Relationships of age and shape of the navicular bone to the development of navicular disease: a radiological study.
Authors: Dik, van den Belt, van den Broek
Journal: Equine veterinary journal
Summary
# Editorial Summary This radiological investigation of 746 normal and 174 affected Dutch Warmbloods (aged 3–19 years) examined whether navicular bone shape and age independently influenced disease development, using radiographic grading of the proximal articular border to classify severity. Whilst bone shape demonstrated a consistent, age-independent association with radiological changes across both populations, clinical disease manifestation proved predominantly grade-dependent rather than shape-dependent: only 15% of radiographically normal horses showed severe changes (grades 3–4), compared with 85% of clinically affected animals. The research suggests that whilst certain bone conformations may predispose horses to navicular pathology, the progression to clinical disease relates more directly to the severity of radiological degenerative changes, implying that shape alone is insufficient to predict which horses will become lame. For practitioners, this underscores the importance of radiographic grading as a more reliable prognostic indicator than morphological assessment alone, and suggests that management strategies should focus on limiting the progression of degenerative change rather than relying solely on conformational risk assessment.
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Practical Takeaways
- •Navicular bone shape on radiographs is a fundamental predisposing factor independent of age; horses with unfavourable shapes require proactive management regardless of age
- •Radiological grade (severity of degenerative changes) is more predictive of clinical disease than bone shape alone; mild radiological changes may not cause clinical signs
- •Older horses developing favourable bone shape morphology may have natural protective mechanisms; monitor younger affected horses more closely for progressive disease
Key Findings
- •Navicular bone shape predisposition to disease is age-independent and fundamental, with significant association between shape and radiological grade in both normal (746) and affected (174) horses
- •Clinical navicular disease manifestation is grade-dependent (85% prevalence of grades 3-4 in affected vs 15% in normal horses) rather than shape-dependent
- •Elderly normal horses show increased prevalence of least susceptible bone shape, suggesting age-related protective morphological changes
- •Inverted flask-shaped channels and enthesophytes in affected horses show age-related appearance but association may be shape-dependent rather than age-dependent