Navicular Lameness

Navicular Lameness may result from a bursitis or inflammation of the synovial fluid filled sac located between the articular cartilage of the navicular bone and the deep flexor tendon.

Lameness may be a result of spraining one or more of the ligamatous attachments holding the navicular bone in place.  Or pain may be the result of:

Thrombosis  -  arterial congestion

Ischemia     -   bone degeneration, due to circulation disturbances.

These conditions cause;

                          Osteochondrosis -  subcartalage bone change,

              Or                  Osteolisis  -  bone destruction.

Concussion or compression forces, may produce the above conditions.

Navicular usually only involves the front feet - may occur in the hind feet - rarely in all four feet.

Navicular lameness may be eased temporarily, but often it progresses to destruction of the;

                         - Articular Cartilage of the Navicular Bone

                         - Deep Flexor tendon adhesions

                         - Navicular Bone cavities

                         - Coffin Joint arthritis      

Concussion or compression forces may traumatize the Navicular Bone - blood vessels. This may happen when a horse is improperly conditioned or lack of conditioning at all, and the animal is expected to perform strenuous work.

The Navicular Bone is the fulcrum of leverage by which the deep flexor tendon travels. Chronic - long toe / low heel - will cause strain on the Navicular Bone, and compromise the blood flow allowing the bone to die and erode away.

The most pain displayed will be after long hours of stillness and then asked to move about. The horse may seem to warm out of the lameness, so the gait will at first appear short strided, moving to a longer normal stride after some time.

Whilst at a stand still the horse will point one foot then the other (in the case of two foot lameness), pointing the toe too the ground and lifting the heel of the ground, to relieve the pressure off the deep flexor tendon. These horses are also known to find a way to point both feet at the same time, finding a depression in the ground, or digging their toes into soft ground or bedding. 

Below, Is As Seen In, The Kootenay Western Star

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