A survey-based study published in the Journal of Small Animal Practice provides an update on the surgical management of acute canine thoracolumbar intervertebral disk extrusion (IVDE). Researchers received 385 responses, and this data was compared to data published in 2016.
The objectives of this study were to document and compare current practice patterns among North American and European veterinary neurologists and surgeons.
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Simon Platt, BVM&S, FRCVS, DACVIM (Neurology), DECVN, runs a veterinary neurology consultancy service in addition to co-directing the teleneurology service of Vetoracle and serving as medical director for Hallmarq Advanced Veterinary Imaging and editor-in-chief of Today’s Veterinary Practice. He has also established a free-access veterinary neurology education site and seizure teleconsulting service. We spoke with Dr. Platt to discuss the study’s main findings, the difference in approach between surgeons and neurologists, and more.
Q: The most commonly used imaging modality to confirm the diagnosis of a nonambulatory dog differed significantly between neurologists and surgeons. The most frequently used modality by neurologists was MRI (92%), and the most frequently used modality by surgeons was CT (44%) followed by MRI (39%). Do you have any insight into this difference in imaging modality preference?
From my perspective, the neurologist’s overwhelming preference for MRI—now at 92%, up from previous years—reflects our training emphasis on evaluating the spinal cord parenchyma itself. When I manage a nonambulatory dog, I need to know not only where the extrusion is located but also the extent of intramedullary hemorrhage, edema, and cord compression. This information directly informs my prognosis, helps me counsel owners realistically about recovery expectations, and occasionally influences my surgical approach. MRI provides this parenchymal detail; CT does not.
However, I must acknowledge that the surgeon’s more balanced approach—44% CT, 39% MRI—is not without merit. The literature supports that for typical chondrodystrophic dogs with an acute, classic presentation, CT alone is often sufficient to identify the extruded disk material and plan a hemilaminectomy. It is faster, less expensive, more widely available, and does not require general anesthesia of the same duration. For a surgeon whose primary goal is localization and decompression, CT is an efficient and effective tool.
The researchers’ call for prospective studies comparing clinical outcomes between dogs imaged with CT versus MRI is exactly what we need. If we can demonstrate that for a well-defined subset of patients—chondrodystrophic dogs with acute onset and clear neurologic localization—CT yields equivalent functional outcomes to MRI, then we can develop evidence-based imaging algorithms. Such algorithms would improve access to care, reduce costs, and ensure that the more expensive and resource-intensive MRI is reserved for cases where it truly adds value: atypical breeds, suspected neoplasia, or cases where the clinical picture and CT findings are discordant.
Q: No statistically significant differences were found in the responses of neurologists and surgeons regarding surgical recommendations based on the severity of clinical signs or lesion localization (i.e., T3–L3, L4–S3). The most common surgical approach was hemilaminectomy with removal of the articular process. But significantly more neurologists (80%) reported performing concurrent fenestration at the time of surgical decompression compared to surgeons (47%). Do these 2 different surgical approaches indicate a shift in the surgical management of these patients?
The divergence on fenestration, despite agreement on the core decompressive procedure, is one of the most striking findings in this study, but has been a point of contention for decades within the profession as a whole.
The fact that 47% of surgeons now report performing concurrent fenestration is itself a substantial increase from historical norms. This suggests that the body of literature demonstrating that fenestration—particularly of the acutely extruded disk—can reduce the risk for same-site recurrence has been persuasive across specialties.
However, the fact that 80% of neurologists routinely fenestrate may indicate a fundamental difference in how the disease is viewed; but I would also consider it to be a decision based on comfort level with the procedure itself. It can be a challenging procedure to perform effectively; it’s not without its risks, and it can lengthen a patient’s anesthesia time. Fenestration of adjacent disks, which 50% of neurologists perform versus only 11% of surgeons, may reflect a philosophy of addressing future risk at the same time as current pathology, but again may just support the need to keep anesthesia times short with as low a risk to the patient.
The literature on fenestration of adjacent disks remains mixed with some studies showing benefit and others not. This is where the debate should focus. The surgeon’s approach—decompression alone or fenestration only of the affected disk—is a more conservative, targeted strategy. The neurologist’s approach—fenestration of adjacent disks—is a more aggressive, and possibly more preventative, strategy. From an evidence perspective, what we need is a prospective, randomized trial comparing outcomes—both short-term recovery and long-term recurrence rates—between dogs undergoing decompression alone, decompression with fenestration of the affected disk, and decompression with fenestration of multiple adjacent disks. Until that data exists, this divergence in practice patterns will persist, reflecting not a right or wrong approach but rather different interpretations of the existing evidence shaped by different clinical experience levels and surgical aims.
Q: What do you consider to be the primary takeaways from this study?
The main takeaway is a clear confirmation of a practice divide between neurologists and surgeons. Data show that neurologists handle the majority of these cases with 48% managing over 100 annually while 55% of surgeons manage only 1 to 25 cases annually. This difference in caseload probably explains many of the other variations observed. Although it’s reassuring that both groups agree on the timing of surgery based on neurologic severity, significant differences remain in their management approaches. For example, 80% of neurologists perform concurrent fenestration compared with 47% of surgeons. And their imaging choices are quite different—92% of neurologists use MRI compared with 39% of surgeons. The study also notes a positive, evidence-based decline in high-dose methylprednisolone use. Overall, this paper highlights that although there is common ground, there are still major differences in how these 2 specialties approach this common condition. However, there’s no evidence to suggest these differences affect patient outcomes.
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Q: Most respondents indicated that they would take dogs with severe acute IVDE to surgery “as soon as possible within a certain time window.” Do you believe there has been a shift in the urgency of taking paraplegic dogs with absent nociception to surgery?
This marks a significant, evidence-based shift in mindset. A decade ago, many believed that dogs without deep pain perception required urgent, around-the-clock surgery. The 2016 survey cited in this paper confirmed this with 65% of specialists operating “as soon as possible, regardless of time of day.” Now, most tend to operate “as soon as possible within a certain time window,” delaying until morning after a specific evening cutoff. This reflects a maturation of our understanding, supported by a growing body of literature, including prospective studies, which have shown no clear link between surgical timing and functional recovery in these severely injured patients. It also demonstrates a pragmatic acceptance of the higher risks linked to overnight surgeries. This isn’t complacency; rather, it’s a more nuanced approach that emphasizes a well-rested, fully staffed surgical team, recognizing that biological outcomes may be less time-dependent than previously thought.
Q: The survey found differences in what neurologists and surgeons consider negative prognostic indicators (e.g., breed, rapid onset of signs) and predictors of progressive myelomalacia (e.g., reduced or absent withdrawal reflex, mid-thoracic cut-off of cutaneous trunci reflex). What do you consider to be negative prognostic indicators and suggestive signs of progressive myelomalacia?
From my perspective, true negative prognostic indicators for recovery are those with strong, prospective evidence. The single most important factor in this case is the presence or absence of nociception; and this should be tested on both medial and lateral digits of left and right limbs as well as the tail head and perineal region. While French bulldogs and other brachycephalic breeds are overrepresented in this disease, their classification as a negative prognostic indicator may be a surrogate for the severity of their clinical signs and the presence of comorbidities; however, we cannot ignore that the French bulldog does not seem to recover as well as other breeds and are more likely to experience myelomalacia.
Regarding progressive myelomalacia (PMM), the literature is clear: the most compelling predictor is the cranial advancement of the cutaneous trunci reflex (CTR) cutoff. A reduced or absent withdrawal reflex can be helpful but can be seen with spinal shock in some patients and so is not a reliable predictor of PMM unless it’s coupled with other clinical signs such as loss of anal sphincter tone, profound hyperesthesia, and sometimes pyrexia. Our focus should be on rigorous, serial neurologic examinations with the CTR as our most vital tool.
Q: With these survey results in mind, the researchers recommend that future studies focus on a comparison of the clinical outcomes of dogs imaged with CT versus MRI as well as prognostic indicators and risk factors for progressive myelomalacia. What areas of research regarding acute canine IVDE do you find most promising right now?
I find the proposed comparison of CT versus MRI outcomes to be both promising and critically important. Although MRI is considered the gold standard for spinal cord imaging, its higher cost and limited availability create significant barriers to care. If a well-designed prospective study can demonstrate equivalent outcomes for the majority of chondrodystrophic dogs with a clear, classic presentation when diagnosed with CT, it would be a game-changer for access to timely surgical care. Beyond that, I’m most excited about research into novel neuroprotective strategies. The failure of methylprednisolone and lack of benefit from durotomy in recent randomized trials have left a void. We need to explore targeted therapies that mitigate secondary injury cascades.
Q: Is there anything you would like our readers to know that has not been mentioned?
A critical point not addressed in the survey is the role and perspective of the general practitioner. This is where the journey for most of these dogs begins. The study highlights a high level of sophistication in specialty care, but it also reveals potential points of delay or confusion for our colleagues in primary care. For instance, the decision to refer a dog with acute pain or mild paresis for an MRI (favored by neurologists) versus a CT (favored by surgeons) could be influenced by the specialist’s preference, not necessarily the dog’s best interest. Furthermore, the ongoing debate about prognostic indicators can lead to conflicting information for owners. My message to readers is to use this information to have informed conversations with your local specialists. Don’t hesitate to ask about their preferred imaging modality, typical surgical timing for a down dog, and thoughts about an individual case’s prognosis. A collaborative approach, built on mutual understanding of current practice patterns, will ultimately provide the most seamless and effective care for our patients.
Read the Full Study
An update on practice patterns of North American and European veterinary neurology and surgery specialists for surgical management of acute canine thoracolumbar intervertebral disc extrusion.
Moore S, Early P, Olby N, Hettlich B. J Small Anim Pract | doi:10.1111/jsap.70029