Reproducible long-term disc degeneration in a large animal model

Study Design. Twelve goats were chemically degenerated and the development of the degenerative signs was followed for 26 weeks to evaluate the progression of the induced degeneration. The results were also compared with a previous study to determine the reproducibility. Objectives. The purpose of this study was determine whether this Chondroitinase ABC ( CABC) induced goat model is reproducible and to study the development of the degeneration in time up to 26 weeks. Summary of Background Data. Injecting CABC into goat intervertebral discs results in mild disc degeneration after 12 weeks. Spontaneous recovery or leveling off of the degeneration has been reported before and is relevant when the goat model is used in regeneration studies. Reproducibility of the induced degeneration is relevant as well. Methods. Twelve goats were used in this study. The development of degeneration was studied after the injection of 0.25 U/mL CABC intradiscally. The development of degenerative signs was studied after 18 (n = 6) and 26 (n=6) weeks by means of radiograph, magnetic resonance imaging, macroscopic analysis, and histology and biochemical evaluation. The induced degeneration was compared with the results from a previous study, in which degeneration was induced similarly and analysis was performed after 12 weeks. Results. The severity of the degenerative signs was mild and was consequently present in all parameters analyzed. When compared with the results after 12 weeks, the degeneration was similar in the present study. Spontaneous recovery was not observed up to 26 weeks. Conclusion. The injection with CABC in the intervertebral disc reproducibly results in mild disc degeneration in the goat. These findings corroborate the goat model as a suitable large animal model to evaluate mild disc degeneration and potential new therapies.