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First Posted: Mar 5, 2009
Updated:Apr 30, 2016

Navicular Disease aka Navicular Syndrome

by Debora Johnson
 

Firocoxib Dose for Navicular Pain and Osteoarthritis Established
Lameness Many Causes Addressed

Image: Drawing of Internal Part of Horse's Foot
Drawing of Internal Part of Horse's Foot

Update: "...What's in a Name?

Wally Liberman, DVM, of Panorama Equine Medical and Surgical Center, in Redding, California, focuses on diagnosing and treating lameness-in particular, hoof problems. 'The evolution of the concept of navicular has changed considerably because of our increased imaging capability through digital radiography, ultrasound, and magnetic resonance imaging (MRI),' he says. 'MRI as the gold standard for diagnosis has allowed us to appreciate how often things are going on in the zone that we refer to as navicular that actually involve multiple anatomical locations.'

Today, the descriptor navicular disease is misleading, inaccurate, and best discarded. 'The term caudal (toward the rear) heel pain is similarly misleading,' says Liberman. 'This syndrome is not an external hoof capsule disease, which could be part of caudal heel pain; it centers within structures that make up the podotrochlear apparatus within the hoof.'

Infographic: Navicular Disease

More appropriate names for navicular disease, he says, are podotrochleitis or podotrochlosis, both of which are correct anatomical descriptions that include the following structures within the podotrochlear apparatus (see illustration on the next page), any of which have the potential to be diseased:

  • Distal interphalangeal (coffin) joint;
  • Cartilaginous component of the dorsal (top) surface of the navicular bone;
  • Subchondral bone, which the cartilage overlies;
  • Medullary (marrow) cavity/trabecular bone (found at the ends of long bones on the limbs, pelvic bones, ribs, skull, and vertebrae);
  • Flexor cortex/cortical-compact bone (the navicular bone's dense outer 'shell');
  • Fibrocartilaginous aspect of the palmar (bottom) surface of the navicular bone;
  • Entire circumferential ligamentous system-distal sesamoidean impar ligament, collateral sesamoidean ligaments, and chondrosesamoidean ligaments-basically, all the ligaments, which connect bone to bone, that hold the navicular bone in place;
  • Deep digital flexor tendon; and
  • Navicular bursa (the cushioning fluid-filled sac between the navicular bone and the DDFT.

'It is not uncommon to find not just one but, rather, a multitude of those tissue masses involved in what people have historically referred to as navicular disease or syndrome,' he says. 'MRI has allowed us to understand this and to diagnose which tissues are involved.'"... The New Navicular Paradigm

Navicular disease is essentially a chronic degenerative condition of the navicular bursa and navicular bone that involves damage to the flexor surface of the bone and the overlying deep digital flexor tendon with osteophyte formation on the lateral and proximal borders of the bone. It is a syndrome with a complex pathogenesis rather than a specific disease entity. It is one of the most common causes of chronic forelimb lameness in horses but is essentially unknown in ponies and donkeys. Palmar foot pain is a modern term for navicular syndrome. Reference will also be made to phrases such as navicular region pain and caudal heel pain to describe horses with chronic forelimb lameness caused by pain stemming from the navicular bone and related structures.

Navicular disease is most commonly diagnosed in horses between 4 and 15 years of age. Quarter Horses and Thoroughbreds are affected more than any other breeds. Ponies and Arabian horses are rarely affected.

Treatment

Navicular disease can be treated but rarely cured.

The following links have comprehensive articles on navicular in horses:

The New Navicular Paradigm
Navicular Disease: Research Needed to Better Understand
Navicular Syndrome in Horses/Robert C. McClure Department of Veterinary Anatomy, School of Veterinary Medicine
Navicular Bursography
Navicular Disease in Horses James M. Casey, D.V.M, M.S., Equine Sports Medicine, Dentistry, & Surgery
Palmar Foot/Heel Pain in Horses
Cases that Mimic Navicular Disease
Microstructural Alterations and Navicular Bone Degeneration

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