Neu Perspectives

The Nail Test


Whether this old wives’ tale for predicting foal gender works or not, it’s entertaining.


By Kelli Neubert

January 28, 2016

Hats off to those who are committed to raising and breeding quality horses. Whether it’s a backyard hobby or a large-scale profession, I can’t help but applaud the people involved and the stamina that they have for the whole process. After doing it a little myself, I am the first to admit that breeding and raising horses requires a great deal of patience.

Once the “magic cross” between mare and stallion is decided, it’s nothing but a marathon of “wait.” We wait for the mare to come into season. Breed the mare. Wait to see if she takes. Wait a little longer, then check for a heartbeat. As the due date nears, it feels as though each day stretches on forever. Continue waiting, and we finally greet a newborn foal. Then wait until it’s old enough to handle, let it grow, and one day, start it under saddle.

We don’t raise many horses, but this year we have a couple of mares that are due to foal early this spring. Of course I am excited, but the 11 months that this process requires is taking its toll on me. The hardest part seems to be the anticipation between a confirmed breeding and the birth of a foal. What’s it going to look like? What color is it going to be? Let’s hope for four straight legs and a pretty head! And of course, the big question: is it going to be a colt or a filly?

Just for fun, this year I decided to utilize an old wives’ tale to pacify my anticipation on my foals’ genders—the nail test.


The nail test is in no way a scientific or confirmed reliable measurement, but it is entertaining. It basically works like this: Take a single hair out of your mare’s tail and tie it securely to the top of a carpenter’s nail. Hold the free end of the hair over the mare’s spine, near the point of her hip, and let the nail dangle a few inches above her. On an open mare (or a gelding) the nail is not supposed to move. On a mare that is going to have a stud colt, the nail will swing back and forth in a straight line. If she’s going to have a filly, the nail will swing around in a circular motion.

The nail test and I have a brief but successful history. When I was 13 years old I tested it out on two mares. The nail told me that one mare was going to have a colt and the other, a filly. My nail test results ended up being 100 percent accurate.

This year, I tested it on four horses: an open mare, a gelding and two bred mares. The nail did not move on the open mare or the gelding. According to the all-knowing nail, my paint mare is in foal to a colt and my sorrel mare, a filly.

I’m not sure how I feel about this. I’ve read other telltale signs about foal gender prediction, and they seem to match my nail test’s results. I can’t help but wonder if I subconsciously moved it on my bred mares (I am hoping for a colt out of my paint and a filly out of the sorrel), because I’ve researched this test and can’t come up with any information that would explain why it would be scientifically accurate at all.

Of course, once my foals are on the ground we will know just how much truth lies in that dangling carpenter nail this year. I will certainly share the results of my experiment here, and would be interested to know if the old wives’ tale works properly for anyone else. But for now (sigh)…we wait. 


2 thoughts on “The Nail Test”

  1. I found your article interesting and fun. Of course I had to try it. The nail went in a circle predicting my mare would have a filly, which she did!!

  2. I use this method to predict pregnancy of my mares here in Iceland. I use a horse shoe nail for this and it has never failed for years and years. Even a mare that met a stallion but didn’t become pregnant, the nail was correct. I just heard that the foal will need to have a heartbeat for the method to work.


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