In the not so conventional practice of Applied Equine Podiatry, they seldom use the term equine navicular disease.
Taking a more holistic approach, they embrace several principles, theorems, and philosophies.
At its foundation is the belief that structure plus function equals performance (S+F=P).
They also know that a horse has an innate ability to heal itself, providing the environment is conducive to healing.
What does this mean to the treatment of the condition defined as equine navicular disease?
First, the horse owner has to understand that in coming to a point where a single disease is defined, as is often the case in conventional veterinary medicine, we have narrowed our focus and become reactive.
As new research provides evidence that there are multiple causes for the clinical manifestations of the lameness associated with navicular disease, it is only logical that a series of connected events may have led to the condition.
As theorized, changes in normal biomechanics of joint movement may lead to inflammation of the soft tissues of the navicular apparatus, but the question is: what is normal biomechanics of joint movement of the navicular apparatus?
To answer this question, you must subscribe to a specific model of foot function. We subscribe to a model that defines the Internal Arch Apparatus.
Understanding the Internal Arch Apparatus
The Internal Arch Apparatus is responsible for both energy utilization and energy dissipation within the foot, and is comprised of the coffin bone, navicular bone, distal articulating surface of the short pastern, all connective tissues (ligaments, tendons, fascia), the digital cushion, and all corium (inner layer of foot, containing nerves and blood vessels).
In short, the Internal Arch Apparatus constitutes all structures of the foot, without the hoof capsule. Applied Equine Podiatry recognizes that true foot function sees all structures working in concert to provide performance. Because this model includes the navicular apparatus as part of the whole, a manifestation of pain within the navicular apparatus would indicate a loss of structure and/or function of the Internal Arch Apparatus.
Taking things a step further, it is understood that the coria (corium) of the Internal Arch Apparatus produce the hoof capsule. It is often said of the foot that the outside is a mirror image of the inside. If one subscribes to this belief, it is only natural that one would become reactive, being held slave to the foot’s internal conformation.
I teach and follow the premise that "everything on the inside is a mirror image of that on the outside." Is this semantics? Hardly, with an understanding that the internal structures health is the result of external stimulus, we become empowered.
So, Where am I going with this?
I am saying that true equine navicular disease (lameness due to bone change) is only apparent following a long series of recurring events.
In this chain of events, soft tissue is the first to undergo change in response to an environmental alteration (balance change, increased vibration, friction and/or pressure), followed by changes to the horn.
- Before any modifications to the bone become apparent, the hoof capsule will show deformity (flare, excessive wear or growth).
- As the horse reacts to pain, he changes the way he loads the foot, and deformity appears.
- The deformity can be minimal, but it will occur.
- On rare occasions, a horse may show an acute-onset unilateral (affecting one limb) lameness, which leads to a diagnosis of navicular disease.
It is my belief that short of a catastrophic insult (injury), pronounced unilateral lameness is more often the result of chronic loss of structure (fallen arch) and proper foot function.