Prevent Abortion

Diagnosis and Treatment of High Risk Mares

The high risk mare is defined as a mare that has a higher risk for abortion than the normal mare. Her high risk may be due to a history of late term abortion with a previous pregnancy or due to clinical signs with her current pregnancy. Not so long ago these mares were treated with a wait and see attitude because the technology did not exist to diagnose their issues. If the issue could be diagnosed there were few treatment options available. Today however, new research helps the veterinarian do a much better job of diagnosis and treatment. We are now able to save many foals that in the past would have been aborted.

Dr. Koontz perfoms transrectal ultrasound

In order to save these foals we need the owner to help identify the high risk mares. Mares that have aborted in the past are immediately placed into the high risk group. Mares that have clinical signs of abortion are also immediately placed in the high risk group. Mares that appear normal and have no history of abortion should have a monthly transrectal ultrasound examination starting at 7 months of gestation to identify internal signs of abortion.

Most abortions occur without any external clinical signs. The owner just walks out to feed and finds a dead fetus in the stall. That is why ultrasound is so important; almost all mares that abort have internal clinical signs that can be identified with ultrasound.

Some external clinical signs you may see include premature mammary (udder) development. The normal mare's udder develops 2 to 4 weeks before foaling. Some mare's udders may not develop until immediately before foaling. Mares that have udder develop more than 4 weeks before their due date or stream milk more than 4 weeks before their due date should be evaluated by a veterinarian.

Mares with vulvar discharge are suspect for bacterial placentitis. Much to the surprise of many owners, most mares with bacterial infections do not have vulvar discharge. These mare need to be identified via monthly ultrasound examinations. The mares that do have discharge most often display white pus or blood tinged pus. Other signs to look for include; sudden enlargement of the abdomen, mares that are more than 25 days overdue, or mares that experience severe colic. (Be aware that mild, intermittent discomfort can be normal for some late term mares). Mares that display any of the above signs should be evaluated by a veterinarian.

When the veterinarian comes to evaluate your mare have her history ready. It is particularly important to have an accurate due date so we are not misinterpreting normal gestational changes as medical issues. The veterinarian will also want to know if the mare has had foaling issues before. If she has aborted in the past, at how many days of gestation did it occur and what was the cause?

To help diagnose a problem the veterinarian may want to perform transrectal ultrasound examination to determine the viability of the fetus, to determine the fetal heart rate, to characterize the amniotic fluid, to access fetal activity, and to measure the combined uterine and placental thickness. The veterinarian may also want to measure progesterone in the blood and the amount of calcium in the milk.

Once a diagnosis is made the appropriate therapy can be initiated. Medical treatment may include; domperidone, antibiotics, pentoxifyline, altrenogist, and nonsteroidal anti-inflammatory drugs. The important thing to remember is that today there are ways to diagnose and treat mares at high risk for abortion. With timely intervention, the high risk mare can deliver a healthy foal.

Robert H Koontz DVM