One of the things we learned from spending 30 years teaching university students about horse management is that the human mind is desperate to reduce complex phenomenon to the least common denominator. Or, to reduce that thought to its simplest expression-"the human mind is determined to look for ways to make hard things easy."

One of the more-challenging tasks is to age a horse with a full mouth of permanent teeth-those over 10 years of age. In the big sale barn horse auctions of years past, the ringman would send the horse in for bidding after looking in his mouth by proclaiming his age: "He's a 5-year-old! He's a 3-year-old!" But if the horse was over 10, the ringman would simply say, "Smooth mouthed!" No one wanted to go out on a limb and say just how much over 10 that horse was.

That's because aging a horse over 10 years of age requires an analysis of dental stars, seven/eleven hooks, the shape of the table surfaces and the pitch of the mouth. Compiling, comparing and evaluating these clues takes study, practice and interpretation-all traits that are lacking in the mental discipline of most 18- to 21-year-old college students. In fact, most human minds prefer to avoid this situation.

The solution to this complex problem devised by equine college students was to search for a "cheat sheet," or crib notes, or a Readers Digest condensed version for older horses. The quickie version is groovy.

First, Galvanie's Groove.

Galvanie's Groove is a dark tarter line that moves up and down the center of a tooth, depending on the age of the horse. Only two teeth have this telltale age line-the last tooth on each side of the upper jaw before the bars-the right and left third incisors.

Try drawing this cheat sheet on the palm of your hand.

• At age 10, the dark tarter line appears at the gum line in the center of the tooth.

• At age 15, the dark line is approximately halfway down the tooth. At 20, the dark line is all the way down the tooth.

• After age 20, the line begins to disappear at the gum line. At 30 years of age, the line has disappeared from the tooth.

After committing this groovy solution to memory, most college students thought they were ready to "Ace" the lab practical. However, this question stumped most of them:

"How do you tell if a horse without a Galvanie's groove is less than 10 or older than 30?"

The students under 25 thought this was a trick question. The students over 40 instantly knew the right answer. Age does bring wisdom and it also brings on striking differences in appearance-in both horses and humans.

Another life's lesson learned by "mouthing" horses is that few things are as simple as they seem. The problem with Galvanie's Groove is that it does not always reflect the truth if the horse is between the age of 10 and 20. That would be too easy.

To be prepared, always have a back-up plan. The back-up plan for aging smooth-mouthed horses is to go to crib note No. 2 - McCall's Groove.

Peal back the upper lip and examine the two front teeth-the right and left first incisors. Horses up to 13 or 14 years of age have two dark grooves down the center of these front teeth. By 15, the two grooves unite to form one brownish groove down the center of each tooth - McCall's Groove.

While not absolute (like most things in life) this groove is more accurate than Galvanie's Groove. And, by mastering these two groovy techniques, you can quickly estimate the age of a smooth mouthed horse without suffering through multi-variable analysis and interpretation. And, it may also give you one more idea for designing teeth for your Halloween pumpkin.

©2002 Dr. Jim and Lynda McCall