Thehorse.com - Full Article
by: Susan Piscopo, DVM, PhD
July 01 2004, Article # 1527
Healthy bone undergoes constant metabolic change to prevent bone loss or abnormal remodeling (cell turnover) that can occur with loading. Horses with navicular disease can have abnormal remodeling and formation of osteolytic lesions (areas of broken-down bone) within the navicular bone. This might be due to an imbalance in bone metabolism, with increased bone resorption. Dominique Thibaud, DVM, of Ceva Santé Animale (CEVA), in Libourne, France, with colleagues in France, Italy, and Germany, set out to evaluate a drug to target abnormal bone metabolism. The drug, tiludronate, inhibits excessive bone resorption, allowing bone metabolism to become balanced once again. The study aimed to assess tiludronate's effectiveness against navicular disease. (The drug is not approved in the United States for use in horses, so any clinical use would be considered off-label).
Fifty horses with moderate to severe navicular disease were studied. Radiographs and videotaped lameness examinations were collected prior to treatment. Horses were randomly assigned to receive either 1 mg/kg tiludronate intravenously (IV) daily for 10 days; 0.5 mg/kg IV daily for five days, followed by five days of placebo; or 10 days of IV placebo. Lameness exams were performed (and videotaped) one, two, and six months after treatment. Radiographs were repeated six months after treatment, and independent examiners reviewed all radiographs and lameness exam tapes. Horses which didn't respond to tiludronate or the placebo by two months, based on clinical examination and owner evaluation, were removed from the study as treatment failures and treated as needed with tiludronate.
Horses responded best (based on improvement of lameness and ability to return to work) to the regimen of 1 mg/kg tiludronate IV daily for 10 days. More recent cases of navicular disease (less than six months duration, 33 horses, no treatment failures) responded better than chronic cases (17 horses, 11 treatment failures). Of recent-case horses, 67% showed a positive response to treatment, and 75% returned to normal activity by six months.