Navicular disease is a common problem in performance horses.  Dr. Steven Colburn from Escondido, California, indicated in the Texas Equine Vet Association Publication the Remuda that he previously treated all navicular cases with therapeutic shoeing, isoxuprine and aspirin and then if they did not respond, he would inject the coffin joint with medication.  However, he now uses osphos and says that up to 70% of his patients have improved. 

Western performance horses commonly have navicular pain but other event horses can have the condition as well.  It is important for your vet to perform a complete exam with X-rays and blocking the feet to make sure of the diagnosis.  In some cases, an MRI is required to make the diagnosis because navicular disease, now called heel pain, can affect structures other than the navicular bone, such as ligaments around the bone.  However, if X-rays indicate the bone is involved, Dr. Colburn treats the horse with osphos, which is a bisphosphonate; those inhibit bone resorption, which decreases loss of bone as bone loss is one thing that occurs in horses with navicular disease.  Dr. Colburn recommends light work after the injection and you will need to stop using NSAIDs such as bute at the same time as both drugs can affect the kidneys.  Some horses can develop colic after the injection, but it is usually mild and walking the horse after the injection can usually decrease symptoms.  Rare signs after osphos injection include a decreased appetite, lethargy, and injection site reactions.  The safe use of osphos has not been studied in horses less than 4 years old and should also not be used in pregnant horses, lactating mares, or those used for breeding.  If you have a horse diagnosed with navicular disease, ask your vet about osphos.