Tildren and Osphos are now FDA approved and available in the US. Previously Tildren was available in the US, but because it was not FDA approved or manufactured in the US it had to be shipped in from France, requiring quite a lot of paperwork. Both drugs belong to a group of drugs called bisphosphonates which are used to treat osteoporosis in humans.
In clinical trains performed by Dechra, the drug company that manufactures Osphos, the drug helped horses improve 1 grade of lameness in 75% of cases. Osphos, which is very similar to Tildren, works by inhibiting bone resorption by binding calcium phosphate crystals, thus reducing bone pain. Clinical improvement is typically most evident at 2 months after this first injection and 65% maintained their level of improvement for 6 months. Further injections can be administered as needed to help maintain improvement.
While the drug has been approved based on the navicular syndrome model, other types of bone related pain may benefit from this drug as well. Osphos is a much less expensive option than Tildren and can be done in 1 visit with an intramuscular injection. Navicular disease is a syndrome, which means it can have many different causes including bony issues, soft tissue issues (including tendons, ligaments, and the navicular bursa) or a combination of both. Because of the many causes of navicular syndrome, these drugs may not help every case of navicular disease.
Call your veterinarian to discuss if your horse is a candidate.