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A Horse of Course

A Horse, Of Course
by Don Blazer

If you love that new foal, don’t feed him--too much!

Yes, I know he’s cute, and you can’t resist. Yes, I know you want him to have the very best. Yes, I know his little ribs are showing just a bit.

That’s the way he is supposed to be!

Feed him too much, make him fat, and he may be a cripple for life.

Epiphysitis—an inflammation of the epiphyseal plate--is caused by a number of factors, excessive weight being first on the list.

The disease occurs in foals ranging in age from one to nine months, and we usually associate it with the knee and fetlock joint although it can occur on any bone. On each end of the shaft of long bone is the epiphysis (epiphyseal plate) which is cartilage which hasn’t yet turned to bone.

This cartilage or soft bone maintains its natural shape as the young horse grows, unless it is “squashed” out of shape by the foal’s own weight. When it is “squashed,” it is often called “big ankles”, “double ankles”, or “hour-glass ankles or knee.” The distinctive hour-glass shape is the result of the epiphyseal plate flattening under the horse’s weight and widening above and below the joint.

Sometimes—but not often—there is no lameness associated with the condition. However, if not recognized and left uncorrected, epiphysitis can and often does result in crippling arthritis.

Excessive weight and a lack of exercise rank as the number one culprit. The disease is almost always seen in the biggest, fattest individuals in the herd. The dams of these foals produce lots of milk and the weight of the foal is simply too much for the epiphyseal plate. Since 65% of the horse’s weight is carried on the forelegs when he is idle, the disease is most often seen first in the front legs.

Foals kept in small areas—and there are way too many of them—are at greater risk for the disease. No exercise, no strengthening of young bones. No exercise, greater chance for a fatter, softer foal.

Other causes include an imbalance in calcium and phosphorous, usually the result of “trying to fatten and build up the young horse.”

The minerals calcium and phosphorous should be kept in ratio—somewhere between 1:1 and 2:1. When a young horse is being fed a lot of grain to “build him”, the ratio gets out of balance. Grains are high in phosphorous and if the phosphorous gets too high, calcium will be then be called from the bone to restore the balance within the blood. The resulting effort is softer bone, and eventually epiphysitis.

Another factor affecting bone development is heredity. Certain inherited factors cause late maturing bone, while other factors cause soft bone. When those factors are combined, the young horse is at high risk for epiphysitis. Be careful in selecting mares and stallions.

Since nutrition can be regulated, that is the first place to start in an effort to protect the young horse.

Most breeders and veterinarians agree that a foal which is showing signs of epiphysitis should be weaned immediately, regardless of age. A blood panel should be run to determine the Ca and P ratio. Depending on the blood results, the young horse may need supplements of calcium or phosphorous. Supplements need to be used judiciously.

Even after you correct any nutritional problem, the disease process may not shows signs of being curtailed for weeks.

The best thing you can do for any foal is see to it he gets plenty of exercise, has a balanced, but not growth inducing, diet, has an abundance of clean, cool water and enjoys fresh air—even without sunshine.

Then enjoy watching him grow—on his own.


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