Bisphosphonates Ban: Keeneland, Fasig-Tipton and Ocala Breeders’ Sales Ban Off-Label Use of Popular Navicular Disease Medication in Young Thoroughbreds

Bisphosphonates are a type of medication used to treat osteoporosis in humans. They have been approved by the US Food and Drug Administration since 2014 for treatment of navicular disease in horses older than four. Research in Europe, conducted by Professor Jean-Marie Denoix and others, has also investigated the possible expanded use of one bisphosphonate, tiludronate (Tildren) for other lameness problems, such as bone spavin and osteoarthritic lesions of the thoracolumbar vertebral column. Professor Denoix also led the initial research on Tildren for navicular disease in older horses.

Navicular Syndrome: Does FDA Approval of Tildren and Osphos Change Anything?

From bone to zone: Focus on navicular-type lameness has evolved from concentrating on identifying bone defects visible in radiography to a more dynamic approach to also detect possible soft tissue injury, deteriorating hoof condition and age- or sport-related stress factors. The navicular bone is circled in this distal limb bone model at the University of Nottingham Vet School.

The landscape of treatment options for equine navicular syndrome is set to change this year, as the U.S. Food and Drug Agency (FDA) recently approved two drugs for use in the treatment of this complex lameness problem in the horse's foot. "Tildren" and "Osphos" are two specific medications that cleared the difficult hurdles of the FDA approval process in May 2014.

Tiludronate (Tildren) Effective for Hind Limb Lameness Caused by Bone Spavin

Spavin is one of the most common causes of lameness in jumping horses.

Newly published trials from a study in England show that horses suffering lameness caused by bone spavin can show marked improvement following treatment with a Tiludronate (Tildren) infusion, when administered in combination with controlled exercise.

Tildren: Denoix Study Shows Drug Helps Horses with Back Pain

Michael Davis, DVM, MS, of New England
Equine Medical Center. Fran Jurga photo.

Hoofcare and Lameness Journal first reported on the clinical trials of the drug tiludronate ("Tildren") about five years ago, when it was first tested on horses with navicular disease under the supervision of one of consulting editors, Jean Marie Denoix, DVM, PhD, Agrege, of France.

Dr. Denoix's team recently tested Tildren on 29 horses with back pain caused by lesions in the vertebrae, as documented in radiographs. Such lesions are common in many horses.

Fifteen horses were given Tildren and 14 horses received a control substance, and the horses were monitored for 120 days. This was a similar protocol to the navicular disease study. The horses given Tildren were significantly improved after 60 days.

The study was published in the March 2007 edition of the American Journal of Veterinary Research.

Tildren is currently not sold in the United States but is being used by some veterinarians in trial situations within FDA guidelines. Fortunately, the drug is being tested near here at the New England Equine Medical Center, by Dr. Michael Davis, and I've been able to follow its progress. So far, all the news is good...except for the price, of course!

Tildren has been used successfully for navicular bone lesions and hock spavin. Hopes have been high for its use in demineralization of the coffin bone but I don't think there is any documentation of tests for that problem.

Denoix's new study opens up the area of the back and makes one wonder about using it for neck and sacroiliac pain...but I'm sure he's working on that!

Photo: Michael Davis DVM MS of New England Equine Medical and Surgical Center has been using Tildren on carefully-screened US horses. 

Study Targets Gene in Bone Loss Similar to Pedal Osteitis, Navicular Degeneration Equine Lameness Conditions

A CT scan of the equine distal limb reveals the bony architecture. Image courtesy of Alex zur Linden, DVM, DACVR, Assistant Professor of Radiology at Ontario Veterinary College.

By now, most Hoof Blog readers know the mechanism behind degenerative bone loss that is so clearly illustrated by foot conditions like pedal osteitis and navicular degeneration. Tildren is the current great hope for treatment of those conditions, although only now it has only been studied in navicular disease and bone spavin. Still, there's hope!

Enter a new hope this week, thanks to a study from the University of Pennsylvania, as mentioned in the journal Nature Medicine. Senior author Yongwon Choi, PhD, professor of Pathology and Laboratory Medicine at the University of Pennsylvania and colleagues report their findings.

To quote from their press release:

"The basic principles behind bone metabolism are largely understood, hence a handful of drugs treating osteoporosis are available. Most drugs inhibit osteoclasts, which cause bone decay. But there is also at least one that stimulates osteoblasts, enhancing bone formation. A combined treatment will not only prevent the occurrence of osteoporosis, but also make the quality of bone even better.

"Our discovery proves that inhibiting osteoclasts while simultaneously stimulating new bone formation can be done.

"Bone health is maintained by the balanced activities of osteoblasts and osteoclasts. The study shows that the inactivation of gene Atp6v0d2 in mice results in dramatically increased bone mass due to defective osteoclasts as well as enhanced bone formation.

"These findings may provide some clarity into the regulation of bone metabolism and show that targeting the function of a single gene could possibly inhibit bone decay while stimulating bone formation."

(end quote)

Before you start lining up all those lame horses, please realize that it may be a while before this gene therapy becomes a reality and trickles down to equine medicine. Then again, the equine model may be a good one for experimentation. Let's hope!