Page 87 - Speedhorse October 2018

Ultrasound is the most common method of basic fetal monitoring, either trans-rectal or transabdominal (shown here), depending on the stage of pregnancy.
MONITORING
“For basic monitoring, the most common method is ultrasound, either trans-rectal or transabdominal, and this will depend on the stage of pregnancy and what you are looking for,” he says. In some cases, especially with placentitis, the veterinarian will pull blood samples to look at progesterone levels and total estrogen to see if there are changes. If these are out of the normal range, and there’s a rise or fall in those values, depending on the hor- mones, this may be indicative of an impending problem. As the pregnancy gets farther along, the veterinarian can also check fetal heart rate.
“Some people also want to look at fetal activity, but this isn’t always a reliable indicator of the foal’s health and status. Some foals will be sleeping very deeply when you are palpating, and they don’t move at all. Then you ultra- sound them, and everything is as it should be, and the heart rate is in the normal range. But when that fetus isn’t moving at all, it can be stressful to the person doing the examination,” says Sheerin.
Sometimes the fetal fluid is checked, but this is not commonly done except in research. “Monitoring changes in the fluid, looking at cytokines and some of the changes in differ- ent hormones have been done in research with placentitis, for example, but it’s not something we do in horses on a regular basis, compared to what is done in humans.”
SIGNS OF PROBLEMS
“If the mare is being monitored, the pla- cental thickness can be measured, and if it is excessive for her stage of pregnancy this tells
us there is some sort of inflammation in the placental tissue. In that situation we’d need to treatthemareappropriately. Thetruemeasure of placentitis can’t be done however until after she foals and then you can examine the placenta histologically,” says Sheerin.
“Many of the cases we’ve looked at and called placentitis may not be true placentitis but we know there is something abnormal going on because the placenta is abnormally thickened.
In many of those cases, however, if we can get the mare to term and she foals and the foal is normal, people don’t worry about doing histol- ogy on the placenta. We have a live foal, and that’s the important thing. Many clients don’t see the need to spend the extra money to make the diagnosis that we suspected,” he says.
Other signs of trouble would be a vaginal discharge or the mare bagging up too soon. “If a client called with a mare that was showing these signs, we would do a physical exam on the mare. If there’s a discharge we would culture the discharge and see what the appropriate antibiotic might be,” he explains.
“We would do a trans-rectal ultrasound, and measure the placental thickness, and see if there is any separation of the placenta from the uterus, palpate the cervix and make sure it is still tight,
etc.” If it isn’t, there would be concern that the mare might foal prematurely or abort.
The ultrasound will also show whether the fetal fluids are clear or if there is a lot of debris floating around. “This will change over time, with a normal pregnancy. As the mare gets later in preg- nancytherewillbemoredebrisfloatingaround; instead of it being clear (black on the ultrasound) there will be black with some gray flecks floating around. A certain amount of that is normal but an excessive amount would be abnormal,” he says.
The examination would also include pulling a blood sample. “We would do a CBC (complete blood count) and potentially send the sample to
a lab to check the levels of progesterone and total estrogens. Depending on the geographic area we might also check for a lepto titer,” says Sheerin. If the fetus is compromised because of disease, the mare may be at risk for abortion.
TWINS
“When we check a mare and she doesn’t have a discharge and the placenta and fluids look normal, the other concern we’d have, depending on how far along she is in the pregnancy, is the possibility that she might have twins. Then we would do a thorough trans-rectal and transab- dominal ultrasound examination to see if there are two foals.” In Thoroughbred mares, instances of twins are usually resolved early on (by elimi- nating one of them when the embryos are small) but sometimes they get missed.
Twins will put the pregnancy and the mare at risk, so she should be checked early and closely monitored.
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EQUINE HEALTH