Association between navicular bone fragmentation and shape in Belgian Warmblood horses

Objectives: To investigate whether in navicular bones (NB) from warmbloods, distal border fragmentation is associated with the shape of the proximal articular border or other radiological findings. Methods: Radiographs of the front feet of 325 normal, subadult horses presented for admission as breeding stallions were reviewed. Results: The proximal articular border of the total of 650 NB was classified as straight (n = 278), convex (n = 184), undulating (n = 147) or concave (n = 41). Distal border fragments were present in 57 NB (8.8%). They were significantly more prevalent in NB with a concave (9/41; 22%) or undulating (19/147; 13%) proximal articular border compared to NB with a straight (17/278; 6%) or convex shape (12/184; 7%). No other significant associations were found. Clinical significance: Hypothetically, since a shape-fragment association was found and the distribution of biomechanical forces exerted on the navicular bone are assumed to be shape dependent, distal border fragments may be a result of unfavourable loading of the navicular region.