Postoperative opioid-free analgesia in dogs undergoing tibial plateau leveling osteotomy: a feasibility study

Objectives

This study was designed to prospectively evaluate the feasibility of an opioid-free anesthesia protocol and describe the quality of recovery and management of postoperative analgesia in dogs after a tibial plateau leveling osteotomy (TPLO).

Methods

In total, 20 dogs presented for TPLO were included. After premedication with intravenous (IV) medetomidine (0.005-0.007 mg/kg) and midazolam (0.2 mg/kg), the dogs were anesthetized using ketamine (2 mg/kg) and propofol and maintained with isoflurane and ketamine CRI (0.6 mg/kg/h). Sciatic and femoral nerve blocks were performed with bupivacaine 0.5% (0.087 +/- 0.01 and 0.09 +/- 0.02 mL/kg, respectively). Meloxicam (0.2 mg/kg IV) was administered intraoperatively, after osteotomy. Fentanyl (0.002 mg/kg IV) was administered intraoperatively, as rescue analgesia in the case of sustained increase in cardiorespiratory variables. Two pain scores (French 4A-VET and Glasgow short form) were performed at conscious sternal recumbency and 2, 4, 6, 8, 12, and 20 h after extubation and compared to baseline using a Friedman test followed by a Nemenyi post-hoc test. The time taken for the first food intake and urination was reported.

Results

Intraoperative opioid-free anesthesia was feasible in 11 dogs, whereas 9 dogs received fentanyl once during arthrotomy. No opioid postoperative rescue analgesia was required. Food intake occurred within 6 h, and all dogs were discharged after 24 h without any complication.

Conclusion

Total opioid-free postoperative analgesia was achieved in all dogs, with adequate recoveries. Although opioid-free anesthesia was feasible in 55% of the population, a single dose of fentanyl was necessary in 45% of the dogs during arthrotomy.

Instrument shank-assisted ovariohysterectomy: a randomized clinical trial of surgical and pain alleviation efficiency of a single-person modified technique

Objectives

To evaluate a modified ovariohysterectomy (OHE) technique performed by a single person and compare it with the conventional method based on time efficiency, trauma, and postoperative pain.

Methods

In a prospective, randomized, experimental study, 18 healthy, large, deep-chested, mixed-breed intact female dogs were randomly allocated to conventional (n = 9) and instrument shank-assisted (n = 9) groups. On the basis of video recordings, the various surgical step durations were analyzed: total surgery time (TST), pedicle intervention time (PIT), suspensory release time (SRT), shanking time (ShT), clamping time (ClpT), ligating time (LigT), and closure time (CT). The Glasgow composite pain scale short-form (GCMPS-SF), university of Melbourne pain scale (UMPS), and Visual Analogue Scales (VAS) were used to measure pain. C-reactive protein (CRP) fluctuation was also investigated. These evaluations were completed before and 6, 24, 48, and 72 h postoperatively.

Results

Instrument shank-assisted OHE was less time-consuming than conventional OHE (p = 0.005), improved PIT by 30.7% (6.44 min for both pedicles, p = 0.014), and correlated strongly with TST (ρ = 0.862, p = 0.003 and ρ = 0.955, p = 0.000, respectively). The two method's surgical step durations were also TST = 47.40 ± 9.9 vs. 34.70 ± 6.7 min, PIT = 20.96 ± 5.78 vs. 14.52 ± 3.73 min, SRT = 78.97 ± 69.10 vs. ShT = 20.39 ± 8.18 s (p = 0.035), ClpT = 50.66 ± 45.04 vs. 63.55 ± 37.15 s (p = 0.662), LigT = 12.82 ± 3.37 vs. 8.02 ± 3.11 min (p = 0.005), and CT = 16.40 ± 4.5 vs. 11.60 ± 2.5 min (p = 0.013), respectively. While both techniques inflicted pain on the animals, the novel approach resulted in a reduction of pain at T6 (GCMPS-SF, p = 0.015 and VAS, p = 0.002), T24 (UMPS, p = 0.003), and T48 (GCMPS-SF, p = 0.015 and UMPS, p = 0.050). Both methods exhibited a peak in CRP level after 24 h, which subsequently returned to baseline after 48 h. However, the shank-assisted method demonstrated a significantly lower reduction in CRP level at the 48-h compared to the other group (p = 0.032).

Conclusion

Instrument shank-assisted technique permitted ovarian removal without an assistant, less damage to animals and reducing its time when compared to a conventional technique, and resulting in an alternative that causes less surgical stress and fatigue. Further research with a larger population size is required to determine the serum CRP levels as an alternative pain biomarker.

Use of pupillometry for the evaluation of analgesia in dogs hospitalized in intensive care: A prospective study

A prospective study was performed on hospitalized conscious dogs. The objectives were: 1) to evaluate the feasibility and reliability of portable infrared pupillometry using a measure of photo light reflexes, 2) to identify parameters influencing measures, and 3) to compare parameters before and after the administration of analgesia. Twenty-nine dogs were included. Pupillometry was feasible by a single person. There was an excellent reliability for the evaluation of pupil diameter. There was poor to good reliability for the other parameters. There was an association between weight and mean pupil diameter (estimate = 0.1 mm, CI95 = [0.0; 0.1], P = 0.02), mean diameter variation (estimate = 0.2%, CI95 = [0.0; 0.4], P = 0.01), and mean velocity (estimate = 0.08 ms, CI95 = [0.03; 0.13], P = 0.002). Male dogs had a significantly larger mean pupil diameter than females (estimate = 1.3 mm, CI95 = [0.1; 2.5], P = 0.03). Independently of weight and sex, there was an association between mean pupil diameter and pain score: the higher the pain score, the lower the mean pupil diameter. There was a correlation between mean pupil diameter and morphine dose (ρ = -0.78, P = 0.0004). There was no significant difference in pupil diameter, velocity, and latency before and after analgesic administration. In conclusion, results do not support the use of PLR measurement by pupillometry as a pain assessment technique in hospitalized conscious dogs.

A Formalized Method to Acclimate Dogs to Voluntary Treadmill Locomotion at Various Speeds and Inclines

The land treadmill is a multipurpose tool with a unique set of behavioral and physical benefits for training and assessing active dogs. Habituation to voluntary treadmill locomotion is crucial for training a dog or accurately assessing a dog's fitness on a treadmill. Therefore, a treadmill acclimation program was developed and evaluated with working dogs in training or working dogs performing detection research. Seven of eight naive dogs became acclimated to the treadmill using the protocol developed. Two previously experienced dogs successfully conducted an acclimation assessment to test for habituation to the treadmill. A muscle soreness protocol was created to evaluate the soreness developed during the acclimation program. This detailed protocol was successful in acclimating dogs to the treadmill at various safe speeds and inclines.

Investigating the effect of anxiety on pain scores in dogs

OBJECTIVE

To investigate the relationship between anxiety and pain scores using the Glasgow Composite Measure Pain Scale-Short Form (CMPS-SF) in dogs.

STUDY

Prospective observational study.

ANIMALS

A group of 18 dogs undergoing surgical management of stifle disease.

METHODS

Preoperatively dogs were scored using the CMPS-SF, the anxiety behaviour-based Reactivity Evaluation Form (REF), a Visual Analogue Scale (VAS) for anxiety and a sedation score. Assessments of pain, anxiety and sedation were repeated approximately 2-6 hours postoperatively. Dogs were divided into groups based on preoperative REF ('Low REF' and 'High REF'), and VAS scores ('Low VAS' and 'High VAS'). Scores (CMPS-SF, REF, VAS and sedation) were compared between groups using Mann-Whitney U tests. Preoperative and postoperative CMPS-SF, REF and VAS scores were compared using Wilcoxon signed-rank tests. Relationships between anxiety and CMPS-SF scores were assessed using a Spearman rank correlation coefficient. Scores are presented as median (range). A p value of < 0.05 was considered significant.

RESULTS

When divided based on REF, CMPS-SF scores did not differ between groups preoperatively [Low REF: 2 (0-3), High REF: 2 (1-3); p = 0.509] or postoperatively [Low REF: 3 (2-5), High REF: 3 (2-5); p = 0.624]. When divided based on VAS, CMPS-SF scores did not differ between groups preoperatively [Low VAS: 2 (0-2), High VAS: 2 (1-3); p = 0.215] or postoperatively [Low VAS: 3 (2-5), High VAS: 3 (2-5); p = 1]. Postoperative REF [pre: 4.5 (2-8), post: 5 (4-10); p = 0.0105] and CMPS-SF scores [pre: 2 (0-3), post: 3 (2-5); p = 0.0318] increased significantly compared with preoperative scores.

CONCLUSIONS AND CLINICAL RELEVANCE

No apparent relationship exists between baseline anxiety levels and CMPS-SF scores. Understanding the influence of anxiety when using the CMPS-SF is important when assessing pain in dogs. Anxiety and pain may increase postoperatively in dogs undergoing orthopaedic surgery.

Histopathological Parameters of Canine Bone Marrow in Cell-Block Preparations

Studies using the cell-block technique for bone marrow (BM) analysis are limited in the veterinary literature. This work assessed whether the histopathological analysis of canine BM was feasible using cell-block cytoinclusions prepared from fine-needle sternal aspirate samples. Eight clinically healthy young-to-middle-aged dogs underwent both fine-needle sternal aspiration for BM cell-block (BM-Cb) processing and iliac-crest BM core biopsy (BM-B). Histopathologic parameters were compared between the 2 methods. There were no statistically significant histopathological differences between hematopoietic tissue areas (P =  .6294) in the BM-Cb and BM-B sections, and they had similar microscopic characteristics and microarchitecture. Cellularity and reticulin-fiber staining were equivalent in the BM-Cb and BM-B preparations in 87.5% (7/8) and 100% (8/8) of the sections, respectively. However, the quantitative results of the megakaryocytic series differed between BM-Cb and BM-B in 37.5% (3/8) of the sections, and the myeloid:erythroid (M:E) ratios differed between the 2 methods in 25% (2/8). These preliminary data indicate that cell-block preparations made from sternal fine-needle aspiration samples warrant continued evaluation in a larger number of animals, including those with various diseases affecting the bone marrow.

Postoperative evaluation of analgesia promoted by the use of dexmedetomidine alone and associated with morphine as an intramuscular pre-anesthetic medication in bitches submitted for ovariohysterectomy

Abstract This study aimed to evaluate the postoperative analgesic efficacy of dexmedetomidine alone and when associated with morphine in patients under general inhalational anesthesia with isoflurane and undergoing elective ovariohysterectomy (OH). Twenty healthy bitches were selected via physical and laboratory examinations. Prior to the study, they underwent a 24-h period of adaptation to the environment and observers. They were then randomly divided into two groups: the dexmedetomidine group receiving a dose of 10 μg/kg, and dexmedetomidine group (10 μg/kg) associated with morphine receiving a dose of 0.3 mg/kg, administered via the intramuscular route. Thereafter, patients were induced with propofol and maintained with isoflurane diluted in 100% oxygen administered through a calibrated vaporizer. To verify postoperative analgesia, pain assessments were performed using the modified Glasgow (EGM) and Melbourne (EM) scales. For sedation assessment, the Dobbins scale was used at different times: before the administration of pre-anesthetic medication (T0) and at another six times in the postoperative period, 1 (T1), 2 (T2), 4 (T3), 8 (T4), 12 (T5), and 24 (T6) h after orotracheal extubation. No statistical differences were observed between groups in the scales according to Dunn’s Kruskal-Wallis post hoc test, and between the times a statistical difference was noticed by the Friedman test (p<0.05) for the EGM and EM scale scores, but there was no need for analgesic rescue. Therefore, we found that isolated dexmedetomidine and morphine produced adequate analgesic effects in the postoperative period of bitches submitted for OH.

Complications associated with bone marrow sampling in dogs and cats

OBJECTIVES

To evaluate the prevalence of complications during bone marrow sampling and associated patient and procedural factors in dogs and cats.

MATERIALS AND METHODS

Retrospective cohort study, records were evaluated to identify dogs and cats that had bone marrow sampling between 2012 and 2019. Data including signalment, the presence of specific clinicopathological findings, anatomical site of bone marrow sampling, number of attempts, diagnostic quality of sampling, analgesia protocol and complications postprocedure were recorded.

RESULTS

A total of 131 dogs and 29 cats were included in the study. Complications were recorded in 22 of 160 (14%) of cases. Pain was the most common complication of bone marrow sampling in 20 of 22 (91%) of cases with bruising reported in the remaining patients. A local anaesthetic block was used in 98 of 160 (61%) of patients.

CLINICAL SIGNIFICANCE

Excluding pain, complications associated with bone marrow sampling were rare and no clear association were detected between patient or procedural variables. Haemorrhage and infection are rare complications in dogs and cats when thrombocytopenia and neutropenia are present. Peri-procedure analgesia is strongly recommended to minimise complications.

The effect of neuraxial morphine on postoperative pain in dogs after extrahepatic portosystemic shunt attenuation

OBJECTIVE

To investigate the analgesic effect of epidural morphine after surgical extrahepatic portosystemic shunt (EHPSS) attenuation.

STUDY DESIGN

Randomized clinical trial.

ANIMALS

A total of 20 dogs with a congenital EHPSS.

METHODS

Dogs were randomly allocated to be given either a single epidural dose of 0.2 mg kg^-1 preservative-free morphine (group M) or not (group C) before surgery. All dogs were administered 0.3 mg kg^-1 methadone intravenously (IV) as preanaesthetic medication. Pain scores were determined every 2 hours for the first 24 hours postoperatively using the short-form Glasgow Composite Measure Pain Scale (GCMPS-SF). Dogs with a GCMPS-SF pain score >4/20 or >5/24 received 0.1 mg kg^-1 methadone IV as rescue analgesia and were reassessed 30 minutes later. If more than three doses of methadone were administered in a 2 hour period, alternative pain relief was provided and a treatment failure recorded. The GCMPS-SF pain scores and number of rescue analgesia injections were analysed over 24 hours. The last observation carried forward method was applied in case of treatment failure. Food consumption and time to first urination were recorded. Data were analysed using a Mann-Whitney U test and presented as median (minimum-maximum range), with significance set at p < 0.05.

RESULTS

Group M showed lower GCMPS-SF pain scores [15 (11-41) versus 31 (11-86); p = 0.023] and lower postoperative methadone requirements [0 (0-0.2) versus 0.25 (0-0.5) mg kg^-1; p = 0.029] than group C. There were three treatment failures in group C only. Food consumption and time to first urination did not differ between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Epidural morphine reduced the requirement for postoperative analgesia in this study population.

Agreement among anesthesiologists regarding postoperative pain assessment in dogs

OBJECTIVE

To establish evidence for the validity and reliability of three commonly used pain scales in dogs when assessed by video by specialists in anesthesia.

STUDY DESIGN

Mixed-method test-retest observational study.

SUBJECTS

A group of six American College of Veterinary Anesthesia and Analgesia board-certified specialists and 31 postoperative dogs.

METHODS

The evaluators scored 31 dogs using a visual analogue scale (VAS), numeric rating scale (NRS), and Glasgow pain scale (GPS). The evaluators individually scored the dogs using all three scales together and subsequently, at 3 month intervals, using each of the scales apart. Then, all evaluators in one room reviewed 23 of the videos. A camera was positioned for video and audio recording of discussion about the videos. Intra- and interobserver reliability was determined using a two-way random model intra-class correlation coefficient (ICC).

RESULTS

Linear regression indicated a strong correlation among all scales when assigned together (VAS versus NRS, p < 0.0001, R² = 0.93; VAS versus GPS, p < 0.0001, R² = 0.59; and NRS versus GPS, p < 0.0001, R² = 0.61) and apart (VAS versus NRS, p < 0.0001, R² = 0.68; VAS versus GPS, p < 0.0001, R² = 0.40; and NRS versus GPS, p < 0.0001, R² = 0.47). Posture, appearance, vocalization, stiffness, interaction between the animal and a person and response to palpation were identified as important variables for assessing pain. Intra-observer reliability produced average ICC values of 0.90 for VAS, 0.89 for NRS and 0.85 for GPS. Interobserver reliability produced average ICC values when scores were assigned together (VAS: 0.93, NRS: 0.93 and GPS: 0.93) and when done separately (VAS: 0.91, NRS: 0.93 and GPS: 0.95).

CONCLUSIONS AND CLINICAL RELEVANCE

The preferred use of the VAS and NRS over the use of the GPS should be cautiously considered for research applications when experts are observers. Revisions of the GPS to clarify descriptors and remove or modify items that may not be associated with pain in dogs should be considered.

Effect of environmental noise and music on dexmedetomidine-induced sedation in dogs

Background

Previous studies in human patients suggest depth of sedation may be affected by environmental noise or music; however, related data in domestic animals is limited. The objective of the current study was to investigate the effect of noise and music on dexmedetomidine-induced (DM- 10 µg/kg, IM) sedation in 10 dogs.

Methods

In a crossover design, post-DM injection dogs were immediately subjected to recorded human voices at either 55–60 decibel (dB) (Noise 1) or 80–85 dB (Noise 2); classical music at 45–50 dB (Music); or background noise of 40–45 dB (Control+). Control− included IM saline injection and exposure to 40–45 dB background noise. Sedation was assessed via monitoring spontaneous behavior and accelerometry (delta-g) throughout three 20-min evaluation periods: baseline, noise exposure, and post-treatment. Sedation was further assessed during two restraint tests at 30 min (R1) and 40 min (R2) post-injection. A mixed model for crossover design was used to determine the effect of noise exposure and time on either spontaneous behavior scores or delta-g. The restraint scores were analyzed using a two-way repeated measures ANOVA.

Results

Spontaneous behavior scores indicated less sedation during Noise 2 compared to Control+ (P = 0.05). R2 restraint scores for all DM treatments except Noise 2 indicated significantly higher sedation than Control− [C+ (P = 0.003), M (P = 0.014) and N1 (P = 0.044)].

Discussion

Results suggest that the quality of sedation is negatively impacted by high-intensity noise conditions (80–85 dB), but exposure to music did not improve sedation in this population of research dogs.

Agreement between veterinary students and anesthesiologists regarding postoperative pain assessment in dogs

OBJECTIVE

To determine the levels of agreement among first- and second-year veterinary students and experienced anesthesiologists in assessing postoperative pain in dogs from video-recordings.

STUDY DESIGN

Cross-sectional study.

SUBJECTS

Twenty-seven veterinary students, five anesthesiologists and 13 canine clinical patients.

METHODS

Prior to their enrolment in a core anesthesia course, veterinary students volunteered to watch 13 90 second videos of dogs. Dogs were hospitalized in an intensive care unit after a variety of surgical procedures. Students were asked to score the level of the dogs' pain using the Dynamic Interactive Visual Analog Scale and the Short Form of the Glasgow Composite-Measure Pain Scale. The same videotapes were scored by five board-certified anesthesiologists. The differences and agreement between the ratings of anesthesiologists and students, and first- and second-year students were determined with Mann-Whitney U-tests and Fleiss' or Cohen's kappa, respectively.

RESULTS

Pain scores assigned by students and anesthesiologists differed significantly (p < 0.01). Students assigned higher pain scores to dogs that were given low pain scores by anesthesiologists, and lower pain scores to dogs deemed to be in more pain by anesthesiologists. On average, students assigned higher scores on both scales.

CONCLUSIONS AND CLINICAL RELEVANCE

Veterinary students early in their training assigned pain scores to dogs that differed from scores assigned by experienced anesthesiologists.

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.

Bone marrow cytological evaluation in dogs with chronic kidney disease

Since anemia is indicated as an important compromising factor for the quality of life of dogs with chronic kidney disease (CKD), bone marrow cytological analysis may provide more information on the hematological profile these dogs and, therefore, allow clinicians to not only choose the most adequate treatment but also monitor the response to therapy. The aim of this study was to investigate the feasibility with sternal bone marrow puncture in chronic kidney disease (CKD) using only local anesthesia and check if the cytological analysis is helpful to determine the hematological status. We found that erythroid hypoplasia occurred only in terminal CKD patients, and that the bone marrows of dogs with CKD stages 2 and 3 were quantitatively similar to those of elderly dogs. All dogs tolerated the bone marrow puncture using only local anesthesia with lidocaine and bone marrow cytological evaluation may be a useful tool for hematopoietic evaluation of anemic dogs with CKD.

Validation of orthopedic postoperative pain assessment methods for dogs: a prospective, blinded, randomized, placebo-controlled study

In the context of translational research, there is growing interest in studying surgical orthopedic pain management approaches that are common to humans and dogs. The validity of postoperative pain assessment methods is uncertain with regards to responsiveness and the potential interference of analgesia. The hypothesis was that video analysis (as a reference), electrodermal activity, and two subjective pain scales (VAS and 4A-VET) would detect different levels of pain intensity in dogs after a standardized trochleoplasty procedure. In this prospective, blinded, randomized study, postoperative pain was assessed in 25 healthy dogs during a 48-hour time frame (T). Pain was managed with placebo (Group 1, n = 10), preemptive and multimodal analgesia (Group 2, n = 5), or preemptive analgesia consisting in oral tramadol (Group 3, n = 10). Changes over time among groups were analyzed using generalized estimating equations. Multivariate regression tested the significance of relationships between pain scales and video analysis. Video analysis identified that one orthopedic behavior, namely ‘Walking with full weight bearing’ of the operated leg, decreased more in Group 1 at T24 (indicative of pain), whereas three behaviors indicative of sedation decreased in Group 2 at T24 (all p<0.004). Electrodermal activity was higher in Group 1 than in Groups 2 and 3 until T1 (p<0.0003). The VAS was not responsive. 4A-VET showed divergent results as its orthopedic component (4A-VETleg) detected lower pain in Group 2 until T12 (p<0.0009), but its interactive component (4A-VETbeh) was increased in Group 2 from T12 to T48 (p<0.001). Concurrent validity established that 4A-VETleg scores the painful orthopedic condition accurately and that pain assessment through 4A-VETbeh and VAS was severely biased by the sedative side-effect of the analgesics. Finally, the video analysis offered a concise template for assessment in dogs with acute orthopedic pain. However, subjective pain quantification methods and electrodermal activity need further investigation.