LOWER LEG LAMENESS

Examination of lameness of the front leg of the horse often leads to a problem in the lower leg, especially in the hoof region.  Because it contacts the ground with significant force in many cases it is subject to various problems due to the concussion it incurs.

Two problems that occur here are laminitis and heel pain that almost always was labeled navicular disease in the past.

                Chronic laminitis, also called founder, is a difficult and frustrating disease to handle.  When there is rotation of the coffin bone (P-III) significant pressure is put on the corium of the sole at the toe.  This pressure significantly retards blood flow to the tissues of the sole and coffin bone.  In a recent talk at the AAEP held in New Orleans in 2003 Dr. Steve O’Grady, who is a farrier as well as a veterinarian, described several goals to achieve to reduce the rotation of the coffin bone.

“Re-establish weight-bearing along the entire solar surface of P-III (rather than being concentrated at the apex of P-III)”

“Aid break over by moving the functional break over point palmarly (toward the heel).”

“Decrease tension in the deep digital flexor tendon (DDFT).”

                Dr. O’Grady further described how to achieve these goals.  He will trim the heels moving  the break over point back.  The shoe is glued to the foot so that the shoe and sole of the coffin bone are parallel.  He will ultimately raise the heels by using the wedge-shaped rails (wider at the heels) attached to the shoe.  Dr. O’Grady had had some success with this procedure returning 62.5% to some level of usefulness.  Some of the cases required an inferior check ligament desmotomy to further release pressure on the downward rotation of the coffin bone.

                Another topic covered at the 2003 AAEP meeting was the subject of magnetic resonance imaging (MRI) and its use in lameness diagnosis.  Dr. Tim Mair located in England talked about his experiences with MRI  in the horse.  Besides being very large and expensive,  horses need to be placed under general anesthesia  to be scanned.

                Recently newer equipment was installed in the Bell Equine Veterinary Clinic Dr. Mair practiced at in England.  This equipment allowed imaging of the standing horse’s leg up to the knee or hock.  The scan protocol required the horse to stand quietly for 60 to 120 minutes.  Sedation allows scanning of the feet, but scanning above the feet requires some type of motion correction.  Supporting the leg in a scanner and holding the head steady will minimize the movement of the leg. 

                Dr. Robert Schneider of Washington State Universities Veterinary Teaching Hospital gave further discussion of the MRI and how it is involved with the diagnosis of navicular disease.  Other problems such as chronic laminitis with mild rotation of P-III, early arthritis of the coffin joint, palmar heel pain, ligament problems inserting on P-2 have been diagnosed through the use of MRI in their diagnostic workups.

                In the US MRI equipment is located in only a few select locations.  Dr. Schneider concluded, “As MRI increases, our knowledge about navicular disease, early diagnosis, new treatments, and/or better case selection for current treatment will hopefully follow.”