There are some breeds that were seen as being “pre-disposed” to Navicular Syndrome because of their conformations. The “hereditary” theory does have some valid points in that many horses have a hoof and limb conformation that makes hoof balance challenging. Within the last 5 years, the latter seems to be the more widely accepted theory in light of the soft tissue lesions occurring before bone changes are seen. Another school of thought is that NS is caused by excessive leverage from a long toe and other hoof imbalances. Some feel that NS is hereditary and that certain breeds and bloodlines are predisposed to having Navicular region lameness. In general, the debates and speculations have centered around heredity and hoof balance. Today, more specific and comprehensive equipment are available to diagnose the condition so treatment can be more effective.įor years the cause of “Navicular Syndrome” has been speculated and debated. Typically, cases would reach the radiographically recognized state before a definitive diagnosis could be made. If left untreated, the lesions can become chronic and progress to arthritic lesions. Lesions to the collateral ligaments of the DIP joint and the collateral sesamoidean ligament (suspensory ligament to the NB) seem to represent a large portion of the current findings with MRI and ultrasound.

With the advent of standing MRI for horses and high quality ultrasound, veterinarians are able to see pathology to connective tissue around the Navicular bone and the distal interphalangeal (DIP) joint, long before changes to the bone are seen radiographically. However, over the last 15 years or so, there have been marked improvements in understanding the lameness in the Navicular region. It was also commonly accepted that the horse would have frequent bouts of discomfort for the remainder of their life. Most horse care professionals and horse owners grew to accept that the NS diagnosis meant limited use of the horse with regular administration of anti-inflammatory injections or a neurectomy. Because both the cause and structure being affected were not fully known, the prognosis for most of these cases was less than bright. Until recently, the NS diagnosis was vague in many cases. The use of the term “disease” seems to be reserved for cases where actual changes to the Navicular bone are seen, however, even then it is a guarded prognosis because calling it a disease would imply that the cause is known and a specific treatment can be implemented. Typically if a horse had heel pain, pain through the frog, and diagnostic anesthesia that localized the area around the Navicular bone, it would receive the diagnosis of “Navicular Syndrome” because the pain seems to be in the Navicular region. It seems that typically horses could exhibit all the clinical signs of Navicular disease, but have no radiographic changes to the bone. Over time there has been considerable debate regarding a Navicular diagnosis. There are generally less than 10% of all horses diagnosed with “Navicular Syndrome/Disease” that actually have radiographic changes or significant degeneration of the Navicular bone (NB). The terms Navicular “Syndrome” (NS) and Navicular “Disease” (ND) are often used synonymously however, there is a definite difference. Although the Navicular region of the hind limbs can be affected in the same way, most Navicular Syndrome diagnoses are on the front feet. It is speculated that Navicular Syndrome is responsible for about 1/3 of all chronic forelimb lameness in horses.

Hind leg lameness in horses