Horses can be affected by some strange things--such as trichobezoars, enteroliths or phosphatic calculi.

All are concretions found in the large intestine, and sometimes, although rarely, in the horse’s stomach.

Concretions, as you may have guessed, are internal stones, about as hard as concrete.

These infernal internal stones are made up of undigested material. They can easily attain a diameter of five to six inches, and are often much larger.

The ordinary weight for phosphatic calculi, which look like rounded and polished stones, is two to three pounds. In exceptional cases they have tipped the scales at 16 pounds.

Of course, no matter the size, they are not good for your horse.

Now, everything we ought to know about concretions we don’t know, but we have some pretty good ideas.

We don’t know everything about how and why they develop, but we do know they develop and cause trouble a lot more frequently in horses which eat a lot of alfalfa. The Center of Equine Health, University of California, Davis, recommends feeding oat or grass hay to reduce incidence of enteroliths, citing the fact that 98 per cent of horses with enteroliths had a diet of 50 per cent or more of alfalfa hay.

Interestingly, there is no factor other than alfalfa hay which comes anywhere close to being that strongly connected to enteroliths. Of course, no scientist will tell you that, but I’m telling you that. I’ll also tell you the problem with concretions is much bigger in California and other alfalfa rich states than in areas where there is little or no alfalfa.

We know concretions involve the presence of indigestible particles, such as small pieces of iron or steel, string, plastic or a chuck of rubber. So it is a good idea to check your horse’s feed for foreign objects, and it is a good idea to feed your horses in a manger on the ground, rather than directly on the ground.

In the case of phosphatic calculi, it has been noted a predisposing, though not an exciting cause, is the consumption of foods rich in phosphates, such as bran. Lots of people like to feed bran or a bran mash weekly. Dr. Alice suggests it may be a good idea to reduce or eliminate bran from a horse’s diet.

Dr. Alice also says a good way to decrease the pH level in the horse’s colon is to increase the grain to hay ratio. For people who don’t want their horses to be too energetic, this may not be appropriate.

Provide daily exercise and avoid prolonged stall or small pen confinement, Dr. Alice says. Horses, she points out, need exercise to maintain intestinal movement of feed. Frequent small feedings, rather than a couple of large ones, will help keep bulk material moving through the large intestine.

Trichobezoars are a very specific kind of concretion made up of hair. A trichobezoar then is nothing more than a hair ball.

An enterolith is not very distinguished; it can be a concretion of any variety.

According to Dr. Alice, concretions can achieve a large size without causing problems. In some cases they are passed with manure; in some cases they simply remain in a portion of the intestine and do not cause discomfort.

There is no characteristic symptom which can determine the presence of concretions. However, reoccurring colic without good reason might suggest a trichobezoar or enterolith, according to Dr. Alice.

Problems for the horse develop when the concretion is dislodged from one place and becomes an obstruction in a portion of the intestine.

Treatment, other than physical removal, is limited to administration of strong purgatives or enemas. Such treatment, according to Dr. Alice, can clear away calculi, but it can also complicate matters.

Unfortunately, trichobezoars, enteroliths and phosphatic calculi are being seen more often. Is it the abundant availability of alfalfa hay, or just the increased awareness of the problems of horses?