Possible Treatment for Bone Fragility Disorder in Horses

Bone fragility disorder (BFD) is a malady that sometimes strikes horses living in northern coastal California. It is characterized by weight loss, stiff gaits, lameness, swayed back, exercise intolerance, and bowing out of the shoulder blades. The cause is unknown, and treatment with corticosteroids and other anti-inflammatory drugs has not been particularly effective. Tiludronate, a bisphosphonate used in humans to prevent bone breakdown and increase bone density, has been used to treat some horses, but results were not promising.

Research was carried out at the University of California, Davis, using 10 horses that had been admitted to the school’s veterinary teaching hospital. The horses had been diagnosed with BFD based on clinical signs and findings from bone-phase nuclear scintigraphy. Each horse was examined and given a lameness score using the AAEP’s grading scale. Zoledronate, a medication similar to tiludronate but with increased potency and duration of action, was infused intravenously to each horse.

The horses were examined six months later and lameness scores were compared with scores assigned before the infusion of zoledronate. All horses were still considered lame, but nine of the ten trial horses showed a reduction in lameness. Eight of the ten horses also had improved scintigraphic findings. None of the horses showed worsening of scintigraphic findings, increased lameness, or any other adverse effects after the treatment. Scott Katzman, the veterinarian leading the study, pointed out that an absolute cause-and-effect conclusion can’t be drawn because of the small sample size and the lack of a control (untreated) group. However, the results of the research suggest that treatment with a bisphosphonate drug may prove to be helpful to horses with BFD.