Understanding Navicular Syndrome...
Symptoms, Causes & Treatment

What is Navicular Syndrome?

It is a catch all term that means a horse has caudal heel pain (pain in the heels of his front feet) but bone damage cannot be seen on an x-ray.

Navicular disease means the same thing, but bone loss/damage is evident on the x-ray.

Signs & Symptoms of Early Navicular Syndrome

  • Short choppy steps in front legs. The horse does not want to stride out because that will force him to land heel first which makes his heel pain worse.
  • Toe first landing. Again, the horse's heels (in his front feet) are sore so the horse tries to lessen the pain by landing on his toes. It's normal for all healthy horses to land toe first some of the time like when walking up hill or when walking slowly but not when trotting or cantering on flat ground.
  • Limping. One side may be sorer than the other so the horse may limp.
  • If you have a horse that walks on hard pavement a lot like a carriage horse or does a lot of jumping and is forced to land on his toes a lot, these types of horses are more prone to navicular syndrome because of the toe first landing.
  • Temporarily nerve blocking (anesthetizing) the horse around the fetlock will resolve the pain.
  • Pressure with hoof testers in the heel or frog area may cause pain.

Where is the Navicular Bone?

The navicular bone is a small bone that sits behind the coffin bone. It is attached by tendons above and below. The navicular bursa is a fluid filled sac which sits behind the navicular bone and in front of the Deep Digital Flexor tendon (DDFT). The navicular bursa cushions the bone from the DDFT which slides across the back of the navicular bone. The DDFT is responsible for flexing the foot. The impar ligament is a tiny ligament which attaches the navicular bone to the coffin bone.

Causes of Navicular Syndrome

Repeated toe first landings cause navicular syndrome! How's that for a simple explanation!

At one time it was thought that a horse first developed navicular disease and then started landing toe first. This is not the case. It is the toe first landing itself which causes navicular disease. This was determined back in the 1970's in a study done with cadaver feet by James Rooney DVM.

That begs the question, what causes a toe first landing?

  1. A weak digital cushion causes toe first landings. Remember that a natural life style with lots of movement is the best thing for your horse? When a wild horse is born it is moving beside it's mother within the first hour of birth. It walks on rocks and everything else its mother walks on. The mother may walk 10 - 20 miles per day or more and the foal must keep up or die. All that movement develops a tough digital cushion.

    The digital cushion starts out as a lump of fat in a young foal foot but with years of daily movement, the digital cushion develops into a tough fibrous, cartilaginous mass that cushions every foot fall. It allows the nerves in the back of the foot to sense the ground but protects the nerve from over stimulation (pain).

    When years of daily movement are replaced by standing around in a tiny stall or paddock all day for years on end, the digital cushion remains a lump of fat. A weak lump of fat is fine for a 100 pound foal but not for a 1000 pound horse. That lump of fat in a full grown horse allows too much nerve stimulation (pain) in back of the foot and the horse starts toe walking to avoid his heel pain.

    The toe walking causes higher than normal peak pressures of the DDFT against the back surface of the navicular bone and this cause inflammation and damage to the 1) the DDFT 2) the navicular bursa and 3) the navicular bone itself, or navicular syndrome.
  2. A horse that is jumped a lot will also land on its toes a lot. The cause of the toe first landing is different, but the result is the same.

Treatment for Navicular Syndrome

Here's where it gets tricky. I think the best thing for a weak digital cushion is lots of exercise with lots of heel first and flat footed landings. This will actually cause the digital cushion to change and become more cartilaginous which will protect the heel from pain.

The problem is how to make a horse stop landing toe first when landing heel first hurts even more.

The answer is boots and pads.

I've used the Easy Boot RX which is a rehab boot designed for recovering from an injury when the horse is not very mobile. It can also be used for light workouts. The soles of the boot offer a thick soft cushion that can encourage a flat footed or heel first landing. Inserting dome pads in the boots adds extra cushioning. If your horse gallops around like a loon he will destroy these boots. I would not recommend leaving the boots on 24/7. They should be put on when you are exercising your horse.

I like to walk around in a large field on a 45' Parelli line attached to a rope halter and change direction of the circle often. It's less boring than a round pen for the horse. Moving in a circle will force your horse to bend and use his shoulders.

If you horse really tries to avoid going in one direction (right or left) it could mean that the outside foot in the direction he does not want to go hurts more than the other foot.

Build your horse up slowly. Ideally you would exercise your horse for 45 minutes a day, 7 days a week but it will take a long time to get to that level of activity. If you can’t workout every day try for every second day. It may take 6 months to 2 years for your horse to heal navicular syndrome.

I've also used the Easy Boot Epics with dome pads. The dome pads are essential for a flat footed or heel first landing. Boots without pads are just another peripheral loading device and will not promote a heel first landing. I've also added flat foam pads underneath the dome pads for added cushioning. Do what ever it takes to get a flat footed or heel first landing.

Avoid lots of up hill work because that will force him to land toe first which is what we want to avoid.

Stretching & Massage

Toe walking forces the horse to use accessory muscles in his shoulder and neck that he wouldn't normally use. His neck and shoulders will be as hard as a rock and extending his leg forward will be difficult. As you lunge your horse stop every 5 minutes or so and stretch his front legs. Mild stretches when he is already warm are best. It's easy to learn half a dozen different types of stretches. Regular massages will also work well to loosen his muscles.

Trimming

Here are my trimming suggestions for navicular syndrome caused by a weak digital cushion:

  • Leave as much dead sole as possible to protect the bottom of the foot. It will add protection to the over stimulated nerves in the heel.
  • Pete Ramey says to consider leaving the heels a touch longer (1/8th inch) than normal to allow the foot to land on the heel wall and not the frog. This will raise the heels higher than they should be but it may be worth it for a period of time until the digital cushion is strengthened. If your horse is prone to under run heels, leaving a long heel is contraindicated.
  • Keep the toe as short as possible to allow ease of break over.
  • Consider leaving the hoof wall longer than the sole to protect the sole and frog.

If you want help fitting boots on your horse or trimming his/her hooves, please call me at 250 377-1104 (Pacific Time). Also check my barefoot trimming services page for more information and to request a quote by email.

 

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