Comparison of the effects of tramadol, codeine, and ketoprofen alone or in combination on postoperative pain and on concentrations of blood glucose, serum cortisol, and serum interleukin-6 in dogs undergoing maxillectomy or mandibulectomy

The Effect of a Subsequent Dose of Dexmedetomidine or Other Sedatives following an Initial Dose of Dexmedetomidine on Electrolytes, Acid-Base Balance, Creatinine, Glucose, and Cardiac Troponin I in Cats: Part II

The administered dose of dexmedetomidine may occasionally fail to produce the anticipated sedative effects. Therefore, a subsequent dose or administration of another sedative may enhance sedation; however, patient safety may be affected. The safety of seven different drugs administered at the following time point after an insufficient dose of dexmedetomidine was evaluated in a crossover, blind, experimental study that included six healthy adult cats. All cats received an initial dose of dexmedetomidine and a subsequent dose of either dexmedetomidine (Group DD), NS 0.9% (DC), tramadol (DT), butorphanol (DBT), buprenorphine (DBP), ketamine (DK), or midazolam (DM). Animal safety was assessed using repeated blood gas analysis and measurement of electrolytes, glucose, cardiac troponin I, and creatinine to evaluate cardiac, respiratory, and renal function. The median values of creatinine, cardiac troponin I, pH, partial pressure of carbon dioxide, potassium, and sodium did not change significantly throughout the study. Heart rate was significantly decreased in all groups after administration of the drug combinations, except for in the DK group. Respiratory rate decreased significantly after administration of the initial dose of dexmedetomidine and in the DBP and DM groups. The partial pressure of oxygen, although normal, decreased significantly after the administration of dexmedetomidine, whereas the median concentration of glucose increased significantly following the administration of dexmedetomidine. The results of our study suggest that the drug combinations used did not alter the blood parameters above normal limits, while cardiac and renal function were not compromised. Therefore, a safe level of sedation was achieved. However, the administration of dexmedetomidine reduced the partial pressure of oxygen; thus, oxygen supplementation during sedation may be advantageous. Additionally, the increase in glucose concentration indicates that dexmedetomidine should not be used in cats with hyperglycaemia, whereas the decrease in haematocrit suggests that dexmedetomidine is not recommended in anaemic cats.

Development of a requirement for exogenous insulin treatment in dogs with hyperglycemia

BACKGROUND

It has been suggested that overt diabetes mellitus in dogs be defined based on a persistent fasting blood glucose concentration (BGC) >144 mg/dL.

OBJECTIVE

Determine the number of dogs with randomly identified hyperglycemia without insulin-treated diabetes mellitus (ITDM) that later develop a need for exogenous insulin treatment.

ANIMALS

A total of 1318 dogs examined at a university teaching hospital without ITDM and with randomly identified hyperglycemia.

METHODS

Retrospective longitudinal study. Hyperglycemia was defined as randomly identified BGC above >112 mg/dL, moderate hyperglycemia as BGC >144 mg/dL but <200 mg/dL and pronounced hyperglycemia as BGC ≥200 mg/dL. Dogs were defined as having ITDM if they were treated with insulin. Follow-up was attempted 7 to 12 years after hyperglycemia was documented to determine if over time dogs developed a need for exogenous insulin treatment.

RESULTS

Twenty-nine of 824 dogs (3.5%) with hyperglycemia and follow-up information developed ITDM, including 3/824 dogs (0.4%) with moderate hyperglycemia, and 2/824 dogs (0.2%) with pronounced hyperglycemia. Most dogs with hyperglycemia that developed ITDM (24/29, 83%) had BGC ≤144 mg/dL. Among dogs that eventually developed a need for exogenous insulin treatment, no association was found between the degree of hyperglycemia and the time interval between documentation of hyperglycemia and diagnosis of ITDM. Logistic regression determined that BGC is not significantly associated with ITDM.

CONCLUSIONS AND CLINICAL IMPORTANCE

Most dogs with randomly identified hyperglycemia did not develop a need for exogenous insulin treatment. Other criteria could be required to augment the definition of overt DM in non-insulin treated dogs.

The Effect of Different Opioids on Acid-Base Balance and Blood Gas Analysis in Hospitalized Dogs

Pain management is central to veterinary practice, contributing to successful case outcomes and enhancement of the veterinarian-client-patient relationship. Analgesic drugs represent one of the pillars of the multimodal approach to acute and chronic pain management. In dogs, the most used opioids are methadone, buprenorphine and tramadol. Several episodes of hypoglycemia in people treated with tramadol and methadone have recently been described. The aim of this work is to evaluate the changes in the glycemic and acid-base balance induced by tramadol, methadone and buprenorphine in hospitalized dogs. A retrospective review of the medical records of dogs hospitalized for both medical and surgical reasons was performed. During 2018-2020, a total of 876 canine patients were treated with opioids, including 228 with tramadol, 273 with methadone and 375 with buprenorphine. Of all these dogs, only a small percentage met the inclusion criteria presented in the initial design. All the hospitalized animals were monitored daily through clinical examination and blood sampling. Blood samples were obtained before opioid administration (T0), and 24 h (T1) and 48 h (T2) after °pioid administration. The following parameters were evaluated: blood gas value (pH, pCO₂), acid-base state (cHCO₃), oxymetric values (ctHb, haematocrit), electrolyte values (K+, Na+, iCa, Cl-) and metabolic values (glucose, lactate, anion GAP K+c). The glycemic value in enrolled dogs showed a decrease over time, regardless of the type of opioid used, but remained within the physiological range. The highest average glycemic drop was recorded for methadone, between T0 and T1, followed by tramadol between T1 and T2, while buprenorphine recorded the highest overall glycemic drop between T0-T2 when compared to the other two opioids. Female dogs showed the greatest drop in glycemic value. Lactate concentration always presented values beyond the physiological range at an early stage, which then normalized quickly. Measurement of electrolyte concentrations showed a consistent increase in the values of iCa, Na and Cl. In hospitalized dogs treated with opioids monitoring of gas analytic parameters is important and more attention should be paid to patients hospitalized with certain metabolic and endocrine diseases.

Pharmacokinetic Evaluation of a Novel Transdermal Ketoprofen Formulation in Healthy Dogs

Dogs undergo various surgical procedures such as castration, ovariohysterectomy, and other orthopedic procedures, which are known to cause inflammation and pain. Non-steroidal anti-inflammatory drugs (NSAIDs) are very effective analgesics for alleviating postoperative pain in veterinary medicine. Ketoprofen is currently approved in Australia and the United States for treating different painful conditions in dogs. This study evaluated the pharmacokinetic parameters of ketoprofen after intravenous (IV) and transdermal (TD) administration in healthy dogs. A novel transdermal ketoprofen (TDK) formulation containing 20% ketoprofen, dissolved in a combination of 45:45% isopropanol and Transcutol, along with 10% eucalyptus oil, was developed and evaluated for in vitro dermal permeation using Franz diffusion cells. A crossover study was then conducted to determine the pharmacokinetic parameters of the formulation in six dogs following IV ketoprofen (1 mg/kg) and TDK (10 mg/kg) administration. A liquid chromatography–mass spectrometry (LC-M/MS) method was used to measure plasma concentrations of ketoprofen over time, and a non-compartmental analysis determined the pharmacokinetic parameters. The mean terminal elimination half-life (T_½ h), AUC_0-t (µg·h/mL), and mean residence time (MRT, h) between IV and TDK groups were 4.69 ± 1.33 and 25.77 ± 22.15 h, 15.75 ± 7.72 and 8.13 ± 4.28 µg·h/mL, and 4.86 ± 1.81 and 41.63 ± 32.33 h, respectively. The calculated bioavailability (F%) was ~7%, with a lag time of 30 min to achieve effective plasma concentrations after the application of TDK.

Interindividual variability in diabetic patients’ response to opium poppy: an overview of impressive factors

Diabetic patients always seek alternative treatments to lower their blood glucose level efficiently, because antidiabetic drugs produce adverse effects and many patients experience reduced response after a treatment period. Opium poppy ( Papaver somniferum) is frequently consumed by diabetic patients for reduction of blood glucose level. Scientific studies found controversial results in the investigation of the blood glucose-lowering effects of opium poppy. In this regard, we explored the antidiabetic effect of opium poppy more closely. The antidiabetic or antihyperglycemic effect of P. somniferum alkaloids were reviewed. Next, opioid receptors and their role in diabetes were explored. In the final part origins of interindividual variabilities in opioid receptors and metabolizing enzymes’ functions including genetic and epigenetic factors were reviewed.

Comparative Multimodal Palliative efficacy of gabapentin and tramadol By Using Two Pain Scoring Systems in Cats Undergoing Ovariohysterectomy

The analgesic efficacy of the gabapentin-tramadol combination was compared with meloxicam-tramadol and tramadol perioperative analgesic regimens in cats brought to the clinic for ovariohysterectomy. Thirty adult cats belonging to comparable demographics (age, body weight), were enrolled into a randomized, blinded study after due consent from their owners into four treatment groups. A Gabapentin-Tramadol group (GT-group, n = 10), Meloxicam-Tramadol group (MT-group, n = 10), and a Tramadol group (T-group, n = 10) were formed. Gabapentin capsules at 50 mg were administered orally 2 hours before surgery while the rest received a placebo dose. Tramadol (2 mg/kg, IM) and meloxicam at (0.2 mg/kg, SC) were injected immediately prior to anesthetic premedication. Anesthetic protocol involved premedication with ketamine and xylazine, while anesthesia was induced using propofol. Inhalant isoflurane anesthesia was used to maintain a surgical plane. GT group scored lower on IVAS as well as CPS than MT group, and T group for up to 8 hours after surgery. The mechanical nociceptive threshold remained higher (98±0) for up to 12 hours postoperatively a nd serum cortisol concentrations remained significantly lower during the 24hr period. The addition of gabapentin to the tramadol regimen significantly improved analgesia and mechanical nociceptive threshold than when used on its own.

Comparison of the analgesic effects of morphine and tramadol after tumor surgery in dogs

BACKGROUND

Pain thresholds may differ between animal species. It may even vary among individuals of the same species. Therefore, assessing pain in animals is challenging.

AIMS

The objective of the present study was to compare the analgesic effects of tramadol with morphine.

METHODS

The study was carried out on randomly selected 20 dogs with tumors in different breeds and gender. After induction of anesthesia with propofol, dogs were intubated, and anesthesia was maintained with sevoflurane. Intravenous fentanyl citrate was used for intraoperative analgesia after stabilization of the anesthesia. When the tumors were surgically removed and the operation was completed, dogs were divided into two groups to give the postoperative analgesic agent. The first 10 dogs to be investigated were identified as the morphine group and the second 10 dogs as the tramadol group. Postoperative pain scores, heart rates, respiratory rates, and body temperatures were recorded at 0, 4, 8, 12, 16, 20, and 24 hours after the operation.

RESULTS

Pain scores were lower in the morphine group than in the tramadol group during all postoperative processes.

CONCLUSION

As a result, it was determined that tramadol has immediate analgesic effects than morphine; however, morphine provides better analgesia than tramadol.

Early Analgesic Efficacy of Morphine, Butorphanol, Lidocaine, Bupivacaine or Carprofen After Periodontal Treatment in Dogs

The early effectiveness of 5 analgesics was investigated after periodontal treatment. Dogs were assigned to 6 groups (n = 14 each). A prospective, randomized and blinded clinical study was performed. Before anesthesia was induced, butorphanol, morphine, carprofen and saline were administered. After induction, a maxillary and mandibular block was performed with lidocaine or bupivacaine. Painful periodontal therapies were performed. Two hours after the administration of analgesics and after anesthesia reversal, pain was scored using the Visual Analog Scale for pain (VAS) and the modified University of Melbourne Pain Score (UMPS). Blood glucose and cortisol levels were measured prior to analgesic administration and again 2 hours later. Rescue analgesia was provided when the VAS exceeded 50 mm or the UMPS exceeded 14 points. Rescue analgesia was required in one patient in the morphine group and one in the carprofen group. The VAS values were significantly lower in the butorphanol group compared to those of the saline group and in the bupivacaine group vs. those in the saline and lidocaine groups. Significantly lower UMPS values were obtained in the bupivacaine group compared to those in the saline, butorphanol and lidocaine groups and in the carprofen group vs. those in the saline and lidocaine groups. Significantly higher serum cortisol values were found in the lidocaine group compared to those in the saline, bupivacaine and carprofen groups. Administration of carprofen or the use of nerve blocks with bupivacaine improved analgesia after periodontal treatment more than did butorphanol, morphine or nerve blocks using lidocaine.

Cyclooxygenases 1 and 2 inhibition and analgesic efficacy of dipyrone at different doses or meloxicam in cats after ovariohysterectomy

OBJECTIVE

To evaluate the cyclooxygenases (COX) inhibition, adverse effects and analgesic efficacy of dipyrone or meloxicam in cats undergoing elective ovariohysterectomy.

STUDY DESIGN

Prospective, blinded, randomized, clinical study.

ANIMALS

A total of 30 healthy young cats.

METHODS

The cats were randomly assigned to three postoperative groups: D25 (dipyrone 25 mg kg^-1 every 24 hours), D12.5 (dipyrone 12.5 mg kg^-1 every 12 hours) and M (meloxicam 0.1 mg kg^-1 every 24 hours). In the first 24 hours, the drugs were administered intravenously (IV), and then orally for 6 (dipyrone) or 3 days (meloxicam). Prostanoids thromboxane B₂ and prostaglandin E₂ concentrations served as indicators of COX activity and, with physiological variables and pain and sedation scores, were measured for 24 hours after first analgesic administration. Rescue analgesia (tramadol, 2 mg kg^-1 IV) was provided if Glasgow feline composite measure pain scale (CMPS-Feline) ≥5. Laboratory tests included symmetric dimethylarginine and adverse effects were evaluated regularly up to 7 and 10 days after surgery, respectively. Parametric and nonparametric data were analyzed with two-way anova and Kruskal-Wallis tests, respectively (p < 0.05).

RESULTS

In the first half hour after analgesic administration, COX-1 activity was close to zero and remained significantly lower than before drug administration for 24 hours in all groups. The inhibition of COX-2 activity was significant for 30 minutes in all groups and up to 4 hours in group M. No alterations in laboratory tests or significant adverse effects were observed. Pain scores and need for rescue analgesia did not differ statistically among groups.

CONCLUSIONS

Dipyrone at both doses and meloxicam provided a nonselective inhibition of COX-1 and -2 activities and effective analgesia without causing significant adverse effects or laboratory tests alterations.

CLINICAL RELEVANCE

Dipyrone at both doses provides equally effective analgesia without causing adverse effects in cats undergoing ovariohysterectomy.

Metabolism, pharmacokinetics and selected pharmacodynamic effects of codeine following a single oral administration to horses

OBJECTIVE

To describe the pharmacokinetics and selected pharmacodynamic variables of codeine and its metabolites in Thoroughbred horses following a single oral administration.

STUDY DESIGN

Prospective experimental study.

ANIMALS

A total of 12 Thoroughbred horses, nine geldings and three mares, aged 4-8 years.

METHODS

Horses were administered codeine (0.6 mg kg-1) orally and blood was collected before administration and at various times until 120 hours post administration. Plasma and urine samples were collected and analyzed for codeine and its metabolites by liquid chromatography-mass spectrometry, and plasma pharmacokinetics were determined. Heart rate and rhythm, step counts, packed cell volume and total plasma protein were measured before and 4 hours after administration.

RESULTS

Codeine was rapidly converted to the metabolites norcodeine, codeine-6-glucuronide (C6G), morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G). Plasma codeine concentrations were best represented using a two-compartment model. The Cmax, tmax and elimination t½ were 270.7 ± 136.0 ng mL-1, 0.438 ± 0.156 hours and 2.00 ± 0.534 hours, respectively. M3G was the main metabolite detected (Cmax 492.7 ± 35.5 ng mL-1), followed by C6G (Cmax 96.1 ± 33.8 ng mL-1) and M6G (Cmax 22.3 ± 4.96 ng mL-1). Morphine and norcodeine were the least abundant metabolites with Cmax of 3.17 ± 0.95 and 1.42 ± 0.79 ng mL-1, respectively. No significant adverse or excitatory effects were observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Following oral administration, codeine is rapidly metabolized to morphine, M3G, M6G, C6G and norcodeine in horses. Plasma concentrations of M6G, a presumed active metabolite of morphine, were comparable to concentrations reported previously following administration of an analgesic dose of morphine to horses. Codeine was well tolerated based on pharmacodynamic variables and behavioral observations.

3D anatomical model for teaching canine lumbosacral epidural anesthesia

Purpose

To develop a 3D anatomical model for teaching canine epidural anesthesia (3DMEA) and to assess its efficacy for teaching and learning prior to the use of live animals.

Methods

The creation of 3DMEA was based on 3D optical scanning and 3D printing of canine bone pieces of the fifth to the seventh lumbar vertebrae, sacrum and pelvis. A total of 20 male dogs were scheduled for castration. 20 veterinary students watched a video showing epidural anesthesia in dogs before the clinical attempt and were assigned to control or 3DMEA groups. Students in the 3DMEA group trained in the model after the video. For the clinical trial, the epidural procedure was performed by students under the veterinary supervision. When observed the absence of response to nociceptive stimuli, the epidural was considered successful. Then, all students answered a questionnaire evaluating the main difficulty founded in the technique and its degree of difficulty.

Results

The 3DMEA group reported a lower degree of difficulty to perform the epidural anesthesia technique when compared with the control group (p=0.0037). The 3DMEA reproduced the anatomical structures, allowing the perception of the distance of needle in relation to the iliac prominences during epidural anesthesia. Its mobility allowed simulation of the animal in standing position and sternal recumbency.

Conclusion

The use of 3DMEA demonstrated greater efficacy in the execution of the technique, being effective in the teaching and learning process before the epidural anesthesia in live animals.

The effect of tramadol on blood glucose concentrations: a systematic review

INTRODUCTION

Studies comprehensively summarizing the impact of tramadol use on glucose homeostasis are very sparse. Thus, the present study was performed to collect and summarize the latest information about this issue in a systematic way.

AREAS COVERED

An exhaustive literature search was carried out using relevant keywords. Web of Sciences, PubMed, Scopus, and Google scholar were interrogated until 30 June 2019. Case-control, cohort, cross-sectional, clinical trial, case report, and animal studies that focused on the objective of the study were retrieved. This review summarizes the results of 761 papers on glycemic changes due to tramadol exposure. Thirty-six publications reported hypoglycemia and 17 hyperglycemia during tramadol use. Twenty-two studies either reported normal blood glucose concentrations, or did not observe any difference in the blood glucose levels following tramadol use. Finally, hypoglycemia was reported in diabetic individuals exposed to tramadol in 12 studies.

EXPERT OPINION

The data suggest that primarily hypoglycemia but some degree of hyperglycemia has been reported with tramadol use. Importantly, all studies on tramadol use in diabetes reported hypoglycemia. Tramadol-induced hypoglycemia may be severe in some cases. The risk of alterations in glucose homeostasis accompanying tramadol exposure indicates time importance of careful blood glucose monitoring during tramadol use.

Evaluation and comparison of postoperative analgesic effects of dexketoprofen and methadone in dogs

OBJECTIVE

To evaluate and compare the analgesic efficacy and adverse effects of dexketoprofen and methadone using a noninferiority trial, during the first 24 postoperative hours in dogs undergoing orthopaedic surgery.

STUDY DESIGN

Randomized, blinded clinical study.

ANIMALS

A total of 38 healthy dogs undergoing orthopaedic surgery.

METHODS

Dogs were premedicated with dexmedetomidine [1 μg kg^-1 intravenously (IV)] followed by dexketoprofen (1 mg kg^-1 IV; group DK) or methadone (0.2 mg kg^-1 IV; group M). Anaesthesia was induced with propofol and maintained with isoflurane in 60% oxygen. Postoperatively, dexketoprofen was administered every 8 hours (group DK) and methadone every 4 hours (group M). Analgesia was assessed at baseline and at 1, 2, 4, 6, 18 and 24 hours after extubation using a dynamic and interactive visual analogue scale (DIVAS), the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF), mechanical wound thresholds (MWTs) and plasma cortisol levels. If CMPS-SF score was ≥5, rescue analgesia was administered. Data were analysed using a general linear mixed model, Mann-Whitney U test and chi-squared test as appropriate; a p value <0.05 was considered significant.

RESULTS

The CMPS-SF and DIVAS scores were significantly higher in group M compared with group DK and remained higher for a longer period in group M, although the differences were not clinically significant. No significant differences were found in MWT assessment between groups. Plasma cortisol level significantly increased 2 hours after extubation, without significant differences between treatments. Rescue analgesia was administered to three animals (one in group DK; two in group M).

CONCLUSION AND CLINICAL RELEVANCE

We conclude that 1 mg kg^-1 IV dexketoprofen administered every 8 hours during the first 24 hours postoperatively is noninferior to methadone in controlling pain after orthopaedic surgery in dog, although frequent pain assessments are recommended to adjust the analgesia plan.

Efeitos adversos da morfina, metadona e tramadol no pós-operatório de cães submetidos à cirurgia da coluna vertebral: 180 casos (2011-2016)

RESUMO: A dor pós-operatória em cães que são submetidos a cirurgias da coluna vertebral é considerada severa e seu manejo inadequado pode influenciar no tempo de recuperação do paciente, na qualidade de vida e no resultado cirúrgico. Dentre os analgésicos indicados para uso no pós-operatório dessas cirurgias tem-se os opioides, que podem apresentar inúmeros efeitos adversos que requerem atenção. Devido à escassez de estudos clínicos acerca desse assunto em se tratando do pós-operatório de cães, objetivou-se com o presente estudo retrospectivo apresentar os efeitos adversos da morfina, metadona e tramadol utilizados no pós-operatório de cirurgias da coluna vertebral. Foram revisadas e avaliadas as fichas de 180 cães e anotadas as alterações observadas no pós-operatório e decorrentes do uso de opioides. Os principais efeitos adversos observados foram anorexia, hiporexia, vômito, salivação, vocalização, bradicardia, hipotermia, ofegação e sedação. Também foi observada persistência da dor em alguns cães mesmo com o uso de analgésicos. Houve diferença na ocorrência de anorexia nos cães tratados com morfina e nos tratados com metadona em relação aos tratados com tramadol. Ocorreu diferença também entre a observação de dor dos grupos morfina e tramadol. A associação de dipirona com morfina e com metadona não revelou diferença com relação à ocorrência de efeitos adversos, bem como a variação de doses. Conclui-se que a morfina, a metadona e o tramadol apresentam efeitos adversos quando empregados para tratamento da dor pós-operatória em cães submetidos à cirurgia da coluna vertebral; a anorexia, a hiporexia e o vômito foram os efeitos adversos frequentes com o uso de morfina e de metadona e, mesmo que o tramadol apresente menor ocorrência desses efeitos, seu uso, na dose estudada, pode não ser vantajoso quando se leva em consideração o grau de dor para cirurgias da coluna vertebral.

Effects of intravenous administration of lidocaine and buprenorphine on gastrointestinal tract motility and signs of pain in New Zealand White rabbits after ovariohysterectomy

OBJECTIVE To compare analgesic and gastrointestinal effects of lidocaine and buprenorphine administered to rabbits undergoing ovariohysterectomy. ANIMALS Fourteen 12-month-old female New Zealand White rabbits. PROCEDURES Rabbits were assigned to 2 treatment groups (7 rabbits/group). One group received buprenorphine (0.06 mg/kg, IV, q 8 h for 2 days), and the other received lidocaine (continuous rate infusion [CRI] at 100 μg/kg/min for 2 days). Variables, including food and water consumption, fecal output, glucose and cortisol concentrations, and behaviors while in exercise pens, were recorded. RESULTS Rabbits receiving a lidocaine CRI had significantly higher gastrointestinal motility, food intake, and fecal output and significantly lower glucose concentrations, compared with results for rabbits receiving buprenorphine. Rabbits receiving lidocaine also had a higher number of normal behaviors (eg, sprawling, traveling, and frolicking) after surgery, compared with behaviors such as crouching and sitting that were seen more commonly in rabbits receiving buprenorphine. Both groups had significant weight loss after surgery. Pain scores did not differ significantly between treatment groups. Significant decreases in heart rate and respiratory rate were observed on the day of surgery, compared with values before and after surgery. Rabbits in the lidocaine group had significantly overall lower heart rates than did rabbits in the buprenorphine group. CONCLUSIONS AND CLINICAL RELEVANCE A CRI of lidocaine to rabbits provided better postoperative outcomes with respect to fecal output, food intake, and glucose concentrations. Thus, lidocaine appeared to be a suitable alternative to buprenorphine for alleviating postoperative pain with minimal risk of anorexia and gastrointestinal ileus.

Effect of laparotomy on the pituitary-adrenal axis in dogs

OBJECTIVE To assess effects of major abdominal surgery on serum cortisol and aldosterone and plasma canine ACTH (cACTH) concentrations. ANIMALS 39 healthy dogs undergoing laparotomy during veterinary student surgical laboratories. PROCEDURES Blood samples were obtained before and at completion of surgery. Serum cortisol and aldosterone and plasma cACTH concentrations were measured by use of validated radioimmunoassays. Changes in concentrations (postoperative concentration minus preoperative concentration) were calculated. Data were analyzed by use of the Wilcoxon signed rank test, Pearson correlation analysis, and Mann-Whitney rank sum test. RESULTS Cortisol, aldosterone, and cACTH concentrations increased significantly from before to after surgery. Although cortisol and aldosterone concentrations increased in almost all dogs, cACTH concentrations decreased in 6 of 32 (19%) dogs. All dogs had preoperative cortisol concentrations within the reference range, but 24 of 39 (62%) dogs had postoperative concentrations above the reference range. A correlation between the change in cACTH concentration and the change in cortisol concentration was not detected. CONCLUSIONS AND CLINICAL RELEVANCE Laparotomy caused a significant increase in serum cortisol and aldosterone concentrations. In most dogs, but not all dogs, plasma cACTH concentrations increased. Lack of correlation between the change in cACTH concentration and the change in cortisol concentration suggested that increased postoperative cortisol concentrations may have been attributable to ACTH-independent mechanisms, an early ACTH increase that caused a sustained cortisol release, or decreased cortisol clearance. Further studies are indicated to evaluate the effects of various anesthetic protocols and minimally invasive surgical techniques on the stress response.

Tramadol metabolism to O-desmethyl tramadol (M1) and N-desmethyl tramadol (M2) by dog liver microsomes: Species comparison and identification of responsible canine cytochrome P-450s (CYPs)

Tramadol is widely used to manage mild to moderately painful conditions in dogs. However, this use is controversial since clinical efficacy studies in dogs showed conflicting results, while pharmacokinetic studies demonstrated relatively low circulating concentrations of O-desmethyltramadol (M1). Analgesia has been attributed to the opioid effects of M1, while tramadol and the other major metabolite (N-desmethyltramadol, M2) are considered inactive at opioid receptors. The aims of this study were to determine whether cytochrome P450 (CYP) dependent M1 formation by dog liver microsomes is slower compared with cat and human liver microsomes; and identify the CYPs responsible for M1 and M2 formation in canine liver. Since tramadol is used as a racemic mixture of (+)- and (-)-stereoisomers, both (+)-tramadol and (-)- tramadol were evaluated as substrates. M1 formation from tramadol by liver microsomes from dogs was slower than from cats (3.9-fold), but faster than humans (7-fold). However, M2 formation by liver microsomes from dogs was faster than from cats (4.8-fold) and humans (19-fold). Recombinant canine CYP activities indicated that M1 was formed by CYP2D15, while M2 was largely formed by CYP2B11 and CYP3A12. This was confirmed by dog liver microsomes studies that showed selective inhibition of M1 formation by quinidine and M2 formation by chloramphenicol and CYP2B11 antiserum, and induction of M2 formation by phenobarbital. Findings were similar for both (+)-tramadol and (-)-tramadol. In conclusion, low circulating M1 concentrations in dogs is explained in part by low M1 formation and high M2 formation, which are mediated by CYP2D15 and CYP2B11/CYP3A12, respectively.

Preliminary investigation of the thermal antinociceptive effects of codeine in cats

OBJECTIVES

The aim of this study was to evaluate the potential thermal antinociceptive effects of oral administration of a single dose of codeine in cats compared with positive (buprenorphine) and negative (saline 0.9%) controls.

METHODS

Six adult healthy cats weighing 5.14 ± 0.6 kg were used. Skin temperature and thermal thresholds (TTs) were evaluated using a wireless device (Topcat Metrology) at baseline, 0.5, 1, 3, 6 and 10 h after treatment. In period 1, TTs were evaluated after subcutaneous administration of saline 0.9%. In period 2, cats were administered either oral codeine (10 mg total, 2.0 ± 0.2 mg/kg) or buccal buprenorphine (0.04 mg/kg) in a cross-over, blinded study design. Half of the volume of buprenorphine was administered into each cheek pouch. Δ TT (difference between TTs after and before treatment) was used for data comparison. Mean ± SD data were analyzed using one-way ANOVA followed by Dunnett's or Tukey's test when appropriate (P <0.05).

RESULTS

Adverse effects did not occur in any group. Skin temperature was not different between groups nor over time. Temporal changes in TTs were not observed after saline or codeine. Buprenorphine increased Δ TT at 3 h (2.7 ± 3.3°C) when compared with baseline or saline (P <0.05). For buprenorphine, TTs were not >47.6°C at any time point in four cats. The mean highest temperature recorded in the two other cats in that group was 54.5 and 52.8°C at 3 h.

CONCLUSIONS AND CLINICAL RELEVANCE

At the dose administered, codeine did not produce thermal antinociception. Mild increases in TT after buccal buprenorphine might be related to the first-pass effect after drug swallowing, drug spillage during administration and/or individual variability. These factors should be taken in to consideration when administering buprenorphine by this route in the clinical setting.

Early pain management after periodontal treatment in dogs – comparison of single and combined analgesic protocols

The aim of this study was to assess the analgesic effectiveness of three analgesic protocols in dogs undergoing a periodontal treatment. The study was performed as a prospective, randomized, “double blind” clinical study. A total of 45 client-owned dogs scheduled for periodontal treatment were included. Dogs of Group C received carprofen (4 mg·kg-1), dogs of Group B received bupivacaine (1 mg·kg-1) and dogs of Group CB received a combination of carprofen (4 mg·kg-1) and bupivacaine (1 mg·kg-1). Carprofen was administered subcutaneously 30 min before anaesthesia, bupivacaine was administered by nerve blocks in anaesthetized dogs. Painful periodontal treatment was performed in all patients, lasting up to one hour. Modified University of Melbourne Pain Score (UMPS), Visual Analogue Scale for pain assessment (VAS), plasma glucose and serum cortisol levels were assessed 30 min before administration of analgesics (C-0, B-0, CB‑0) and 2 h after recovery from anaesthesia (C-2, B-2, CB-2). For statistical analysis Friedman test, Mann-Whitney U-test, ANOVA and Fischer exact tests were used (P < 0.05). In CB‑2 compared to CB‑0 significantly decreased modified UMPS values. In CB‑2 UMPS values were significantly lower compared to C‑2 or B‑2. In C‑2 VAS values were significantly increased compared to C‑0, and in B‑2 VAS values were significantly increased compared to B‑0. Visual Analogue Scale values were significantly lower in CB‑2 compared to C‑2 or B‑2. Significantly increased plasma glucose concentrations were found in C‑2 compared to C‑0 and in B‑2 compared to B‑0. No other significant differences were detected. Administration of carprofen, bupivacaine or their combination is sufficient for early postoperative analgesia following periodontal treatment. Carprofen-bupivacaine combination is superior to carprofen or bupivacaine administered separately.

A comparison of pre and post-operative vedaprofen with ketoprofen for pain control in dogs

Background

This prospective randomized blinded clinical study aimed to investigate the potential of vedaprofen for preventive analgesia, comparing its analgesic effects with ketoprofen administered post-operatively in dogs undergoing maxillectomy or mandibulectomy.

Results

Pain control was effective and rescue analgesia was not necessary in any group. Pain scores were not significantly different between groups. The respiratory rate and rectal temperature were decreased in all groups at extubation until 6 hours post-extubation compared to baseline. Cortisol and epinephrine levels were increased only at 0.5 hours after extubation in all groups compared to baseline.

Conclusions

Vedaprofen did not present any preventive analgesic effect. Pre- and postoperative vedaprofen were as effective as ketoprofen for postoperative pain control.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-015-0338-4) contains supplementary material, which is available to authorized users.

Adjunctive, pain-modifying, analgesic drugs

Outside the realm of nonsteroidal antiinflammatory drug(NSAID) and opioid exist a broad range of medications that exert an analgesic effect, or otherwise modify and protect against pain, by manipulating various targets along the nociceptive pathway. Strength of evidence for dogs and cats can vary widely, and this article will review the available literature that may guide clinical usage in these species.

Comparison of preoperative tramadol and pethidine on postoperative pain in cats undergoing ovariohysterectomy

Background

A variety of analgesic agents are available, and which one can be used in dogs and cats is a highly controversial issue, existing however a fear in the use of opiates due to possible adverse effects that these drugs can cause. The aim of this study was to compare the analgesic effect provided by the administration of tramadol or pethidine on early postoperative pain of cats undergoing ovariohysterectomy in a double-blind prospective study. Fourty-two animals were randomly assigned into three groups. Pet received pethidine (6 mg/kg), Tra 2 received tramadol (2 mg/kg) and Tra 4 received tramadol (4 mg/kg); all intramuscularly and associated with acepromazine (0.1 mg/kg). The efficacy of each analgesic regimen was evaluated prior to surgery (baseline - T_BL), during surgery and 1, 3 and 6 hours after extubation with subjective pain scale, physiologic parameters, serum concentrations of glucose, cortisol and IL-6.

Results

Changes in cardiovascular system were not clinically relevant. There were no significant differences in pain scores (P > 0.05) during the study, although the number of rescue analgesia was significantly higher (P < 0.05) at Pet group (5/14) than Tra 4 group (0/14), whereas in Tra 2, two animals (2/14) required additional analgesia. The serum cortisol values of Pet group were significantly higher at T_1h T_3h (P < 0.05) and T_6h (P < 0.01) when compared to baseline (induction), also it was noticed a significant difference among the groups at T_6h (Pet values were higher than Tra 2 and Tra 4; P < 0.05).

Conclusions

Tramadol provided adequate analgesia and it was more effective than pethidine to at least six hours for the studied animals. At the higher dose (4 mg/kg) tramadol is probably more effective, since rescue analgesia was not necessary. No significant changes were observed physiological parameter that could contraindicate the use of these opioid in described doses, for the feline species.

Evaluation of the effects of methadone and tramadol on postoperative analgesia and serum interleukin-6 in dogs undergoing orthopaedic surgery

BACKGROUND

Acute postsurgical pain is of great interest due to potential risk of becoming chronic if not treated properly, worsening patient's recovery and quality of life. Twenty-eight dogs with ruptured cruciate ligaments were divided into three groups that received intramuscular injections of 4 mg/kg of tramadol (TRA), 0.5 mg/kg of methadone (MET0.5), or 0.7 mg/kg of methadone (MET0.7). Physiological parameters (heart and respiratory rates and blood pressure) were evaluated at specified times: baseline (TBL), 1 (T1), 2 (T2), 4 (T4), 6 (T6), and 24 (T24) hours after premedication. Pain scores were described by visual analogue scale (VAS), modified Glasgow Composite, and Colorado University Acute Pain scales. Blood samples for measurement of interleukin (IL)-6 were collected at TBL, T1, T6, and T24. This was a prospective, randomised investigation to evaluate the efficacy of tramadol and methadone as premedications in dogs undergoing osteotomies.

RESULTS

There were no statistically significant differences between groups with respect to age, weight, gender, surgery time, and time to extubation. Heart rate, respiratory rate, and blood pressure values were maintained within acceptable ranges, and a reduction was observed at T2 in MET0.5 and MET0.7 compared with TBL. Increases in VAS scores were observed in TRA at T4 compared with TBL, T1, and T24 and between T1 and T6 (p < 0.001). In MET0.5, there was significant increase in VAS score at T4 compared with T1 (p < 0.001). TRA and MET0.5 showed significantly higher mean ± SD VAS scores (3.4 ± 2.5 and 2.5 ± 2.6, respectively) than MET0.7 (1.1 ± 1.5) at T4 (p < 0.001). TRA showed greater demand of rescue analgesia (four animals in T4 and two in T6) (p < 0.037). There were no statistically significant differences in sedation scores, Colorado Scale scores, or interleukin levels between groups and time points.

CONCLUSIONS

Methadone given as premedication in doses of 0.7 mg/kg was better at controlling pain compared with lower doses and tramadol. However, dosage increases, administered as rescue analgesia, promoted adequate pain control even in tramadol group. Influence of these analgesics on IL-6 release could not be demonstrated, but significant levels were not found.

The challenge of evaluating pain and a pre-incisional local anesthetic block

Background. Our objective was to test the effectiveness of a local anesthetic line block administered before surgery in reducing postoperative pain scores in dogs undergoing ovariohysterectomy (OVHX).

Methods. This study is a prospective, randomized, blinded, clinical trial involving 59 healthy female dogs. An algometric pressure-measuring device was used to determine nociceptive threshold, and compared to three subjective pain scales. Group L/B received a line block of lidocaine (4 mg/kg) and bupivacaine (1 mg/kg) subcutaneously in the area of the incision site and saline subcutaneously as premedication; group L/BM (positive control) received a similar block and morphine (0.5 mg/kg) subcutaneously for premedication; and group SS (negative control) received a saline line block and saline premedication. Criteria for rescue analgesia were defined before the study. Dogs were assessed prior to surgery, at extubation (time 0) and at 2, 4, 6, 8 and 24 h post-recovery. The data were analyzed with one-way ANOVA, and a Split Plot Repeated Measures ANOVA with one grouping factor and one repeat factor (time). P < 0.05 was considered statistically significant.

Results. Approximately 33% of dogs required rescue analgesia at some point during the study, with no significant difference between groups. There was no significant difference between treatment groups with any assessment method.

Conclusions. As there were no statistically significant differences between positive and negative controls, the outcome of this technique cannot be proven.

Postoperative analgesic effects of dexketoprofen, buprenorphine and tramadol in dogs undergoing ovariohysterectomy

The objective of this study was to compare the postoperative analgesic effects of dexketoprofen, tramadol, and buprenorphine in dogs undergoing ovariohysterectomy. Seventy-five adult female dogs were randomly assigned to receive an intravenous injection (IV) of 1mg/kg of dexketoprofen (D), 0.02 mg/kg of buprenorphine (B) or 2mg/kg of tramadol (T). Pain assessment was performed during 48 h after ovariohysterectomy using a dynamic interactive visual analogue scale (DIVAS) and Glasgow composite measure pain scale (CMPS-SF). Rescue analgesia was required in 43%, 21%, and 5% of dogs in the B, T, and D groups, respectively, with significant differences between B and D (p=0.010) groups. The DIVAS and CMPS-SF values of the B group were significantly higher than those of the T and D groups. The most common undesirable effect was dysphoria in dexketoprofen group. Tramadol and dexketoprofen provide superior postoperative analgesia compared with buprenorphine in dogs undergoing ovariohysterectomy.

Effect of analgesic therapy on clinical outcome measures in a randomized controlled trial using client-owned dogs with hip osteoarthritis

Background

Pain and impaired mobility because of osteoarthritis (OA) is common in dogs and humans. Efficacy studies of analgesic drug treatment of dogs with naturally occurring OA may be challenging, as a caregiver placebo effect is typically evident. However, little is known about effect sizes of common outcome-measures in canine clinical trials evaluating treatment of OA pain. Forty-nine client-owned dogs with hip OA were enrolled in a randomized, double-blinded placebo-controlled prospective trial. After a 1 week baseline period, dogs were randomly assigned to a treatment (ABT-116 – transient receptor potential vanilloid 1 (TRPV1) antagonist, Carprofen – non-steroidal anti-inflammatory drug (NSAID), Tramadol - synthetic opiate, or Placebo) for 2 weeks. Outcome-measures included physical examination parameters, owner questionnaire, activity monitoring, gait analysis, and use of rescue medication.

Results

Acute hyperthermia developed after ABT-116 treatment (P < 0.001). Treatment with carprofen (P ≤ 0.01) and tramadol (P ≤ 0.001) led to improved mobility assessed by owner questionnaire. Nighttime activity was increased after ABT-116 treatment (P = 0.01). Kinetic gait analysis did not reveal significant treatment effects. Use of rescue treatment decreased with treatment in the ABT-116 and Carprofen groups (P < 0.001). Questionnaire score and activity count at the end of treatment were correlated with age, clinical severity at trial entry, and outcome measure baseline status (S_R ≥ ±0.40, P ≤ 0.005). Placebo treatment effects were evident with all variables studied.

Conclusion

Treatment of hip OA in client-owned dogs is associated with a placebo effect for all variables that are commonly used for efficacy studies of analgesic drugs. This likely reflects caregiver bias or the phenomenon of regression to the mean. In the present study, outcome measures with significant effects also varied between groups, highlighting the value of using multiple outcome measures, as well as an a priori analysis of effect size associated with each measure. Effect size data from the present study could be used to inform design of future trials studying analgesic treatment of canine OA. Our results suggest that analgesic treatment with ABT-116 is not as effective as carprofen or tramadol for treatment of hip arthritis pain in client-owned dogs.

A comparison of extradural tramadol and extradural morphine for postoperative analgesia in female dogs undergoing ovariohysterectomy

PURPOSE: To compare the postoperative analgesic effects of the extradural tramadol or morphine in female dogs undergoing ovariohysterectomy. METHODS: Sixteen female dogs were randomly assigned to two groups of eight animals each and received morphine (0.1mg kg-1 M group) or tramadol (2mg kg-1 T group). The pre-anesthetic medication was intravenously (iv) acepromazine (0.05mg kg-1). Anesthesia was induced with propofol (4mg kg-1iv) and maintained with isoflurane. The degree of analgesia was evaluated using a numerical rating scale that included physiologic and behavior variables. Dogs were scored at one, three, six and 12 hours after surgery by one blinded observer. Dogs were treated with morphine (0.5mg kg-1) if their scores were >6. Serum cortisol was measured before the pre-anesthetic medication was administered (basal), at the time of the ovarian pedicle clamping (T0), and at 1 (T1), 6 (T6) and 12 (T12) hours postoperative. RESULTS: The pain score did not differ between morphine and tramadol treatments. Rescue analgesia was administered to one dog in the T treatment group. Serum cortisol did not differ between treatments. CONCLUSION: The extradural administration of morphine or tramadol is a safe and effective method of inducing analgesia in female dogs undergoing ovariohyterectomy.

Efficacy and safety of deracoxib for the control of postoperative pain and inflammation associated with dental surgery in dogs

The efficacy and safety of deracoxib administered at 1-2 mg/kg/day for 3 days was assessed for the control of postoperative pain and inflammation associated with dental surgery in dogs. Client-owned dogs scheduled for dental extractions were premedicated with butorphanol and randomly assigned to receive either deracoxib (n = 31) or placebo (n = 31) preoperatively and again once daily for 2 additional days. Dogs were evaluated prior to and after surgery using a modified Glasgow Composite Pain Scale (mGCPS). Dogs could be rescued at any time if they scored ≥4 on the mGCPS or in cases of obvious discomfort. Rescued dogs were considered treatment failures for determining treatment response and were removed from the study. Of the 62 dogs enrolled, 57 were usable for the efficacy analyses and all were assessed for safety. Four of 27 deracoxib-treated dogs (14.8%) were rescued compared to 20 of 30 placebo dogs (66.7%) (P = 0.0006). Deracoxib-treated dogs also had numerically lower mGCPS scores. Eight of 31 deracoxib dogs (26%) had adverse events reported compared to 6 of 31 placebo dogs (19%). Results indicate perioperative administration of deracoxib to dogs at 1-2 mg/kg/day for 3 days significantly improves analgesia after dental surgery.