used for IA analgesia lasting at least 24 hours and give strong support to the theory that previously observed analgesic and anti-inflammatory effects of IA morphine in horses are most likely to be mediated peripherally.     

Analgesic efficacy of intra‐articular morphine in experimentally induced radiocarpal synovitis in horses

ObjectiveTo compare the analgesic effect of intra-articular (IA) and intravenous (IV) morphine in horses with experimentally induced synovitis.AnimalsEight adult horses.Study designRandomized, observer blinded, double dummy trial with sequential crossover design.MethodsRadiocarpal synovitis was induced by IA injection of lipopolysaccharide on two occasions separated by a 3-week washout period. In one study period horses received treatment IA; morphine IA (0.05 mg kg^?1) plus saline IV and in the other study period they received treatment IV; saline IA plus morphine IV (0.05 mg kg^?1). Lameness and pain were evaluated repeatedly by two observers throughout each of the two 168-hour study periods. Pain was evaluated by use of a visual analogue scale of pain intensity (VAS) and a composite measure pain scale (CMPS). Comparison of treatments was performed by analysis of variance with repeated measurements. Significance level was set to p ≤ 0.05. Inter-observer agreement and agreement between the VAS and CMPS was assessed by use of the Bland–Altman method.ResultsIntra-articular injection of LPS elicited a marked synovitis resulting in lameness and pain. IA morphine resulted in significantly less lameness than IV morphine (p = 0.03). CMPS (p = 0.09) and VAS (p = 0.10) pain scores did not differ significantly between treatments. Inter-observer agreement of the CMPS was classified as good, but only fair for the VAS. Agreement between the two pain scales was considered fair.Conclusions and clinical relevanceAn analgesic effect of IA morphine was demonstrated by significantly reduced lameness scores. The results support the common practice of including IA morphine in a multimodal analgesic protocol after arthroscopic surgery, although further studies in clinical cases are needed. The employed CMPS had good reproducibility, and was easy to use, but may have limited sensitivity at mild intensity pain.     

Analgesic and gastrointestinal effects of epidural morphine in horses after laparoscopic cryptorchidectomy under general anesthesia

ObjectiveTo evaluate the hypothesis that epidural morphine (0.1 mg kg^?1) decreases pain in horses after laparoscopic surgery without adversely affecting gastrointestinal (GI) motility.Study designRandomized clinical trial.AnimalsEighteen horses undergoing laparoscopic cryptorchidectomy under general anesthesia.MethodsHorses were randomly assigned to receive either epidural morphine (0.1 mg kg^?1) or no epidural before the start of surgery. Pain behaviors were assessed during the first two post-operative days using a numerical rating scale. Barium-filled spheres were administered through a nasogastric tube before anesthesia. GI motility was assessed by recording manure production, by quantitating the spheres in the manure, and by abdominal auscultation of intestinal sounds. Heart rates and cortisol concentrations were also measured during the post-operative period.ResultsPain scores increased for 12 hours after surgery in the control group and were significantly higher than in the morphine group for the first 6 hours. Pain scores remained unaltered in the morphine group throughout the observation period. Heart rate and plasma cortisol concentrations did not differ between groups or with time. No signs of colic were observed in any horse.Conclusion and clinical relevanceEpidural morphine (0.1 mg kg^?1) did not adversely affect GI motility in horses after laparoscopic surgery under general anesthesia.     

Effects of peri-operative morphine administration during halothane anaesthesia in horses

OBJECTIVE: To study the effects of morphine on haemodynamic variables, blood gas values and the requirement for additional anaesthetic drugs in horses undergoing surgery. STUDY DESIGN: Prospective randomized study. METHODS: Thirty-eight client-owned horses, ASA(American Society of Anesthesiologists) category I or II, undergoing elective surgical procedures, were studied. Horses were divided between two groups, and were paired according to operation, anaesthetist, body position during surgery, mass and breed. Group M+ received morphine by intravenous (IV) injection (0.15 mg kg(-1)) before induction of anaesthesia and then by infusion (0.1 mg kg(-1) hour(-1)) throughout anaesthesia. Group M- received the same anaesthetic technique (pre-anaesthetic medication with romifidine (100 microg kg(-1)) IV; induction with ketamine (2.2 mg kg(-1)) and diazepam (50 microg kg(-1)) IV; maintenance with halothane), except that morphine was excluded. Both groups received flunixin IV (1.1 mg kg(-1)) before surgery. Both groups also received 50% nitrous oxide for the first 10 minutes of anaesthesia. During anaesthesia, end-tidal halothane was maintained at 0.9% (+/-0.1%) in both groups. Heart rate (HR) and respiratory rate (fr), systolic, mean and diastolic arterial pressures were recorded every 5 minutes. Arterial blood samples were analysed every 20 minutes. Additional anaesthetics (ketamine and midazolam) were administered whenever the horse moved. Dobutamine was infused to maintain mean arterial pressure (MAP) > 58 mm Hg, but was discontinued when MAP reached 68 mm Hg. Mechanical ventilation was imposed when PaCO(2) exceeded 9.3 kPa (70 mm Hg). RESULTS: Haemodynamic data (HR and MAP) and blood gas measurements were analysed using repeated measure analysis using a mixed covariance pattern model (SAS version 8.2). A Student's t-test was used to investigate differences between groups in the doses of additional anaesthetics required. There were no significant differences between M+ or M- groups in MAP (p = 0.65), HR (p = 0.74), PaO2 (p = 0.40) or PaCO2 (p = 0.20). Fewer horses in the M+ group received additional anaesthetics (15.8% compared to 21.1% in M- group), and the mean dose of ketamine required was higher in the M- group (mean +/- SD: M-, 0.93 +/- 0.70; M+, 0.45 +/- 0.17). These differences were not statistically significant (p = 0.28). CONCLUSIONS: Pre-anaesthetic and peri-operative morphine administration is not associated with significant haemodynamic or ventilatory changes. Horses receiving morphine tended to receive fewer and lower doses of additional anaesthetic drugs, although this was not statistically significant.     

A comparison of epidural buprenorphine plus detomidine with morphine plus detomidine in horses undergoing bilateral stifle arthroscopy

ObjectiveTo compare the analgesic efficacy of buprenorphine plus detomidine with that of morphine plus detomidine when administered epidurally in horses undergoing bilateral stifle arthroscopy.Study designProspective, randomized, blinded clinical trial.AnimalsTwelve healthy adult horses participating in an orthopedic research study. Group M (n = 6) received morphine (0.2 mg kg^?1) and detomidine (0.15 mg kg^?1) epidurally; group B (n = 6) received buprenorphine (0.005 mg kg^?1) and detomidine (0.15 mg kg^?1) epidurally.MethodsHorses received one of two epidural treatments following induction of general anesthesia for bilateral stifle arthroscopy. Heart rate (HR), mean arterial blood pressure (MAP), end-tidal CO₂ (Pe’CO₂), and end-tidal isoflurane concentrations (E’Iso%) were recorded every 15 minutes following epidural administration. Post-operative assessment was performed at 1, 2, 3, 6, 9, 12, and 24 hours after standing; variables recorded included HR, respiratory rate (f_R), abdominal borborygmi, defecation, and the presence of undesirable side effects. At the same times post-operatively, each horse was videotaped at a walk and subsequently assigned a lameness score (0-4) by three ACVS diplomates blinded to treatment and who followed previously published guidelines. Nonparametric data were analyzed using Wilcoxon’s rank-sum test. Inter- and intra-rater agreement were determined using weighted kappa coefficients. Statistical significance was set at p = 0.05.ResultsNo statistically significant differences were found between groups with respect to intra-operative HR, MAP, E’Iso%, or post-operative HR, gastrointestinal function and cumulative median lameness scores. Post-operative f_R in group B [24 (12-30), median (range)] breaths per minute was significantly higher than in group M [18 (15-20)] breaths per minute, p = 0.04.Conclusions and clinical relevanceIn horses undergoing bilateral stifle arthroscopy, these doses of buprenorphine plus detomidine injected epidurally produced analgesia similar in intensity and duration to that of morphine plus detomidine injected epidurally.     

Comparison of cervical epidural morphine with intravenous morphine administration on antinociception in adult horses using thermal threshold testing

ObjectiveTo compare the antinociceptive effects of morphine administered via cervical epidural catheter to intravenously administered morphine using a thermal threshold (TT) testing model in healthy adult horses.Study designProspective, randomized, blinded experimental study.AnimalsA total of six university-owned adult horses.MethodsHorses were instrumented with a cervical (C1–C2) epidural catheter and TT testing device with probes at withers and thoracic limb coronary bands. All horses underwent three TT testing cycles including cervical epidural morphine administration (treatment EpiM; 0.1 mg kg^–1), systemic morphine administration (treatment SystM; 0.1 mg kg^–1) and no morphine administration (treatment Control). Baseline TT was established prior to treatments, and TT was tested at 15, 30, 60, 90, 120, 150, 180, 240, 300, 360, 420, 480, 600 and 720 minutes following treatment. Horses underwent a 5 day washout period between treatments and the order of treatment was randomized. Differences between treatments were analyzed with repeated measures anova.ResultsSystemic and epidural morphine administration resulted in significantly higher TT values compared with baseline and control treatment. The duration of effect was significantly longer in treatment EpiM (10–12 hours) than in treatment SystM (1.5–2.0 hours). Horses in treatment EpiM had significantly higher TT values at time points 180–600 minutes (withers) and 300–600 minutes (coronary band) than horses in treatment SystM.Conclusions and clinical relevanceCervical epidural administration of morphine provided antinociceptive effects as measured by increased TT for 10–12 hours compared with 1.5–2.0 hours for intravenously administered morphine. No complications or adverse effects were noticed following epidural placement of a C1–C2 catheter and administration of morphine. The use of a cervical epidural catheter can be considered for analgesia administration in treatment of thoracic limb and cervical pain in the horse.     

The effects of morphine on the recovery of horses from halothane anaesthesia

OBJECTIVE: To investigate the effects of peri-operative morphine on the quality and duration of recovery from halothane anaesthesia in horses. STUDY DESIGN: Prospective randomized study. ANIMALS: Twenty-two client owned horses, ASA category I or II. METHODS: Horses undergoing elective surgical procedures were divided into two groups and paired according to procedure, body position during surgery, body mass and breed. Group M+ received morphine by intravenous injection (0.15 mg kg(-1)) before induction of anaesthesia and then by infusion (0.1 mg kg(-1) hour(-1)) during anaesthesia. Group M- received the same anaesthetic agents except that morphine was excluded. At the end of surgery, the horses were placed in a recovery box and allowed to recover without assistance. Recoveries were recorded on videotape, beginning when the anaesthetist left the recovery box, and ending when the horse stood up. Recoveries were assessed from digital video recordings by three observers, unaware of treatment. The time to first movement, attempting and attaining sternal recumbency and standing were recorded. The quality of various aspects of the recovery was assessed to produce a total recovery score; high numerical values indicate poor recoveries. The duration of anaesthesia and the total dose of morphine administered were recorded. RESULTS: The mean morphine dose (95% CI) was 147 (135-160) mg [equivalent to 0.27 (0.25-0.29) mg kg(-1)]. The recovery scores (median, 95% CI) for the M- and M+ groups were 25, 19-41 and 20, 14-26, respectively. Total score increased as duration of anaesthesia increased, independent of treatment. Untreated (M-) horses made more attempts to achieve sternal recumbency: mean number of attempts (95% CI) for M- was 4.5 (2.7-6.2) compared with 2.0 (1.4-2.6) (M+). Untreated horses made more attempts to stand (2.1, 1.6-2.6) compared with the morphine recipients (1.3, 1.1-1.5). Time to standing (in minutes) was significantly (p = 0.0146) longer for the untreated (31.3, 24.3-38.3) compared with treated animals (26.6, 20.9-32.3). The interval between the first movement in recovery to the time at standing was significantly (p < 0.001) longer for M- (14.5, 12.1-16.9 minutes) compared with M+ animals (7.4, 5.0-9.8 minutes). CONCLUSIONS AND CLINICAL RELEVANCE: Recoveries from anaesthesia in the morphine recipients were characterized by fewer attempts to attain sternal recumbency and standing, and a shorter time from the first recovery movement to the time of standing.     

Prospective study of blackthorn injury and synovitis in 35 horses

The objective of this prospective clinical study was to investigate the cause and describe the presentation, diagnosis, treatment techniques and outcome of Prunus spinosa (blackthorn) injury and synovitis in the horse. In all cases presented with blackthorn injury and synovitis, surgical treatment was performed within 24 h, using a two-stage procedure: 1-Perisynovial technique using ultrasound guided electrosurgical dissection; 2-Endoscopic technique. The diagnosis was confirmed by retrieval of black plant material from or close to the affected synovial structure. Mean lameness score on presentation was 4/5 (range 1–5). The most commonly affected structures were extensor tendon sheaths (12/35) and fetlock joints (11/35). All cases had thorn material removed, 80% had thorn material removed at surgery and in 49% it was intra-synovial. On presentation, the mean synovial fluid total protein level (TP) was 47.6 g/L (range 18–66); mean total nucleated cell count (TNCC) was 176 × 10⁹ cells/L (range 12–312). Two days post-surgery, mean total protein levels were 33 g/L (range 16–52), mean TNCC was 13 × 10⁹ cells/L (range 1–35). At 5 days post-surgery, the mean total protein was 23 g/L (range 12–28) and TNCC was 5 × 10⁹ cells/L (range 1–12). All synovial fluid cultures were negative. Twenty-eight (80%) horses were sound 5 days post-operatively, seven (20%) were not lame in walk; they all returned to full work in an average time of 8 weeks (range 3–48 weeks). Surgery achieved accurate identification and removal of thorn material. In contrast to previous studies of synovial sepsis, these cases had a positive outcome despite high pre- and post-operative synovial fluid TP and TNCC. These findings suggest that Prunus spinosus (blackthorn) synovitis has a different aetiology to synovitis originating from sepsis or other types of contamination.     

Effects of epidural morphine on gastrointestinal transit in unmedicated horses

ObjectiveTo evaluate the effect of epidural morphine on gastrointestinal (GI) motility in horses.Study designRandomly ordered crossover design.AnimalsSix healthy adult horses weighing 585 ± 48 kg (mean ± SD).MethodsHorses were randomly assigned to receive either 0.2 mg kg^?1 morphine or an equal volume (0.04 mL kg^?1) of saline epidurally (the first inter coccygeal space) with 2 weeks between treatments. The horses were stabled, fed a standardized diet and allowed water ad libitum throughout the duration of the study. Radiopaque spheres were administered by stomach tube. Xylazine 0.2 mg kg^?1 intravenously was administered prior to epidural injection. Heart rate, respiratory rate, GI sounds score and behavior score were recorded before drug administration and after epidural injection at 4, 8, 12, 18, 24 hours and every 12 hours thereafter for 6 days. Feces were weighed, radiographed and the number of spheres counted. Data were analyzed using a mixed effect model.ResultsAt no time did horses exhibit signs of colic or show significant differences between treatments regarding heart rate, respiratory rate, GI sounds score, behavior score, or cumulative number of spheres. The concentration of spheres per kg of feces was significantly lower (p < 0.05) for the morphine group at 18 and 24 hours. Using the centroid of the curves (spheres kg^?1 plotted versus time) the average transit time after saline epidural was 38 hours and after morphine it was 43 hours. The weight of feces hour^?1 was significantly lower (p < 0.05) at only 4 and 8 hours after morphine.Conclusions and clinical relevanceEpidural morphine, at a dose of 0.2 mg kg^?1, temporarily reduced GI motility but did not cause ileus or colic in this small group of healthy unfasted horses. Care should be taken when extrapolating these data to situations in which other factors may also affect GI motility.     

Characterization of the pharmacokinetics,behavioral effects and effects on thermal nociception of morphine 6-glucuronide and morphine 3-glucuronide in horses

ObjectiveTo describe the pharmacokinetics, behavioral and physiologic effects and effects on thermal thresholds of morphine, morphine 6-glucuronide (M6G) and morphine 3-glucuronide (M3G) following administration to horses.Study designRandomized balanced crossover study.AnimalsA total of seven University-owned horses, five mares and two geldings, aged 3–6 years.MethodsHorses were treated with a single intravenous dosage of saline, morphine (0.2 mg kg^–1), M6G (0.01 mg kg^–1) and M3G (0.03 mg kg^–1). Blood was collected prior to (baseline) and at several times post administration. Drug and metabolite concentrations were determined by liquid chromatography–mass spectrometry, and plasma pharmacokinetics were calculated. Behavioral observations and physiologic variables (heart rate, step counts, packed cell volume, total plasma protein and gastrointestinal sounds) were determined at baseline and for up to 6 hours. The effects on thermal nociception were determined and thermal excursion was calculated.ResultsThe volumes of distribution were 4.75–10.5, 0.244–0.295 and 0.215–0.356 L kg^–1 for morphine, M6G and M3G, respectively. Systemic clearances were 26.8–39.6, 3.16–3.88 and 1.46–2.13 mL minute^?1 kg^?1 for morphine, M6G and M3G, respectively. Morphine administration resulted in signs of excitation as evidenced by an increase in step counts and subjective behavioral observations, whereas M6G and M3G, based on the same criteria, appeared to cause sedative-like effects. Significant effects on thermal nociception were observed until 4 hours post morphine administration, 1 hour post M6G administration and at various times post M3G administration.Conclusions and clinical relevanceResults of this study provide additional information regarding the use of morphine in horses. Less locomotor excitation and gastrointestinal adverse effects, compared with morphine, coupled with favorable effects on thermal nociception are encouraging for further study of the pharmacodynamics of both M6G and M3G in horses.     

Comparison of intraperitoneal ropivacaine and bupivacaine for postoperative analgesia in dogs undergoing ovariohysterectomy

Objective

To compare postoperative analgesia following either intraperitoneal (IP) ropivacaine or bupivacaine in dogs undergoing ovariohysterectomy (OVH) in the scope of multimodal analgesia.

Tumescent local anesthesia with ropivacaine in different concentrations in bitches undergoing mastectomy: plasma concentration and post‐operative analgesia

ObjectiveTo compare two concentrations of ropivacaine administered for tumescent local anesthesia (TLA) in dogs undergoing mastectomy.Study designProspective randomized clinical study.AnimalsSeventeen bitches of various breeds, aged 12 ± 2 years and weighing 10 ± 6.5 kg requiring total unilateral or bilateral mastectomy.MethodsDogs were premedicated with acepromazine (0.04 mg kg^?1) and morphine (0.4 mg kg^?1) intramuscularly. Anesthesia was induced with propofol (2.5 mg kg^?1) and midazolam (0.2 mg kg^?1) intravenously, followed by intubation and maintenance with isoflurane and TLA. Dogs were randomly allocated to receive TLA either with 0.1% ropivacaine (group G1) or with 0.05% ropivacaine (group G05). TLA was performed by insertion of a multihole needle under the skin and infusion of ropivacaine and lactated Ringer’s solution at a fixed volume of 15 mL kg^?1. Ropivacaine concentrations in arterial blood were measured by high-performance liquid chromatography. Post-operative pain was assessed using two scales (University of Melbourne pain scale and a modified composite measure pain scale) and von Frey filaments, 4 hours after TLA and at 1 hour intervals until sensitivity was regained. A score above 30% of the maximum possible score was considered a positive indicator of pain.ResultsPeak plasma concentrations of ropivacaine were measured 240 minutes after TLA in G1. Low concentrations were measured in G05 for 60 minutes, with subsequent increase. Analgesic rescue and return of sensitivity occurred at 7 ± 2.3 and 7 ± 1.9 hours (mean ± SD) after TLA for G1 and G05, respectively.Conclusions and clinical relevanceTumescent local anesthesia with ropivacaine provided satisfactory post-operative analgesia that lasted for several hours, with no difference in duration between the concentrations. No serious side effects were attributed to TLA. Results indicated that 0.05% ropivacaine provided adequate analgesia for mastectomy, however, more studies are required to support this conclusion.     

Analgesic effects of morphine and butorphanol in broiler chickens

Objective

To evaluate analgesic efficacies of morphine and butorphanol in lame broiler chickens.

Problems associated with perioperative morphine in horses: a retrospective case analysis

Objective To identify the incidence of adverse effects caused by morphine 100–170 µg kg^?1 administration during surgery in horses. Design Retrospective case record analysis (1996–2000). Animals Eighty‐four healthy (ASA 1 or 2) horses, mean age 5.5 ± 3.1 (SD) years (2 months to 16 years), mean weight 524 ± 14 kg (100–950). Methods Physiological data and evidence of complications were collected from the anaesthetic records of all animals anaesthetized with romifidine, ketamine, diazepam and halothane and undergoing laryngeal surgery or orchiectomy at the Royal (Dick) School of Veterinary Studies. Cases were divided into those receiving (group M+; n = 18) and those not receiving morphine (M?; n = 29), and the data compared. Values for heart and respiratory rate and mean arterial pressure were compared at 15‐minute intervals between 30 and 120 minutes after induction using anova for repeated measures. The incidence of intraoperative problems was compared using Fisher's exact test. Recovery scores were compared using Student's unpaired t‐test. The records of a further 37 horses undergoing umbilical herniorrhaphy (n = 5), arthroscopy (n = 29) or tarsal arthrodesis (n = 3) were also studied but not analysed statistically due to disparate treatment distribution. Results There were no significant differences between the M+ and M? groups. The incidence of post‐operative complications such as box‐walking and colic were similar in each group. Conclusions Morphine doses of 100–170 µg kg^?1 do not increase the risk of problems when used to provide perioperative analgesia in horses anaesthetized with romifidine, ketamine, diazepam and halothane. Clinical relevance Morphine provides an acceptable and relatively inexpensive way to provide perioperative analgesia in horses.     

Caudal epidural co-administration of methadone and morphine in horses: An evaluation of analgesic properties and effects on locomotor function,mentation and physical examination parameters

Caudal epidural analgesia is a well-established therapeutic modality for pain alleviation in horses. Additionally, epidural analgesia could potentially be a complementary diagnostic tool for confirmation of pain-related conditions in horses presenting with nonspecific signs of poor performance or rideability issues. To use the epidural as a diagnostic tool, the administered medications should provide efficient analgesia without accompanying adverse effects. Therefore, the objectives of the current study were to evaluate the analgesic properties and effects on locomotor function, mentation and physical examination parameters of caudal epidural co-administration of methadone and morphine in horses. Five mares received a caudal epidural injection of 0.1 mg/kg bwt methadone and 0.1 mg/kg bwt morphine diluted to a total volume of 4.4 mL/100 kg. Before and several times thereafter, horses were subjected to mechanical nociceptive threshold evaluation, physical examination, assessment of mentation and locomotor function examination. Horses were assigned ataxia scores (0–4) by a group of inexperienced raters (three senior-year veterinary students) and a group of experienced raters (two board-certified internal medicine specialists) that assessed the locomotor examinations either live or video-based. The epidural co-administration of methadone and morphine resulted in clinically relevant and statistically significant increases of horses’ tolerance to mechanical noxious stimuli at the coccygeal, perineal, sacral, lumbar and thoracic regions. Analgesia was evident after 4.4 h and lasted at least 5 h. Regional differences in the onset of analgesia reflected a cranial spread of the analgesic solution. No horses showed signs of gait disturbances; the overall median ataxia score was 0 at all times; and the average difference in scores between two randomly selected raters for a random horse at a random time point was 0.377 indicating high inter-rater agreement. There were no adverse changes of mentation and physical examination parameters. Observed side effects included signs of decreased frequency of defaecation, generalised sweating, and pruritus.     

Combination of magnesium sulphate and ropivacaine epidural analgesia for hip arthroplasty in dogs

Objective

The aim of this study was to determine whether lumbosacral epidural administration of magnesium sulphate added to ropivacaine prolongs and improves perioperative analgesia, without adverse effects on motor block duration or hind limb neurological function, in dogs undergoing hip arthroplasty.

Evaluation of analgesia provided by the administration of epidural ketamine in dogs with a chemically induced synovitis

OBJECTIVE: To determine if epidural ketamine provides analgesia in dogs with a chemically induced synovitis. STUDY DESIGN: Prospective randomized experimental trial. ANIMALS: Thirty-two healthy, adult mongrel dogs (13-30 kg). METHODS: (Part I) Synovitis was induced in the right stifle of 16 dogs and allowed to develop for 12 hours. Epidural injection at the lumbosacral space of either ketamine (2 mg kg(-1); n = 8) or placebo (n = 8) was performed. Limb use and pain were measured using a force platform and numerical rating scale (NRS). Assessments were performed before and at 12, 14, 16, 18, 20, and 24 hours after the induction of synovitis. (Part II) Epidural injection of either ketamine (n = 8) or placebo (n = 8) was performed immediately before the induction of synovitis. Analgesia was assessed as in Part I. Assessments occurred before and at 2, 4, 6, 8, and 12 hours after the induction of synovitis. RESULTS: (Part I) Vertical ground reaction forces (VGRF) significantly decreased and NRS scores of total pain significantly increased after the induction of synovitis in all dogs (p < 0.05). No significant differences in VGRF or NRS scores were measured between treatment groups at any assessment period. (Part II) Dogs that received ketamine had significantly lower NRS scores 2 hours after treatment (p < 0.05). NRS scores did not differ between groups at any other evaluation. VGRF did not differ significantly between treatment groups at any assessment period. CONCLUSION: Epidural ketamine at a dose of 2 mg kg(-1) administered after the development of synovitis does not provide significant levels of analgesia. Administration of ketamine before the induction of synovitis significantly decreased the NRS score 2 hours post-induction. CLINICAL RELEVANCE: Administration of epidural ketamine before tissue injury may provide analgesia of short duration in dogs.