Normal forces placed on the hoof are then strong enough to tear the remaining laminae, resulting in a failure of the interdigitation of the epidermal and dermal laminae between the hoof wall and the coffin bone. When severe enough, this results in displacement of the coffin bone within the hoof capsule. Most cases of laminitis occur in both front feet, but laminitis may be seen in all four feet, both hind feet, or in cases of support limb laminitis, in a single foot. Mechanism
The mechanism remains unclear and is the subject of much research. Three conditions are thought to cause secondary laminitis:

Sepsis/endotoxemia or generalized inflammation
Endocrinopathy
Trauma: concussion or excessive weight-bearingInflammationInflammatory events that are associated with laminitis include sepsis, endotoxemia, retained placenta, carbohydrate overload (excessive grain or pasture), enterocolitis, pleuropneumonia, and contact with black walnut shavings. In these cases, there is an increase in blood flow to the hoof, bringing in damaging substances and inflammatory cells into the hoof. EndocrinopathyEndocrinopathy is usually the result of improper insulin regulation, and is most commonly seen with pituitary pars intermedia dysfunction (also called equine Cushings syndrome) and equine metabolic syndrome (EMS), as well as obesity and glucocorticoid administration. In cases of EMS, most episodes occur in the spring when the grass is lush. TraumaMechanical laminitis starts when the hoof wall is pulled away from the bone or lost, as a result of external influences.
Anonychia is the absence of fingernails or toenails, an anomaly which may be the result of a congenital ectodermal defect, ichthyosis, severe infection, severe allergic contact dermatitis, self-inflicted trauma, Raynaud phenomenon, lichen planus, epidermolysis bullosa, or severe exfoliative diseases. : 784

Congenital form
This is rare and is usually due to mutations in the R-spondin 4 (RSPO4) gene which is located on the short arm of chromosome 20 (20p13). Clinically it is manifest by the absence (anonychia) or hypoplasia (hyponychia) of finger- or toenails. See also
List of cutaneous conditions

References


== External links ==