Laminitis: Horse Disease

Laminitis Information

The unmistakable sound of a horse crashing into the metal rails of its stall echoed through the barn during morning rounds at the veterinary hospital. We rushed over to find the 22-year-old stallion violently rolling on his back. His dilated pupils and tortuous thrashings clearly conveyed the agony that comes with the sudden onset of colic, or abdominal pain.

The stallion was sedated and quickly settled down. Sure enough an exam revealed a sky-high heart rate and brickred gums--unmistakable signs of colic. A belly tap, done by carefully inserting an 18-gauge needle into the horse's abdomen, yielded a tube of thick, brownish blood-tinged fluid. A ruptured stomach was suspected. Too many injections of painkillers, given to treat the stallion's laminitis, had eaten through his stomach wall, allowing feed to spill into the abdominal cavity and causing severe infection and the resulting colic. Laminitis was attempting to claim yet another victim.

Emergency surgery was needed. The once champion racehorse was led, legs trembling and wobbling, to the surgery room. A catheter was quickly placed, and the horse collapsed to its knees as the anesthetic coursed through its veins.

Twenty years earlier, on the first Saturday in May, Foolish Pleasure pranced rebelliously. His handlers steered him toward the starting gates of Churchill Downs, as a buzzing sellout crowd anxiously anticipated the start of the Kentucky Derby. Finally settled into their gates, the three-year-olds bolted as the starter's gun released them. Foolish Pleasure quickly moved up along the rail.

Anatomy of the Equine Foot

Laminitis is a debilitating, painful disease that causes the delamination of the equine hoof. The sensitive tissues' underneath the hoof wall become excruciatingly painful as the layers of hoof wall, or laminae, separate. Usually the front feet are affected, where two-thirds of a horse's heft are concentrated. On a thousand-pound horse each front foot, measuring roughly the size of a human hand, carries approximately 350 pounds of weight.

The anatomy of the horse's foot yields clues as to why these animals are susceptible to laminitis (see illustration). The horse is a single-toed animal, and the last bone, or phalynx, of the digit is encased in multiple layers of a tough protein called keratin, the same stuff our fingernails are made of. These protective layers comprise the hoof and are supplied with nutrients by a complex system of microscopic blood vessels.

Certain substances in the blood can cause changes in the blood flow to the hoof. The layers of the hoof begin to separate, causing severe pain to the underlying tissue. Worse, the most distant bone of the foot begins to rotate within the delaminating hoof as it is pulled by the deep digital flexor tendon. In severe cases the bone can rotate right through the sole of the hoof and come in contact with the ground.

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