Answered by, Jillian Mills, DVM, DACVSMR, CERP, CVA, Starwood Equine Veterinary Services, Redwood City, CA, Courtesy of AAEP
Question: What are your thoughts on barefoot trimming for horses with moderate navicular disease?
Answer: Navicular disease is a syndrome affecting not just the navicular bone itself, but the entire podotrochlear apparatus located in the heel of the foot. Advanced imaging modalities, such as MRI, have allowed us to determine the specific structures that are injured when a horse is experiencing heel pain. The more specific the diagnosis, the better your veterinarian can direct their treatment and shoeing recommendations.
In general, there are two things we would like to accomplish when shoeing a horse with heel pain. These principles include reducing extension of the coffin joint, and decreasing the peak pressure on the navicular bone by unloading the deep digital flexor tendon (DDFT). With farriery you are able to provide pain relief by applying both static and dynamic shoeing principles. An example of a static shoeing principle for heel pain would be the use of a wedge pad to raise the heel and unload the DDFT. In this scenario, a wedge pad changes the biomechanics of the foot at all times, even while at rest. With navicular disease, permanent heel elevation can sometimes be detrimental as it can induce contraction of the DDFT. Barefoot trimming would require you to implement similar static shoeing principles, with the goal of heel elevation and improving breakover at the toe and quarters.
Therapeutic farriery also emphasizes the use of shoeing principles that have a dynamic effect. In the case of dynamic shoeing, the biomechanical effect only occurs in deformable footing. At rest, the biomechanics of the foot are unchanged. An example of a dynamic shoeing principle for heel pain would be the use of a flat reverse shoe. A reverse shoe prevents the heel from sinking while the horse is being worked, unloading the DDFT. The absence of a bar at the toe also encourages the toe to sink and allows the horse to wear its toe, maintaining ease of breakover throughout its shoeing cycle.
Both static and dynamic shoeing principles have their place in certain scenarios and for specific injuries. In the case of navicular disease, barefoot trimming requires you to apply static shoeing principles and may not be as beneficial as utilizing a dynamic therapeutic shoeing principle for the management of heel pain.
Question: As I watch my horse walk towards me, I can see that the outside of her left front foot lands first then the inside. She also has a lot of arthritis in her left fetlock area. Can my farrier do anything to make her front feet more balanced?
Answer: Uneven hoof placement does not necessarily mean that your horse’s feet are unbalanced. Foot fall can also be significantly affected by conformation. The two main means for evaluating medial-to-lateral (inside-to-outside) hoof imbalance include hoof measurements and radiographic evaluation. Radiographs (x-rays) are beneficial because they can make subtle imbalances more obvious and identify other abnormalities that may also require correction, such as a negative palmar angle. A radiographic shoeing consultation will allow your veterinarian and farrier to collaborate on what is best for your horse’s specific ailment.
Abnormal foot fall, regardless of the cause, can result in asymmetric joint loading. Abnormal joint loading has been implicated in the progression of osteoarthritis. Your farrier could apply a shoe with a heavily beveled medial (inside) quarter and branch to aid in medial breakover. This will reduce the strain on the lateral (outside) tendons and ligaments of the limb. To further reduce the concussive forces on the inside sole and limb, the width of the outside branch of the shoe should be widened to aid in redistributing the load.