08/09/2026
This is the navicular bone of a 10-month-old c**t.
This slice is approximately 1 cm from sagittal, meaning 1 cm away from the midline, so the navicular bone will look a slightly different shape to what you may be used to seeing on my posts
The tip of my scalpel is pointing to a very specialised area called the flexor surface.
The flexor surface of the navicular bone is covered by fibrocartilage, creating a specialised smooth surface against which the deep digital flexor tendon glides. You can see the DDFT as that big white structure underneath my scalpel blade.
The bone and its flexor surface are simply beautiful.
This is a baby who has never had a saddle or a human on his back. He has been allowed to play, move, grow and simply enjoy being a baby.
When I study equine feet, I quite commonly see changes to this surface. The fibrocartilage can become damaged and thin and, with advanced disease, areas of underlying bone may eventually become exposed. By that stage we may also see significant damage to the deep digital flexor tendon.
The relationship between these two structures is incredibly important. The DDFT passes over the flexor surface of the navicular bone before inserting onto P3, and the tendon and navicular bone are therefore mechanically very closely related.
We need to be careful about saying which structure starts the disease process, because it may not be the same in every horse. Damage can occur within the DDFT, within the fibrocartilage and navicular bone, or within several structures of the navicular apparatus together.
But hoof biomechanics absolutely matter.
A hoof with poor dorsopalmar balance — for example, excessively low or underrun heels combined with a long toe — can alter the forces acting through the DDFT and the navicular apparatus. This can increase mechanical stress within this region. It is one of the reasons I believe we need to think about the navicular bone, DDFT and the rest of the foot as a whole mechanical system, rather than looking at one structure in isolation.
Over time the DDFT can develop fibrillation, tearing and other degenerative changes, while the fibrocartilage covering the flexor surface of the navicular bone can also deteriorate. In advanced cases we can see adhesions and lesions developing at the interface between the tendon and the navicular bone.
This is why I find this little 10-month-old foot so fascinating.
I am looking at these structures before years of work, trimming, shoeing, riding and environmental influences have been added to the equation.
Navicular disease was once regarded almost as a death sentence for a horse. Today we understand that “navicular disease” is far more complicated than simply having a bad navicular bone, and the term navicular syndrome is often much more appropriate.
We cannot reverse every structural change once it has occurred, but with appropriate veterinary assessment, hoof care, trimming and, where appropriate, a carefully considered shoeing or support package, many horses can be managed very successfully.
And this beautiful young foot gives us an opportunity to see what these structures can look like before a lifetime of loading and use.
