The identification of pregnancy is important for several reasons,
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Obviously to identify the pregnancy and avoid the need to return to the stud or be covered again.
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To identify multiple pregnancies and deal with the situation as early as possible.
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To ensure the pregnancy is normal and growing at an appropriate rate.
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Identify mares that suffer early loss of the pregnancy so that they may be returned to stud the same year if appropriate.
Scans should ideally be done at 16 –18 days after covering, again at 25-28 days after covering and a third time at 42 days after covering.
The 16-18 day scan is looking to identify a pregnancy and also the first opportunity to identify possible twin or multiple pregnancies. A twin pregnancy can be squeezed to remove it. Up to 18 days the pregnancies move freely within the uterus and can be manipulated apart to avoid traumatising the remaining pregnancy. After 18 days they implant into the wall of the uterus and cannot be moved, if twin pregnancies are identified after 18 days and they are close together, then attempts to squeeze one is likely to traumatise the other one which dramatically increases the chances of loosing that pregnancy also.
The 25-28 day scan is checking that any pregnancy seen at the first scan is still present and has grown at a normal rate. From 25 days, the pregnancy should contain a heartbeat which is visible on the scan, this is a good sign that the pregnancy is growing, normally and is viable. If no heartbeat is seen the mare should be re-scanned a few days later, if no heartbeat is seen and the pregnancy has not grown, at this stage, abortion should be considered. It is also an opportunity to look for any additional pregnancies that may be some days younger than the initial pregnancy and therefore may have been too small to identify at the first scan.
The 16-18 day scan is looking to identify a pregnancy and also the first opportunity to identify possible twin or multiple pregnancies. A twin pregnancy can be squeezed to remove it. Up to 18 days the pregnancies move freely within the uterus and can be manipulated apart to avoid traumatising the remaining pregnancy. After 18 days they implant into the wall of the uterus and cannot be moved, if twin pregnancies are identified after 18 days and they are close together, then attempts to squeeze one is likely to traumatise the other one which dramatically increases the chances of loosing that pregnancy also.
The 25-28 day scan is checking that any pregnancy seen at the first scan is still present and has grown at a normal rate. From 25 days, the pregnancy should contain a heartbeat which is visible on the scan, this is a good sign that the pregnancy is growing, normally and is viable. If no heartbeat is seen the mare should be re-scanned a few days later, if no heartbeat is seen and the pregnancy has not grown, at this stage, abortion should be considered. It is also an opportunity to look for any additional pregnancies that may be some days younger than the initial pregnancy and therefore may have been too small to identify at the first scan.
The 42 day scan is performed to check the pregnancy has grown and is healthy. Most early pregnancy loss occurs prior to 42 days, so if a pregnancy has survived to 42 days it stands a reasonable chance of making it to term. This scan is also a last chance to ensure there is only one pregnancy present.
