Evidently, there's quite a lot you can learn about a cow's health by sticking your hand up her butt.

More specifically, the cow's rectum is positioned so that you can feel her reproductive tract -- ovaries, uterus, and often the cervix. It's useful for doing pregnancy exams, diagnosing ovarian cysts and uterine infections, and performing artificial insemination.

The wall of a cow rectum is tough, flexible, and hard to tear -- but that doesn't mean ol' Bessie's going to be very pleased about having someone who doesn't know what he's doing sticking his hand up her rear. And every year, scores of veterinary students have to learn their way around a cow's backside.

I almost saw a practice session in the parking lot of my undergraduate college, which has a large agriculture department. I was walking to the biology building early one morning when I saw a cowboy leading a spotted Holstein on a leash toward a cluster of students. I wondered why the heck they had a cow in the parking lot ... until I saw the shoulder-length rubber glove the cowboy wore.

I hurried on, silently wishing that the ag students had access to some kind of model they could use in the privacy of their own laboratory instead of a very public cow-poking demonstration.

A University of Glasgow researcher named Sarah Baillie has made just such a model, citing an increase in students and a lack of test cows.

The simulator is housed in a life-size fiberglass model of the back half of a cow. The student inserts his or her hand in an appropriately-placed orifice, and sensors pick up the student's hand position and generate a 3D model of it on a nearby computer so that the instructor can critique the student's handwork.

To improve the realism of the experience, the cow model is equipped with a haptic force-feedback device called PHANToM, which is produced by SensAble Technologies.

If you want to see pictures of the bovine rectal palpation simulator in action, visit http://www.dcs.gla.ac.uk/~sarah/brps.htm.

The same research group is working on a model for horses.