Modic changes in the lumbar vertebral column of chondrodystrophic and non-chondrodystrophic dogs with intervertebral disc disease

Dyah Agustini, Mary K. Heimann, Megan Co, Benjamin A. Walter, Devina Purmessur, Sarah A. Moore

Background

Modic changes are pathological alterations in the vertebral bodies adjacent to degenerated intervertebral discs, visible on MRI scans and associated with low back pain in humans. These changes have been categorized into three types based on MRI signal characteristics. While also observed in dogs, the relationship between MC and spinal pathologies, including breed-specific predispositions, remains underexplored. This study investigates the prevalence of MC in dogs with IVDD, their association with demographic criteria, and disc width index (DWI), differentiating findings between chondrodystrophic (CD) and non-chondrodystrophic (NCD) breeds.

Methods

The study was a retrospective analysis of medical records and MRI images from 104 dogs (54 CD and 30 NCD with IVDD, and 20 control dogs with other spinal diseases). Dogs were classified based on breed-related predisposition to IVDD, and MRI images were assessed for MC presence and type. The disc width index was calculated for intervertebral discs to explore potential associations with MC.

Results

Older age and a diagnosis of IVDD were significantly correlated with the presence of MC in dogs. Type 2 MC was most common in CD dogs, while Type 3 MC was more prevalent in NCD dogs. Type 2 MC were distributed evenly across the lumbar spine, whereas Type 3 MC primarily appeared at the L7-S1 level.

Limitations

The study acknowledges limitations such as the inability to correlate MRI findings with clinical symptoms due to its retrospective nature and the exclusion of dogs with prior spinal surgery. Additionally, the use of a heterogeneous breed population may have introduced variability in vertebral body and disc width measurements.

Conclusions

MC occurs spontaneously in dogs with IVDD and varies by breed, with CD dogs predominantly developing Type 2 MC and NCD dogs more often showing Type 3 MC. The findings suggest potential genetic or biomechanical underpinnings to these differences. The study underscores the relevance of CD dogs as models for studying disc degeneration and associated vertebral changes in humans, highlighting the need for further research into the pathogenesis of MC and their clinical implications in dogs.

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