In order to understand flares and how they can affect the hoof’s healthiness, a dive into the anatomy and physiology of the hoof wall and its growth process must be taken.
The hoof wall is comprised of Stratified Epithelial Tissue. Basically, what that means is that the outside horny structure is avascular and contains few nerve endings. Just like any epithelial tissue, the hoof wall requires dermal layers to provide its nutrition. This nourishment comes from the coronary and lamellar coriums. In other words, the hoof wall grows downwards from the coronary band and is also nursed internally by the laminar corium.
Epithelial cells grow from a germinative (basal) layer through mitotic division (proliferation) of the basal cells. This growth is very systematic as the cells organize themselves into tubular horns that grow linearly from the coronary band and are often visible to the naked eye. As new cells are formed, the older ones get “pushed away” from the basal layer and start undergoing the process of cornification. This is when the cell nucleus starts to deteriorate and keratin filaments start to fill the cell’s cytoplasm – thus the smell of “burned hair” when your farrier hot fits horseshoes!
The hoof wall is connected to the distal phalanx through its laminar attachment.The relative pliability of the younger cells gives the wall its resilience to handle pressure with minimal distortion over the distal phalanx region. However, the section of the wall below the level of the coffin bone is connected to the sole of the hoof through the white line, and this region is usually the first to distort.
By definition, flares correspond to any deformation of the wall caused by changes in the morphology of the tubular horns. Pressure caused by movement and weight bearing will inherently cause the hoof wall to distort. This is a normal process of hoof growth and that is why regular trimming intervals are essential.
A farrier should remove the flares during the trimming of the hoof. Evidently, this task requires the animal’s cooperation as trying to do so on a horse that won’t hold his foot still on the stand can be quite an exhausting task. There is a lot of discussion whether or not flares should be addressed. However, the physiology of hoof growth should leave no doubt about the importance of dressing in order to maintain a healthy hoof capsule.
Excessive flaring can potentially become the antecedent for pathologies like abscesses, white line disease and, in some cases, even laminitis. Flares will “pull” the white line causing it to stretch which makes room for the entrance of foreign bodies and possible abscess development. Excessive flaring (as seen in chronic foundered horses) can also increase tension in the laminar attachment and trigger a laminitis outburst.