Relationships of age and shape of the navicular bone to the development ofnavicular disease: a radiological study

Estimating the shape of the proximal articular border of the navicular bone and grading the radiological navicular bone condition (grades 3 and 4 repr esenting the most severe changes), the aim of this study was to assess pote ntial age-related implications of the previously reported shape predisposit ion to navicular disease in 746 normal and 174 clinically affected Dutch Wa rmbloods age 3-19 years. A significant, age-independent, shape-grade associ ation found in normal and affected horses emphasises the fundamental charac ter of the shape predisposition to navicular disease. A significant age-rel ated increase of the least susceptible shape prevalence was found in elderl y normal horses. A shape-independent low grades 3 and 4 prevalence (mean 15%) was found in n ormal horses, vs. a high grades 3 and 4 prevalence (mean 85%) in the affect ed horses. Therefore, the clinical manifestation of the disease is grade-ra ther than shape-dependent. A significant age-related appearance of inverted flask-shaped channels and enthesophytes was found in the clinically affected horses. However, conside ring the significant shape-radiological features association previously rep orted in 3-year-old normal horses, this association may be shape- rather th an age-dependent.