Navicular Disease: Recent Advancements and Potential Treatments

Navicular disease or syndrome is one of the most common causes of performance limiting lameness in the front legs of many different types of horses. Despite how frequently the disease occurs and how long it has been recognized and treated by veterinarians, the cause of the problem is poorly understood. As a result, a wide variety of treatments have been used on horses that have clinical signs. Most of these treatments have proven ineffective in stopping the chronic, progressive degeneration that occurs in the navicular bone of affected horses. While treatment can help horses with navicular syndrome, most horses continue to have repeated episodes of lameness that eventually result in these horses being retired from performance.

The use of magnetic resonance imaging (MRI) to evaluate the feet of affected horses has been the biggest single step forward in understanding navicular disease in the last 50 years. MRI has allowed us to see tendons, ligaments and bones in the horse’s foot in ways never before possible. Our 10 years of experience with MRI evaluation of horses with navicular disease has opened our eyes and taught us much about this disease. We have learned that it is not one disease but in fact many different problems that cause the same clinical signs in horses. We are probably at a point where the term navicular disease no longer applies to many of the horses that are evaluated with MRI. New and better terminology is developing that more accurately reflects the cause of the problem in individual horses. We are currently restricting the use of this term to horses that truly have inflammation or degeneration of the navicular bone observed with MRI or in chronic cases on x-rays of the front feet.

An accurate diagnosis is a necessary step to selecting appropriate treatment for any horse with a lameness problem. MRI allows us to determine the source of inflammation and pain in more than 90% of the horses with pain that has been localized to the foot. Although we still treat horses with foot lameness without an MRI, our experience with MRI has taught us that we greatly increase the chances of helping the horse return to performance when we know the cause of the problem. When radiographs (x-rays) of the feet do not give us a diagnosis, MRI is indicated. MRI was first used to evaluate the lower legs of horses with lameness at Washington State University in 1997. We are at a point, 10 years later, when we can say that it is a necessary procedure to make appropriate treatment decisions in many horses. Many horses with clinical signs of navicular disease need an MRI.

New Treatments: Seeking for Horses

Because of what we are learning from MRI evaluation of horses with navicular disease, new treatments are being used. Selecting an appropriate treatment depends on an accurate diagnosis. For example, a horse with tendonitis of the deep flexor tendon should be treated for tendonitis, not for navicular disease. More importantly, now that we are recognizing other locations of damage in the horse’s foot, new treatments are being developed for specific problems. These treatments need to be adequately evaluated before they can be recommended for routine use in performance horses. We are currently performing 2 studies on 2 new treatments for horses with navicular disease. These studies are supported by the American Quarter Horse Association and by CEVA, a pharmaceutical company that produces a drug for navicular disease. MRI is essential to select horses for these studies.

General requirements

* Horses must be 4 years of age or older, any sex & breed
* Cannot be pregnant or lactating or have systemic disease
* Cannot have navicular bone flexor cortex defects present on radiographs
* Free MRI Evaluation

Horses with clinical signs of navicular disease are needed for these studies. Horses for these 2 studies must have clinical signs typical of horses with navicular disease and have radiographs of their front feet that do not have defects on the flexor cortex. Horses that meet these criteria will receive MRI evaluation of the front feet at no charge to the owner. The owner must agree to participate in either study if their horse meets the criteria for either study based on MRI findings. In one study, all costs are covered by the study and in the other study, expenses for the owner would not exceed $2000 dollars.

Contacts

Please contact Dr. Sarah Sampson at the Washington State Veterinary Teaching Hospital if you would like more information on these studies.