Navicular Syndrome Myria Shipman, Dr. Frank Flanders and Asha Wise Navicular has been described as one of the most common causes of chronic forelimb lameness Myria Shipman, Dr. Frank Flanders and Asha Wise Georgia Agricultural Education Curriculum Office Georgia Department of Education February 2006

Disease or Syndrome? Because there is no proven cause or treatment it is better referred to as a syndrome Navicular Syndrome is generalized heel pain due to problems with the navicular bone Other causes of heel pain are often misdiagnosed as Navicular Syndrome Navicular was at first called a disease. Recently, researchers have begun to refer to it as a syndrome because: Lack of a specific etiology-meaning there is no one specific cause that has been proven as resulting in navicular, rather it appears that there are several different causes Lack of a specific treatment or therapy for navicular. These days, you will hear it called both navicular disease or navicular syndrome but the two terms are used to describe the same thing. Usually occurs in the forelimbs, rarely in the hind limbs. Usually both forelimbs are involved, but one may be worse than the other. Some of the other causes of heel pain: bruised heels, underslung heels and misbalanced feet.

Three Causes of Navicular Concussion or trauma to the Navicular bone Thinning and erosion of the cartilage Degeneration of the Navicular bone Injuries of the Navicular bone and surrounding areas Arterial obstruction strain and inflammation of the impar ligament can obstruct these blood vessels and reduce blood flow to and from the navicular bone 1a: around the navicular bone 1b: usually occurs in the advanced stages, after cartilage has eroded. Can be accompanied by adhesions between the bone and the deep digital flexor tendon. 1c: injuries that occur during locomotion can cause trauma to the area. 2. Blood flow can become decreased if the blood vessels to the navicular bone are obstructed.

*Osteoarthrosis (degenerative joint disease) Changes in the Navicular bursa synovium *Osteoarthrosis (degenerative joint disease) Has been compared to DJD (degenerative joint disease) because of similarities in the changes that occur with each: Degenerative changes Increased pressure on the area Bone remodeling response to the degeneration

Predisposing Factors Poor hoof conformation long toes and low heels narrow upright feet Extreme work on hard surfaces Standing in stalls for extended periods of time Improper trimming and shoeing Also, impact on the hooves will eventually lead to navicular. Horses that are trained to jump obstacles endure impact on the hooves every time they land off of a jump. Many jumping horses will eventually have navicular.

Symptoms Often a unilateral lameness Usually restricted to the forelimbs Walking toe to heel Short choppy strides Reduced wear of the heel region

Management Practices Medication Reduce intensity of training vasodilators anti-inflammatory corticosteroids Reduce intensity of training Exercise program should be determined by the severity of problem There are ways to manage pain but the horse will never fully recover

Corrective shoeing corrective trimming: raise heel, role toe types of shoes : keg, conventional bar, egg bar, aluminum, rolled-toe (any of these can be combined with pads) conformation of hoof and location of pain determines trimming and shoeing methods Egg bar is pictured. Management of navicular horses can become expensive!

– Many times bone disorders are caused by an excess of Aluminum Surgery Neurectomy (nerving): severing of the palmar digital nerves on either side of the deep flexor Gallium Nitrate ??? – Many times bone disorders are caused by an excess of Aluminum – Gallium competes with Aluminum for absorption in the bone, causing a delay in further degeneration – Fed as a supplement Gallium nitrate is not fully accepted as helpful for navicular horses.