Okay so I know there are some tests out there where you can use a calcium test strip on the mare's milk and when the calcium level spikes, she will foal within 12 - 24h. It's supposedly really accurate, and I'm interested to learn more.
Here's a link: Mother Natures Mare Foaling Predictor Kit
However if the deal is that you are just looking for the spike in calcium before the mare foals, I've also heard that pool strips work fine and are about 1/3 of the price. Has anyone done this and how does it work?