Welcome to Markie's Choice, Inc.
Founder & Sinking
Hoof specimen, sagittal section. Severe hoof capsule rotation and P3 penetration into the sole
Rotation and sinking are two possible consequences of a single severe laminitic episode or of repeated episodes. The latter is less common and much more severe.
Sinking results when there is a cataclysmic failure of the interdigitation between the sensitive and insensitive laminae around the entire perimeter of the hoof. Apparently this event allows the entire bony column, often described by its most distal bone, the third phalanx (aka: PIII, P3, coffin bone, pedal bone, distal phalanx) to sink within the bottom of the hoof capsule. In some texts, the term 'founder' is now used synonymously with laminitis, although they are not the same. Rotation occurs when the damage to the laminae is less severe and it will show up mainly in the toe area of the foot. One possible reason for this is the pull of the tendon attached to the coffin bone, the deep flexor tendon, literally pulling the dorsal face of the coffin bone away from the inside of the hoofwall. It is also theorized that the body weight of the animal contributes to rotation of the coffin bone. Rotation results in an obvious misalignment between PII (the short pastern bone) and PIII (the coffin bone). In some cases, the rotation may also result in the tip of PIII penetrating the sole and becoming exposed externally.
Depending upon the severity at the onset of the pathology, there may be no movement of the pedal bone, rotation only, sinking only or a combination of both rotation and sinking, to varying extents.
Not all horses that experience laminitis will founder but all horses that founder will first experience laminitis.
In laminitis cases, a clear distinction must be made between the acute situation, starting at the onset of a laminitis attack and a chronic situation. A chronic situation can be either stable or unstable. The difference between acute, chronic, stable and unstable is of vital importance, when choosing a treatment protocol.
Laminitis can be mechanical or systemic, unilateral (on one foot) or bilateral (on two feet) or may also occur in all four feet.
Systemic laminitis follows from some metabolic disturbance within the horse, from a multitude of possible causes, and results in the partial dysfunction of the epidermal and dermal laminae, which attach the distal phalanx to the hoof wall. With this dysfunction, the deep digital flexor tendon (which attaches to the semi-luner crest of the distal phalanx and serves to flex the foot) is able to pull the bone away from the wall, instead of flexing the foot. When the coffin bone is pulled away from the hoofwall, the remaining laminae will tear. This may lead to abcesses, within the hoof capsule, that can be severe and very painful. Also, a laminar wedge may form, between the front of the hoof wall and the pedal bone. This laminar wedge may, in some cases, prevent the proper re-attachment (interdigitation) of the laminae. Under certain conditions and only after consultation with an experienced veterinarian and farrier team, a dorsal hoof wall resection, to remove this laminar wedge, may be undertaken.
Systemic laminitis is usually bilateral and is most common in the front feet, although it sometimes affects the hind feet.
Mechanical laminitis or 'mechanical founder' does not start with laminitis or rotation of the distal phalanx. Instead, the wall is pulled away from the bone or lost, as a result of external influences. Mechanical founder can occur when a horse habitually paws, is ridden or driven on hard surfaces or loses laminar function, due to injury or pathologies affecting the wall.
Mechanical founder can be either unilateral or bilateral and can affect both front and hind feet.
It is important to note that, once the distal phalanx rotates, it is essential to de-rotate and re-establish proper spatial orientation of p3 within the hoof capsule, to ensure the best long-term prospects for the horse. With correct trimming and, as necessary, the application of orthotics, one can effect this re-orientation. This attempt at re-orientation may be less than one hundred per cent effective, however.