Correlation between fat signal fraction of vertebral body and intervertebral disc degeneration in dogs using magnetic resonance imaging.

Importance: In human medicine, research using magnetic resonance imaging (MRI) has shown that an increase in the vertebral body fat signal fraction (FSF) is associated with the severity of intervertebral disc (IVD) degeneration. Nevertheless, veterinary medicine has limited information on the relationship between the vertebral body FSF and IVD degeneration.

Objective: This study evaluated the relationship between IVD degeneration and the vertebral body FSF in dogs and compared these factors between chondrodystrophic (CD) and non-chondrodystrophic (NCD) dogs.

Methods: IVD degeneration in dogs was classified morphologically using the Pfirrmann grade, and the vertebral body FSF was evaluated quantitatively.

Results: The vertebral body FSF showed a statistically significant difference among the age groups. The vertebral body FSF was significantly higher in Pfirrmann grades 3-5 than in grades 1 and 2. The mean Pfirrmann grade of CD dogs was higher than that of NCD dogs in the four-to-six-year-old group. The mean vertebral body FSF of CD dogs was higher than that of NCD dogs in the group of seven years and above.

Conclusions and relevance: In dogs, the vertebral body FSF increased significantly with age and Pfirrmann grade. The CD dogs showed a higher degree of IVD degeneration at a younger age than the NCD dogs. CD dogs appeared to experience more severe fat deposition of the vertebral body in old age than NCD dogs. MRI examinations are helpful for evaluating IVD degeneration and vertebral body fat deposition.