Ovine models of intervertebral disc degeneration

The development and evaluation of effective therapeutic strategies for intervertebral disc degeneration (IVDD) and their successful incorporation into clinical practice remain challenging, largely due to the absence of an optimal preclinical animal model. While both induced and spontaneous IVDD animal models have provided valuable insights, they also present inherent limitations that restrict their translational applicability. Increasing evidence supports the use of sheep as a highly relevant large animal model, as spontaneous spine disorders in this species closely mirror many features of human IVDD. Sheep exhibit remarkable similarities to humans in terms of disc cellular composition, anatomical configuration, physiological loading, histological architecture, and molecular signaling pathways. These features make the ovine model uniquely positioned to bridge the gap between basic science and clinical translation, fulfilling both scientific and regulatory requirements. In this review, we highlight the shared features of IVDD between sheep and humans and examine both spontaneous and induced ovine models currently used to study disc degeneration. Furthermore, we discuss how the integration of advanced technologies, such as surgical navigation systems can refine the reproducibility and precision of these models. These innovations not only enhance experimental rigor but also strengthen the translational value of the ovine model, advancing our understanding of IVDD pathophysiology, diagnosis, prevention, and treatment. Continued refinement of ovine models will play a critical role in the development of effective therapeutic strategies for managing IVDD in humans.