Navicular Syndrome
This Navicular Bone displays several small bony protuberances known as “osselots”. Seems like such a small little bone for all the trouble the pesky device causes, but as the main fulcrum for the Deep Digital Flexor Tendon this small, two inch long bone takes a heck of a load every time a hoof hits the ground.
Navicular Diagnosis Revealed
Navicular Disease (or syndrome is the more accurate term) is the inflammation of the Navicular bone and it’s surrounding tissues. It has three major stages, beginning with:
Stage One: Navicular Bursitis
The Navicular Bursa is small fluid filled sac between the deep digital flexor tendon and the Navicular bone that, when over pressured or strained, can produce excess synovial fluid causing swelling and pain in the back of the hoof.
Some symptoms of early stage Navicular include a lameness after hard work, that may disappear after a rest period, or a lameness that seems to ease off with a little light exercise.
Stage Two: Navicular Tendonitis
In this case the deep digital flexor tendon, at the point which it rides over the Navicular bone . Inflammation caused by a damaged Navicular bursa becomes irritation of the DDFT and it’s sheath resulting in chronic hoof pain.
Symptoms will include a short, choppy, toe first gait and often you will see an unusually large amount of wear at the toe of the hoof.
As the coffin joint takes more damage and strain, the small canoe shaped bone known as the Navicular bone takes more stress and wear. Pressure from one or both sides pull this little fulcrum device beyond it’s limits causing it to wear down and form spurs on it’s ends, seen in radiographs and known as “Lollypopping”. It may be pressured into the distal phalanx, causing erosion there as well.
The horse begins to take on a characteristic shuffling or stumbling gait, and may often extend the more painful of it’s hooves out at rest, anything to relieve and unload the back of it’s hoof.
It can’t be cured, but we can manage the stages of the disease.
Navicular Anatomy
This is the basic layout of the Navicular and other hoof structures, with our little Navicular pest highlighted in red. The bone itself is small, and bears a huge amount of pressure seemingly for it’s size. It doesn't always take much to set it off given enough time. “Long toe Low heel” shoeings are often to blame in many pleasure horses, and breed related tragedies are fairly common, especially in large horses with small hooves, as well as in horses with a job specific to this particular form of strain.
The pastern axis and poor position of this distal phalanx contribute significantly to the animal’s Navicular strain, as shown in this radiograph to the left. This would be an excellent example of poor pathology, and can significantly contribute to the acquisition and progression of the disease.
Risk Factors of Navicular Syndrome
-Breed issues. Like it or not the Paint and Quarter Horse breeds are particularly susceptible to Navicular diagnosis, as well as Thoroughbreds and some Appaloosa bloodlines (usually ones boasting a large percentage of Quarter horse blood). I have seen diagnosis made by radiograph as early as 2 years of age in Paint horses and these are cases of terribly tragic pathology in the horse on the day it is bred.
-Shoeings and Farrier issues. Oh man, these are a no brainer to me, any structure that bears enough pressure for too long will begin to break down. Put that toe too far ahead of that hoof under the right circumstances, and your asking for trouble, I think this is why I hear so often “shoes are bad for Navicular horses.” It’s not true… simply put the wrong shoes are bad for Navicular horses.
-Performance related issues. It is a ridiculous thing to put a Tennessee Walker in a stacked and banded package and not expect problems when you trot them around every other day. Steeple Chasing, Racing, and competitive Show Jumping are also examples of job specific risk factors to that little canoe shaped pest which can be disastrous over enough time if care is not taken to ensure the horse is not over strained while it is performing.
-Neglect issues. If you trim your horses twice a year (whether they need it or not.) and fail to see the strain your putting on those hooves in our environment, your flirting with disaster. Works in Arizona, defiantly not here. Laminitis is often more common the effect, but Navicular strain occurs on the wrong hooves too and it is a costly choice to make in the end, one the horse usually pays for.
Jan and Huey's Story
Thank you to Jan and Huey, for showing us why we only give up when the horse is ready to. He and his owner are living their dreams today, Huey is even able to show at times again. He is living proof there is life after Navicular diagnosis.
When Dave started with Huey, he was unable to lift himself from the ground alone (the barn staff was having to help him up) and had Navicular Bursitis in all four feet. He had a pretty sizable dose of pain in his hooves and Dave decided that since his work load was practically nothing, to try him out barefoot. Over time, Huey responded positively to the removal of his shoes and seemed to be fairly comfortable. He was at least leisurely cruising his pasture on those tiny 0 sized feet. When he developed an abscess which left open a piece of Huey’s sole (the size of a small lime!) in his hind hoof, Dave and Sarah applied an EDSS wedge pad and support shoe to each of his hinds. The packing material did it’s magic and Huey really began to respond to the increased circulation and ease of break over. The heat in his hooves was drastically reduced and I was stunned one cycle later to actually see Huey jog lazily for a few steps. The shoeing after, Huey took a normal set of shoes and then took off across the pasture, to the surprise of his owner (and frankly, to us as well). He can be ridden by Jan’s daughter today, and has healthy looking, non distorted, size 1hooves. He will always have Navicular disease and some days are better than others but he is in less pain for what Dave and Jan have offered him. He is an exceptionally kind, fun horse, who seems to be enjoying his quality of life just fine thank you, and would I’m sure have words with anyone who thinks a horse’s life is over after Navicular diagnosis.
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