Prevent Laminitis and Founder

By Doug Stewart

Laminitis is a serious and common disease of the hoof. Although it is rarely fatal, in serious cases the horse is put down either for humane reasons (the horse is in pain and permanently crippled) or economic reasons (the horse can no longer be used for its intended purpose). Such cases of euthanasia are sufficiently common that laminitis is the second most common cause (after colic) of premature death in domestic horses.

The horse hoof contains connective tissue which holds the hoof bone (the pedal bone) in place and connected to the hoof wall. This tissue is known as laminae and if it becomes damaged the result is known as 'laminitis'. Minor damage results in inflammation of the tissue and temporary pain. More severe cases reduce the strength of the connective tissue, allowing the pedal bone to rotate and sink within the hoof. In the most extreme cases, the pedal bone will actually penetrate the sole of the hoof and be visible. In mild cases the horse can return to normal duties but in more severe cases (depending on the amount of rotation and sinking of the pedal bone) the horse will have to be retired, with the worst cases requiring that the horse is immediately put down. Although there are a number of treatments for laminitis, once the damage is done they can provide only minor improvements, so the emphasis needs to be on prevention rather than treatment.

One hears the term 'founder' in relation to 'laminitis'. Unfortunately, not everyone uses the term in the same way. Some people use both terms interchangeably, while others use founder to describe the more serious cases of laminitis (e.g. bone penetration of the sole).

There are various causes of laminitis but they can be grouped into three categories. The first is overly rich feed, which upsets digestion, resulting in the release of toxins into the blood, where they then travel to the laminae and cause inflammation and tissue break down. The second category is mechanical separation, where the laminae is damaged from repeated shocks to the hooves (from running or jumping or hard ground). The third category is toxins, either ingested in the feed, or produced internally as a result of an infection.

Excessively rich feed results in changes to the bacteria population in the digestive system, causing the release of toxins by the bacteria. It occurs when a horse has too much carbohydrates or nitrogen, either from excessive amounts of rich feed (e.g. grain) or lush pasture. Pasture is most likely to be excessively rich in spring, when rain follows a drought, or if it has been fertilized. As some breeds (in particular, ponies) are more sensitive than others, one should take special care with sensitive breeds to restrict the amount of rich food and to keep them off rich pasture. Alternatively, one can put them on pasture for a limited time but use a grazing muzzle to restrict the amount they eat.

For both competition horses and pleasure horses, one should try to avoid working them on hard ground, as the repeated shocks can cause mechanical damage to the laminae. When travelling over hard surfaces, try reducing the pace as there is less shock when walking than when running. Shock absorbency can be improved by correct trimming, especially avoid trimming for long toes or over-trimming. Ensure that shoeing is done by a competent professional, if the horse is shoed. Consider the use of shock absorbing shoes (they have a rubber component) or shock absorbing boots, both of which are being increasing used, even during professional competitions.

Check that the horse's feed does not contain any fungus, mold or chemicals. Do not allow them to eat chemically treated grass (e.g. herbicides). All serious infections should be aggressively and promptly treated, to prevent the release of infection related toxins into the blood stream. - 29953

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