This study investigating bisphosphonate residence time in bones took bone samples of horses treated and not treated with bisphosphonates. | Photo: Courtesy Dr. Heather Knych

A team from the University of California, Davis, (UC Davis) and the University of Kentucky recently took the first step toward describing bisphosphonates’ residence time in horses’ bones. Heather K. Knych, DVM, PhD, Dipl. ACVCP, professor of Clinical Veterinary Pharmacology at UC Davis’ K.L. Maddy Equine Analytical Pharmacology Lab, presented their findings at the 2020 American Association of Equine Practitioners’ convention, held virtually.

How Do Bisphosphonates Work?

Knych first described what we do know about bisphosphonates and their mechanism of action. Under normal circumstances, the processes of bone formation and bone resorption are in balance. However, she explained, in some circumstances, such as aging, this balance can become disrupted, and resorption can overwhelm formation. The result is weakening of the bone.

Doctors use bisphosphonates to increase bone density and treat disorders of bone resorption (e.g., osteoporosis, Paget’s disease) in humans. In horses, these drugs (tiludronate, clodronate) are labeled to treat the clinical signs associated with navicular disease; however, veterinarians also administer them off-label for other bone disorders