Navicular Bone Disease

When a horse comes up lame, it can be disastrous for the owners and riders who love them. Whether the animal is an expensive sport horse or a "pasture pet," navicular bone disease is a common cause of pain and lameness and must be managed with good veterinary and farrier care.

  1. Features and Causes

    • Navicular disease in horses is an inflammation of the navicular bone and its bursa, the small, fluid-filled sac that surrounds it. The navicular bone is a small, oval-shaped bone in the heel portion of the hoof that serves as a fulcrum for the deep flexor tendon. This tendon and its supporting bone are responsible for extension of the foot during a stride. General conformation, poor angling of the bones of the foot, inadequate nutrition and hard work during the horse's younger, formative years are all considered causative factors in this disease

    Symptoms

    • A horse with navicular syndrome will show a progressive lameness in one or both front feet. The lameness will go away with stall rest and worsen after a day of work. One foot may show more signs of lameness than the other. The horse will usually shorten its stride and can stumble during the trot. The toe of the hoof may show excessive wear due to the horse landing on its toe in an effort to keep weight off the heel during movement.

    Diagnosis and Treatment

    • A veterinarian will usually check for clinical symptoms by running a "lameness exam"---the horse is run through all three gaits while the vet watches for overt signs of lameness. He may also recommend that radiographs or an infrared thermograph be taken of the affected area. Thermography gives visual evidence of heat and inflammation in the bursa and around the bone. The vet may also request an anesthetic block of the nerves surrounding the flexor tendon showing the specific area and intrusion of the disease. Treatment of navicular syndrome must be tailored to each individual horse. This usually involves corrective shoeing and trimming of the foot by a qualified farrier and prescriptions of drugs to improve blood flow to the hoof and provide pain relief.

    Considerations

    • Navicular disease is one of the most common causes of front leg lameness in young horses aged four to nine years. Occurring more frequently in males, it affects geldings (neutered males) more often that stallions (intact males) and is even less prevalent in mares. Standard-bred and quarter horses show a higher incidence of this syndrome than do other breeds.

    Warning

    • Horses with navicular disease often are not able to return to a full work schedule even with treatment and corrective shoeing. A veterinarian may recommend the horse receive stall rest for an extended time, and then have the owner hand walk the animal for some period after that. It may be anywhere from a few weeks to a few months before a vet will release a horse to do more than walk with a rider on its back. Sport horses that jump or race may have to be retired to pleasure riding to prevent recurrence of pain and lameness.