What is navicular?
Navicular is a collective term used to describe lameness radiating from the back part of a horse's foot centered on the navicular bone (often called navicular syndrome). It is progressive; starting with humble symptoms under saddle (such as a reluctance to travel down hill, unwillingness to work on one particular lead, a shifting stance when tied up etc, etc - there are many early warning signs that all is not well). Eventually it progresses to clinical lameness.
Navicular is basically caused by a horse erroneously landing on its toes instead of landing heel first, which creates enormous tension in the deep flexor tendon that in turn produces inflammation and soreness around the navicular bone.
Why do horses begin landing toe first?
They are mostly trying to avoid pain that exists in the back of the feet (from heel bruising or thrush), but the feet may be so deformed that breakover is sufficiently delayed to make heel first landing impossible. Or they simply may be fatigued.
Once the die is cast, a vicious cycle is spawned. The more often they land on their toes, the more inflammation and friction is created in the navicular area, and on it goes.
What's the link between navicular and performance?
Horses with navicular have incorrect bio-mechanics. When they are working at low levels of athletic effort, they seem to be able to get along okay and the symptoms remain humble. However, when a horse starts competing at higher levels, the work becomes physically more demanding, so much greater is the impact of incorrect bio-mechanics and lameness is the inevitable outcome.
Navicular has traditionally been considered incurable. Manageable in the short term, but incurable in the long term. Corrective shoeing aims to postpone the inevitable; returning some level of comfort for some period of time. It is based on shortening the breakover and raising the heels. Such treatment can only be palliative because it treats the symptoms and not the underlying cause. It does not solve the problem. Often it actually hastens the eventual demise of the horse because it takes the 'diseased' parts of the back of the foot further away from a functioning framework.
Barefooting has been spectacularly successful with navicular rehabilitation.
Barefooting works by returning correct function to the back part of the foot. This is achieved by restoring correct movement.
How is correct movement returned?
By removing any disease or deformity and providing immediate comfort (either rubber laneways or padded boots) until such time as a horse can land comfortably on its landing gear.
Heel first landing is the default position for horses.
Remove the discomfort and correct movement will return - a simple solution to a complex and for many years a baffling problem.
With barefoot rehab, the outcome has been so consistently successful, that bold statements can be made about navicular
. if barefoot rehab was to be widely adopted, navicular disease will become a dinosaur.
. there is probably no reason for a navicular horse to be de-nerved or euthanased.
Written by Andrew Bowe
CASE STUDIES :
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Navicular lameness has long been the curse of performance horses. It seems that the higher the level of competition achieved, the more likely a horse will succumb to the insidious ravages of navicular.