Intervertebral disc disease is a common cause of pain and neurological deficits known to be associated with degeneration and calcification of discs in humans and animals. Here, we analysed samples of herniated disc material and compared it to material taken from non-herniated discs following surgical treatment in dogs. Our clinical approach to these cases allowed collection of approximately 100 samples providing a unique opportunity for a substantial case-controlled study, an opportunity not available to the human neurosurgeon. We analysed all samples using Fourier transform infrared (FTIR) spectroscopy, as well as subsets of 10 samples by X-ray diffraction (XRD) and two samples by transmission electron microscopy (TEM). We show the majority of herniated samples have FTIR spectra consistent with the presence of crystalline hydroxyapatite (HAp), whereas most non-herniated discs showed spectra consistent with amorphous phosphate. XRD and TEM confirmed these findings and the two samples examined with TEM identified the amorphous material as amorphous calcium phosphate (ACP) nanoparticle clusters of approximately 20 nm diameter and the crystalline HAp as polycrystalline needles up to 100 nm in length. Our data suggest that the intervertebral disc degenerative process involves conversion of ACP into crystalline HAp, which might predispose a disc to herniate.

Intervertebral disc extrusion (IVDE) is a common neurological condition in veterinary medicine, with chondrodystrophic breeds being particularly susceptible. Studies have compared breed-related risks and clinical characteristics, but here, we investigate the disease in three common chondrodystrophic breeds, the English cocker spaniel, French bulldog and dachshund, and aim to describe and compare the clinical features and anatomical distribution between them. We performed a multicentre retrospective observational study that included 465 dachshunds, 327 French bulldogs and 145 English cocker spaniels with an imaging confirmed diagnosis of IVDE. The mean age at presentation differed in all three breeds, with the French bulldog presenting youngest and English cocker spaniels presenting oldest. IVDE was most common in the thoracolumbar region in all three breeds, although French bulldogs showed the highest proportion of cervical IVDE, dachshunds the highest proportion of thoracolumbar IVDE, and English cocker spaniels the highest proportion of lumbosacral IVDE. The results of this study suggest a differing clinical presentation for IVDE between these three breeds with regard to both the age of onset and the anatomical region most likely to be affected.

The effect of midline shift identified on brain MRI on survival time in dogs with structural brain disease is relatively unknown. This retrospective single-centered cohort study reviewed medical and imaging data of 77 dogs with structural brain lesions evident on MRI. Images were reviewed for the presence of midline shift, brain edema, foramen magnum herniation, and ventriculomegaly. Kaplan-Meier method and Cox regression analysis were undertaken to compare survival between dogs with and without midline shift. Midline shift was present in 40 of 77 (52%) dogs and absent in 37 of 77 (48%). Univariate analysis revealed that dogs with midline shift had a median survival time of 34.5 days (95% CI, 4-108 days) compared with 241 days (95% CI, 133,- days) in dogs without midline shift (hazard ratio = 2.67, 95% CI, 1.5-4.49). Multivariate Cox regression analysis revealed a hazard ratio of 3.6 (95% CI, 1.7-7.6; P-value < .001) for dogs with midline shift. Shorter median survival times remained significant in all groups after segregation based on etiological diagnosis. The significantly shorter survival times observed herein for dogs with midline shifts, regardless of etiologic cause, provide further evidence that midline shift holds value as a negative prognostic factor in diagnostic imaging.

AbstractBackgroundCurrently, 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.ObjectivesDetermine 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.AnimalsSeventy‐two client‐owned nonambulatory dogs with acute thoracolumbar intervertebral disk extrusion.MethodsThis 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.ResultsForty‐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 ImportanceA 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.

Abstract Background Thoracolumbar intervertebral disc extrusion (TL IVDE) is a common reason for the veterinary hospital admission. Various imaging factors including degree and length of compression have been tested for correlation with clinical severity, but no reliable correlation has been found. Half‐Fourier acquisition single‐shot turbo spin echo (HASTE) magnetic resonance imaging (MRI) sequences highlight the dorsal and ventral cerebrospinal fluid (CSF) columns and have been used to demonstrate spinal cord swelling in dogs with TL IVDE. This has been used as a predictor of progressive ascending‐descending myelomalacia but has not been correlated with neurological grade. Objective This study aims to investigate the correlation between the attenuation of CSF HASTE signal and clinical severity in dogs suffering from TL disc extrusions. Methods Dogs less than 15 kg who were non‐ambulatory due to suspected TL IVDE were prospectively recruited for a study into conservative management. MRI studies were undertaken under sedation including HASTE sequences. The ratio of the length of CSF attenuation to the length of the L2 vertebra was calculated and correlated with clinical severity. Results Twenty dogs met the inclusion criteria. No statistically significant difference was demonstrated between the mean CSF attenuation and neurological grade (p = 0.17 but there was a significant difference in the mean CSF attenuation in those who retained deep pain perception and those who did not (p = 0.02). Time to loss of ambulation was also found to not be correlated with CSF attenuation (p = 0.95). Conclusion In conclusion, the length of CSF attenuation of HASTE MRI sequences in dogs less than 15 kg suffering from IVDEs may be correlated with a loss of deep pain perception.

OBJECTIVE:To compare spinal cord-to-vertebral canal area ratios measured with CT between the cervical and thoracolumbar regions in French Bulldogs.ANIMALS:37 French Bulldogs presented to a referral hospital between 2016 and 2019.PROCEDURES:The study was conducted as a retrospective observational study. Exclusion criteria were evidence of vertebral malformations or spinal cord compression at the sites where measurements were obtained and the presence of cervicothoracic or thoracolumbar transitional vertebrae or neurologic deficits. CT images were reviewed, and measurements were performed by 2 investigators. Measurements of the spinal cord and vertebral canal were made at the level of or immediately cranial to the midbodies of C5 and L1.RESULTS:A 2-tailed, paired t test indicated that the mean spinal cord-to-vertebral canal area ratio differed significantly (P < .01) between C5 (0.726) and L1 (0.605). The ratio was lower in the thoracolumbar region, suggesting that the vertebral canal was relatively larger in this region.CLINICAL RELEVANCE:The epidural space did not appear to be larger in the cervical than in the thoracolumbar region in this population of French Bulldogs, contrary to previous reports. The reason for the more severe deficits observed with thoracolumbar disk extrusion in this breed remains to be characterized.

AbstractBackgroundThe aims of this retrospective study were to estimate interobserver agreement in detecting disc calcification with computed tomography (CT) and to compare the number of calcified intervertebral discs identified on CT and radiography in healthy British Dachshund dogs that underwent a screening programme. The current screening programme uses radiography to identify calcified intervertebral discs.MethodsHealthy Dachshunds aged between 2 and 5 years presenting for spinal radiography and CT as part of a disc scoring scheme were included. The spinal radiographs were scored by an independent assessor as per the screening programme protocol. The CT images were blinded and reviewed by three different observers of differing levels of experience. The number of discs identified as being calcified was then compared between imaging modalities and between observers.ResultsThirteen dogs were included. Overall, 146 calcified discs were identified by CT compared with 42 by radiography. There was an almost perfect agreement among the three observers identifying calcified discs with CT images (k = 0.92). There was a significant difference between the radiography scores and CT scores.ConclusionsThis study demonstrated a significant difference in the number of calcified intervertebral discs identified in the vertebral column of a small population of healthy Dachshunds between CT and radiography. Given the high agreement between the observers with CT, this may be a reliable method for assessing disc calcification in Dachshund dogs and could be a good candidate for future breeding schemes.

Whilst multi‐planar imaging has allowed advances in diagnosis and treatment of canine spinal cord disorders, it is sometimes inaccessible to pet owners leading to a reliance on imaging modalities and ancillary tests that are more readily available. For this reason, this essay considers how Bayesian clinical reasoning may aid in deciding which tests, if any, are most useful for the diagnosis of spinal disease in clinical practice and choosing reasonable empiric therapies.

OBJECTIVES:The aim of this study was to describe how the addition of contrast-enhanced low-field magnetic resonance imaging sequences can confirm or change the initially planned surgical approach for canine intervertebral disc extrusions.STUDY DESIGN:Magnetic resonance imagings of 20 dogs diagnosed with intervertebral disc extrusions were retrospectively reviewed by a board-certified neurologist for the location of extradural disc material, contrast enhancement, and whether enhancement reinforced or changed the initially planned surgical approach.RESULTS:Extradural compressive material contrast-enhanced in 17/20 dogs. In 14/20 dogs, enhancement was considered to increase the confidence level of the location for surgery including two cases where the surgical approach was altered.CONCLUSION:Gadolinium-based contrast agents in low-field magnetic resonance imaging can aid the surgical planning of intervertebral disc extrusions in dogs by improving the confidence level of location and extent of extradural material and occasionally altering the surgical approach.

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A 23-month-old German shepherd dog (GSD) with chronic intermittent gastrointestinal signs presented following acute deterioration compatible with gastrointestinal obstruction and suspected peritoneopericardial diaphragmatic hernia (PPDH). Physical examination revealed depression, abdominal pain, decreased pulse quality, reduced heart sounds and tachypnoea with a shallow breathing pattern. Radiography confirmed PPDH and a granular, 1.3 cm mineral opacity cranial to the cardiac silhouette within the cranioventral thorax. Coeliotomy and median sternotomy revealed strangulated jejunum within the cranial mediastinum, cranial to the pericardium. This was resected and herniorrhaphy was performed. Postoperatively the dog became normal. Midline fusion defects, including the pericardium, can be associated with PPDH and in such cases sternotomy may be required. This is the first report of surgical management of strangulated intestine secondary to an initially conservatively managed PPDH. Mineral opacity on radiography associated with PPDH may represent chronic partial obstruction. This possibly represents a second GSD with Cantrell’s pentalogy.