Navicular Syndrome / Disease

The navicular bone acts as a pulley for the deep flexor tendon. It is classically thought that the navicular bone would go through changes & develop lesions, spurs that would cause pain to the back of the foot and it was thought to be incurable. Navicular Syndrome simply means that the horse hurts in the back of the foot but the cause is unknown. Navicular Disease is when there are actual changes in the bone that shows up on x-rays.

Traditional methods would typically use bar shoes and then pads, just bandaiding the problem, continually raising the heel driving the coffin bone tip down into the sole.

James R. Rooney DVM:

Toe first landings have been proven to lead to navicular syndrome and navicular disease. James R. Rooney DVM (The Lame Horse, among many other books) spent a career studying the whole horse and performing thousands of dissections. During his studies, he found that the damage was happening to the deep flexor tendon first, not to the bone. In no cases was there damage to the bone and not the tendon. He found yellowing of the cartilage that surrounds the navicular bone and he could recreate this yellowing with heat from a light bulb. The only thing that could cause this on its own was higher friction. What causes higher friction in this area? Excessive force. Unnatural force. Dr. Rooney built a machine to put the limb of the cadaver in a constant toe first landing position and was able to duplicate this observation he'd seen in his dissections. He then built other models and examined the various forces to the leg, which further confirmed his theory that chronic toe first landings lead to navicular. Horses should only land toe first as they move up hill or on rocky terrain. Even after Dr. Rooney published his findings in 1974, tradition won out over science.

Robert M. Bowker, VMD, PhD - Michigan State University Equine Foot Laboratory:

Dr. Bowker furthered this navicular research. General loss of mass in the coffin bone, when it reaches 30-40%, will begin to spread to the navicular bone and affect it. This is blamed on peripheral loading, forcing the horse to bear all of its weight on the hoof wall and taking away the pressure on the frog, sole and bars.

NASA has proven that when astronauts are in space too long and have a lack of pressure to their bones, the bone starts to take away density. This is why weight bearing exercise helps us build strong bones. The exact same thing happens to equines when they don't get enough sole pressure. It registers to the horse as a lack of necessary force and the body starts to remodel the bone. Excessive pressure removes bone as a whole, at the distal border of the coffin bone. Inadequate pressure can remove bone density. The horse needs the right amount of pressure that is provided by natural movement, heel first landings, sole, frog and bar pressure.

Washington State University studies using MRI technology, found damage to the soft tissue that we never knew existed, shows up long before x-rays show changes to the navicular bone. This is just one more study that comes right back to the toe first landing compensating for back of the foot pain, that leads to navicular syndrome/disease.

navicular_1So, when we talk about Navicular we are talking about heel pain in our horse. Unlike Laminitis or Founder, Navicular Syndrome is hard to see in a picture and almost impossible to predict by x-ray.

Low resolution image!

What can be done for the navicular horse or mule?

  • Develop the back of the foot
  • Increase exercise
  • Bring in pea gravel
  • Trim for heel first landing
  • Use pads and boots to develop the frog/digital cushion
  • Treat the hoof for bacterial and fungal infections

A horse can have lots of damage to the navicular bone and not be the source of the pain. Damage to the bone is the result of the pain in the back of the foot causing the horse to walk toe first. While you can't fix changes to the bone, it doesn't necessarily cause pain to the horse either.

Rehabilitation has less to do with the changes in the navicular bone and more to do with how poorly developed the back of the foot is, and how much you can get the horse owner to take steps to develop the back of the foot. It doesn't have to be a death sentence. Treat the horse or mule with a barefoot trim. If there is still pain, boot and pad the horse. Successful rehabilitation of Navidular pain also involves daily exercise, constant testing of the feet, and adjustment of the remedial pressure that is exerted on the frog and sole.

While some horses will remain pasture sound, needing to be ridden in boots and pads, others can recover and be sound riding barefoot animals.

No hour of life is wasted that is spent in the saddle.  ~ Winston Churchill