Back in the old days, foal watch was something that could span the course of weeks. Sleeping in the barn, getting up every couple hours to check on the mare, obsessing over every little change in her demeanor. Then somebody figured out milk testing and everything got a whole lot easier.
There are “official” milk test kits on the market, like Predict-A-Foal or Chemetrics, but you can accomplish the same general type of testing with plain old pool testing strips – ones that measure pH and calcium. It’s pretty simple really… you collect a little bit of “milk” (which may or may not look like actual milk until foaling. Sadie’s is still more yellow and clear-ish.), dilute it with a specific ratio of distilled water, and then use the strip to test it.
Some people rely solely on the color of the milk to tell how imminent foaling is, but some mares don’t really produce much until right at foaling time, and others may not have true white milk until the very last minute either. Testing the calcium content and the pH of the milk are more accurate indicators than just using color alone.
Beyond getting the ratio of milk to water correct, it’s actually a super simple method of testing. As the mare gets close to foaling, the pH will drop and the ppm of calcium will increase. Once you hit 200ppm of calcium, you’re probably within 24-48 hours… 400-500 usually means you’re imminent (although some mares can have a big spike in calcium a day or so in advance). Using the calcium in conjunction with pH gives you a little bit of a closer window, since pH drops dramatically just before foaling. Once your calcium is high and your pH is low, baby horses are about to happen.
Granted, you don’t want to constantly be testing the milk or you run the risk of depleting the colostrum. As the mare’s udder starts to develop, testing every few days is fine until the numbers start to change, and very little milk is required to test. Although this method of testing works well on most mares, you’ll find one sometimes that doesn’t go by the book. Still though, it typically helps reduce the sleepless nights to just one or two instead of MANY.
So, what does all this mumbo jumbo really mean? It means I get to go audit the FEH/YEH clinic in Dallas this weekend, because Sadie’s still testing low on calcium and high on pH!!! We’re not super close.