If you want to send chills up the spine of the owner of a competitive equine athlete, just mention the “N” word, navicular. Navicular syndrome, (formerly known as navicular disease) is often a debilitating condition that requires intense medical management coupled with a proper shoeing methodology in order to produce a comfortable and sound horse.
Navicular syndrome typically has many factors and is bilateral, (affecting both front feet). Anatomical structures commonly involved in and affected by this lameness include the navicular bone, navicular bursa, deep digital flexor tendon (DDFT), distal interphalangeal joint (coffin joint), impar ligament, and the supporting ligaments of the coffin joint. The syndrome manifests itself with a pain and inflammatory process that may include any or all of these structures, creating sensitivity in the caudal (back) 1/3 or ½ of the foot.
Just as with many lameness issues, early detection and treatment of navicular syndrome may decrease the potential degenerative nature of this condition. If the condition does progress, the horse can experience either initial or progression of demineralization and/or calcification of the bonny structures involved. The more these structures change due to this remodeling, the more difficult treatment and pain relief become.
Diagnosis of navicular syndrome requires many “tools” on the part of the veterinarian. A complete and thorough lameness examination, including a hoof tester evaluation, diagnostic nerve blocks, and radiographs of the foot are essential and are the most commonly utilized for the diagnosis of navicular syndrome. Additional diagnostic techniques may include joint blocks, ultrasound, thermo-graphic and nuclear scintigraphy, and more recently, MRI examinations. Despite numerous techniques for diagnosis, a diagnosis of navicular syndrome can be a bit of a challenge in certain cases. Some of the complicating issues include the fact that:
- 1. Not all caudal heel pain is causes by the structures involved in navicular syndrome.
2. Certain horses, under adverse conditions, can experience temporary pain in the navicular region, which can either be alleviated with proper treatment or on the other hand, exacerbated, leading to permanent changes and a true disease process.
3. Some horses with radiographic indications of navicular syndrome never show clinical signs of the disease (pain).
4. A percentage of horses with navicular syndrome do not show any radiographic evidence of the disease.
For these reasons, one must be careful before extolling a diagnosis of navicular syndrome. The preferred phrase to use is “caudal heel pain” until one is certain of the diagnosis.
Many quality treatments now exist for horses with navicular syndrome. The treatments include proper farrier care and therapeutic shoes, calling for an experienced and cohesive team of veterinarian and farrier. The term “proper” is used because each case and each foot must be analyzed and considered on an individual basis; there is no single proper method for therapeutic shoeing of navicular syndrome. There are numerous specialty shoes available including: egg bar shoes, heart bar shoes, digital support shoes, and glue-on therapeutic shoes. Selection of proper shoes and shoeing angles may require multiple attempts by the veterinary/farrier team. Additional therapies include non-steroidal anti-inflammatory drugs (bute, banamine, ketoprofen), vasodilator drugs, vasomodulator drugs, joint therapies (Hylaronic Acid, Glucosamino Glycans), and steroids. The drugs may be administered orally, intravenously, or intra-articularly. Newer drugs have recently come out on the market and approved by the U.S. Food and Drug Administration for the treatment of navicular disease in horses. These new drugs reduce the amount of bone remodeling and seems to reduce the pain associated in the bone from this disease. (See the article “New Equine Drugs on the Market” in this newsletter)
Hopefully you don’t, but should you suspect one of your horses might have navicular syndrome, please call Equine Medical Services for an examination and consultation.