With the new year upon us, it is getting very close to foaling season, my favorite time of the year. For those of you with mares which are pregnant, final preparations soon will need to be made so that the newborn foal gets the best chance at a healthy start to life. Vaccinations will be given to the mare to protect the foal, ultrasound examinations might be needed to monitor the health of the fetus, and at the least, the diet of the mare will be increased to accommodate her need for increased energy as her baby grows.

As the final days before foaling approach, the mare will be watched closely for signs of impending birth, such as enlargement of the mammary gland and relaxation of the perineum. "Waxing" also is one of the signs that indicate the mare is preparing to foal. Waxing is the secretion of a sticky, yellow substance from the mare’s teats–it looks like wax, hence the name. This secretion, which is the colostrum or first milk produced by the mare, usually indicates the impending birth of a foal. Unfortunately, impending birth might mean a few hours, days, or in unusual cases, a week or more before the foal is born.

With advances in knowledge about the milk that a mare produces before foaling, veterinarians can more accurately predict foaling by looking at the electrolyte content of the milk. Determining the changes in the electrolytes, or more specifically, the amount of calcium secreted in the mare’s milk prior to birth, helps veterinarians judge when the mare is about to foal. This technology greatly assists those people monitoring mares for delivery in order to be present in cases where difficult births (dystocias) might be expected or in cases where the foal is at risk of neonatal isoerythrolysis (jaundice).