caslick |
foaling area | twins | prepubic
tendon rupture | uterine torsion |
leaking milk | equipment |
how to determine when a mare is about to foal
Introduction: The time surrounding the birth of a foal is full of
excitement and also stress. The objective of the following information is to
help alleviate some of that stress by identifying what is normal and should be
expected. Suggestions will also be given on when a veterinarian should be
involved and what steps should be taken to ensure a healthy foal and mother. The
process of successfully raising a healthy foal should begin long before the mare
actually gives birth and should include many of the following considerations:
Exam: A breeding soundness exam should be performed by a veterinarian
prior to breeding the mare. This exam may include taking a detailed reproductive
history, looking at the external genitalia, palpation/ultrasound of the internal
reproductive organs, and an examination of the cervix. Cultures and biopsies of
the uterus can also be taken at this time.
Vaccination/De-worming: It is essential that the mare be placed on a
vaccination and de-worming program prior to conception and throughout the
pregnancy. For specific suggestions, refer to pages A620 and
A905 for details. A
veterinarian should be consulted before using some products. Some recommend that
the mother be de-wormed the day she gives birth. This is because the parasite
Strongyloides westerii can be shed in the milk to the foal when it nurses.
Nutrition: The mare should also be placed on a balanced diet. Realize
that 65% of the fetal growth occurs in the last three months of gestation. The
mare’s calcium and phosphorus requirements are also 50% higher. Refer to the
nutrition information found on page A575. If supplements are needed they should
be started prior to the onset of the pregnancy.
Caslick: Some mares should be evaluated prior to breeding to determine if
a caslick is required. A caslick is a surgical procedure where part of the vulva
lips are sewn shut to prevent manure and contamination from entering the vagina.
A mare that has a vulva that slopes towards the center of the body and does not
stay mostly upright is a candidate for a caslick. These abnormalities of the
vulva often occur in older mares. This surgery is usually performed after the
mare is confirmed pregnant. The caslick should be removed at least 1-2 weeks
prior to the foaling date.
Foaling Area: An area that is dry, warm, well bedded, and clean (manure
free), should be prepared for the birthing process. Plenty of room should be
allowed for the mare to get up and down frequently and safely. A clean pasture
is a fine place to have a mare foal. It should be manure free and have good
fences. It is wise to not have other horses (mares and geldings) with the
expecting mother. Horses that have had problems in the past or are first time
mothers should probably foal in a paddock or stall. Animals that are normally
out on pasture can be moved to the foaling stall as the delivery date
approaches.
Potential Problems:
- Twins: Mares can be double ovulators. Thus, it is fairly common
for a mare to conceive twins; however, in the vast majority of cases, one of
the embryos will die during the first 40 days of the pregnancy or both fetuses
will eventually be aborted. In fact, the chances of a mare having a live set
of twins is fairly rare (2 sets per every 1,000 live births in Quarter
horses).
Because of the high possibility of the pregnancies ending in abortion, twin
pregnancies are not desirable. There is really no practical way to prevent a
mare from conceiving twins; however, there are ways of preventing the mare
from maintaining a set of twins. The most effective way is to have the mare
ultrasounded at day 14 of her pregnancy. At this stage, if two embryos are
found on the exam, one can be destroyed by pinching or crushing it. If it is
not possible to crush one of the embryos at day 14, the mare should be re-ultrasounded
again at day 28-30 and one of the embryos crushed. If it is early enough in
the season, another option is to terminate both embryos by giving an injection
and then re-breeding the mare. If the twin pregnancy is not detected until
after 35 days, a difficult situation arises. There are really three options:
One is to let the pregnancy advance naturally and rely on the small
possibility that the mare will abort one of the embryos. The second is to try
and crush one of the embryos; this usually results in the death of both
embryos. The third option is to abort both fetuses and try again next year if
it is too late in the breeding season.
- Prepubic Tendon Rupture: This problem can occur in a mare during
the last 3 months of pregnancy. It most commonly occurs in an older mare that
has been pregnant before. The prepubic tendon helps the mare’s abdomen resist
the added tension and pressure placed on the mare when she is pregnant. The
prepubic tendon attaches part of the abdominal muscles to the horse’s pelvis.
The muscles and tendon form a sort of hammock that cradles the contents of the
abdomen. The prepubic tendon anchors the back half of the hammock to the
pelvis. When the prepubic tendon ruptures, the weight of the fetus and
abdominal organs cause the abdomen and skin of the mare to stretch excessively
and sag. This causes pain for the mare and an obvious swelling and sagging of
the abdomen.
If this problem is suspected, a veterinarian should be contacted
immediately. The optimal solution is to deliver the foal as soon as possible.
If the foal is valuable, some attempts may be made to help prolong the
pregnancy (if it is not full term) by providing the mare with additional
abdominal support. However, this treatment is rarely successful.
Some mares that have a prepubic tendon rupture must be put down, while
others may recover enough to be a backyard horse. A few may be helped with
surgical repair. Mares that have ruptured the tendon should not be bred again.
In almost all cases, the mare will not foal naturally without assistance
because she cannot push effectively with her abdominal muscles.
- Uterine Torsion: This is an emergency situation where the mare’s
uterus twists around itself. This usually happens in the last 3 months of
pregnancy and can be a serious problem for both the foal and the mother. When
the problem occurs, the mare may act like she is colicking or is having
difficulty giving birth. To treat a uterine torsion, the veterinarian will try
and correct the twist by rolling the mare or untwisting the uterus with
surgery. If the foal is full term (at least 330 days along), it is usually
delivered promptly after the torsion is corrected. If the foal is not yet full
term, the pregnancy is allowed to progress normally; however, many mares may
still deliver as soon as the problem is corrected.
- Leaking Milk: Many mares will drip a small amount of milk out of
the udder right before birth. A small amount of dripping is normal; however,
if milk begins to stream out and colostrum is being lost, problems can arise.
In these cases, the mare’s udder should be cleaned with soapy water and the
colostrum collected in a clean container. The colostrum can then be frozen and
fed to the foal after it is born. Some mares will begin leaking milk during
the middle of their pregnancy. If this occurs, call a veterinarian.
How to Determine When a Mare is About to Foal:
- The length of gestation for most horses varies from 330-340 days, with
335 being the average. Swelling and softening of the vulva lips, relaxing of
the area surrounding the tail head, waxing to the teat ends, and an enlarged
udder are some outward physical signs that may be present in the mare just
prior to giving birth. Seeing any of these signs can indicate that the mare
may be ready to foal, but may not indicate how soon the birth will occur. For
example, the udder may begin to swell and the area and ligaments surrounding
the tail head can soften as early as 3-6 weeks before foaling.
Generally, if the mare has a prominent udder and has waxing of the teat
ends, the mare will likely foal within 48-72 hours. If all of the previous
signs (softening of the vulva lips, relaxing of the area surrounding the tail
head, waxing to the teat ends, and an enlarged udder are present), the mare
may likely foal within 12-48 hours.
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| This mare has a swollen udder
and waxing of the teat end (identified by the white arrow). |
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- One of the more accurate ways of determining when a mare will foal is by
evaluating the consistency of her milk. This can be done by visually observing
a few drops of the milk at about the same time each day. As the mare nears the
time to give birth, the milk will turn from a light, milky color to a thicker,
non-transparent (opaque) color. The milk can be evaluated when it is placed on
a black surface. Before the mare is ready to foal, it will be easy to see the
black surface through the milk. As parturition nears, it becomes more and more
difficult to see the black surface through the milk. Within 24 hours of
foaling, the milk becomes completely non-transparent and the black surface
cannot be seen through the milk sample. A more accurate method of determining
when a mare will foal is by measuring the amount of calcium found in the milk.
There are on farm tests available that measure the calcium in the milk. See
page D246 for an example of this type of test.
Selected References:
Bennett, Dwight G. "From Breeding to Weaning," Western Horseman Inc. 1999
Beeman, Marvin. "Foaling," Western Horseman March 1992: 22-28.
Smith, Bradford P. Large Animal Internal Medicine. St. Louis: Mosby
1996.