Navicular syndrome

Veterinary advice should be sought before applying any treatment or vaccine.

Navicular Syndrome

Navicular Disease

Navicular syndrome, also known as navicular disease, is a chronic and often progressive disease process that affects the horse's hoof. It specifically involves the navicular bone, navicular bursa, deep digital flexor tendon (DDFT), and soft tissue structures making up the navicular apparatus. Navicular is one of the most common causes of chronic intermittent forelimb lameness in horses, accounting for one-third of all chronic lameness cases in one study. There are many different types of treatments, however none have proven to be a consistently effective form of therapy. In fact, in a study conducted in 2006, only 65-75 percent of affected horses improve in performance and only 40-50 percent were able to stay sound for 1 to 2 years.

The primary function of the navicular bone is to provide a constant angle of insertion for the DDFT. The specific cause of the syndrome is unknown, however there are three proposed theories which include vascular alterations, chronic inflammation and repetitive biomechanical forces applied to the hoof.

When moving, horses with navicular syndrome tend to place move weight on the toe of their foot in order to avoid exerting pressure on the heel. This is because the heel is where the navicular bone and bursa are located. This shifting of weight alters the horse's gait to a rough, choppy stride. Horses will have varying degrees of lameness, with a sudden or insidious onset. The lameness starts out mild initially and appears to get better when the horse is exercised. Sometimes the horse is lame after work, but will get better with rest. Over time, the lameness gets worse with exercise and is made worse on hard surfaces. Horses often show increased discomfort when turning or when asked to make tight circles. Navicular horses also trip frequently. When stationary, the horse will often be seen pointing the lame leg, stand camped-out with both front legs, or continuously shifting their weight in their front legs due to pain.

Over time, in cases of chronic lameness the horse's hoof conformation may change and present as a contracted (small and narrow) hoof with a high heel. Upon application of hoof testers, horses with navicular syndrome will often demonstrate a pain response (immediate limb withdrawal) when pressure is applied to the middle third region of the frog.

Of the various treatments available, bisphosphonate medications (tiludronate and clodronate) have been shown to be promising. Researchers at Oklahoma State University (OSU) are currently in the process of conducting a clinical trial to test the effectiveness of bisphosphonate therapy on eligible horses.

Symptoms

Intermittent mild to moderate lameness
Hoof tester response
Short and choppy gait
Stumbles often
Increased discomfort when turning
Increase in digital pulse
Lameness gets worse when asked to make a tight circle or working on a hard surface
Points front foot when at rest
Continuously shifts weight at rest
Standing camped-out with both front legs
Changes in hoof shape

Diagnosis

  • History
  • Clinical signs
  • Physical examination
  • Hoof testers
  • Lameness examination
  • Peripheral and/or diagnostic anesthesia
  • Radiography
  • Ultrasonography
  • Nuclear scintigraphy
  • Thermography
  • Computed tomography (CT)
  • Magnetic Res

Treatment

TherapiesDetails
Clodronate Disodium
Tiludronate
Controlled exercise
Rest
Corrective shoeing
NSAIDs
Corticosteroid Injections
Acupuncture
Shockwave therapy
Warfarin Therapy
Isoxsuprine hydrochloride therapy
Gallium nitrate alternative therapy
Oral joint supplements
Surgery

Prognosis

The outlook for recovery is guarded to poor, but a carefully designed treatment plan can prolong the usefulness of most horses. Athletes may even temporarily return to competitive status. However, over months or years, all affected horses eventually stop responding to treatment

Scientific Research

General Overviews

  • navicular disease icon
  • Hoof tester response icon
  • Corrective Farrier techniques icon

Risk Factors

  • Quarter horses in particular, have a heighten risk of developing navicular syndrome.

Commonly Affected Breeds

Quarter Horse iconBelgian Warmblood iconDutch Warmblood iconSwedish Warmblood iconThoroughbred icon