Waiting for Foals
We’ve all spent many a night losing sleep and gaining anxiety while watching a pregnant mare stretch her gestation from the average expected 335-340 days to a long 355 days or more.

We watch for the physical signs: udder enlargement, relaxation of the muscles and ligaments around the tail head, and finally relaxation of the lips of the vulva and waxing on the teats (the oozing of colostrum, the thick, honey-colored, sticky “first milk” that is rich in protective antibodies.)

Recent studies of milk electrolyte changes—especially calcium--have increased the ability to predict foaling time. These electrolyte changes may be related to the maturity of the foal and it’s preparation to survive after foaling.

Several test kits and monitors are available to assist with prediction and notification of foaling. The CHEMetrics FoalWatch Kit (CHEMetrics Inc, Calverton, VA) that measures calcium carbonate levels in prefoaling milk samples has been extremely reliable in our hands.

The Testing Timetable
Begin observation of the mare’s udder at 300 days. Have a friend hold the mare with her head tilted towards the left side where you should stand against her shoulder. Have your assistant give the mare a treat as you gently scratch her belly in front of the udder and then gradually move back until you can clean between the nipples. Then gradually accustom the mare to your cleaning the udder with a warm, damp cloth. Eventually, gently milk the nipples using your thumb and middle finger until the mare is comfortable with your handling her in the area. Maiden mares may be especially shy at first, and may not produce secretions until two weeks before parturition.

Beginning at approximately 320 days gestation, or as soon as secretions can be obtained from the udder, sample the secretions once daily, in the late afternoon or early evening, since most mares foal at night, and run a FoalWatch test until you begin to get test results above 125 ppm. Then twice daily sampling is recommended.

The Test Procedure
  1. Wipe the udder and teats with a clean, dry, soft paper towel
  2. Obtain 2 mL of udder secretion by gently milking a small amount from each teat into the small plastic beaker.
  3. Using the 3 cc syringe, draw up 1.5 mL into the sample cup.
  4. Add 9 ml distilled water. Mix gently
  5. Add 1 drop of color indicator and mix
  6. Using the testing ampoule and valve and titrator assembly, draw a sample of the milk mixture into the ampoule, invert and watch for color change from orange to bright blue. Repeat until sample remains blue. Remove the ampoule and read the test results on the scale provided.
  7. Rinse syringes, sample cup and beaker with distilled water and air dry.
Interpretation of Results
When test results first meet or exceed 200 parts per million (ppm) there is a 98% probability that the mare will foal within 72 hrs (and a 98% probability that she will not foal if she has not reached 200 ppm).

Watching the change within 12 hours after 200 will further predict timing. Mares reaching 300 or more will foal within a short period of time.

The small volume of secretion that is required for testing will not deprive the foal of significant amounts of colostrum and the colostrum content is not affected. Mares that drip or stream milk prior to foaling will do so whether they are tested or not.

Watch for any signs of clumping or blood in milk samples and consult with your veterinarian.

Case Studies
  • 10 year old maiden Quarter Horse mare. Closed circuit TV on at day 330. No mammary secretions until 332 days gestation. Foal Watch test 335 days at 50 for three days, 125 on day 339, 140 on day 340, 160 on day 341, 175 on day 342, 200 morning of day 343, 250 pm of day 343. Set up to stay in barn. Mare foaled at 10:30 pm. Normal, healthy filly
  • 17 year old Quarter Horse mare, second foal. Closed circuit TV on at day 320. Mammary secretions very thin. Foal Watch test at 50 ppm day 320-324, 125 ppm day 325, 160ppm in am day 326, 175 pm day 326, 275 am day 327 at 7 am. Constant watch begun. Mare foaled at 9:30 am, normal healthy filly.
  • 6 year old Clydesdale mare, first foal. Owners ran tests, foal watch at 275 ppm evening before foaling. Foaling observed.
  • 10 year old Hanovarian mare, first foal. Owners ran tests, foal watch at 250 ppm evening before foaling.
  • 10 year old Morgan mare, first foal. Owners ran test. FoalWatch at 275 ppm in morning, 325 evening. Mare slightly colicy overnight. Dystocia discovered in the am. Foal delivered by caesarian had contracted tendons.

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