Podotrochlear Syndrome (also referred to as navicular syndrome or navicular disease) affects the podo­trochlear apparatus (PTA) of the equine foot and typically occurs in the forelimbs. [1]

The condition can cause a variable degree of lameness. Horses affected by Podotrochlear Syndrome may display changes in their gait including shorter stride length and a general decline in performance.

There is no single cause of Podotrochlear Syndrome. Multiple structures including bones, tendons, and ligaments within the foot can be affected. [1]

A definitive diagnosis of Podotrochlear Syndrome requires a veterinary clinical evaluation and testing modalities including diagnostic analgesia and radiographic imaging. [1]

Although there is no cure for Podotrochlear Syndrome, the condition can be treated with corrective trimming and shoeing, medications, and non-surgical and surgical interventions. [2]

What is Podotrochlear Syndrome?

Podotrochlear Syndrome is a leading cause of lameness in sport horses and those used for recreational riding. The condition occurs most commonly in the front legs and rarely in the hind legs.

There is no single cause of Podotrochlear Syndrome. The condition is believed to result from multiple injury and disease processes. [3]

Horses with Podotrochlear Syndrome experience pain in the heel of one or more of their feet. The condition affects the podo­trochlear apparatus (PTA) of the equine anatomy.

Navicular Bone in Horses | Mad Barn Canada

The PTA includes the navicular bone, the navicular bursa (the fluid-filled sac between the deep digital flexor tendon (DDFT) and the navicular bone), the coffin joint, the collateral ligament, the impar ligament, the suspensory ligament of the navicular bone, and DDFT. [1]

The navicular bone is often affected in horses with Podotrochlear Syndrome, which is why this condition is commonly referred to as Navicular Disease.

This bone is an important component of the distal interphalangeal (DIP) joint which plays an integral role in hoof function and serves as a fulcrum for the DDFT. [1]

Development & Effects in the Equine Foot

The rear portion of the foot in horses affected by Podotrochlear Syndrome can undergo a range of changes due to the condition.

Podotrochlear Syndrome often involves a disruption to the normal bone remodelling processes that occur in the navicular bone. When the rate of bone absorption exceeds the rate of bone rebuilding, degeneration and lesion formation occurs in the navicular bone. [4]

The compact and spongy components of the navicular bone and fibrocartilage tissue located at the insertion points of ligaments and tendons may be eroded in horses with Podotrochlear Syndrome.

The condition may also cause thickening to occur in the compact bone. [1][3]

The altered bone remodelling processes associated with Podotrochlear Syndrome are believed to possibly result from trauma to the bone or compromised blood supply to the bone. [5]

Podotrochlear Syndrome can cause the development of inflammation, lesions, and adhesions in the DDFT and lesions in the collateral and impar ligaments. Inflammation may also occur in the synovial membranes of the DIP and in the navicular bursa. [1][3]

Research demonstrates that the flexor tendons of horses with Podotrochlear Syndrome display a higher proportion of non-aligned collagen compared to horses without the condition. This is thought to occur as part of a process caused by excessive tension and compression forces in the forelimb. [6]

Horses affected by Podotrochlear Syndrome have demonstrated abnormalities in specific biochemical markers associated with collagen, cartilage, and bone formation. [3]