Page 88 - December 2017

Some people worry about progesterone defi- ciency causing early embryonic loss, and like to put some mares on a progesterone supplement. If the mare’s history has indications that she may be at higher risk of losing the pregnancy or if she had loss of pregnancy before, the client often puts the mare on progesterone supple- mentation. “In the mare, her CL will produce progesterone initially, so many people pull blood and evaluate her progesterone level at the time they do the first pregnancy exam,” says Sheerin. “If it’s low, they can treat the mare
at that point. After about 110 to 120 days of pregnancy, the placenta starts to take over the job of producing the progesterone.
“After that point, checking for proges- terone is a little dicey because the placenta isn’t actually producing progesterone, per
se. It produces progestin. Depending on the lab that you use for the test, your results will vary. Some assays are more specific for just progesterone, so if you measured the levels of a pregnant mare later in gestation, the levels will be low. There are other assays that have more cross-reactivity, so the test can pick up other progestins. It may not pick up 100% of it, but can pick up some of it, to say that it’s there. Those levels will be a little higher. So, it all depends on the specificity of the assay that the lab is using,” Sheerin explains.
“This can be very confusing to try to explain to the client because you have to get into how the assay works,” he says. “If you are going to sample the mare for progesterone or progestin later in pregnancy, you need to know the assay that the lab is using and if it has cross- reactivity with other progestins. The only way to know is to call the lab.”
Another form of monitoring pregnant mares is simple external observation - watching the mare, and looking at her udder and vulva. Some mares will show signs of udder development ear- lier than others, and sometimes too early. Others may not develop much udder until right before they foal, and can surprise you.
The LasT TrimesTer
Major changes occur in the mare during final stages of gestation. Most of the fetal growth occurs during the last three months, so the mare’s abdomen usually becomes larger. Juan Samper DVM (Langley, British Columbia) says the mare changes significantly during this time.
“There are several things you need to keep in mind during late pregnancy,” says Samper. “The mare needs to be living in the place where she will foal so she will develop the immu-
nity she needs for that environment.” Then
her colostrum will have protective antibod-
ies for her foal that is being born into that environment.
“About 4 to 6 weeks before foaling, I also recommend that we do a rectal and ultrasound examination to determine whether the foal is presenting head first or backward. The other thing I do when we check the mare before foaling is to see if she had a Caslick’s opera- tion. If so, this is the time to open it up, unless the mare has such poor conformation that we need to wait until she actually starts early labor. Another thing that should be done, especially for maiden mares, is to start touching and cleaning the udder and working with her sev- eral weeks before foaling. Then when the foal
is born and goes up to her to try to nurse, the mare won’t be squealing and kicking because her udder is sensitive.” She will be accustomed to having her udder and teats touched, and it won’t be a new and startling experience.
“This is also the time to make sure the mare has no vaginal discharges or secretions, no clumping of the hairs at the back of the tail which could indicate a discharge. Vulva dis- charges should not be ignored or taken lightly, nor is premature udder development,” Samper says. These signs indicate that the fetus is not in a happy environment and may be at risk for premature birth.
“A mare should start to bag up a little dur- ing the last 6 weeks of gestation, but should only make serious progress in the last 1 to 2 weeks. She should not have a really big udder 4 to 6 weeks ahead of time,” Samper explains.
If a mare starts to show signs of premature foaling, there are several things the owner
and veterinarian can do. “The first thing is to determine what is wrong,” he says. “Are there premature contractions of the uterus? Is the mare experiencing a little premature placental separation, with no infection? Is there infection associated with it? If so, what kind of infection
is it? Is it coming from the bloodstream of the mare, or moving up through the vagina and into the cervix? These are all things we need to know.
“Once we know, there are things we can do, if it’s not too late,” Samper continues. “If it’s an infection, we will treat the mare with antibiot- ics and anti-inflammatory drugs. If it’s just a premature placental separation and the mare is having premature contractions, often we just put her on progesterone (such as Regumate®) to quiet down the uterus and she will continue on with the pregnancy. Treatment will depend entirely on the diagnosis. You should not assume that just because one of your mares had a bit of a vaginal discharge last year and was put on an antibiotic, that you should put this one on antibiotics, too.” It might be a com- pletely different problem. A veterinarian should examine and diagnose the mare to determine what the most appropriate treatment would be.
Some mares, especially older mares, may have bloody discharge in late pregnancy or
Watch for signs that a mare is starting to lactate before she should. She ought to start to bag up
a little during the last 6 weeks of gestation and should only make serious progress in the last 1 to 2 weeks. She should not have a large udder 4 to 6 weeks ahead of time.
even some blood coming from the vagina. “This may be very alarming to the mare owner, especially if it occurs a month or two before foaling,” says Samper. “What often happens
is that some of the veins in the vagina rupture because it is becoming stretched and pulled forward. If those veins break, you will see
a little hemorrhaging, or bloody discharge from the vulva.” This happens most often in older mares because the muscles of the vagina become weaker, and there are also a lot of superficial veins that might break. This condi- tion can be related to age of the mare and/or many foalings.
Sheerin says some mares in late pregnancy might have a vaginal discharge which needs to be evaluated because it could signal a problem, but if you don’t pick up her tail and look, you might miss this clue. “Depending on the situ- ation, it may be easy or not so easy to check them closely and frequency of those examina- tions will vary from farm to farm.” The mares may be in stalls or small paddocks or out in a big field somewhere.
“You can use the mare’s history as a guideline as to how frequently she should be checked,” Sheerin continues. “Even if the mares are outside, whoever feeds them will be seeing them every day and you’d hope that they would at least look at the udders.” You can see what
a mare’s udder looks like today compared to yesterday or last week.
The person feeding them may not pick up
all their tails, but could look at the udders to
see if there are any changes,” Sheerin says. “If a mare does show signs of development too early, it would be a good idea to have the veterinar-
ian palpate and ultrasound her to examine the placental thickness, fetal fluids, and pull blood to evaluate progesterone and total estrogen. After these assessments, the veterinarian can then decide what therapy should be utilized.” This moves into the realm of a high-risk pregnancy.
86 SPEEDHORSE, December 2017
equine health