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Advances in Intervertebral Disc Disease in Dogs and Cats defines our present knowledge of this common clinical problem, compiling information related to the canine and feline intervertebral disc into a single resource. As a comprehensive, focused work, the book is an authoritative reference for understanding and treating disc disease, providing a sound scientific and clinical basis for decision making. Offering an objective synthesis of the current literature, the book supplies guidance on the approach to a potential disc rupture, surgical and medical strategies, and management of the patient. Offering a complete understanding of intervertebral disc disease, the book describes and discusses the controversies and issues surrounding this topic, acknowledging the gaps in our knowledge. Advances in Intervertebral Disc Disease in Dogs and Cats presents up-to-date, reliable information on this common condition for veterinary surgeons, neurologists, and general practitioners. Key Features Describes the current knowledge of disc disease in dogs and cats, Provides a state-of-the-art, complete resource focused entirely on this common clinical problem, Gives an objective picture of the controversies around intervertebral disc disease in canine and feline patients, Presents evidence-based and clinically relevant information for understanding and treating intervertebral disc disease, Offers clear clinical recommendations grounded in the current literature, Part of the Advances in Veterinary Surgery series copublished with the ACVS Foundation Book jacket.

Abstract Background Prophylactic fenestration (PF) has been reported to protect against recurrent intervertebral disc extrusion (IVDE), but recurrence is not always confirmed. No published studies address the cost–benefit of PF. Objectives Observe the association between PF and intervertebral disc (IVD) survival and conduct cost–benefit analysis. Animals Eighty chondrodystrophic dogs with recurrent IVDE. Methods Longitudinal assessment with follow-up magnetic resonance imaging (MRI) was performed to retrospectively observe the survival of in situ IVDs. The association between PF and IVD survival was analyzed using a multivariable survival model, which included Pfirrmann grade as a covariate. Worst-case, base-case, and best-case cost–benefit simulations were conducted, corresponding to the lower 95% confidence interval (CI), point estimate, and upper 95% CI of the effect size of PF. Results For IVDs treated with PF, 4/31 (12.9%) IVDs were documented to subsequently extrude on follow-up MRI. For IVDs not treated with PF, 76/602 (12.6%) were documented to subsequently extrude on follow-up MRI. There was no association between the use of PF and IVD survival (time ratio: 1.17; 95% CI: 0.49–2.76; p = 0.72). An increase in Pfirrmann grade was associated with a decrease in IVD survival (time ratio: 0.34; 95% CI: 0.26–0.46; p < 0.001). Prophylactic fenestration was only cost-effective under a limited range of conditions. Conclusions and Clinical Importance There was no evidence that PF prevented IVDE under study conditions. Pfirrmann grade was the strongest predictor of IVD survival. Universal use of PF was not cost-effective in multiple simulations. Targeted PF of high-risk IVDs may be considered the most cost-effective approach.

BackgroundAcute paralysis is a common presentation in small animal emergency clinics, but the aetiological prevalence has not been reported. Knowledge of diagnosis frequency aids prioritisation of differential diagnoses, facilitates resource planning and clinical trial design.MethodsMedical records from NC State Veterinary Hospital Emergency Room were searched over a five-year period to identify cases presenting with acute non-ambulatory paraparesis or paralysis. Signalment and diagnosis category were extracted.ResultsAcute paralysis was the presenting problem in 845 of 21,535 (3.9 per cent) dogs and 66 of 4589 (1.4 per cent) cats admitted over this period. Intervertebral disc disease (IVDD) was the most common cause (608 of 845; 72 per cent) in dogs, followed by vascular disease (34 of 845; 4.0 per cent). Other diagnostic categories accounted for the remaining 20 per cent. Dachshunds were the most common breed (263 of 845; 31.1 per cent), then Labrador retrievers (57 of 845; 6.7 per cent). In cats, aortic thromboembolism (ATE) was the most common diagnosis, occurring in 40 of 66 (60.6 per cent), followed by IVDD (7 of 66; 10.6 per cent). Other diagnostic categories accounted for 30.3 per cent. Six of 845 (0.7 per cent) dogs and two of 66 (3 per cent) cats were categorised as pseudoparalysis with a non-neurological diagnosis.ConclusionsIVDD and ATE are the overwhelming causes of acute paralysis in dogs and cats, respectively, with approximately 28 per cent of dogs and 40 per cent of cats having a different diagnosis.

Abstract Background Cross-sectional imaging, with particular regard to computed tomography (CT) and magnetic resonance imaging (MRI), has been shown to be accurate in the diagnosis of intervertebral disc extrusion (IVDE) in dogs, with MRI having higher diagnostic accuracy. However, the cost-effectiveness of veterinary diagnostic imaging has not been investigated. Hypothesis/Objectives Comparative evaluation of the cost-effectiveness of 5 cross-sectional imaging strategies in the diagnosis of thoracolumbar IVDE. Animals No live animals were used. Methods A probabilistic decision-analytical model was developed based on a hypothetical cohort of dogs suspected to have thoracolumbar IVDE. Five imaging strategies based on a combination of noncontrast CT, CT-myelography (CTM), and MRI were tested (CT-only, noncontrast CT only; conditional-CTM, noncontrast CT followed by CT-myelography if nondiagnostic; unconditional-CTM, noncontrast CT followed by CT-myelography; conditional-MRI, noncontrast CT followed by MRI if nondiagnostic; MRI-only, MRI only). Effectiveness was defined as the probability of a correct diagnosis. Results Across probabilistic simulations, CT-only and unconditional-CTM were consistently less effective and more costly than other options and therefore were never preferred (strictly dominated). Magnetic resonance imaging-only was less cost-effective than strategies based on noncontrast CT (extendedly dominated). Conditional-CTM and conditional-MRI provided the best balance of diagnostic accuracy and cost (the non-dominated efficient set of strategies). Conclusions and clinical importance Conditional imaging strategies beginning with noncontrast CT and escalating only if nondiagnostic were the most cost-effective strategies in diagnosing thoracolumbar IVDE in dogs. An MRI-only strategy was rarely cost-effective despite similar diagnostic sensitivity. From this decision-analytic modeling study, strategic use of cross-sectional imaging in the diagnosis of thoracolumbar IVDE has the potential to optimize the use of finite resources.

Abstract Background Progressive myelomalacia (PMM) is a catastrophic disease associated with acute intervertebral disc extrusion (IVDE). Published data on the clinical characteristics of this disease are limited. Objective To describe the onset and progression of clinical signs of PMM in a large case cohort. Animals Fifty-one dogs, 18 with histopathologically confirmed PMM, 33 presumptively diagnosed based on clinical signs and diagnostic imaging. Methods Retrospective study. Dogs with confirmed IVDE and either a histopathologic diagnosis of PMM or a high clinical suspicion were identified by medical record search. Data on nature and progression of signs were extracted. Results Twenty-four of 51 dogs were Dachshunds. T12–T13 was the most common site of disc extrusion (12 of 56), and 18 of 55 of mid-to-caudal lumbar discs (between L3 and L6) were affected. Onset of PMM signs ranged from present at first evaluation (17/51) to 5 days after presentation, with 25 of 51 cases developing signs within 48 hours. Progression of signs from onset of PMM to euthanasia or death, excluding 7 cases euthanized at presentation, ranged from 1 to 13 days with 23 being euthanized within 3 days. Nonspecific systemic signs were documented in 30 of 51 dogs. Conclusion and Clinical Importance The majority of dogs developed PMM within 2 days of presentation and was euthanized within another 3 days. However, onset can be delayed up to 5 days after presentation with progression to euthanasia taking as long as 2 weeks. Mid-to-caudal lumbar discs might be associated with an increased risk of PMM.

Abstract Background Acute non-compressive nucleus pulposus extrusion (ANNPE), fibrocartilaginous embolism (FCE), and hydrated nucleus pulposus extrusion (HNPE) all present with acute to peracute onset of myelopathic signs in dogs, for which treatment usually is medical. Conservative management including a period of strict rest usually is recommended because of concern about relapse if immediate exercise is allowed. Hypotheses Allowing exercise after a diagnosis of ANNPE, FCE, or HNPE does not decrease the chance of recovery or predispose to relapse in the short-term follow-up period (4 weeks) after discharge. There is no difference in clinical outcome between rested and exercised groups. Animals Forty cases of ANNPE, FCE, or HNPE with follow-up including at minimum a 4-week evaluation after discharge. Methods Retrospective study. The exercise group (n = 22) included all dogs the owners of which were not explicitly instructed to rest their dogs, whereas the rest group (n = 18) included all dogs the owners of which were specifically advised to rest their dogs or to restrict their exercise. Results No dogs relapsed or deteriorated between discharge and 4-week re-evaluation. No significant difference was found between the rest and exercise groups. Conclusions Allowing exercise after confirming a diagnosis of ANNPE, FCE, or HNPE did not predispose to relapse of clinical signs in the 4 weeks after discharge in our cohort, but the rest group had a higher proportion of HNPE cases, which means interpretation of our findings in this diagnosis must be made with caution.

Abstract Background Limited data exist on intervertebral disk disease (IVDD) prevalence and risk factors in English cocker spaniels. Hypothesis/Objectives IVDD risk factors and prevalence vary between breeds and within sub-populations. Animals Two thousand six hundred fifty-four English cocker spaniels. Methods An online survey investigating prevalence and factors associated with IVDD was distributed via the UK Kennel Club to registered English cocker spaniel owners (November 14, 2022 to February 2, 2023). Prevalence estimates with 95% confidence intervals were calculated (Wilson score interval). Descriptive statistics were applied to demographic, exercise, and diet variables. Univariable associations were explored using unadjusted odds ratios with 95% CI (Wald method). Results Overall IVDD prevalence was 5.73% (95% CI, 4.82-6.62) and was greater in the show [8.99% (95% CI, 7.30-11.03)] than the working [3.44% (95% CI, 2.61-4.49)] dogs. Dogs in the show group were taller relative to their length compared to those in the working group. The lumbar region accounted for 53.02% (n = 79) cases, with an onset time most frequently of less than one day (40.14%, n = 59). Males were at greater odds of IVDD in our study compared to females (OR:14.39, 95% CI, 7.30-28.36), with neutered males or females at greater odds compared to the entire dogs (OR:7.9, 95% CI, 4.25-14.67). Conclusions and clinical importance IVDD is common in English cocker spaniels, with a higher prevalence in the show dogs.

Abstract Background Radiographic signs of intervertebral disc mineralization are thought to indicate sites of future recurrence of disc extrusion (Hansen type I) but the relationship between evidence of disc degeneration on magnetic resonance imaging (MRI) and future disc extrusion with recurrence of clinical signs has not been examined. Objectives To examine the relationship between MRI-assessed degeneration of thoracolumbar intervertebral discs and late recurrence of clinical signs in dogs presented with acute thoracolumbar intervertebral disc extrusion and treated by hemilaminectomy alone. Animals Ninety-two client-owned dogs presented to 2 referral hospitals between 2009 and 2014. Methods Retrospective analysis of association between clinical signs consistent with recurrent thoracolumbar intervertebral disc extrusion and MRI evidence of disc degeneration in dogs undergoing hemilaminectomy for acute thoracolumbar intervertebral disc extrusion. Univariable and multivariable Cox regression analyses were used to explore associations between recurrence of clinical signs and several characteristics of T10-L3 discs at initial diagnosis. Results Ninety-two cases were included, of which 42 (46%) were Dachshunds and median age was 5.3 years. Clinical signs recurred in 33/92 (36%) dogs. Finding a completely degenerate disc in the T10 to L3 region (in addition to the operated site) at the time of surgery was associated with a hazard ratio of 2.92 (95% confidence interval: 1.37-6.20) for recurrence of clinical signs. Conclusions and clinical importance Our results suggest that in cases of thoracolumbar intervertebral disc extrusion in dogs, recurrence of signs is likely if at least 1 completely degenerate disc in addition to the currently symptomatic disc is visible on MRI.

Abstract Background Approximately 50%–60% of paraplegic deep pain negative (DPN) dogs secondary to thoracolumbar intervertebral disc extrusion (TL-IVDE) recover ambulation after surgery. Mean F-wave duration has been associated with injury severity in TL-IVDE in dogs, but the relationship to outcome is unknown. Objective Evaluate the prognostic utility of F-waves in DPN dogs secondary to TL-IVDE treated surgically. Animals Thirty client-owned, acutely paraplegic DPN dogs secondary to TL-IVDE were managed surgically. Methods Multi-center prospective and observational study. F-waves were performed at baseline (within 24 h post-operatively), 2–4 weeks and 3 months post-operatively. Outcome was categorized as successful or unsuccessful, with success defined as independent ambulation at 3 months post-operatively. F-wave variables were compared between dogs with a successful or unsuccessful outcome and over time using generalized estimating equations. Receiver-operating characteristic curves were generated for baseline F-wave variables. Results F-waves were well-tolerated in all dogs. Of 30 enrolled dogs, 12 dogs had a successful outcome, 10 dogs were unsuccessful, and 8 dogs were removed from outcome analysis (3 progressive myelomalacia, 1 severe spinal shock, 2 technical error, and 2 unknown outcome). Baseline mean F-wave duration (displayed as median (range)) was longer in unsuccessful dogs (31.7 (11.4–60.8) ms) versus successful dogs (19.6 (10.8–27.3) ms), p = 0.003. Mean F-wave duration > 28.5 ms was 70% sensitive (95% confidence interval (CI): 40%–100%) and 100% specific (95% CI: 100%–100%) in predicting an unsuccessful outcome. Conclusions and Clinical Importance F-waves performed shortly post-operatively could aid in predicting outcomes in DPN dogs secondary to TL-IVDE treated surgically.

Abstract Background Currently, low-level evidence suggests loss of ambulation associated with acute thoracolumbar disk extrusion is best treated by decompressive spinal surgery. Conservative management can be successful, but the proportion of dogs that recover and the fate of herniated material are uncertain. Objectives Determine the proportion of nonambulatory dogs with conservatively treated acute thoracolumbar disk extrusion that recover ambulation and measure the change in spinal cord compression during the first 12 weeks after presentation. Animals Seventy-two client-owned nonambulatory dogs with acute thoracolumbar intervertebral disk extrusion. Methods This is a prospective cohort study. Enrolled dogs underwent magnetic resonance imaging at presentation and owners were provided with conservative management recommendations. Imaging was repeated after 12 weeks. Recovery of ambulation was defined as 10 consecutive steps without falling. Spinal cord compression was determined from the cross-sectional area of the vertebral canal and extradural compressive material at the lesion epicenter. The association between recovery and change in compression over the 12-week observational period was examined. Results Forty-nine of fifty-one (96%; 95% confidence interval [CI], 87%-99%) of deep pain-positive and 10/21 (48%; 95% CI, 28%-68%) of deep pain-negative dogs recovered ambulation within the 12-week period. The median time to ambulation was 11 and 25 days for deep pain-positive and -negative dogs, respectively. Reduction in spinal cord compression varied among individuals from minimal to complete and apparently was unrelated to the recovery of ambulation. Conclusions and Clinical Importance A high proportion of conservatively treated dogs recovered ambulation after conservative management of acute thoracolumbar disk herniation. Recovery was not dependent on the resolution of compression.