MR-imaging of lumbosacral intervertebral disc degeneration in clinically sound German shepherd dogs compared to other breeds

Accuracy of low-field magnetic resonance imaging for differentiating intervertebral disc extrusions and protrusions at the lumbosacral disc space in dogs

Introduction/Purpose

MRI features differentiating extrusion from protrusion in thoracolumbar discs have been published, however little specifically evaluates the lumbosacral disc. The high prevalence of degenerative changes in apparently normal animals complicates assessment of this region and features relevant elsewhere in the spine may not apply. The aims of this study were to determine the accuracy of MRI in differentiating IVDE and IVDP at the lumbosacral disc space in dogs and determine which MRI characteristics discriminate between IVDE and IVDP.

Method

MRI examinations from dogs with surgically confirmed IVDE or IVDP at the lumbosacral disc space were collected retrospectively (2011-2019). Two radiologists independently recorded a diagnosis of IVDE or IVDP, gave a confidence rating, and evaluated specific MRI features. Univariable statistical analysis was performed to identify which MRI characteristics might help distinguish IVDE from IVDP.

Results

117 dogs with lumbosacral IVDE (n = 16) or IVDP (n = 101) were included. Features associated with IVDE were in concordance with previous studies and included interruption of the dorsal annulus, suspected epidural hemorrhage, dispersed (rather than confined) intervertebral disc herniation on T2W sagittal images, lateralized intervertebral disc herniation and displacement of the cauda equina. Overall diagnostic accuracy was 68.8% and interobserver agreement was fair (κ = 0.37), which is lower than has been reported in thoracolumbar disc herniation, but accuracy increased to 85.3% with substantially improved agreement (κ = 0.87) in "confident" diagnoses.

Discussion/Conclusion

MRI characteristics used in differentiating thoracolumbar IVDE and IVDP can be extrapolated to the lumbosacral intervertebral disc space, but diagnostic accuracy in low-field MRI is lower than previously reported in herniations involving the thoracolumbar spine.

[Long-term examinations of the lumbal disc and facet joint changes in 5 German Shepard dogs]

OBJECT AND PURPOSE

The purpose of this first-time long-term observational study was to evaluate the changes of the caudal lumbar spine at the locations L5/6, L6/7, and L7/S1 in 5 German shepherd dogs over a 6-year time period using computed tomography (CT) and magnetic resonance imaging (MRI). The dogs had a mean age of 26 months at the time of the first examination. In addition, it was evaluated whether a breeding examination, with regard to disc degeneration, is justified in young dog.

MATERIAL AND METHODS

The locations L7/S1, L6/7, and L5/6 were examined in more detail with regard to their signal intensity changes, the facet joint angle changes in dorsal (dors) and transverse (trans) planes, and disc surface changes in sagittal (sag) and transverse (trans) reconstruction planes with CT and MRT in 2015 and 2021. All data were collected computer-based and analyzed statistically. Subsequently, the results were compared to the measured signal intensity and to the subjective disc degeneration grading according to Seiler used in practice.

RESULTS

Over the period of 6 years a significant loss of the measured signal intensity of the intervertebral discs in the transverse plane and an overall facet joint widening in the transverse plane of 0.54° as well as in the dorsal plane of 1.8° was evident. In addition, there was no evidence of a relationship between the size of the facet joint angle and the degree of disc degeneration. Furthermore, regardless of the initial degree of degeneration, the discs showed low signal intensity and higher Seiler grade during follow-up.

CONCLUSION AND CLINICAL RELEVANCE

The results of the present study group indicate that an inconspicuous condition of the lumbar intervertebral discs at the time of the initial breeding examination in the young dog does not allow an accurate prediction of the subsequent degree of degeneration and that there are ongoing remodeling processes at the facet joints even in healthy German shepherd dogs.

Neurogenic Bladder in Dogs, Cats and Humans: A Comparative Review of Neurological Diseases

Lower urinary tract disease (LUTD) includes abnormalities in the structure and function of the bladder and the urethra. LUTD caused by neurological disease is defined neurogenic bladder (NB). The integrity of the central nervous system (CNS) and peripheral nervous system (PNS) is required to explicate normal micturition, maintaining the proper function of bladder and urethra. The location and type of neurological lesions influence the pattern of clinical manifestations, potential treatment, and prognosis. Though, in dogs and cats, spinal cord injury is considered mainly responsible for bladder and/or urethra incompetence, other disorders, congenital or acquired, involving CNS or PNS, could play a role in NB. In veterinary medicine, the information about the epidemiology, prevalence, etiopathogenesis, diagnosis and treatment of NB are scattered. The aim of this study is to provide an overview of the epidemiology, prevalence, clinical findings, diagnosis and prognosis for NB in dogs and cats compared with humans.

Three-Dimensional Kinematics of the Pelvis and Caudal Lumbar Spine in German Shepherd Dogs

Lumbosacral vertebral motion is thought to be a factor in the development of degenerative lumbosacral stenosis in German shepherd dogs. So far, few studies exist describing natural canine lumbosacral movement in vivo. Therefore, this investigation aims to achieve a detailed in vivo analysis of bone movement of the lumbosacral region to gain a better understanding of the origin of degenerative lumbosacral stenosis using three-dimensional non-invasive in vivo analysis of canine pelvic and caudal lumbar motion (at L6 and L7). Biplanar cineradiography of the pelvis and caudal lumbar spine of four clinically sound German shepherd dogs at a walk and at a trot on a treadmill was recorded. Pelvic and intervertebral motion was virtually reconstructed and analyzed with scientific rotoscoping. The use of this technique made possible non-invasive measurement of physiological vertebral motion in dogs with high accuracy. Furthermore, the gait patterns of the dogs revealed a wide variation both between individual steps and between dogs. Pelvic motion showed a common basic pattern throughout the stride cycle. Motion at L6 and L7, except for sagittal rotation at a trot, was largely asynchronous with the stride cycle. Intervertebral motion in all dogs was small with approximately 2–3° rotation and translations of approximately 1–2 mm. The predominant motion of the pelvis was axial rotation at a walk, whereas lateral rotation was predominant at a trot. L7 showed a predominance of sagittal rotation (with up to 5.1° at a trot), whereas lateral rotation was the main component of the movement at L6 (about 2.3° in both gaits). During trotting, a coupling of various motions was detected: axial rotation of L7 and the pelvis was inverse and was coupled with craniocaudal translation of L7. In addition, a certain degree of compensation of abnormal pelvic movements during walking and trotting by the caudal lumbar spine was evident.

Intervertebral disc disease in Dachshunds radiographically screened for intervertebral disc calcifications

BACKGROUND

Intervertebral disc disease (IDD) is a very common neurological disease, Dachshunds being the breed most often affected. In this breed, IDD has a hereditary background and is associated with intervertebral disc calcification (IDC), an indicator of severe intervertebral disc degeneration. In Finland, spinal radiography is used, when screening for IDC before breeding Dachshunds. We evaluated the association between IDC and IDD in Finnish Dachshunds radiographically screened for IDC. A questionnaire was sent to owners of 193 radiographically screened Dachshunds aged at least ten years. Clinical signs indicative of IDD were compared with IDC grade (grade 0 = no calcifications, grade 1 = 1 - 2 calcifications, grade 2 = 3 - 4 calcifications and grade 3 = 5 or more calcifications) and with age at the time of the radiographic examination. The diagnosis of IDD was confirmed by a veterinarian.

RESULTS

IDD was common in the study population with 31% of dogs being affected. IDD and IDC were clearly connected (P < 0.001); IDD was rare in dogs with no calcifications (grade 0) and common in dogs with severe IDC (grade 3). The IDC grade was strongly positively associated with frequency of back pain periods (P < 0.001), and dogs with IDC grade 3 had frequent periods of pain. Reluctance to jump onto a sofa had a strong positive association with back pain. No association existed between age of the dog at the time of the radiographic examination and clinical signs indicative of IDD.

CONCLUSIONS

Radiographically detected IDC and IDD are common in Finnish Dachshunds and are strongly associated with one another. Spinal radiography is an appropriate screening tool for breeders attempting to diminish IDC and IDD in Dachshunds. A breeding program that screens dogs and selects against IDC can be expected to reduce the occurrence of IDD in future. Twenty-four to 48 months of age is a suitable age for screening.