Effects of postoperative ketamine infusion on pain control and feeding behaviour in bitches undergoing mastectomy

Qualitative behavioral assessment of dogs with acute pain

Free Choice Profiling (FCP) methodology allows observers to qualitatively assess animal behavior using their own vocabulary. This study aims to investigate the ability of 3 different observer groups to recognize pain-related emotions in 20 dogs using FCP methodology, and to compare FCP data with the Glasgow Composite Pain Scale-Short Form (GCPS- SF) scores. The observer groups consisted of 10 dog owners, 10 veterinary students and 10 veterinarians. Ten healthy ("healthy") dogs and 10 dogs showing clinical signs of pain ("pain") were filmed, and the resulting 20 footages were shown to observers who were blind to the pain-related nature of the study. All observers described and scored animals' emotional expression using FCP; then, students and veterinarians scored all dogs using GCPS- SF. FCP data were analyzed using Generalized Procrustes Analysis (GPA). Spearman correlation coefficient (ρ) was used to determine the correlation among observer groups' FCP scores of the first two FCP dimensions (DIM1 and DIM2), and to compare GCPS-SF scores with FCP scores for the students and veterinarian observer groups. Each observer group reached a significant (p < 0.001) good consensus profile. "Healthy" dogs were mainly described as "quiet" and "lively", while the majority of "pain" dogs were considered "in pain" and "suffering". The correlation among FCP scores was high between owners' DIM1 and students' DIM1 (ρ = -0.86), owners' DIM2 and students' DIM2 (ρ = 0.72) and students' DIM2 and vets' DIM1 (ρ = 0.70). The correlation between GCPS-SF scores and FCP scores was high for students' DIM2 (ρ = 0.77) and for veterinarians' DIM1 (ρ = 0.92). Qualitative methods such as FCP could be used in association with semi-quantitative methods to evaluate the effect of pain on animal emotional expression. Observers' cultural background and personal experience did not substantially affect qualitative behavioral assessment in dogs with acute somatic pain.

Stereoselective Pharmacokinetics of Ketamine Administered at a Low Dose in Awake Dogs

The present study aimed to examine the stereoselective pharmacokinetics of racemic ketamine in dogs at low doses. The secondary aims were to identify associated behavioural effects and propose a ketamine infusion rate. The study was conducted on nine intact male beagles, with each dog undergoing two treatments (BOL and INF). For treatment BOL, an intravenous bolus of 1 mg/kg was administered over 2 min. The treatment INF involved an initial bolus of 0.5 mg/kg given over 1 min, followed by an infusion at 0.01 mg/kg/min for 1 h. Blood samples were collected for pharmacokinetic analysis. The median R/S enantiomer ratio of ketamine remained close to 1 throughout the study. Levels of S-norketamine were significantly higher than those of R-norketamine across all time points. Based on the collected data, the infusion rate predicted to achieve a steady-state racemic ketamine plasma concentration of 150 ng/mL was 0.028 mg/kg/min. Higher scores for behavioural effects were observed within the first five minutes following bolus administration. The most common behaviours observed were disorientation, head movements and staring eyes. Furthermore, employing ROC curve analysis, a racemic ketamine plasma concentration of 102 ng/mL was defined as the cut-off value, correlating with the occurrence of undesirable behavioural patterns.

Influence of Constant Rate Infusions of Fentanyl Alone or in Combination With Lidocaine and Ketamine on the Response to Surgery and Postoperative Pain in Isoflurane Anesthetized Dogs Undergoing Unilateral Mastectomy: A Randomized Clinical Trial

The aim of this study was to compare the effects of constant rate infusions (CRI) of fentanyl alone or combined with lidocaine and ketamine (FLK), on physiological parameters, isoflurane requirements and the number of postoperative analgesic rescues in dogs undergoing unilateral mastectomy. Twenty-two dogs were premedicated with acepromazine 0.02 mg/kg and morphine 0.5 mg/kg and anesthetized with propofol and isoflurane. Dogs were randomly assigned to 1 of 2 groups: Fentanyl group (fentanyl 5 µg/kg loading dose [LD] and 9 µg/kg/h CRI; n = 11); FLK group (fentanyl [same doses]; lidocaine 2 mg/kg LD and 3 mg/kg/h CRI; ketamine 1.0 mg/kg LD and 0.6 mg/kg/h CRI; = 11). Intraoperative evaluations were performed before the start of surgery and administration of the treatments (T0); three minutes after the LD (T1); during incision and tissue divulsion (T2); during closure of the surgical wound (T3). Meloxicam (0.1 mg/kg) was administered at T3. Blood samples were collected for determination of plasma concentrations of fentanyl, lidocaine and ketamine. Pain scores and the number of postoperative analgesic rescues with morphine (0.5 mg/kg) were evaluated for 24 hours postoperatively using the short form of the Glasgow Composite Measure Pain Scale. Compared to T0, significant decreases in heart rate (from 84 ± 28 to 53 ± 16 bpm in the Fentanyl group and from 93 ± 16 to 63 ± 15 bpm in FLK) and mean arterial pressure (from 61 ± 5 to 49 ± 10 mmHg in Fentanyl and from 59 ± 3 to 38 ± 6 mmHg in FLK) were observed at T1. Arterial hypotension was transient, with normalization of values at T2 and T3. The expired fraction of isoflurane did not differ significantly between the groups. Plasma concentrations of fentanyl, lidocaine and ketamine remained within the therapeutic range. Postoperatively, the number of dogs requiring analgesic rescue was significantly lower in the FLK (0/11, 0%) than in the Fentanyl group (5/11, 45%). In dogs administered morphine and meloxicam as part of the anesthesia protocol, an intraoperative CRI of FLK abolished the requirement for postoperative analgesic rescue for 24 hours in dogs undergoing mastectomy.

Plasma concentration, cardiorespiratory and analgesic effects of ketamine-fentanyl infusion in dogs submitted to mastectomy

Background

The analgesic and cardiorespiratory effects of ketamine, fentanyl, or ketamine-fentanyl constant rate infusion (CRI) in dogs undergoing mastectomy were evaluated. Seventeen female dogs received CRI of ketamine (GK [n = 6]: bolus 0.5 mg/kg; CRI 20 µg/kg/min in intra- and postoperative periods], fentanyl (GF [n = 5]: bolus 20 µg/kg; intraoperative CRI 5 20 µg/kg/hour and postoperative CRI 2 20 µg/kg/hour), or combination of ketamine-fentanyl (GKF [n = 6]: aforementioned doses) for 8 h. Cardiorespiratory, blood gas analyses, plasma drug concentrations, sedation score (SS), Pain Scores were evaluated.

Results

The heart rate decreased in the GF and GKF (p < 0.04); the mean arterial pressure was lower in the GKF than in the GK at 35 min (p < 0.001). Maximum plasma concentrations were observed 5 min after bolus in the GK (2847.06 ± 2903.03 ng/mL) and GKF (2811.20 ± 1931.76 ng/mL). Plasma concentration in intraoperative period of ketamine was of > 100 ng/mL in 5/5 and 2/5 animals in the GKF and GK, respectively; and > 1.1 ng/mL of fentanyl in 4/5 and 3/5 in GKF and GF, respectively.

Conclusion

Ketamine with/without fentanyl provided analgesia without significant cardiorespiratory and guaranteed the minimal plasma levels with analgesic potential during the 8 h.

Stability of dilutions of methadone alone, and in combination with lidocaine and ketamine

OBJECTIVES

To assess stability and degradation over time, of methadone alone, and mixed with lidocaine and ketamine, using various diluents and storage conditions.

MATERIALS AND METHODS

Solutions of methadone diluted in 0.9% NaCl, and methadone-lidocaine-ketamine diluted in 0.9% NaCl or Hartmann's solution, and stored at room temperature with exposure to light, or refrigerated at 4°C and protected from light, were maintained over 10 days. Chemical stability was determined using liquid chromatography immediately after preparation and following 4, 24, 48, 96 and 240 hours of storage. Physical stability of the solutions was evaluated by visual examination and absorbance of ultraviolet/visible light. A linear model assessed the impact of different diluent solutions and storage conditions on drug degradation over time.

RESULTS

There was no evidence of physicochemical incompatibility for any solution. Methadone concentration, when diluted alone or in methadone-lidocaine-ketamine with Hartmann's solution at 4°C, did not decline over time. Ketamine and lidocaine decreased to a similar extent over time, regardless of the diluent used or storage method, while methadone in methadone-lidocaine-ketamine diluted with 0.9% NaCl or with Hartmann's solution at room temperature exposed to light, also declined over time; however, all three methadone-lidocaine-ketamine components retained acceptable stability (<10% degradation) for at least 48 hours following preparation, irrespective of diluent or storage conditions.

CLINICAL SIGNIFICANCE

Regardless of the diluent or storage method, methadone-lidocaine-ketamine solutions degrade over time, but this only becomes clinically significant after 48 hours. Solutions of 1 mg/ml methadone in 0.9% NaCl are stable for at least 10 days under storage conditions likely to be encountered in general practice.

Fentanyl patch versus tramadol for the control of postoperative pain in canine ovariectomy and mastectomy

OBJECTIVES

The purpose of the present study was to evaluate the postoperative analgesic efficacy of fentanyl patches versus subcutaneous tramadol after canine ovariectomy, with and without unilateral mastectomy.

MATERIALS AND METHODS

A total of 40 female dogs were included in the present study, all of which were domesticated, healthy and 4-12 years of age. The animals were divided into four groups (n = 10 per group) based on the surgery and the analgesic protocol used: the TO group only underwent ovariectomy, and received postoperative tramadol; the TM group underwent both ovariectomy and mastectomy, and received postoperative tramadol; the FO group only underwent ovariectomy, and received fentanyl patches; and the FM group underwent both ovariectomy and mastectomy, and received fentanyl patches. Postoperative pain was evaluated every 4 h for 24 h using a numeric analogue scale (NAS) and a modified Glasgow Composite Measure Pain Scale Short Form (CMPS-SF).

RESULTS

The results of the present study showed that patients in all four groups tolerated postoperative surgical stress well. Analysis of variance for repeated measures did not show significant differences in the NAS scores and in Glasgow CMPS-SF between groups in terms of pain scores or rescue analgesia.

CLINICAL SIGNIFICANCE

These results indicated that the analgesic effect of the fentanyl patch was similar to that of subcutaneous (SC) tramadol in female dogs after ovariectomy, with and without unilateral mastectomy, suggesting that the fentanyl patch may represent a valid supplementary tool for the control of postoperative pain in animals after surgery.

Constant Rate Infusion of Lidocaine, Tumescent Anesthesia and Their Combination in Dogs Undergoing Unilateral Mastectomy

Tumescent anesthesia (TUM) is a technique that was initially used to perform liposuction under local anesthesia, which consists of the injection of such large volumes of local anesthetic until to produce swelling and firmness (tumescence) of the surgical area. The aim of this study was to compare the intraoperative analgesic efficacy of lidocaine (LID) constant rate infusion (CRI), of TUM, or their combination (LID/TUM) and the postoperative pain and analgesic requirement in dogs undergoing unilateral mastectomy. Twenty-four dogs were premedicated with dexmedetomidine (3 μg/kg) and methadone (0.2 mg/kg) intravenously (IV). After induction with propofol IV to effect, dogs were randomly allocated to receive a loading dose of lidocaine (2 mg/kg) followed by a CRI of 100 μg/kg/min (Group LID) in addition to an equivalent volume of lactated Ringer's solution instead of local TUM; a loading dose of lactated Ringer's solution followed by a CRI of Ringer's solution in addition to TUM (Group TUM); a loading dose of lidocaine (2 mg/kg) followed by a CRI of 100 μg/kg/min in addition to TUM (Group LID/TUM). Anesthesia was maintained with isoflurane in oxygen. Postoperative pain scores were assessed once the dogs had fully recovered from the sedative effects, and following 15, 30, 45 and 60 min. The results of the current study allow us to assert that all three treatments provided satisfactory intraoperative antinociceptive effects but administration of LID/TUM induced greater inhibition on sympathetic stimulating effect up to 60 min from recovery, thus, providing better early postoperative pain relief in dogs undergoing mastectomy.

A virtual issue highlighting animal studies of eating disorders as valuable tools for examining neurobiological underpinnings and treatment of eating disorders

While studies in humans suggest a role for psychosocial factors as well as biological and genetic processes in the development of eating disorders, the specific etiologic mechanisms remain largely unknown. In this virtual issue, we present a collection of 14 archived articles from the International Journal of Eating Disorders to highlight the utility of animal studies of eating disorders to advance our understanding of eating disorder etiology. Selected articles establish animal studies as valid tools to study disordered eating behavior, offer insight into potential neurobiological mechanisms, and highlight novel targets for future pharmacological treatments. Clinical implications of each article's findings are included to demonstrate the translational value of animal studies for the eating disorders field. We hope that the exciting concepts and findings in this issue inspire future animal studies of eating disorders.

Evaluation of a Single Intra-Articular Injection of Autologous Adipose Tissue for the Treatment of Osteoarthritis: A Prospective Clinical Study in Dogs

OBJECTIVE

 The aim of this study was to investigate the safety, feasibility and clinical efficacy of a single intra-articular injection of autologous and purified micro-fragmented adipose tissue for the treatment of osteoarthritis (OA) in dogs.

STUDY DESIGN

 Twenty-one client-owned dogs with radiographically confirmed OA were recruited into this prospective study. Lameness and discomfort were evaluated by physical examination at day 0 and then 14, 30, 60 and 180 days after injection. Kinetic data and temporospatial parameters were obtained using a pressure-sensing walkway. Peak vertical force, vertical impulse and percentages of body weight distribution were determined. Owner perception data regarding their own dog's physical activity were also collected using the Canine Brief Pain Inventory.

RESULTS

 Radiographic scores for OA from days 0 to 180 were similar, except in two dogs. No major side effects were noted after injection. Lameness and Canine Brief Pain Inventory scores were significantly lower at all time points compared with day 0. Post-injection results demonstrated gradual improvement of kinetic data up to day 180 compared with pre-treatment values: vertical impulse (>2.25%), peak vertical force (>5.32%) and percentages of body weight distribution (>3.6%). In dogs with elbow OA, gait analysis values significantly increased at all time points compared with day 0.

CONCLUSION

 Regenerative autologous adipose tissue injection therapy is a promising alternative to traditional analgesics treatment in patients with OA, associated with significant reductions in pain and lameness, delayed disease progression and improved quality of life.

Pharmacokinetics, absolute bioavailability and tolerability of ketamine after intranasal administration to dexmedetomidine sedated dogs

Intranasal ketamine has recently gained interest in human medicine, not only for its sedative, anaesthetic or analgesic properties, but also in the management of treatment resistant depression, where it has been shown to be an effective, fast acting alternative treatment. Since several similarities are reported between human psychiatric disorders and canine anxiety disorders, intranasal ketamine could serve as an alternative treatment for anxiety disordered dogs. However, to the authors knowledge, intranasal administration of ketamine and its pharmacokinetics have never been described in dogs. Therefore, this study aimed to examine the pharmacokinetics, absolute bioavailability and tolerability of intranasal ketamine administration compared with intravenous administration. Seven healthy, adult laboratory Beagle dogs were included in this randomized crossover study. The dogs received 2 mg/kg body weight ketamine intravenously (IV) or intranasally (IN), with a two-week wash-out period. Prior to ketamine administration, dogs were sedated intramuscularly with dexmedetomidine. Venous blood samples were collected at fixed times until 480 min post-administration and ketamine plasma concentrations were determined by liquid chromatography-tandem mass spectrometry. Cardiovascular parameters and sedation scores were recorded at the same time points. Non-compartmental pharmacokinetic analysis revealed a rapid (Tmax = 0.25 ± 0.14 h) and complete IN bioavailability (F = 147.65 ± 49.97%). Elimination half-life was similar between both administration routes (T1/2el IV = 1.47 ± 0.24 h, T1/2el IN = 1.50 ± 0.97 h). Heart rate and sedation scores were significantly higher at 5 and 10 min following IV administration compared to IN administration, but not at the later time-points.

Adjuvant Analgesics in Acute Pain Management

Adjuvant analgesics (ie, gabapentin, tramadol, and ketamine) are commonly used in small animal practice. Most of these drugs are prescribed for outpatients, when pain is refractory to classic analgesics (ie, local anesthetics, opioids, and nonsteroidal antiinflammatory drugs [NSAIDs]), or when contraindications exist to the administration of other analgesics, including NSAIDs. This article reviews the mechanisms of action, clinical use, potential adverse effects, and current evidence of adjuvant analgesics in the treatment of acute pain in companion animals. These drugs should be considered as alternatives aimed at reducing or replacing opioids.

The influence of subanaesthetic ketamine on regional cerebral blood flow in healthy dogs measured with 99mTc-HMPAO SPECT

Subanaesthetic ketamine has recently been proven to be a highly effective and fast acting alternative treatment for several psychiatric disorders. The mechanisms responsible for ketamine's antidepressant effects remain unclear, but a possible explanation could be that ketamine interacts with regional cerebral blood flow (rCBF). Therefore, the effects of two subanaesthetic ketamine doses on rCBF were evaluated. Twelve dogs were randomly assigned to one of the three treatment conditions (condition saline, condition 0.5 mg/kg ketamine or condition 2 mg/kg ketamine) and received in total five saline or ketamine infusions, with one week interval. Single Photon Emission Computed Tomography (SPECT) scans with the radiotracer 99mTc-hexamethylpropylene amine oxime were performed before the start of the infusions (baseline) and 24 hours after the first (single) and last (multiple) infusion. After a wash out period of 3 months, the animals were again assigned to one of the three treatment conditions described above and the infusion/scan protocol was repeated. During the infusions, cardiovascular parameters were evaluated every ten minutes. A one-way repeated measure ANOVA was set up to assess perfusion index for each ketamine dose for the left frontal cortex (alpha = 0.05). The remaining 11 brain regions were post hoc assessed. Perfusion index was significantly increased in the left frontal cortex and in the thalamus 24 hours after single and multiple ketamine infusions compared to baseline in the 2 mg/kg condition. No clinically relevant cardiovascular effects were observed during the ketamine infusions. This study shows that subanaesthetic ketamine can increase neuronal perfusion and therefore alter neuronal function in brain regions involved in depression and anxiety disorders. These perfusion increases may possibly contribute to ketamine's beneficial effects in these psychiatric disorders.

Single injection of ketamine during mid-adolescence promotes long-lasting resilience to activity-based anorexia of female mice by increasing food intake and attenuating hyperactivity as well as anxiety-like behavior

OBJECTIVE

This study tested the effects of ketamine on vulnerability of female adolescent mice to activity-based anorexia (ABA).

METHOD

Twenty-four female C57Bl/6 J mice underwent ABA induction, which involved exposing wheel-acclimated adolescent mice to two bouts of food restriction (FR)-the first ABA (P41-44, mid-adolescence) and the second ABA (P55-59, late adolescence), with recovery in between. Ketamine (3 or 30 mg/kg) or vehicle was given once, on the second day of FR of the first ABA (P42). Food consumption, body weight and wheel running activity were measured daily. Anxiety-like behaviors were accessed by elevated plus maze on P49 and P62, after weight restoration during the recovery phase.

RESULTS

Ketamine (30 mg/kg) increased food intake during the first ABA (+38%, p = .015) and facilitated weight gain during recovery (+42%, p = .003). During the second ABA, the effect was manifested as increased food intake (+38%, p = .001) and weight gain (+47%, p = .001) while attenuating FR-induced wheel running activity (-24%, p = .09) and weight loss (-17%, p = .056). Ketamine also reduced anxiety-like behaviors.

DISCUSSION

Thus, single injection of ketamine during mid-adolescence effectively attenuates vulnerability of female mice to repeated ABA exposures.

Comparison of Morphine, Morphine-Lidocaine, and Morphine-Lidocaine-Ketamine Infusions in Dogs Using an Incision-Induced Pain Model

We aimed to compare antinociceptive effects of IV infusions of morphine (M), morphine-lidocaine (ML), or morphine-lidocaine-ketamine (MLK) combined, in a mild-to-moderate pain model in dogs. Eighteen adult hounds were heavily sedated with IV morphine (0.2 mg/kg) and dexmedetomidine to undergo thoracic skin incisions. After reversal, dogs were randomly assigned to receive loading doses of lidocaine and ketamine (MLK), lidocaine and saline (ML), or equivalent volume of saline (M), followed by 18 hr constant infusions of morphine (0.12 mg/kg/hr), lidocaine (3 mg/kg/hr) and ketamine (0.6 mg/kg/hr); morphine (0.12 mg/kg/hr) and lidocaine (3 mg/kg/hr); or morphine (0.12 mg/kg/hr), respectively. Pain was assessed with Short Form Glasgow Composite Measure Pain Scale and mechanical nociception with von Frey filaments (VFFS). Data were analyzed with linear mixed model on ranks. Independently of treatment, Short Form Glasgow Composite Measure Pain Scale was significantly higher than baseline for 24 hr (p < .0001), while VFFS was significantly lower than baseline for 48 hr post-recovery (p < .0001), with no difference between MLK and M groups. The ML group recorded significantly lower VFFS (p = .02) than the M group for the entire study. In conclusion, there was no significant analgesic difference between MLK and M alone.

Serum concentration of ketamine and antinociceptive effects of ketamine and ketamine-lidocaine infusions in conscious dogs

Background

Central sensitization is a potential severe consequence of invasive surgical procedures. It results in postoperative and potentially chronic pain enhancement. It results in postoperative pain enhancement; clinically manifested as hyperalgesia and allodynia. N-methyl-D-aspartate (NMDA) receptor plays a crucial role in the mechanism of central sensitisation. Ketamine is most commonly used NMDA-antagonist in human and veterinary practice. However, the antinociceptive serum concentration of ketamine is not yet properly established in dogs. Six dogs were used in a crossover design, with one week washout period. Treatments consisted of: 1) 0.5 mg/kg ketamine followed by continuous rate infusion (CRI) of 30 μg/kg/min; 2) 0.5 mg/kg ketamine followed by CRI of 30 μg/kg/min and lidocaine (2 mg/kg followed by CRI of 100 μg/kg/min); and 3) 0.5 mg/kg ketamine followed by CRI of 50 μg/kg/min. The infusion was administered up to 120 min. Nociceptive thresholds and ketamine serum concentrations were measured before drug administration, and at 5, 10, 20, 40, 60, 90, 120, 140 and 160 min after the start of infusion.

Results

Maximum concentration recorded was 435.34 ± 26.18 ng/mL, 582.34 ± 227.46 ng/mL and 733.77 ± 133.6 ng/mL for K30, KL30 and K50, respectively. The concentration at 120 min was 250.87 ± 39.87, 221.73 ± 91.03 and 343.67 ± 63.21 ng/mL at 120 min in K30, KL30 and K50, respectively. All the three infusion regimes maintained serum concentrations above 200 ng/mL. The thresholds returned towards baseline values within 20 min, after cessation of infusion.

Conclusion

Serum concentration to produce mechanical antinociceptive effects in dogs is between 100 and 200 ng/mL. All the three infusion regimes in this study provided antinociceptive effects throughout the infusions. In this study, we found that the serum concentration of ketamine to produce mechanical antinociceptive effects in dogs is above 200 ng/mL. All three infusion regimes provided antinociceptive effects throughout the infusions without causing harmful effects. Further studies are recommended in a clinical setting.

Botulinum toxin type A as an adjunct in postoperative pain management in dogs undergoing radical mastectomy

The aim of this randomised placebo-controlled, observer-blinded study was to evaluate the analgesic effects of botulinum toxin type A (BoNT-A) as an adjunct for postoperative pain control in dogs. Sixteen dogs undergoing bilateral radical mastectomy for treatment of mammary tumours were enrolled. Twenty-four hours before surgery, the subjects were distributed into two groups of eight dogs each: 7 iu/kg BoNT-A (BoNT-A) or saline (Control) was administered subcutaneously in each mammary gland. Following sedation with intramuscular 0.03 mg/kg acepromazine and 0.3 mg/kg morphine, anaesthesia was induced intravenously with 4 mg/kg propofol and maintained with isoflurane/O2. Postoperative analgesia was evaluated for 72 hours after extubation using the Visual Analogue Scale (VAS) and modified Glasgow Composite Measure Pain Scale (modified-GCMPS). Rescue analgesia was provided with intramuscular morphine (0.5 mg/kg). Data were analysed using analysis of variance, Tukey's test, Mann-Whitney U test and Friedman test (P<0.05). The pain scores were significantly lower in the BoNT-A than in the Control from 8 hours to 60 hours and from 12 hours to 60 hours after extubation, based on the VAS and modified-GCMPS, respectively. Rescue analgesia was required by significantly more dogs in the Control (7/8) compared with the BoNT-A (2/8) (P=0.022). Pre-emptive BoNT-A appears to be effective as an adjuvant for postoperative pain management in dogs undergoing bilateral radical mastectomy.

Gabapentin as an adjuvant for postoperative pain management in dogs undergoing mastectomy

This study aimed to evaluate the analgesic efficacy of gabapentin as an adjuvant for postoperative pain management in dogs. Twenty dogs undergoing mastectomy were randomized to receive perioperative oral placebo or gabapentin (10 mg/kg). All dogs were premedicated with intramuscular acepromazine (0.03 mg/kg) and morphine (0.3 mg/ kg). Anesthesia was induced with propofol (4 mg/kg) intravenously and maintained with isoflurane. Intravenous meloxicam (0.2 mg/kg) was administered preoperatively. Postoperative analgesia was evaluated for 72 hr. Rescue analgesia was provided with intramuscular morphine (0.5 mg/kg). Dogs in the Placebo group received significantly more morphine doses than the Gabapentin group (P=0.021), despite no significant differences in pain scores. Perioperative gabapentin reduced the postoperative morphine requirements in dogs after mastectomy.

2015 AAHA/AAFP pain management guidelines for dogs and cats

RATIONALE

The robust advances in pain management for companion animals underlie the decision of the American Animal Hospital Association (AAHA) and American Association of Feline Practitioners (AAFP) to expand on the information provided in the 2007 AAHA/AAFP Pain Management Guidelines. The 2015 Guidelines summarize and offer a discriminating review of much of this new knowledge.

RELEVANCE

Pain management is central to veterinary practice, alleviating pain, improving patient outcomes, and enhancing both quality of life and the veterinarian-client-patient relationship. These Guidelines support veterinarians in incorporating pain management into practice, improving patient care.

APPROACHES

The management of pain requires a continuum of care that includes anticipation, early intervention, and evaluation of response on an individual patient basis. A team-oriented approach, including the owner, is essential for maximizing the recognition, prevention and treatment of pain in animals.

EVIDENCE BASE

The Guidelines include both pharmacologic and non-pharmacologic modalities to manage pain; they are evidence-based insofar as possible and otherwise represent a consensus of expert opinion. Behavioral changes are currently the principal indicator of pain and its course of improvement or progression, and the basis for recently validated pain scores. Post-surgical pain is eminently predictable but a strong body of evidence exists supporting strategies to mitigate adaptive as well as maladaptive forms. Chronic pain is dominated by degenerative joint disease (DJD), which is one of the most significant and under-diagnosed diseases of cats and dogs. DJD is ubiquitous, found in pets of all ages, and inevitably progresses over time; evidence-based strategies for management are established in dogs, and emerging in cats.

Electroencephalographic changes associated with antinociceptive actions of lidocaine, ketamine, meloxicam, and morphine administration in minimally anaesthetized dogs

Effects of ketamine and lidocaine on electroencephalographic (EEG) changes were evaluated in minimally anaesthetized dogs, subjected to electric stimulus. Six dogs were subjected to six treatments in a crossover design with a washout period of one week. Dogs were subjected to intravenous boluses of lidocaine 2 mg/kg, ketamine 3 mg/kg, meloxicam 0.2 mg/kg, morphine 0.2 mg/kg and loading doses of lidocaine 2 mg/kg followed by continuous rate infusion (CRI) of 50 and 100 mcg/kg/min, and ketamine 3 mg/kg followed by CRI of 10 and 50 mcg/kg/min. Electroencephalogram was recorded during electrical stimulation prior to any drug treatment (before treatment) and during electrical stimulation following treatment with the drugs (after treatment) under anaesthesia. Anaesthesia was induced with propofol and maintained with halothane at a stable concentration between 0.85 and 0.95%. Pretreatment median frequency was evidently increased (P < 0.05) for all treatment groups. Lidocaine, ketamine, and morphine depressed the median frequency resulting from the posttreatment stimulation. The depression of median frequency suggested evident antinociceptive effects of these treatments in dogs. It is therefore concluded that lidocaine and ketamine can be used in the analgesic protocol for the postoperative pain management in dogs.

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.

Anestesia convencional e técnica de tumescência em cadelas submetidas à mastectomia. Avaliação da dor pós-operatória

As neoplasias mamárias são as mais comuns em cadelas e geralmente acometem fêmeas de meia-idade a idosas, não castradas ou que foram submetidas ao procedimento de ovario-histerectomia tardiamente. A principal forma de tratamento é a excisão cirúrgica, sendo a ressecção unilateral das glândulas mamárias o procedimento mais realizado na prática veterinária. O objetivo do presente estudo foi comparar a dor pós-operatória em cadelas submetidas ao procedimento de mastectomia unilateral sob efeito das técnicas anestésicas de tumescência ou convencional. Foram utilizadas 20 cadelas, divididas em dois grupos: um grupo recebeu apenas a anestesia geral inalatória (grupo convencional), e o outro recebeu adicionalmente a anestesia infiltrativa por tumescência (grupo tumescência). Elas foram avaliadas nas primeiras 24 horas do período pós-operatório, e o processo álgico foi avaliado pela escala de dor da Universidade de Melbourne. As médias dos escores obtidos ao longo do tempo foram submetidas ao teste de Tukey a um nível de 5% de significância (p<0,05). Não foram observadas diferenças significativas entre os grupos com relação à dor pós-operatória. A técnica anestésica infiltrativa por tumescência apresentou a vantagem da redução do sangramento transoperatório e mostrou-se exequível em pequenos animais, entretanto seu uso está relacionado à experiência e à preferência do cirurgião e do anestesista.

Postoperative analgesic effects of either a constant rate infusion of fentanyl, lidocaine, ketamine, dexmedetomidine, or the combination lidocaine-ketamine-dexmedetomidine after ovariohysterectomy in dogs

OBJECTIVE

To evaluate the postoperative analgesic effects of a constant rate infusion (CRI) of either fentanyl (FENT), lidocaine (LIDO), ketamine (KET), dexmedetomidine (DEX), or the combination lidocaine-ketamine-dexmedetomidine (LKD) in dogs.

STUDY DESIGN

Randomized, prospective, blinded, clinical study.

ANIMALS

Fifty-four dogs.

METHODS

Anesthesia was induced with propofol and maintained with isoflurane. Treatments were intravenous (IV) administration of a bolus at start of anesthesia, followed by an IV CRI until the end of anesthesia, then a CRI at a decreased dose for a further 4 hours: CONTROL/BUT (butorphanol 0.4 mg kg(-1), infusion rate of saline 0.9% 2 mLkg(-1) hour(-1)); FENT (5 μg kg(-1), 10 μg kg(-1) hour(-1), then 2.5 μg kg(-1) hour(-1)); KET (1 mgkg(-1) , 40 μg kg(-1) minute(-1), then 10 μg kg(-1) minute(-1) ; LIDO (2 mg kg(-1), 100 μg kg(-1) minute(-1), then 25 μg kg(-1) minute(-1)); DEX (1 μgkg(-1), 3 μg kg(-1) hour(-1), then 1 μg kg(-1) hour(-1)); or a combination of LKD at the aforementioned doses. Postoperative analgesia was evaluated using the Glasgow composite pain scale, University of Melbourne pain scale, and numerical rating scale. Rescue analgesia was morphine and carprofen. Data were analyzed using Friedman or Kruskal-Wallis test with appropriate post-hoc testing (p < 0.05).

RESULTS

Animals requiring rescue analgesia included CONTROL/BUT (n = 8), KET (n = 3), DEX (n = 2), and LIDO (n = 2); significantly higher in CONTROL/BUT than other groups. No dogs in LKD and FENT groups received rescue analgesia. CONTROL/BUT pain scores were significantly higher at 1 hour than FENT, DEX and LKD, but not than KET or LIDO. Fentanyl and LKD sedation scores were higher than CONTROL/BUT at 1 hour.

CONCLUSIONS AND CLINICAL RELEVANCE

LKD and FENT resulted in adequate postoperative analgesia. LIDO, CONTROL/BUT, KET and DEX may not be effective for treatment of postoperative pain in dogs undergoing ovariohysterectomy.

Assessment of postoperative pain after unilateral mastectomy using two different surgical techniques in dogs

Background

There are few studies reporting pain and postoperative analgesia associated with mastectomy in dogs. The aim of this study was to evaluate postoperative pain after unilateral mastectomy using two different surgical techniques in the dog.

Findings

Twenty female dogs were assigned (n=10/group) to undergo unilateral mastectomy using either the combination of sharp and blunt dissection (SBD) or the modified SBD (mSBD) technique, in which the mammary chain is separated from the abdominal wall entirely by blunt (hand and finger) dissection except for a small area cranial to the first gland, in a prospective, randomized, clinical trial. All dogs were premedicated with intramuscular acepromazine (0.05 mg/kg) and morphine (0.3 mg/kg). Anesthesia was induced with intravenous ketamine (5 mg/kg) and diazepam (0.25 mg/kg), and maintained with isoflurane. Subcutaneous meloxicam (0.2 mg/kg) was administered before surgery. Postoperative pain was evaluated according to the University of Melbourne pain scale (UMPS) by an observer who was blinded to the surgical technique.. Rescue analgesia was provided by the administration of intramuscular morphine (0.5 mg/kg) if pain scores were >14 according to the UMPS. Data were analyzed using t-tests and ANOVA (P>0.05). There were no significant differences between the groups for age, weight, extubation time, and duration of surgery and anesthesia (P>0.05). There were no significant differences for postoperative pain scores between groups. Rescue analgesia was required in one dog in each group.

Conclusions

The two surgical techniques produced similar surgical times, incidence of perioperative complications and postoperative pain. Multimodal analgesia is recommended for treatment of postoperative pain in dogs undergoing unilateral mastectomy.

Electroacupuncture versus morphine for the postoperative control pain in dogs

PURPOSE

[corrected] To compare the postoperative analgesic effects of electroacupuncture, morphine or sham acupuncture in dogs undergoing mastectomy.

METHODS

Thirty client-owed dogs undergoing to mastectomy were randomly assigned to three groups of 10 animals each and received either morphine (T-M), the electroacupuncture (T-EA) or sham procedure (T-Sham). Pre-anesthetic medication was acepromazine (0.05 mg kg(-1), IM). Anesthesia was induced with propofol (4 to 5 mg kg(-1), IV) and maintained with isoflurane. Postoperatively pain degree was assessed using a numerical rating scale. Dogs were scored at 1, 3, 6 and 12 hours post-extubation. If the pain score was ≥6, supplemental morphine was administered. Serum cortisol concentration was measured before pre-anesthetic medication, at 45 minutes after the anesthetic induction, and at 1, 3 and 6 hours post-extubation.

RESULTS

The pain score did not differ among the treatments, but rescue analgesia was lower in the T-EA group (2 of 10 dogs), when compared with T-Sham (6 of 10 dogs) and T-M (6 of 10 dogs) groups. Serum cortisol concentration did not differ among the treatments.

CONCLUSION

Electroacupuncture reduces the postoperative analgesic requirement and promotes satisfactory analgesia in dogs undergoing mastectomy.

Canine mammary tumours, an overview

Canine mammary tumours (CMTs) are the most common neoplasms in intact female dogs. Although the prevalence of these tumours decreases in regions where preventive ovari(ohyster)ectomy is performed, it remains an important disease entity in veterinary medicine. Moreover, treatment options are limited in comparison with human breast cancer. Nevertheless, recent human treatment protocols might have potential in bitches suffering from CMTs.

Effect of ketamine on the limb withdrawal reflex evoked by transcutaneous electrical stimulation in ponies anaesthetised with isoflurane

The purpose of this study was to evaluate the anti-nociceptive activity of ketamine and isoflurane in horses using a limb withdrawal reflex (WR) model. Single and repeated stimulations were applied to the digital nerve of the left forelimb in ponies anaesthetised with isoflurane before, during and after intravenous administration of racemic ketamine. Surface electromyographic activity was recorded from the deltoid muscle. Higher stimulation intensity was required to evoke a reflex during ketamine administration. Furthermore, the amplitudes of response to stimulations were significantly and dose-dependently depressed and a flattening of the stimulus-response curves was observed. The reflex activity recovered partially once the ketamine infusion finished. The results demonstrated that the limb WR can be used to quantify the temporal effect of ketamine on the sensory-motor processing in ponies anaesthetised with isoflurane.

Analgesic management of an eight-year-old Springer Spaniel after amputation of a thoracic limb

Analgesic agents were administered perioperatively to an eight-year-old Springer Spaniel undergoing amputation of its right thoracic limb. The amputation was carried out due to a painful, infiltrative and poorly differentiated sarcoma involving the nerves of the brachial plexus. A combination of pre-emptive and multimodal perioperative analgesic strategies was used; including intravenous (IV) infusions of fentanyl, morphine, lidocaine and ketamine.

Adjunctive analgesic therapy in veterinary medicine

Adjunctive analgesic therapies are interventions for pain that involve agents or techniques other than the traditional analgesics (opioids, nonsteroidal anti-inflammatory drugs, and local anesthetics). Adjunctive therapies may be pharmacologic or nonpharmacologic in nature. The focus of this article is on pharmacologic interventions with potential utility as adjunctive analgesics in veterinary medicine. Pharmacology of selected agents, including medetomidine, ketamine, amantadine, gabapentin, systemic lidocaine, and pamidronate, is discussed in addition to evidence for their safety and efficacy and guidelines for their use in veterinary patients.

Analgesia for the critically ill dog or cat: an update

Acute pain reliably accompanies severe illness and injury, and when sufficiently severe, it can complicate the recovery of critically ill patients. Because acute pain is closely tied to the neurologic process of nociception, pharmacologic therapy is often essential and effective. This update focuses on two methods of treatment of acute pain-local anesthetic infusion and continuous intravenous infusion of multimodal agents-that can be layered on top of standard care with other drugs.

Neuropathic pain in dogs and cats: if only they could tell us if they hurt

Neuropathic pain is difficult to diagnose in veterinary patients because they are unable to verbalize their pain. By assuming that neuropathic pain may exist based on the history of events that each patient has experienced, a focused client history and neurologic examination may identify a lesion resulting in persistent or spontaneous pain. Once neuropathic pain is diagnosed, a trial analgesic or acupuncture session(s) should be prescribed with instructions for owners to observe behavior. Dosing of the analgesic can be titrated to the patient's needs while avoiding adverse effects. When a particular analgesic may be ineffectual, an alternate class should be tried. As research into the neurobiologic mechanisms of neuropathic pain continues, specific therapies for its management should eventually appear in the human clinical setting and subsequently be investigated for veterinary clinical use.