Open access publications in the SLU publication database

Abstract

Back pain is common in both dogs and humans, and is often associated with intervertebral disc (IVD) degeneration. The IVDs are essential structures of the spine and degeneration can ultimately result in diseases such as IVD herniation or spinal instability. In order to design new treatments halting or even preventing IVD degeneration, more basic knowledge of the disease process is needed. The aim of this thesis was to increase the knowledge of IVD degeneration in dogs and to evaluate the similarities and differences between IVD degeneration in dogs and humans, in order to establish whether spontaneous IVD degeneration occurring in both chondrodystrophic (CD) and non-chondrodystrophic (NCD) dog breeds can be used as translational animal models for human spine research. The key findings of the thesis were: • The division of the processes underlying canine IVD degeneration into chondroid or fibroid degeneration appears to be inaccurate. The biochemical, histopathological, and morphological alterations examined during the process of IVD degeneration were found to be similar in CD and NCD dog breeds. • IVD degenerative diseases were most common in CD breeds, especially in Dachshunds, and were 1.5 times more common in male than female dogs. Case fatality rates were found to be higher than previously suggested, with rates of 34% in the overall population, around 20% in most CD breeds, and over 50% in the NCD breeds at highest risk such as the Doberman and the German Shepherd Dog. • IVD degeneration in dogs could accurately be diagnosed, early in the degenerative process, by using low-field magnetic resonance imaging (MRI). The MRI based grading scheme used in humans could reliably be used in dogs, and was found to be highly correlated with pathological changes found post mortem. Early diagnosis facilitates the possibility of preemptive treatments. • A new nucleus pulposus prosthesis, made of an intrinsically radiopaque hydrogel, was tested ex-vivo in dogs. Surgical implantation of the prosthesis in canine lumbosacral IVDs via a dorsal laminectomy was clinically applicable. After absorbing fluid from the surrounding tissue the swollen implant could restore disc height, which could be monitored by radiography, computed tomography and MRI. • Many similarities were found between the processes of IVD degeneration in humans and CD and NCD dog breeds. Both dog-types may serve as translational animal models of spontaneous IVD degeneration for human research. Synergistic effects of studying IVD degeneration in veterinary patients could lead to new treatment modalities for both dogs and humans, a reduced need for animal testing, and lower cost of research. It is also likely that spontaneous IVD degeneration in dogs more resembles the true disease process, as it occurs in humans, than induced IVD degeneration in experimental animals.