By Tim G. Eastman, DVM, DACVS, MPVM
It is an exciting time to be a veterinarian who makes his/her living by diagnosing and treating lameness in horses. First of all, our ability to diagnose lameness has improved dramatically over the past decades, with the explosion of technology available. The digital revolution has improved our ability to manipulate images to better evaluate them and to share the information with colleagues for consultation. Equine veterinarians are getting better ultrasound equipment and are becoming more adept at its use. Digital X-Ray equipment is becoming more affordable and more portable. Advanced imaging modalities such as MRI, Nuclear Scintigraphy (“Nuke Scans”), and Cat Scans are increasingly available and being utilized with increasing frequency. The ability to record these images digitally has made consultation with colleagues so easy that getting multiple opinions from specialists across the country is commonplace. With this diagnostic equipment available, conditions that used to be chalked up to a “foot lameness” can now be specifically diagnosed and treatment plans custom tailored.
There are several new therapeutic options that have become available over the last several years for arthritis, tendon and ligament injuries, as well as other sport related injuries. The purpose of this article is to provide readers with some background information on a variety of new treatments you might here discussed around the barn.
Tildren® is a drug that has been available in Europe for many years to treat navicular disease and has recently become available in the United States to veterinarians who go through special licensure. It is similar to drugs used to treat osteoporosis in people. The activity of the cells that cause the destructive changes we see on X-rays with navicular disease is suppressed. Apparently the activity of these cells is very painful and by reducing their activity, many horses become much more comfortable. There are many different treatment protocols being utilized with Tildren but most involve placement of an iv catheter and administration of a large amount of the drug as an iv drip for about an hour. Generally in 2- 4 weeks the benefits are beginning to be realized and the effect lasts for approximately six months. Horses may remain sound longer by giving monthly boosters. In addition to navicular disease, many veterinarians use Tildren to treat horses with hock pain. Many lameness diagnosticians feel that Tildren has been the first major breakthrough in the treatment of navicular disease in horses.
IRAP II™ is not a music group, it is a somewhat new treatment for arthritis in horses and in humans. A chemical that is largely responsible for the pain associated with arthritis is called Interleukin 1. IRAP decreases joint pain by interfering with the activity of Interleukin 1 and similar compounds. For the procedure, you obtain a large syringe of blood. The syringe you pull the blood into has hundreds of glass balls that have been exposed to a certain gas that favors the “IRAP” and helps amplify it. Once the blood is obtained, it is incubated overnight and then spun in a centrifuge to separate the serum from the other components. This serum is rich in IRAP and once passed through a filter, is injected directly into the desired joint. Extra serum is frozen for subsequent treatments. Typically, a series of 3 injections are performed 1 week apart to treat 1 affected joint. Coffin joints and stifles that don’t respond well to steroid injections seem to be the most popular condition to treat. Reactions are uncommon largely due to the fact that it is the patients own serum.
Stem cells have been injected into injured ligaments for many years now and are becoming increasingly popular as a treatment for joint disease as well. The idea is that by providing a large population of cells at the site of injury that are not yet committed to becoming any one tissue, you encourage them to become what is needed for repair. There are different ways to obtain stem cells for use in horses. One is to take bone marrow from the horse and inject it directly into the damaged tissue straight or after some modification. Another is a commercially available product called “A-cell” in which the source of stem cells is fetal pig bladder. A-cell comes in an injectable form used for tendon injuries and as a sheet used for treatment of wounds (A-cell is currently off the market but reports say it will soon be back). We have been using a 3rd source for the past several years with very promising success, a company called Vet-Stem. The stem cells used are not of embryonic origin but come from the patient’s own adipose tissue. By using the patients own fat, rejection becomes almost a non-issue. Apparently fat is a storage reservoir for stem cells which is handy because it is readily accessible. The fat is typically harvested through a surgical incision made above and to the side of the base of the tail. This fat is stored in a special container and sent overnight to a lab in southern California where the stem cells are separated out, suspended in saline, and sent back to the veterinarian again by overnight mail. Ultrasound guidance is then used to inject the stem cells directly into a torn ligament or tendon. Alternatively, the stem cells may be directly injected into a badly damaged joint. Initial research with fat derived stem cells in horses has been encouraging. Clinically, the ultrasound scans of tendon or ligament injuries is amazingly improved 60 days after injection and we feel like more horses are going back to their previous level of work with less recurrences.
Shock-wave therapy has stood the test of time for treatment of many lameness conditions. By sending “shock-waves” through damaged tissue you may enhance the healing process by rejuvenating the inflammatory stage. It also has a short-term pain killing effect. This is of concern because for example with a suspensory ligament injury we perform shock-wave therapy with the hope of an improved end product with less chance of recurrence. The short-term pain killing effect may tempt horse owners to begin training prematurely once an improvement in lameness is noted. Shock-wave therapy is used for a myriad of conditions including but not limited to: bowed tendons, suspensory ligament desmitis, “splints”, non-healing wounds, navicular disease, and hock pain.
In closing, Tildren, IRAP, Stem Cells, and shock-wave treatment are several newer therapies available for certain lameness conditions. They have not replaced joint injections and many of the other treatments historically used for the management of lameness, but have sure been a nice addition to the therapeutic options available. Of course, different veterinarians have had different experiences with these modalities and will all have different opinions on effectiveness and case selection. Contact your veterinarian if you think your horse may benefit from one of these therapies.