Bone fragility disorder (BFD)

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

Bone Fragility Disorder (BFD)

Bone Fragility Syndrome

Bone fragility disorder (BFD) is a progressive, debilitating bone disease of horses that results in severe bone loss and weakening, leading to spontaneous bone fractures. The disease is a type of silicate-associated osteoporosis (SAO) that affects horses that have previous or currently live in the state of California in the United States, particularly the northern coastal mountain range and the Sierra Mountains. The soil in this geographic region contains silica crystals (e.g., quartz, cristobalite and tridymite) that are toxic to horses if they are inhaled while grazing in pastures. Once inhaled, these crystals migrate into the horse's lung tissue and surrounding lymph nodes, causing chronic inflammation.

Early clinical signs of BFD in horses consist of exercise intolerance, body and neck stiffness, and intermittent lameness. As the disease progresses, horses often have difficulty breathing and develop outward bowing of their shoulder blades and swayback. Affected horses are at an increased risk of spontaneous bone fractures, and often die from catastrophic injuries or are euthanized.


Exercise intolerance
Neck or body stiffness
Decreased range of motion
Loss of appetite
Severe weight loss
Difficulty breathing
Outward bowing of the shoulder blades


  • History
  • Physical exam - Can provide a diagnosis of horses with severe disease.
  • Nuclear scintigraphy - Provides the most definitive test for all stages of BFS, as areas of high bone activity associated with bone loss can be seen as bright spots.
  • Ultrasound - scapular spine‚Äôs widened appearance.


BisphosphonatesAdministering Tildren and ZoledronateTarget the bone cells that cause osteoporosis to help prevent bone resorption.
Pain managementAdministering NSAIDs (phenylbutazone or flunixin meglumine) or steroids (such as dexamethasone)May be helpful during the initial stages of the disease, however becomes ineffective as it progresses.


  • Perform soil testing on horse pastures that are located along the Northern California coastline, or in any pasture land suspected of containing silica crystals.
  • Prevent exposure to dust, particularly during high winds.
  • Keep horses inside and away from exposure to blown dust and soil during days with moderate to high winds.

Scientific Research References

Good Overviews

Risk Factors

  • Horses living and grazing in pastures located along the coastal mountain region of Northern California
  • Silica crystal exposure
  • Exposure to high amounts of dust, especially coupled with high winds.