Long-term postoperative pain evaluation in dogs with thoracolumbar intervertebral disk herniation after hemilaminectomy

Comparing intramuscular ketamine with peri-incisional bupivacaine with or without ketamine in dogs undergoing hemilaminectomy

OBJECTIVE

To investigate whether infiltrating bupivacaine with ketamine into the epaxial muscles improves quality and duration of analgesia perioperatively compared with bupivacaine alone or ketamine intramuscularly.

STUDY DESIGN

Prospective blinded randomized clinical study.

ANIMALS

A group of 66 dogs randomized into three groups (n = 22).

METHODS

Before surgery, bupivacaine 0.5% 2 mg kg-1 alone (group B) or combined with ketamine 2 mg kg-1 (group BK) was infiltrated peri-incisionally into the epaxial muscles. Group K received ketamine 2 mg kg-1 injected intramuscularly into a cervical muscle without infiltration. Meloxicam 0.2 mg kg-1 was given intravenously (IV) before moving to theatre. Cardiovascular variables: heart rate and systolic, mean and diastolic blood pressure were recorded. Intraoperative fentanyl 5 μg kg-1 IV was administered if these variables increased by 20% from baseline. Fentanyl continuous infusion (5 μg kg-1 hour-1) was started if more than three boluses were required. The Glasgow Composite Pain Scale-Short Form was used pre- and postoperatively for acute pain assessment at different time intervals; methadone 0.2 mg kg-1 IV was administered if scores were greater 5/20. Analgesia requirements, time to first administration, pain scores, total opioids interventions, need for sedation, first food intake and adverse effects were recorded. Continuous, normally distributed and non-normally distributed variables were analysed using ANOVA or Kruskal Wallis test, respectively.

RESULTS

No significant difference was found for cardiovascular variables between groups over time, intra- or postoperative analgesia requirements, time to administration, pain scores total opioids, time to first food intake, sedation and occurrence of adverse effects.

CONCLUSIONS AND CLINICAL RELEVANCE

No difference in perioperative rescue analgesia was found between groups.

Case report: Resolution of lameness via compartmental resection of a malignant nerve sheath neoplasm of the median nerve in a dog

A 7-year-old golden retriever was evaluated for a 6-month history of progressive right thoracic limb lameness. A lameness (grade 3 out of 5 on visual gait analysis) and pain with palpation of the medial aspect of the brachium proximal to the elbow were identified on exam. Magnetic resonance imaging of the right thoracic limb revealed a well-delineated, ovoid mass arising from the median nerve just proximal to the elbow. Compartmental resection of the mass with limb preservation was performed. Microscopically, the mass was a malignant nerve sheath neoplasm. One week postoperatively, the lameness was mild (grade 1). Three months postoperatively, the lameness had resolved (grade 0). One year postoperatively, the dog's gait remains normal. Malignant nerve sheath neoplasms commonly arise in the brachial plexus or cervical spinal nerves, often affecting the innervation provided by the radial nerve. Given its role in providing weight support, dysfunction of the radial nerve significantly impacts the gait. Conversely, dysfunction of the median nerve should not impair the gait. In the present case, compartmental resection of the neoplasm affecting the median nerve resolved the dog's lameness. The return of normal limb function supports the contention that the lameness was consequent to general somatic afferent dysfunction, neuropathic pain, rather than general somatic efferent function (paresis).

Outcome of the Use of Clinical Reasoning Alone in Dogs with Acute Thoracolumbar Myelopathy and/or Pain

Acute thoracolumbar myelopathy is a common neurological presentation in dogs. Although certain spinal conditions present with characteristic clinical pictures, managing such cases with clinical reasoning alone (i.e., without cross-sectional imaging) has never been explored. The aim of this study was to define the outcome of patients with suspected intervertebral disc extrusion (IVDE), ischaemic myelopathy (IM) or acute non-compressive nucleus pulposus extrusion (ANNPE) that were managed with clinical reasoning alone. The database of the Queen's Veterinary School Hospital (Cambridge) was searched for paraparetic or paraplegic dogs with suspected IVDE or IM/ANNPE that were initially managed medically without undergoing imaging. Clinical presentation and outcome were recorded. If cross-sectional imaging was subsequently performed, information about the final diagnosis was collected and compared with the initially suspected diagnosis. A total of 123 IVDE cases were collected: 81% had a successful outcome with no imaging performed; 16% had IVDE confirmed with imaging and successful outcome with surgery or medical management; and just 3% were found to have an alternative diagnosis or were euthanised without imaging. A total of 16 IM/ANNPE cases were collected: 94% had a successful outcome, and one dog was euthanised. Successful outcomes can be obtained by using clinical reasoning alone in most dogs with suspected IVDE or IM/ANNPE.

Case report: Neuropathic pain versus undesirable behavior in a Dachshund after hemilaminectomy surgery for an intervertebral disc extrusion

A 5.5 years-old male Dachshund was presented for evaluation because of undesirable behavior including barking, biting, sucking and licking the right-side flank, ventrally and slightly caudally to the level of the surgical incision 7 days after hemilaminectomy for a right-sided L1-2 intervertebral disc extrusion. The dog was being treated with oral gabapentin 10 mg/kg q8h. Repeat clinical examination on three occasions after post-operative discharge did not reveal any signs of hyperesthesia or neurological deficits and the behavior was not observed in the clinic during consultations. During a separate day of hospital admittance with the aim of evaluating for the presence or absence of the behavior, the dog also did not exhibit the behavior. Oral paracetamol 12 mg/kg q8h was added to medical treatment. When the dog was discharged and returned home, the behavior was immediately seen again. When the owners implemented verbal punishment, the behavior immediately ceased. The owner verbally corrected the dogs' behavior for two excitative days. Upon telephone consultation 3 days later, the owner reported that they only had observed three recurrences of the behavior that immediately ceased following verbal correction and did not recur thereafter. Oral analgesic medication was tapered and discontinued. No recurrence of the behavior was noticed during the next 2 months. The authors postulated the dog possibly expressed signs of neuropathic pain in the post-operative period, or that the behavior was of a "compulsive disorder-like" nature as it only occurred when the dog was at home and in the presence of the owner. The eventual outcome and result of verbal corrections implemented by the owner seem to support the latter. In conclusion, compulsive-like undesirable behavior should be considered a differential diagnosis in dogs in the post-operative period of procedures possibly associated with the development or expression of signs of neuropathic pain.

Thoracolumbar retrolaminar block in seven dogs undergoing spinal surgery

Background

Thoracolumbar intervertebral disc extrusion is a common neurologic complaint in dogs and is associated with debilitating pain that requires careful analgesic management to avoid the transition to a chronic pain state. Recently, there has been an increased effort to incorporate regional anaesthetic techniques whenever possible, both for perioperative analgesia management and for prevention of chronic pain. A novel regional anaesthetic technique named retrolaminar block is a fascial plane block where the local anaesthetic is injected directly on top of the dorsal aspect of the vertebral lamina, in the fascial plane between the lamina and the epaxial muscles. The technique was recently described in humans and it is claimed to provide analgesia in patients undergoing thoracic and lumbar procedures. To the authors’ knowledge, the retrolaminar block has not been previously reported in live dogs.

Case presentation

Seven dogs presented to our hospital for suspected thoracolumbar intervertebral disc extrusion were anaesthetised using an anaesthetic premedication and induction protocol tailored for each individual animal. Once the suspected diagnosis was confirmed, all seven dogs were placed in sternal recumbency, and the target thoracolumbar vertebral spinous process was identified with palpation. A unilateral retrolaminar block was performed in all dogs with 2 mg/kg of 0.25% bupivacaine. Physiologic parameters, as well as responses to nociceptive stimuli, were monitored throughout the anaesthetic event.

Intraoperatively, one dog required a bolus of fentanyl to control nociceptive stimulation while the epaxial muscles were retracted. No further intraoperative rescue analgesia was required in any of the cases. The postoperative pain was assessed using the Short Form of Glasgow Composite Measure Pain Scale for dogs every four hours for the duration of the dogs’ hospitalization. The retrolaminar block reduced the intraoperative requirement for systemic opioids and other adjunct analgesic agents and all dogs were comfortable throughout their hospitalization and up until the time of their discharge.

Conclusions

This case report presents the performance of the retrolaminar block technique as part of multimodal analgesia management in seven dogs undergoing thoracolumbar spinal surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13620-022-00224-7.

ACVIM consensus statement on diagnosis and management of acute canine thoracolumbar intervertebral disc extrusion

Background

Thoracolumbar intervertebral disc extrusion (TL‐IVDE) is the most common cause of acute paraparesis and paraplegia in dogs; however, guidelines on management of the condition are lacking.

Objectives

To summarize the current literature as it relates to diagnosis and management of acute TL‐IVDE in dogs, and to formulate clinically relevant evidence‐based recommendations.

Animals

None.

Methods

A panel of 8 experts was convened to assess and summarize evidence from the peer‐reviewed literature in order to develop consensus clinical recommendations. Level of evidence available to support each recommendation was assessed and reported.

Results

The majority of available literature described observational studies. Most recommendations made by the panel were supported by a low or moderate level of evidence, and several areas of high need for further study were identified. These include better understanding of the ideal timing for surgical decompression, expected surgical vs medical outcomes for more mildly affected dogs, impact of durotomy on locomotor outcome and development of progressive myelomalacia, and refining of postoperative care, and genetic and preventative care studies.

Conclusions and Clinical Importance

Future efforts should build on current recommendations by conducting prospective studies and randomized controlled trials, where possible, to address identified gaps in knowledge and to develop cost effectiveness and number needed to treat studies supporting various aspects of diagnosis and treatment of TL‐IVDE.

Pilot Study on Feasibility of Sensory-Enhanced Rehabilitation in Canine Spinal Cord Injury

Physical rehabilitation is frequently recommended in dogs recovering from acute thoracolumbar intervertebral disc extrusion (TL-IVDE), but protocols vary widely. The objective of this study was to evaluate the feasibility of incorporating sensory-integrated neurorehabilitation strategies into a post-operative rehabilitation protocol in dogs with TL-IVDE. Non-ambulatory dogs with acute TL-IVDE managed surgically were prospectively recruited to this unblinded cross-over feasibility study. Eligible dogs were randomized to start with tactile-enhanced (artificial grass) or auditory-enhanced (floor piano) basic rehabilitation exercises performed twice daily for the first 4 weeks before switching to the opposite surface for the subsequent 4 weeks. Neurologic examination, open field gait scoring, girth measurements and an owner-completed feasibility questionnaire were performed at baseline and 2, 4, 6, and 8 weeks post-operatively. Twenty-four dogs were enrolled, 12 randomized to each order of exercises. Gait scores did not differ between the two groups at baseline, 4 or 8 week visits. All modified exercises could be performed and compliance was high. Adverse events potentially attributable to the study surface were mild, self-limiting and occurred in 2/24 dogs. The most common surface-related limitations were that the piano was slippery and that both surfaces were too short. The artificial grass was preferred by owners and dogs compared to the floor piano surface, but this was influenced by which surface was utilized first. Auditory and tactile modifications were feasible and safe to incorporate into a standardized rehabilitation protocol. This pilot study could prompt larger efficacy studies investigating the benefit of sensory-integrated rehabilitation in dogs with TL-IVDE.

Long-term postoperative pain evaluation in dogs with thoracolumbar intervertebral disk herniation after hemilaminectomy

BACKGROUND

Chronic neuropathic pain is a common complication in people with spinal cord injury (SCI) but has not been investigated in dogs.

OBJECTIVE

To determine the reliability of measuring spinal mechanical sensory thresholds (MSTs) in dogs and to compare MSTs of healthy dogs and dogs with SCI caused by acute thoracolumbar intervertebral disk extrusion after hemilaminectomy over a 1-year period.

STUDY DESIGN

Prospective study.

ANIMALS

Thirty-two healthy and 40 SCI dogs.

METHODS

Dogs were divided into group 1 (healthy Dachshunds), group 2 (healthy dogs including several breeds), and SCI group. The MSTs were measured using algometry at an incision (thoracolumbar) and control site. Dogs in group 1 were tested once; those in group 2 were tested for 5 consecutive days; and SCI dogs were tested on days 7, 14, 28, 42, 180, and 365 postoperatively. The MSTs were compared among days in healthy and SCI dogs and between SCI and healthy dogs using mixed effect models. P < .05 was considered significant.

RESULTS

At the incision site of SCI dogs, MST was significantly lower than in healthy dogs for 42 days postoperatively, but not subsequently. However, 4/27 dogs had control site MST below the reference range 1 year after surgery.

CONCLUSIONS AND CLINICAL IMPORTANCE

Mechanical sensory thresholds normalize by 6 months after surgery in most dogs with SCI. Approximately 15% of SCI dogs may develop chronic neuropathic pain. Improving long-term pain assessment of SCI dogs is important for offering treatment options and advising owners.