The navicular bone is a small, flat bone located behind the heel within the horse’s hoof. Whilst small, the navicular bone serves an important function by helping the deep digital flexor tendon run smoothly down to the pedal bone and aids shock absorption during movement.
Navicular disease arises as a result of inflammation or degeneration to this bone which can also affect the surrounding tissues. Navicular disease most commonly occurs in the front feet, in most affected horses, it will be present in both front feet. Navicular in the rear feet is possible but much more uncommon.
Navicular disease is a degenerative condition which means it will get progressively worse over your horse’s life span. Unfortunately there is no cure for navicular disease however the condition can be managed.
Symptoms of navicular
- Changes in gait
- Lameness
- Decreased stride length
- Decreased athletic performance
- Difficulty turning or working on a circle
- Pointing a toe whilst at rest
- Reluctance to work
Early signs and progressive symptoms
As a progressive disease, the symptoms of navicular will worsen with time. In the initial stages of the condition, lameness may only be apparent every so often, this is known as intermittent lameness. Whilst the condition typically affects both front limbs, lameness will often appear worse in one foot. As navicular progresses, lameness will normally become more apparent and chronic.
Causes of Navicular Disease
Navicular disease can be caused by a number of factors. Horses with poor hoof conformation are also more likely to develop navicular as imbalances in the foot can put excessive strain on the navicular bone and associated structures. Long toes, low heels, and poor hoof angles can contribute to this imbalance.
Trauma to the hoof such as repetitive concussive forces from hard surfaces or excessive strain during exercise can also contribute to the development of navicular disease.
Genetic and environmental influences
Whilst any horse can develop navicular, it is more common in thoroughbred, warmbloods and quarter horses. These breeds are thought to be more genetically predisposed to the condition however research to back this up is limited.
Sport horses who tend to have higher workloads are also more likely to develop Navicular due to extra strain being placed on the structures within their legs
Navicular is rarely seen in younger horses. The condition is more predominant in middle aged and mature horses with the average age of onset being 8-14 years of age.
Diagnosing Navicular Disease in Horses
When diagnosing navicular disease, a vet will normally conduct a lameness assessment, assessing the horse’s way of going on different surfaces as well as on turns and circles. Lameness assessments will often include flexion tests and in some cases nerve blocking techniques may be utilised. This is where a vet will inject anaesthesia into a point within the horse’s limb to see if lameness is reduced. This allows them to more accurately determine sites of pain. A lameness
assessment alone will not confirm a diagnosis of navicular, this is where diagnostic imaging plays an important role.
Advanced imaging techniques
Diagnostic imaging can also be used to confirm or rule out a diagnosis of navicular disease. Imaging techniques can be used to determine the severity and progression of the condition and any damage that may be present on surrounding tissues.
Whilst X-Rays will give a good image of the navicular bone. Ultrasounds and MRI scans can provide a more in-depth view of the extent of the condition as they can evaluate damage to the surrounding tissues and structures as well.
Treatment options
Whilst there is no cure for the conditions, thankfully there are many treatment options available that can slow progression and improve quality of life of affected horses
- Medication - Anti-inflammatory drugs such as Bute may be prescribed to help manage some of the symptoms associated with the condition. When using bute it is important to be aware of the side effects associated with long term usage. Devils Claw and White Willow Bark are natural alternatives to bute that can also be effective in managing pain and inflammation particularly during early stages of the condition
- Farriery - it is important that all horses receive routine farriery care, even more so in cases of navicular. Regular farriery appointments can help keep the hoof balanced and minimise further strain placed on the structures within the leg, slowing down the progression of the condition.
- Shoeing - Some horses with navicular may benefit from remedial shoeing to provide the hoof with extra support, this should be done on a case-by-case basis following discussion with a farrier and a vet.
- Surgery - If your horse is experiencing a great deal of pain due to navicular disease, a neurectomy surgery can be carried out in which the posterior digital nerve is cut. Whilst surgery will not reverse the damage of the condition, it can be used to alleviate the pain associated with it. This surgery is not considered a permanent fix, most horses will experience a few years of pain relief however the cut nerve can eventually grow back.
Managing navicular
Lifestyle and exercise adjustments
Following a diagnosis of navicular, many horses can still live comfortably for years to come so long as there is a proper care plan in place. As progression of the condition is likely to speed up with hard exercise, affected horses will often require a reduced workload. Working on hard surfaces and uneven surfaces should be avoided as this puts greater concussion on the limbs. Jumping and exercises involving tight turns and circling should also be avoided in order to minimise the strain put on the legs.
Weight management is crucial for horse’s with navicular as excess weight can put further strain on the affected structures. Closely monitor your horse’s condition and avoid using high sugar and starch feeds that may contribute to unwanted weight gain. Ideally any feeds given should have a combined sugar and starch content no greater than 10%.
Whilst no feeds or dietary supplements have been shown to improve navicular disease, it is still important that your horse receives a balanced diet that meets all of their nutrient requirements. Incorporating additional Omega 3 and biotin into the diet can be beneficial for horses with navicular as these nutrients are known to promote overall hoof health.
Ensuring Your Horse's Health and Comfort: Next Steps
Unfortunately many cases of navicular disease will progress to the point where a horse will need to be euthanised for their own welfare. Working alongside a reputable equine vet following a navicular diagnosis will help owners to make the most informed decisions regarding their horse’s care and should help maintain a higher quality of life for as long as possible.