Article appears in our Nov./Dec. 2013 Issue
Written by Dr. Courtney Bowers and Dr. Jonathan Hirsch of Woodside Equine Clinic
As veterinarians, we are frequently asked about products to treat chronic conditions, subtle lameness or lameness that has not responded to other therapies. One of the most exciting products to come along in the last few years is Tildren. It is a medication that has allowed us to offer a novel therapy for some of the most chronic causes of lameness that are often unresponsive to other therapies.
How does it work?
Tildren, or Tiludronate for all you pharmacology buffs, is a non-nitrogen containing bisphosphonate. The bisphosphonates are a class of drug that work at the cellular level to slow down or prevent bone loss. Bone is constantly changing and remodeling based on the forces applied to it. Osteoclasts are specialized bone cells which resorb bone, while osteoblasts are bone cells which serve to lay down new bone, a process known as mineralization. Tildren is thought to regulate bone remodeling by reducing the activity of osteoclasts while increasing osteoblastic activity. Bone loss is reduced, resulting in the maintenance of or increase in bone density and strength. Tildren was first used in human medicine for treating diseases that cause bone loss such as osteoporosis and Paget’s disease. Other bisphosphonate drugs include Fosamax, Boniva, Actonel and Reclast. In horses, Tildren has been studied for treatment of navicular disease, osteoarthritis and lesions of the thoracolumbar vertebral column.
Navicular disease, or caudal heel pain, is seen most often as a low-grade front end lameness of both front feet. The discomfort can be caused by changes to the bones as well as the soft tissues within the hoof. The cause of navicular disease is still not well understood, and each individual horse may suffer from differing pathologies. Often, the navicular bone itself is affected when it undergoes excessive bone degeneration or proliferation. These changes can weaken the bone, causing pain in the back of the foot. A drug that affects the cells that mediate bone resorption and proliferation like Tildren can therefore be helpful. Clinical trials have shown that Tildren is effective in treating navicular disease when given at a total dose of 1 milligram per kilogram of body weight broken up into 10 daily intravenous injections. A recent research study showed that 100 percent of horses suffering from acute navicular disease (affected by the disease for six months or less) responded to Tildren treatment, whereas only 60 percent of horses that had chronic disease (affected by the disease for greater than six months) responded, and that of the horses with more acute navicular disease, 75 percent returned to normal work within six months. Therefore it’s very important that Tildren be given earlier rather than later in the disease process. Although there was clear success in horses treated with Tildren in this study, it’s important to keep in mind that not all horses diagnosed with navicular disease have disease of only the navicular bone. Therefore, Tildren, which treats bony lesions, may not help every horse with navicular syndrome.