Intervertebral Disc Degeneration in Warmblood Horses: Morphology, Grading, and Distribution of Lesions.
Authors: Bergmann Wilhelmina, Bergknut Niklas, Veraa Stefanie, Gröne Andrea, Vernooij Hans, Wijnberg Inge D, Back Willem, Grinwis Guy C M
Journal: Veterinary pathology
Summary
# Intervertebral Disc Degeneration in Warmblood Horses: Morphology, Grading, and Distribution of Lesions Despite limited evidence, intervertebral disc degeneration (IVDD) has long been assumed rare in horses and of questionable clinical significance; this study addresses that knowledge gap by establishing standardised gross and histological criteria for assessing equine disc pathology. Researchers examined spinal units from 33 warmblood horses, analysing 286 intervertebral discs grossly and subjecting 107 normal-to-mildly-degenerate discs (37% of the total) to histological assessment, with rigorous inter- and intra-observer reliability testing. Key morphological findings included consistent identification of nucleus pulposus, annulus fibrosus and transition zone structures, with degeneration manifesting as yellow discoloration, cleft formation and altered nuclear consistency—patterns closely mirroring those documented in humans and dogs, predominantly affecting the caudal cervical spine. The authors propose a five-point grading scheme with higher grades correlating strongly to advancing age, notably excluding vertebral bony changes from the classification since these changes (most prevalent in the thoracolumbar region) showed no correlation with disc degeneration severity. For equine practitioners, this framework provides an objective, reliable tool for diagnosing and monitoring IVDD in clinical and research settings, whilst highlighting that cervical discs warrant particular scrutiny and that secondary bone changes should not be conflated with primary disc pathology.
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Practical Takeaways
- •Intervertebral disc degeneration is common in warmblood horses (63% prevalence) and increases with age—this may be clinically relevant more often than previously thought
- •Caudal cervical spine is the primary location for disc degeneration; look here when investigating neck pain or neurological signs
- •Do not assume vertebral osteophytes indicate disc degeneration in horses, as they occur independently and more commonly in the thoracolumbar region
Key Findings
- •37% of 286 equine intervertebral discs showed normal morphology (grades 1-2), while 63% exhibited degenerative changes
- •Intervertebral disc degeneration was most prevalent in the caudal cervical spine and increased with age
- •Degenerative changes (yellow discoloration, cleft formation, consistency changes) were similar to those in humans and dogs, but were NOT associated with osteophyte formation as in other species
- •Vertebral bone changes occurred primarily in thoracolumbar spine but were independent of disc degeneration grade, so should be excluded from grading schemes