By Dr. Kim Garner, DVM
Spring is on its way. It may not look like it; and it may not feel like it. But as sure as grass is green, spring is coming. And with it comes the equine breeding season.
You've spent all winter looking at the breed magazines, checking bloodlines, researching how well each stallion's offspring have performed, comparing conformational attributes, and you've decided on a stallion. For HER. For your mare, your baby. How much thought have you put into HER end of the deal?
Remember, genetically she's half of the baby. Temperament wise, she's closer to 70 to 90 percent. How many times have you heard "Well, she won't perform, and she's hard to handle, so let's breed her!" Does that really make any sense?
Horses are expensive to keep. It's expensive, time consuming, and potentially very emotionally demanding to go through the breeding process. And you know what you get if everything goes well? Another horse! Hopefully THE horse: the one you've waited for your whole life. But according to the American Association of Equine Practitioners, there is a huge glut of unwanted horses. And a lot of those unwanted horses were someone's attempt at the ideal horse at some point in time. In fact, you can probably find a young horse for sale, for very little money, with close to the perfect bloodline, and you get to pick the size, sex, color and markings!
So, if you still want to breed your mare, there are some things you need to consider. Mares are considered to be most fertile between 3 to 12 years of age. Older mares should be considered "problem mares," especially if they have never been bred before. Mother Nature's breeding season is from April to June or July. In most breeds, the earlier the foal is born in the year, the better. To get your mare in foal earlier requires that she have a fertile heat period, usually as early as February. To make your mare think that it's May, she will need to be exposed to a longer light period. This can easily be accomplished by using a simple timer and light bulb, available at your local hardware store. She will need to be exposed to a level of light that is sufficient to read a newspaper for a period of 16 hours daily. Usually a single 100 watt bulb will be bright enough. This elongated day length will stimulate her hormones and make her come into a fertile heat. It will take about 60 days of the longer day length to get her cycles regulated, so if you want a January foal, you should start her under lights no later than mid-November.
If you are considering natural breeding, you will most likely transport your mare to the stallion's facility for live cover. Be sure that her basic vaccines are up to date. She should also have a negative EIA (Coggins) test. She should not be thin, but obese mares are often difficult to get in foal, also. Most live-cover operations require a pre-breeding uterine culture. A visit to your veterinarian prior to breeding is a good idea, even if your mare is a maiden mare (never bred before). A reproductive ultrasound exam may be performed just to be sure that "all the parts are there:" to check the ovaries for the presence of follicles; to check the uterus for muscle tone, edema, and fluid. Sometimes a speculum exam is performed to examine the internal vaginal vault and cervix. With a maiden mare, this may allow the hymen to be broken so that the breeding itself is not uncomfortable.
If your mare is not a maiden mare, and has been bred previously with no problems, perhaps a pre-breeding exam can be eliminated. If, however, your mare has been previously bred and did not conceive, then the pre-breeding exam is even more important. Ideally, if problems are present, the pre-breeding exam will have taken place in the summer or fall. This way, problems can be identified and treatments can be initiated in time to avoid losing an entire breeding season. Exams that may be required to determine the reason for infertility include: an ultrasound exam to verify the appearance of all the physical parts of the reproductive system (ovaries, uterine body and horns, and cervix); uterine culture and cytology to determine the presence or absence and type of any infection; uterine biopsy to determine the ability of the uterine wall to provide adequate support and nutrition for a pregnancy; and perhaps a hormone analysis.
If a culture is to be performed, then it is best to perform the exam when the mare is in heat. Sometimes it is difficult to determine when that is! If that is the case, once your mare starts to cycle, then her hormones and her heat cycle can be regulated. By using progesterones, prostaglandins, or a combination of both, the mare can be brought into heat within a window of just a day or two. If an infection is found, intra-uterine treatments will usually be required. It is also recommended to re-culture after treatment, prior to breeding, to be sure the infection has been cured.
Cycle regulation becomes more important when the breeding is to be done via artificial insemination. Most AI is done with fresh, cooled semen. If that is what you have planned, you need to contact the stallion manager and determine when the stallion is to be collected, and how the semen will be shipped. Some stallion managers are very accommodating and will ship on short notice. Other farms are more highly regimented, and collect only on a preset schedule. You will need to make arrangements with the farm manager prior to the mare needing semen and relay this information to whoever will be inseminating your mare. They will need to know when the stallion is collected; how the semen is shipped; if the mare needs to be put on a "waiting list;" and the "cut off" time for ordering semen for that particular day. If frozen semen is used, the semen can be shipped for storage on-site at the veterinary hospital in a liquid nitrogen tank.
Once the arrangements are made and any problems have been identified and treated, then the mare can be bred. Breeding occur near the end of the heat cycle. For ordering semen, the mare needs to have a follicle of at least 35 millimeters. This usually requires repeat ultrasound exams to monitor the follicle size to determine when to order the semen. Once the follicle is at 35 mm, then the semen is ordered for delivery the next morning (usually FedEx or UPS). It is sometimes difficult to predict how the follicle will mature; some mares go from 35 mm to ovulation overnight, and other mares can take several days. It can even be variable on the same mare from one heat cycle to the next.
When the timing is correct, insemination is performed by inserting a sterile "straw" through the cervix into one of the horns of the uterus. Frozen semen has a shorter life in the uterus than fresh cooled semen, and can induce significant inflammation within the mare's uterus. Thus, frozen semen must be inseminated within 6 hours of ovulation. Following insemination and ovulation, most mares develop significant inflammatory response to the frozen semen, and are often flushed post-insemination to remove these irritants.
Pregnancy can usually be detected reliably around 17 days post insemination, sometimes, as early as 14 days. If the possibility of twins exists, it is best to check for pregnancy around 17 days, because at that stage it is possible to "pinch" one vesicle and eliminate the twins.
Once the mare is confirmed pregnant at 17 -18 days, it is advisable to re-confirm the pregnancy around 35 -50 days, and again around 5 months. If the mare has had instances where she becomes pregnant but loses the foal prior to 5 months, she may be deficient in progesterone. A blood test can determine her progesterone level and it can be supplemented if it is low. By 150 days of pregnancy, the uterus, and not the ovary, makes the progesterone and so low blood levels should not be an issue after that point.
Once the mare is confirmed pregnant at 5 months, bi-monthly vaccination for infectious abortion by Equine Rhinopneumonitis (equine Herpes) virus should be initiated, and should be repeated at 7, 9, and 11 months of pregnancy. Routine deworming and other health related procedures should be continued throughout the pregnancy to ensure the health of the mare. At approximately 330 days of gestation, hopefully, a healthy filly or colt will be delivered. THAT will be an entirely different article!
Spring is on its way. It may not look like it; and it may not feel like it. But as sure as grass is green, spring is coming. And with it comes the equine breeding season.
You've spent all winter looking at the breed magazines, checking bloodlines, researching how well each stallion's offspring have performed, comparing conformational attributes, and you've decided on a stallion. For HER. For your mare, your baby. How much thought have you put into HER end of the deal?
Remember, genetically she's half of the baby. Temperament wise, she's closer to 70 to 90 percent. How many times have you heard "Well, she won't perform, and she's hard to handle, so let's breed her!" Does that really make any sense?
Horses are expensive to keep. It's expensive, time consuming, and potentially very emotionally demanding to go through the breeding process. And you know what you get if everything goes well? Another horse! Hopefully THE horse: the one you've waited for your whole life. But according to the American Association of Equine Practitioners, there is a huge glut of unwanted horses. And a lot of those unwanted horses were someone's attempt at the ideal horse at some point in time. In fact, you can probably find a young horse for sale, for very little money, with close to the perfect bloodline, and you get to pick the size, sex, color and markings!
So, if you still want to breed your mare, there are some things you need to consider. Mares are considered to be most fertile between 3 to 12 years of age. Older mares should be considered "problem mares," especially if they have never been bred before. Mother Nature's breeding season is from April to June or July. In most breeds, the earlier the foal is born in the year, the better. To get your mare in foal earlier requires that she have a fertile heat period, usually as early as February. To make your mare think that it's May, she will need to be exposed to a longer light period. This can easily be accomplished by using a simple timer and light bulb, available at your local hardware store. She will need to be exposed to a level of light that is sufficient to read a newspaper for a period of 16 hours daily. Usually a single 100 watt bulb will be bright enough. This elongated day length will stimulate her hormones and make her come into a fertile heat. It will take about 60 days of the longer day length to get her cycles regulated, so if you want a January foal, you should start her under lights no later than mid-November.
If you are considering natural breeding, you will most likely transport your mare to the stallion's facility for live cover. Be sure that her basic vaccines are up to date. She should also have a negative EIA (Coggins) test. She should not be thin, but obese mares are often difficult to get in foal, also. Most live-cover operations require a pre-breeding uterine culture. A visit to your veterinarian prior to breeding is a good idea, even if your mare is a maiden mare (never bred before). A reproductive ultrasound exam may be performed just to be sure that "all the parts are there:" to check the ovaries for the presence of follicles; to check the uterus for muscle tone, edema, and fluid. Sometimes a speculum exam is performed to examine the internal vaginal vault and cervix. With a maiden mare, this may allow the hymen to be broken so that the breeding itself is not uncomfortable.
If your mare is not a maiden mare, and has been bred previously with no problems, perhaps a pre-breeding exam can be eliminated. If, however, your mare has been previously bred and did not conceive, then the pre-breeding exam is even more important. Ideally, if problems are present, the pre-breeding exam will have taken place in the summer or fall. This way, problems can be identified and treatments can be initiated in time to avoid losing an entire breeding season. Exams that may be required to determine the reason for infertility include: an ultrasound exam to verify the appearance of all the physical parts of the reproductive system (ovaries, uterine body and horns, and cervix); uterine culture and cytology to determine the presence or absence and type of any infection; uterine biopsy to determine the ability of the uterine wall to provide adequate support and nutrition for a pregnancy; and perhaps a hormone analysis.
If a culture is to be performed, then it is best to perform the exam when the mare is in heat. Sometimes it is difficult to determine when that is! If that is the case, once your mare starts to cycle, then her hormones and her heat cycle can be regulated. By using progesterones, prostaglandins, or a combination of both, the mare can be brought into heat within a window of just a day or two. If an infection is found, intra-uterine treatments will usually be required. It is also recommended to re-culture after treatment, prior to breeding, to be sure the infection has been cured.
Cycle regulation becomes more important when the breeding is to be done via artificial insemination. Most AI is done with fresh, cooled semen. If that is what you have planned, you need to contact the stallion manager and determine when the stallion is to be collected, and how the semen will be shipped. Some stallion managers are very accommodating and will ship on short notice. Other farms are more highly regimented, and collect only on a preset schedule. You will need to make arrangements with the farm manager prior to the mare needing semen and relay this information to whoever will be inseminating your mare. They will need to know when the stallion is collected; how the semen is shipped; if the mare needs to be put on a "waiting list;" and the "cut off" time for ordering semen for that particular day. If frozen semen is used, the semen can be shipped for storage on-site at the veterinary hospital in a liquid nitrogen tank.
Once the arrangements are made and any problems have been identified and treated, then the mare can be bred. Breeding occur near the end of the heat cycle. For ordering semen, the mare needs to have a follicle of at least 35 millimeters. This usually requires repeat ultrasound exams to monitor the follicle size to determine when to order the semen. Once the follicle is at 35 mm, then the semen is ordered for delivery the next morning (usually FedEx or UPS). It is sometimes difficult to predict how the follicle will mature; some mares go from 35 mm to ovulation overnight, and other mares can take several days. It can even be variable on the same mare from one heat cycle to the next.
When the timing is correct, insemination is performed by inserting a sterile "straw" through the cervix into one of the horns of the uterus. Frozen semen has a shorter life in the uterus than fresh cooled semen, and can induce significant inflammation within the mare's uterus. Thus, frozen semen must be inseminated within 6 hours of ovulation. Following insemination and ovulation, most mares develop significant inflammatory response to the frozen semen, and are often flushed post-insemination to remove these irritants.
Pregnancy can usually be detected reliably around 17 days post insemination, sometimes, as early as 14 days. If the possibility of twins exists, it is best to check for pregnancy around 17 days, because at that stage it is possible to "pinch" one vesicle and eliminate the twins.
Once the mare is confirmed pregnant at 17 -18 days, it is advisable to re-confirm the pregnancy around 35 -50 days, and again around 5 months. If the mare has had instances where she becomes pregnant but loses the foal prior to 5 months, she may be deficient in progesterone. A blood test can determine her progesterone level and it can be supplemented if it is low. By 150 days of pregnancy, the uterus, and not the ovary, makes the progesterone and so low blood levels should not be an issue after that point.
Once the mare is confirmed pregnant at 5 months, bi-monthly vaccination for infectious abortion by Equine Rhinopneumonitis (equine Herpes) virus should be initiated, and should be repeated at 7, 9, and 11 months of pregnancy. Routine deworming and other health related procedures should be continued throughout the pregnancy to ensure the health of the mare. At approximately 330 days of gestation, hopefully, a healthy filly or colt will be delivered. THAT will be an entirely different article!
