|You've poured over stallion breeding ads. You've put your mare under
lights and checked her health to be sure she's ready to breed. You may have even thought
up possible names for your hoped-for foal. So now you're ready to let nature take its
Wrong! Unless you send your mare to a breeding farm for the duration of
her pregnancy, you are the most important person to ensure the success of this breeding
endeavor. What you know can mean the difference between having a healthy foal next spring
and being disappointed or worse.
So we've put together a little test to find out how much you know. Once you've answered
the questions, take a look at the answers, tally your score, and see how you fared.
1. What condition should your mare be in before breeding?
a. Thin, with ribs and backbone easily visible.
b. In "show shape" with an inch or so of fat covering her ribs.
c. Moderately fit so that you can feel, but not see, her ribs.
d. Aerobically fit - lean, with hard muscles.
2. On what type of diet is your mare most likely to get pregnant?
a. 21% protein alfalfa
b. Spring pasture grass
c. Pelleted feed
d. Grass hay
3. In the northern hemisphere and without exterior help, such as light or hormone
therapy, what month is your mare most likely to get pregnant?
4. Your mare is not due to foal for another 6 to 8 weeks, but she's already developed
an udder and looks big enough to foal tomorrow. What should you do?
a. Call your veterinarian and have her checked right away. The foal is probably in
b. Get the foaling stall ready - she will probably foal early.
c. Stop feeding her so much - excess fat can make it harder for her to foal.
d. Check her for signs of colic.
5. You want to rebreed your mare who just foaled. Under what condition should you breed
on her foal heat?
a. You want her to foal earlier next year.
b. She had no problems foaling this year.
c. The stallion is returning to the show ring and will not be available for breeding in a
few more weeks.
d. Your mare only foals every other year even though you breed her every year.
6. During pregnancy your mare should get what amount of exercise?
a. Very little exercise until after she foals.
b. Continue riding and/or showing her the same as before she was bred.
c. Group trail rides at a walk or jog.
d. Moderate exercise, no hard gallops, either by herself or with one of her buddies.
7. When should you vaccinate your mare?
a. On the day she's bred and monthly until she foals.
b. At least three weeks before she's bred, during pregnancy (depending on the product),
and about four weeks before she foals.
c. At least three weeks before she's bred, during pregnancy (depending on the product),
and about four weeks after she foals.
d. At least three weeks before she's bred and about four weeks after she foals.
8. Your veterinarian can determine pregnancy how early using an ultrasound?
a. 3 to 5 days after breeding
b. 9 to 11 days after breeding
c. 21 to 25 days after breeding
d. 60 to 65 days after breeding
9. Why should you have your veterinarian ultrasound you mare as soon as possible?
a. So you can start her on a supplementation program as soon as possible.
b. To prevent from over exercising a pregnant mare.
c. To separate her from other horses.
d. To prevent a twin pregnancy.
10. Your pregnant mare is grazing on a pasture of fescue grass. What should you do?
a. Move all horses off of it immediately.
b. Have the pasture treated for fungus.
c. Have the foal aborted before it damages the mare.
d. Nothing. Fescue grass is excellent forage.
Okay, you've made it though the quiz. Now you'd probably like to know how well
1. c. Moderately fit so that you can feel, but not see, her ribs.
You need to have your mare in moderate condition for the best chance of getting her in
foal. If a mare is too thin (answer a) she may not be able to conceive. If she is too fat
(answer b) her body has to work harder to eliminate waste. A mare that is too fit (answer
d) may have shut down her reproductive system in order to deal with the stress of
high-level training. Some people feel that a mare who is a little thin coming out of
winter and is gaining weight when she is bred makes for the ideal candidate. If your mare
is not in ideal condition start working toward it gradually. Allow at least three to four
weeks after the change and before attempting to breed her in order to allow her body to
adjust. If your mare is far removed from her ideal weight you might want to postpone
breeding her until next year and concentrate on getting her healthy this year.
2. b. Spring pasture grass
A mare eating fresh, spring grass is more likely to conceive than on any other diet.
Spring grass contains a hormone that helps a mare to cycle regularly. Other factors that
usually go along with spring grass are the increase in daylight and the increase in
temperature. Both help a mare's reproductive cycle to get started in the spring. Mares
that are kept in stalls and fed hay tend to start cycling later in the spring and often
have a longer transitional period than mares out on the fresh pasture.
3. a. June
The most natural month for mares to conceive (in the northern hemisphere) is June. They
have already gone through the spring transitional period when they have erratic heat
cycles as they transition from winter dormancy. And they haven't started into the fall
transition period when they again have erratic heat cycles as they transition back into
winter dormancy. Conception in June also leads to foaling the next May when the spring
storms have ended, grass is plentiful, and the summer bugs haven't yet hatched in great
4. a. Call your veterinarian and have her checked right away. The foal is probably
A mare that looks like she's carrying triplets, or at least some big twins, and develops
an udder more than a month before she's due to foal probably has a problem. The placenta
may be detaching from the uterus, in which case the foal may not be getting enough oxygen
and is probably in trouble. It is better to have the mare checked and risk being wrong
than it is to lose the foal.
5. d. Your mare only foals every other year even though you breed her every year.
Some mares who are heavy milkers won't conceive while they are nursing. The hormones
necessary to produce milk may be interfering with the hormones necessary to conceive. So
the more milk she produces, the less chance she has of getting pregnant. When a mare comes
in heat about 7 to 10 days after foaling, her milk production has not yet peaked, but by
the time she comes in heat again, her milk production might be high enough for those
hormones to interfere with breeding. If you have a mare who consistently foals every other
year despite being bred every year, you might want to consider breeding her on her foal
heat. Just be sure she has had no problems when she foals and have your veterinarian check
her to be sure. Also the conception rate on foal heat breedings is only about 45% as
compared to about 65% when bred during other cycles.
6. d. Moderate exercise, no hard gallops, either by herself or with one of her
A moderate amount of exercise during pregnancy is very important for a mare. It helps
maintain good circulation and muscle tone, plus it helps her mentally. A mare with poor
muscle tone may have trouble delivering which can cause complications for her foal who is
without oxygen during the birthing process. It's also best to limit her contact with other
horses and high-stress situations such as at shows. Although a good vaccination program
can help protect your mare, it's not foolproof. You can lope her some during the first 6
to 8 months, if she is in good shape. After that time it is better to restrict her to a
walk and jog to avoid the possibility of damaging the mare, the foal, or the placenta.
7. b. At least three weeks before she's bred, during pregnancy (depending on the
product), and about four weeks before she foals.
It's best to vaccinate your mare at least three weeks before breeding her to allow her
system to develop some immunity and to allow her to recover from the stress of
vaccination. Also some vaccines are "modified-live vaccines" (MLV) meaning the
virus or bacteria has been altered to prevent causing the disease, but are still alive.
Although they have been tested as safe for pregnant mares, why take the chance that they
could affect the developing foal? During pregnancy you should avoid using the MLV, but you
should vaccinate against herpesvirus-1 and -4 (also known as "rhino") at five,
seven, and nine months. Then about four weeks before she is due to foal you should boost
her immunity again. Check with your local veterinarian to find out which diseases are a
problem in your area. It's important that this vaccination is timed right to allow her
enough time to build immunity to pass to her foal through the colostrum, but not so early
that her immune response begins to fade.
8. b. 9 to 11 days after breeding
Experienced veterinarians with a quality ultrasound machine may be able to detect a
pregnancy as early as nine days when the embryo is about the size of the head of a pin.
Within a few more days the embryo will have grown to about the size of a dime. (Or about
1.6 centimeters for the rest of the world.) If you're not sure exactly when she ovulated,
you may want to wait until about 13 to 15 days after you think she ovulated to be sure
your veterinarian will be able to see the embryo (in case you're are off by a couple of
9. d. To prevent a twin pregnancy.
Although the thought of having two foals out of your mare is tempting, it is very
dangerous for the foals and for your mare. A mare's uterus is usually too small to support
twins plus there is the danger that if they both survive gestation they could still get
entangled during birth which could lead to the death of the foals and of the mare. Another
danger is that one foal might die and emit toxins as he starts to decompose inside the
mare. If you have your mare checked by ultrasound at 12 to 15 days, the veterinarian can
detect twins and easily "pop" one of the embryos without causing any pain to
your mare. Although it sounds harsh, it is much safer for the mare and remaining foal.
10. b. Have the pasture treated for fungus.
Fescue grass is actually a good forage for horses. However it can become infected with a
fungus called endophyte. It is estimated that the majority of fescue grass in the United
States is infected. This fungus is not harmful to most horses, but you should prevent
pregnant and lactating broodmares from eating it, although some sources say it is only
harmful to broodmares in their last trimester. A pregnant mare that eats it may abort her
foal, may have trouble foaling, or may not produce enough milk. If you find out that your
mare is grazing in an infected pasture, remove her from it immediately and provide her
with fungus-free forage. Be sure to have the pasture treated before allowing the mare to
return to that pasture.
So, how did you do?
If you answered 9 or 10 questions correctly you are an expert! Even though you
did well be sure to continue to learn as there are always new developments.
If you answered 6 to 8 questions correctly you've got a good grasp of horse
breeding, but you probably should study a little more. Be sure to read recent articles
because of all of the new developments.
If you answered less than 6 questions correctly you definitely need to study
more! If you still plan to breed your mare be sure to study, whether by taking a course on
mare care or by reading books and articles. One book I recommend is called Breeding
Management & Foal Development. It is a bit technical, but does a great job of
telling you what you need to know. If you can't get up to speed before breeding your mare
be sure to seek qualified advice from your veterinarian or breeding farm.