Assessing the health and progress of the late-term pregnant mare is an important skill. Mares near foaling may eat less, and act lethargic and look miserable.
Distinguishing between this expected lethargy from a significant health problem can be challenging. The better job you do of observation, the better able you are to tell when you need to consult with your vet.
To perform the Whole Horse Exam on the late-term pregnant mare, start by standing quietly and watching her from a distance to evaluate her demeanor, attitude and appetite. Is she eating and drinking, urinating and passing manure? How large is her abdomen? Does it seem normal? Is it symmetrical side to side? How large is her udder? How has it changed recently? Try to gently strip the teats to get a drop of liquid. Is there liquid? What does it look like?
Now halter the mare. Stand in front, behind, then on the left and right sides, and look down her body and legs for anything seemingly abnormal or asymmetrical side to side.
Staying in contact with the mare, gently move down her left side and insert the thermometer. While you are there, examine her vulva for length, degree of change, any vaginal discharge or anything else that seems abnormal. Return to the mare’s head and check mucous membranes, capillary refill time, pulse quality and rate. Pinch the skin on the left shoulder to assess hydration.
Put on your stethoscope and listen to the heart. Move the stethoscope head to the trachea for respiratory rate and clarity of the trachea. Slide back and listen to the two left quadrants of the abdomen, slide around the back of the horse and listen to the two right quadrants of the abdomen.
Take the stethoscope out of your ears and move back to the left side of the horse. Strip a few drops of milk out of each teat and inspect its color and consistency.
Tips for safety & Success
Download and print copies of the WHOLE HORSE EXAM FORM to keep in your barn for later use. This form can be found attached to this record as an Outside Resource.
I use a mercury thermometer because it can be inserted and clipped to the tail (string and alligator clip attached) while the rest of the exam is completed. But you can adapt this to the use of a digital thermometer, which many people prefer.
Note: A firm, doughy swelling of the lower belly (ventral abdomen) is normal in the final weeks before foaling.
The udder starts enlarging at about 4-6 weeks in most mares. At a few weeks prior to foaling, there is usually a sudden step up in size. Then a few days before foaling, there is a final enlargement. At this point, the teats have a honey colored to clear, sticky liquid in them. As the mare nears foaling, this will change to a more white, true milky appearance. Ion tests done on this milk show an increase in calcium corresponding to this color change.
Dripping of milk should only commence right before foaling. Dripping of milk that lasts more than a few hours long before foaling should prompt a call to your vet.
Vaginal discharge should only commence hours before foaling. Vaginal discharge without foaling should prompt you to call your vet.
Mares in the final trimester of pregnancy may have a heart rate that is somewhat higher than average. 48 BPM is not unusual.
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