It is not always possible to pinpoint the exact cause of Navicular syndrome, even veterinarians do not agree as to a specific cause. Because there are a variety of causes, no one treatment is always successful. However, one of the more common causes of Navicular syndrome is the degradation of the Navicular bursa. This bursa lies between the deep digital flexor tendon and the Navicular bone and acts as a lubricating cushion. When the bursa becomes inflamed or loses lubricating fluid the flexor tendon is at risk of rupture. This is similar to the condition of “tennis elbow” found in humans.

While the joints surfaces of the phalanges may not be affected the tendon adjacent to the Navicular bursa may be progressively destroyed with eventual rupture. The deep digital flexor tendon is critical because it flexes the joints of the foot, allowing the toe to move up and down. As the coffin joint flexes, the deep digital flexor tendon glides against the Navicular bone. This rubbing action would cause tissue damage and pain if it were not for the bursa, which is located between the tendon and the bone. In its normal state, the Navicular bursa is filled with a lubricated substance which prevents pain and tissue damage. However, when the bursa is damaged, tendon on bone contact sets the foundation for the symptoms of Navicular syndrome.