move pain free. This procedure removes the symptoms of disease but may have an accelerating effect on the degree of damage to the hoof structures as the removal of the symptoms allows the horse to move in a way that increases the force experienced by the navicular bone. is also becoming a more common widespread treatment for Navicular as it acts to increase blood supply to the area. Prognosis for horses affected by navicular disease is poor as the disease is degenerative & progressive. The degree of lameness may fluctuate but ultimately the degradation of the hoof structures becomes worse with time and the horse’s quality of life is negatively affected.
Laminitis
Laminitis is defined as the inflammation of the laminae of the hoof. In reality, it is the dissolution of the basement membrane in the foot between the sensitive & insensitive laminae resulting in mechanical failure. It is commonly called “ ” though this term describes the downward rotation of the third phalanx and may or may not be related to laminitis.
The exact cause of laminitis is not clear. There are many factors that are linked with laminitis:
Old Theory peripheral vascular disease resulting in a decrease of blood supply to the foot.
Endotoxemia occurs when the environment inside the gastrointestinal tract becomes too acidic to support G- bacteria. When these bacteria die, they breakdown, releasing endotoxins into the lumen of the gastrointestinal tract. The endotoxins are absorbed into the blood stream along with other nutrients and spread throughout the body. The endotoxins trigger peripheral vasoconstriction, which causes ischemia of the foot. Ischemia causes swelling of the tissues of the foot, especially the laminae, and progresses to ischemic necrosis if the ischemia is prolonged. Necrosis of the laminae result in the weakening, or loss, of the attachment that suspends the third phalanx from the hoof wall. Without a healthy lamellar junction, the force of the body’s weight tears the third phalanx off of the hoof wall and rotates the bone downward. Continued force will act to push the tip of the third phalanx toward the sole of the foot and may result in the protrusion of the third phalanx through the sole. Repeated concussion from high impact work on hard surfaces leads to peripheral vasoconstriction and increased development of AVA’s. This causes ischemia, swelling and ultimately ischemic necrosis of the laminae. The concussive forces tear the third phalanx off of the weakened laminae and cause downward rotation and sinking of the third phalanx. This type of laminitis is commonly called “road founder” as it is often seen in horses that work on paved roads.
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