Laminitis and Founder

Micaela Myers

When a horse suffers from laminitis, it means the laminar tissue that hold the bones in place within the hoof have begun to fail. Laminitis is painful to the horse and can progress quite rapidly. While the term founder is often used synonymously with laminitis, founder refers to the coffin bone actually sinking or rotating, which can happen in more severe cases of laminitis.

In healthy hooves, the epidermal laminae interlock with the dermal laminae to form a strong bond that holds the coffin bone in place within the hoof. The epidermal laminae are lined with what is called basement membrane-a critical sheet of connective tissue forming the binding interface with the dermal laminae. When a horse develops laminitis, the laminar tissue and basement membrane begin to fail. They may fail only in certain places or all over. Because this process takes place quickly, sometimes within hours, prompt veterinary treatment is critical.

Although laminitis can affect only one foot or all four, the front feet are most commonly affected. Many problems in the horse's body can predispose a horse to laminitis, including carbohydrate overload and insulin resistance, obesity, pregnancy, stress and other injuries or illness. Researchers are studying the complex process that triggers laminitis and causes the laminae and basement membrane to fail.

Because laminitis can be deadly, treating horses for any predisposing conditions and managing such issues as Cushing's disease and Equine Metabolic Syndrome, is critical for preventing laminitis. Carbohydrate and starch overload caused by too much lush grass may be the number one cause of laminitis, so monitoring a horse's grass intake and working with your veterinarian to create a balanced diet for your horse is also imperative.

Symptoms that your horse may be suffering from laminitis include increased heat in the hoof, a throbbing digital pulse (pulse in the lower leg), soreness when walking, shifting weight from one foot to another or standing in awkward positions. Immediate veterinary attention is required to ease the horse's pain and help prevent founder.

Treatment for acute laminitis usually includes non-steroidal anti-inflammatory medications (NSAIDs) to help ease the pain. Other medications, such as vasodilators to improve blood flow to the hoof, may also be prescribed. Removal of shoes and providing hoof support in the form of Styrofoam molds or lily pads is often recommended along with restricted movement and appropriate bedding/footing. If there is an underlying disease or illness that caused the laminitis, this must also be treated.

X-rays can determine if rotation or sinking has occurred. In cases that do not involve sinking or rotation of the coffin bone, the horse may make a full recovery. When rotation or sinking of the coffin bone occur, laminitis can be life threatening or turn into a chronic problem. Rotation usually means the laminar tissue at the front of the hoof has failed, allowing the toe of the bone to rotate down. Sinking is more severe, indicating all laminar tissue has failed, allowing the entire bone to sink down. In the worse cases, the coffin bone can actually protrude through the hoof or cause the hoof capsule to detach.

Some cases of founder (rotation and/or sinking) are so severe that the only option is humane euthanasia. In other cases the horse's pain can be managed with NSAIDs and specialty shoeing. However, most horses that have foundered cannot return to their previous athletic careers.


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