Many horse owners have probably heard the phrase, “My horse is navicular.” Navicular degeneration, sometimes referred to as caudal heel syndrome or podotrochleosis, affects a significant number of horses. Diagnosing it involves a combination of clinical exams, nerve blocking, and radiographs.
As we’ve seen advancements in imaging and learned more about the biomechanics of the equine foot, the diagnosis of “Navicular”, is slowly becoming less popular. While primary navicular bone degeneration remains a genuine concern and does exist, we’re discovering that other potential issues could be broadly labeled under “Navicular”.
Lets Dive Deeper into the Findings! When we talk about “Navicular Disease” in radiographs, what do we see? Common findings are the so-called “lollipops” or synovial invaginations into the navicular bone. These are easy to see on radiographs and therefore commonly identified and attributed to “navicular disease”. Newer research is finding that these synovial invaginations are linked to the coffin joint, making understanding, and diagnosing this disease even more challenging. Another common finding is hardening or sclerosis of the navicular bone, or decreased cortico-medullary distinction. This occurs when the navicular bone is subject to excess stress and responds by laying down additional mineralized bone in response. These are just a few of the radiographic changes we can see in the navicular bone.
It’s becoming clear that these bone changes often go hand in hand with injuries to the soft tissues that support and interact with the navicular bone. While some soft tissues like the deep digital flexor tendon will sound familiar and is frequently discussed among horse owners, others like the impar ligament, the collateral ligaments of the navicular bone, and the chondrosesamoidean ligaments might not be as familiar. In addition to these structures, there are also three synovial structures in this area, the distal interphalangeal or coffin joint, the navicular bursa, and the digital tendon sheath. Understanding all these components and their function is a vital piece of the puzzle in finding the root of the issue.
So how do we as veterinarians, owners, farriers and the rest of the team sort through this to restore comfort and ultimately the goal of restoring function to horses affected by this complex disease? The answer lies in obtaining an accurate diagnosis. Using a combination of the horse’s history and clinical exam, radiography, ultrasonography, and often advanced imaging such as MRI or CT to determine exactly what structures are affected and what the therapeutic plan needs to be to address these injuries.
Great we have a diagnosis, now what? In my opinion, one of the main focuses of the therapeutic plan is proper foot care. Using radiographs to ensure balance and proper shoe placement is critical in these cases while maintaining a shortened trimming/shoeing cycle to ensure the horse maintains appropriate break over to reduce the stress on the injured structures. In addition to this, there are direct treatments such as injecting the navicular bursa and/or coffin joint. These injections can be done with orthobiologics (think stem cells, PRP, Alpha-2 Macroglobulin), polyacrylamide gels (Noltrex or Arthramid), or steroids and hyaluronic acid. Treatments beyond shoeing and injections include NSAIDs (Bute or Banamine), Bisphosphonates (Osphos or Tirdren), shockwave therapy, magnawave and appropriate rehabilitation.
While the diagnosis “Navicular” still remains, it’s crucial for horse owners and equine professionals to appreciate the intricate anatomy of the equine foot and the various factors at play. You can now have a better understanding of the depth and complexity of navicular and why exploring deeper to pinpoint the actual underlying issue, can more precisely diagnose and customize treatments, ultimately paving the way for the horses’ optimal recovery and well-being.
Written by: Colton Ramstrom, VMD