Navicular Disease (in horses)
The navicular bone in a horse is a small flattened bone which is positioned along the back of the coffin joint. The navicular bone then attaches to the pedal bone via the impar ligament and to the pastern joint by a series of 'suspensory' ligaments. It is important that when diagnosing new cases that these two ligament structures are inspected, which can be achieved through MRI scans.
Navicular is a commonly found issue for horse owners to manage (particularly in older horses) and in this article we look at the common symptoms associated with Navicular, possible causes and what treatments are recommended within the equine community.
In the majority of cases the issues occur in the front legs and it is extremely rare to find navicular issues in the hind legs.
The condition is found across all breeds and disciplines.
If your horse has been diagnosed with Navicular it is likely to prevent you from riding them, however, in some cases and with your vets approval they may be able to be ridden for short periods of time - often depending on the severity of the navicular issue and pain levels the horse is experiencing.
It is worth noting that due to the vast numbers of causes within the navicular area of the hoof that every case is different and should treated as such. In essence, Navicular Syndrome is an overly simplified diagnosis for an extremely complicated area of the horses hoof.
Navicular syndrome (or navicular disease, or caudal heel syndrome) is a degenerative condition of structures in the horse’s heel, which is responsible for over a third of chronic lameness in horses. But equally, if the horse is managed properly, not all cases of navicular will lead to your horse being unsound and in some cases will allow the horse to be rideable for many years to come.
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.
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 positive effects.
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 or 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 immediately.
Early indications of your horse developing navicular symptoms include an increase in stumbling or tripping, visible discomfort when planting the foot and a shortened stride pattern.
Keep an eye on the following factors which may effect a horse with Navicular:
– The degree (angle) of the front-to-back movement in the hoof.
– A lack of mobility in the hoof. (severe stiffness/reduced mobility)
– 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.
Establishing and diagnosing the exact issue
Technology has progressed so much in the past few years that using imaging techniques is often the most accurate form of diagnosis. Many vets will use a tried-and-tested walk-and-trot examination first and rank the level of lameness from 1-10.
The next most common step on the quest for an accurate diagnosis is to use nerve blocks to identify the area of the horses lameness. This is carried out prior to any imaging techniques to focus on the exact area of concern.
Once the lameness has been located to the specific area of the foot, a selective desensitisation of the navicular bursa is then performed.
Once the localised area of the foot has been established technologies now widely available allow the horses hoof to be captured using imagine techniques.
Warning; these imaging techniques used by veterinary professionals can be incredibly expensive.
X-rays can be carried out on both front feet which allows your vet to examine the navicular bone, pedal bone and coffin joint. By taking imaging of both feet it allows an evaluation of the severity of the changes in each hoof and eliminates misdiagnosis of the condition. This includes health conditions such as arthritis in the coffin joints and any potential fractures to the pedal bone.
More recent technologies now used are Ultrasounds. Ultrasonography can be a useful tool and enables examination of the collateral ligaments of the coffin joint, and the deep digital flexor tendons. As opposed to showing bone, ultrasounds show ligaments and tendons in great detail.
Thermal imaging technology also provides an interesting option for horse owners, with advancements in this technology significantly improving their reputation. An infrared thermal heat inspection from a thermal digital camera can confirm whether there may be heat anomalies in the hoof, such as excessive heat or cooler areas, often the symptoms of poor blood flow.
In more recent years, there has been an increase in using MRI (Magnetic Resonance Imaging) to diagnosis navicular syndrome extremely accurately. Although this provides the most clear picture of inside the horses hoof, the biggest issue and most prohibitive reason why they are used less than the above options are the huge costs associated with MRI scans and how many insurers do not cover MRI scans as part of their insurance policy. Prices often start at around £1200 for one visit!
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 can only be prescribed by veterinary professionals and are mot sold over the counter. 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. Administering bisphosphonate medications is certainly not a natural and holistic approach and comes with quite a serious health warning.
Can navicular syndrome be cured?
There is no cure for Navicular, it is a case of managing the horse and doing what is possible to reduce/eradicate pain levels.
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.
The most important aspect of supporting a horse with Navicular is rest - this cannot be under estimated.
For many years the equine community has looked towards holistic therapies and methods to support their horses navicular and associated pain with more natural approaches.
Tack used to support horses with Navicular?
With a plethora of horse tack products on the market aimed at supporting a horse with navicular it is often hard to 'see the leaves through the trees'.
Firstly, finding the correct supplement to support your horses ongoing recovery is important. E-Vet, one of the UK's largest veterinary suppliers, recommends a few products which support your horses recovery by aiding a reduction in inflammation and thus reducing the associated pain.
Traditional magnetic products claim to offer beneficial support, however, using traditional magnetism increases heat which in most cases should be avoided when looking to reduce inflammation. Advanced Magnetic Technology, now available for horses by UK manufacturer StreamZ Global, EQU StreamZ Magnetic Bands, are recommended by some vets to aid a reduction in inflammation without increasing heat. This allows horse owners to provide long-term magnetic benefits to their horse without the concern that creating heat is leading to further issues. Advanced Magnetic Technology creates a non-invasive spinning action around the horses leg which was developed to rebalance the system on a molecular level. Significant impact has been shown within anecdotal studies, although not clinically proven, Advanced Magnetism provides a complementary form of treatment for any horse with navicular and should be investigated.