What is navicular syndrome?
Navicular syndrome (or navicular disease) is a degenerative condition of structures in the horse’s heel, which is responsible for over a third of chronic lameness in horses. Damage to any of the structures supporting the navicular bone can result in pain for a horse, as well as direct damage to the bone itself. Navicular fractures or navicular stress fractures can also occur.
Navicular Disease (Horses) – Symptoms, Causes & Treatments
What is navicular syndrome?
Navicular syndrome (or navicular disease) is a degenerative condition of structures in the horse’s heel, which is responsible for over a third of chronic lameness in horses. The navicular bone in horses is a small boat-shaped bone, which is tucked behind the larger pedal bone and then lies at the back of the heel. The deep digital flexor tendon runs down a horse’s leg, and then wraps itself under the navicular bone, before anchoring to the coffin bone. Damage to any of the structures supporting the navicular bone can result in pain for a horse, as well as direct damage to the bone itself.
‘The vascular theory’ states that: any interruption to the blood supply to the navicular bone can result in navicular disease. Although opinion is divided on the theory, treatments aimed at restoring and increasing blood flow have been proved to have some effect.
What causes this condition?
No one knows exactly what causes navicular syndrome, although, like many other lameness issues, it’s likely a combination of factors are to blame. Navicular Syndrome is most commonly found in horses with certain foot conformations; for example, overlong toes and collapsed heels.
It is believed that there is a genetic component to navicular syndrome, as it is more common in certain breeds of horses, such as thoroughbreds, warmbloods and quarter horses. A greater number of affected horses have a history of front-leg impact work, such as jumping, roping, and reining; or increased concussion (work on rocky or hard surfaces)
Although Navicular Syndrome has been seen in horses as young as 3 years old, the average age to develop signs of navicular disease for a horse is reported to be 7-11 years. This potentially highlights the degenerative nature of the issue and the fact wear-and-tear must play a part.
Many horse owners will refer to the condition as ‘heel pain’ prior to a professional diagnosis is issued. The pain within the heel will often lead to a level of lameness, often mild and intermittent. The lameness may switch from the left to the right, the fore to hind – it may not be consistent and often will occur in both front legs.
What are the warning signs?
It is advised that if you notice any changes within your horses demeanour that you consult your veterinarian professional. Early indications of your horse developing navicular symptoms include an increase in stumbling or tripping, visible discomfort when planting the foot and a shortened and choppy stride.
Keep an eye on the following factors which may effect the horse:
– The degree (angle) of the front-to-back movement in the hoof.
– A lack of mobility in the hoof. (severe stiffness)
– The hardness/firmness of the ground.
– The speed in which the horse moves.
– The duration of the horses movement.
– The length of stride.
– The size of the navicular bone.
– The size of the deep-digital flexor tendon.
How can you treat navicular syndrome?
Treatment options for navicular syndrome have improved dramatically in recent years, as vets, scientists and associated studies have provided a better understanding of the condition. Firstly, the treatment should be aimed at the actual structures identified in each individual case. It’s essential to work with both a vet and a farrier to come up with a combined plan to keep the horse comfortable and sound.
The aim is to re-establish the best foot shape possible to fine-tune the forces placed on the foot to avoid over-loading and cope with the demands of work, specifically the rear third of the hoof.
Advancements in equine MRI technologies have led to a more precise method of identification to the horses specific injury or abnormality. As with many advancements in health related technologies this allowed vets and professionals to diagnose the condition more accurately. MRI technology is now so advanced that professionals can see firsthand the structures in the back of the hoof and give them a far clearer picture of how to treat the condition.
Careful use of oral anti-inflammatories may help, but it’s vital not to make the horse so comfortable that they don’t rest sufficiently and end up making the injury worse. Vets will often inject an anti-inflammatory (such as a steroid), directly into either the navicular bursa or the coffin joint.
As well as anti-inflammatory and anti-arthritic drugs, there is also a number of alternative therapy options that can be considered. These include acupuncture, homeopathy or navicular accessories such as magnetic devices.
In 2014 the FDA (Food and Drug Administration) in USA approved two medications for the ongoing treatment of Navicular Disease. Both of these are prescribed medications, only presribed by veterinary professionals. Both of these medications (T*ldern & O*phos) belong to a class of medication known as Bisphosphonates. These were originally synthesized in 1897 by chemists in Germany looking at preventing calcium build up within industrial applications. Over 100 years later and those same chemicals are now administered to animals and humans to help bone remodelling by applying the same rebalancing effect as discovered a century ago.
One thing to note is that bisphosphonates should not be administered to a horse with colic. A few other potential adverse effects have been reported by users who had a horse with renal problems (kidneys) and should not be used alongside pain medication such as NSAIDS.
Can navicular syndrome be cured?
Not easily. This can be a particular challenge when hoping to treat your horse long term and in a holistic, non-invasive way.
The first steps in combating navicular syndrome are consultations with a vet or farrier. While there is no specific cure which works for every horse, a prompt diagnosis allows for treatment and a medical plan early on in the course of the disease, which will give the horse the best chance of improvement.
Therapeutic shoeing and proper trimming can provide pain relief for many horses. Generally a shortened toe, either through shoe design or trimming, is a goal. It is estimated that proper trimming and shoeing can relieve discomfort in about 30% of horses with navicular syndrome.
As outlined above, there are various treatments available that can improve Navicular Syndrome, so it’s a case of trying to treat the condition as early as possible and finding a solution that works best for the horse.