Pathophysiology of navicular syndrome.

This research article focuses on the pathophysiology of Navicular Syndrome, a degenerative disorder affecting horses, caused by nonphysiological pressure on the proximal sesamoid bone due to faulty foot conformation. This abnormal pressure triggers a bone remodeling response and leads to various adverse effects, including hyperemia, edema, vascular bone pain, and noticeable clinical symptoms.

Introduction to Navicular Syndrome

• Navicular Syndrome refers to a degenerative disorder that primarily affects the distal half of the flexor surface of the proximal sesamoid bone in horses.
• The condition is associated with abnormal or faulty foot conformation in the animal.

The Impact of Faulty Foot Conformation

• Faulty or abnormal foot conformation can lead to nonphysiologic pressure being exerted by the deep digital flexor tendon on the flexor cortex of the bone.
• If a horse with a faulty foot conformation becomes symptomatic, this kind of persistent abnormal pressure becomes apparent.

Response to the Nonphysiologic Pressure

• In response to the applied nonphysiologic pressure, the bone undergoes an intense remodeling process, an attempt to mitigate the pressure effects.
• This remodeling response, however, has several negative repercussions.

Negative Effects of the Bone Remodeling Response

• One of the consequences of the bone remodeling response is the activation of hyperemia, an excess of blood in the blood vessels, and the formation of edema, a condition characterized by an excess of watery fluid collecting in the cavities or tissues of the body.
• The edema that forms in the bone’s medullary cavity gets organized by fibrous tissue, hence leading to venous entrapment and venous hypertension, conditions which ultimately contribute to vascular bone pain.
• The above-mentioned conditions then culminate in the clinical signs that are characteristic of Navicular Syndrome.