Founder is a disease of the feet in horse. When one says a horse has been foundered, it means that the horse has been affected, or is affected with this foot disease. The technical term for founder is laminitis. Laminitis is defined as inflammation of the laminae of the feet. The laminae are the tissues between the goof and the bone of the foot. They serve to attach the hoof to the bone. When these tissues become inflamed, it causes varying degrees of pain in the affected feet.
The exact causes of laminitis are still unknown, but there have been many predisposing, or risk factors identified. These risk factors include inflammatory conditions of the gastrointestinal tract (i.e., colic), eating too much grain or other rich feed, retained placenta or uterine infection, generalized infection, prolonged weight bearing on one limb, and exposure to black walnut wood shavings. Other less common risk factors include trimming hooves too short, exercising on hard surfaces, and medicating with corticosteroids. Ponies seem to be particularly susceptible to laminitis.
Laminitis can be divided into acute and chronic forms. With acute laminitis, the clinical symptoms are related to the degree of damage that has occurred to the laminae. Horses with minimal damage will have mild signs and probably respond quickly to medication. Horses with extensive damage will have severe signs and may not respond well to treatment.
Acute laminitis most often affects both front feet, but all four feet or only one foot may be involved. When both front feet are involved, the hind feet are placed well up under the body and the front feet are placed forward with the weight on the heels of the feet. If all four feet are affected, the horse will lie down for extended periods. In both cases, the horse will resist moving and when it does move, it will walk as if on eggshells.
Laminitis becomes chronic when the horse responds poorly to treatment of the acute stage. This stage begins when there begins to be rotation downward of the bone inside the hoof. Rotations occur because the laminae, which hold the hood to the bone, become damaged to the point where the connection between bone and hoof is not secure. Once rotation of the bone occurs, it cannot return to the normal position. Treatment at this point is directed toward supporting the foot and minimizing further rotation of the bone. In some cases the bone rotates to the point of penetrating through the sole of the foot.
Laminitis can be successfully treated if caught in the early stages. Treatment consists of medications to reduce inflammation and increase blood flow to the laminae. Measures are also usually recommended to help support the soles of the feet. This can be done by placing the horse in a stall with six inches of sand, or by applying special shoes.
The best treatment for laminitis is prevention. Prevention is best achieved by eliminating the risk factors previously mentions. Excessive grain, lush pasture, and lawn clippings should be avoided as these can commonly lead to laminitis. If you suspect your horse may have laminitis, you should contact your veterinarian and have it examined, so treatment can be initiated and laminar damage is minimized.