Welcome to the NZERF Equine Questions Forum. From this page you can access information on frequently asked questions on a variety of topics.
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When is the best time to breed my mare?
Horses cycle seasonally; they are known as long day breeders because their peak breeding season occurs in summer, when the day length is longest...>>more
When do I need to deworm my broodmare?
Parasite control in broodmares is especially important because they are a potential source of infection for their foals...>>more
How do I take care of my mare during pregnancy?
Health and well-being of the pregnant mare. We often think of pregnancy...>>more
What can I expect when my mare is foaling?
If your mare has made it through 11 months of pregnancy, you're almost home free...>>more
What does a foal need to be fed for optimum growth and development?
A healthy foal will grow rapidly, growing in height, weight, and strength almost before your very eyes...>>more
What do I need to know about equine artificial insemination and breeding with transported semen?
Today's breeding technology provides owners with more options than were available in the past...>>more
When is the best time to breed my mare?
Horses cycle seasonally; they are known as long day breeders because their peak breeding season occurs in summer, when the day length is longest. Mares begin to ovulate in spring (Sept-Nov), entering a cyclical pattern and showing behavioural oestrus through the summer (Dec-Feb), and progressively stop ovulating during autumn (Mar-May). A few mares may continue to ovulate through the winter months, and many mares will show variable signs of oestrus behaviour in winter even though they are not ovulating.
The change from the winter anovulatory state to the breeding season is known as spring transition. It involves a complex series of hormonal changes regulated largely by the changing day length, but can also be modulated by other factors including nutrition, extreme cold, disease, and stress. The first ovulation marks the end of the spring transition and the beginning of the breeding season; after ovulating for the first time in the spring the mare will continue to ovulate regularly every 21-22 days. During spring transition, mares may display irregular teasing behaviour and prolonged periods of oestrus-like behaviour, but as they are not ovulating breeding will not be successful in this period.
In the Thoroughbred racing industry, problems occur because the breeding season begins during a time when most mares will still be in spring transition. In order to have foals born as soon after August 1 as possible owners wish to breed their mares starting from early September. Unfortunately, in most cases these early breedings may not be successful without artificial advancement of spring transition (using artificial lighting and/or hormones). The time of year when the majority of mares can be expected to have optimal natural fertility is from November to March.
Mares have an oestrus period of about 5-7 days, with ovulation occurring towards the end of oestrus. Fertility is generally highest when mares are bred in a window from 48 hours before to 6 hours after ovulation. The practical recommendation is to breed mares every 2 days from early estrus until they ovulate or tease out. Predicting ovulation can be quite challenging in mares. A decision to breed should be based on information of her records of previous oestrus cycles, teasing behaviour, vaginoscopy, and rectal palpation and ultrasound.
*source: notes by Dr. Nigel Perkins on Equine Reproduction, 2002.
When do I need to deworm my broodmare?
Parasite control in broodmares is especially important because they are a potential source of infection for their foals. The main parasites that cause problems in adult horses are the small strongyles and Strongylus vulgaris.
The small strongyles, scientifically referred to as cyathostomes and also known as redworms, live in the intestine and feed on the cellular lining or on partially digested food in the gut. There are over 40 different types but they are not all equally common; many thousands can be present in an individual horse. The larval stagest encyst in the intestinal wall and can become dormant - known as the 'inhibited' or 'hypobiotic' state. While they remain dormant they are not affected by drugs that kill adults and normally developing larvae.
When the larvae emerge they cause damage to the intestinal wall with leakage of blood and protein. If large numbers emerge at once the horse can develop severe bloody diarrhoea and colic that can be difficult to treat. Most of these severe cases occur in winter and spring, but are not often seen in New Zealand. However, small strongyles can still have serious effects on the health and performance of adult horses.
Strongyloides vulgaris is a migratory parasite that burrows into the arteries supplying blood to the intestine, causing inflammation and blockage. Without a good blood supply, parts of the intestine can start to die off, causing fever and colic. The severity depends on how much of the blood supply is affected; some horses may die. Colic can appear less than a week after the horse has eaten infective larvae and continue for up to three weeks, and only a small number of larvae can produce colic. The larvae then continue up to where the major artery supplying the intestine branches from the aorta. Here they mature for about 4 months, again causing inflammation and blocking the blood supply. While there, they can cause the horse to develop colic again, peritonitis, or very rarely they can cause an aneurism in the artery wall. Later this may burst, usually when the horse is at full gallop or the blood pressure is high, and the result is collapse and death. S. vulgaris is common in NZ horses but less of a problem than overseas, where it is considered to be one of the most important single causes of colic.
Adult horses were commonly treated for these parasites at 6-8 week intervals throughout the year. This is effective as long as the treatments work, but unfortunately the frequency of drenching has led to the development of drench resistance. Since adults are less susceptible to the effects of parasites than young horses, there is some scope to change management procedures to reduce the frequency of drenching, especially where only a few horses are kept or plenty of grazing is available.
Mares should be drenched at least twice yearly. One should be given in spring just prior to foaling in order to remove adult small stronglyes and larvae developing after overwintering in the horse. This should substantially reduce pasture contamination for their foals. The second treatment should be given in late autumn (May/June), with an optional third treatment at the end of summer (March) if necessary. These drenches should remove any worms picked up over the summer/autumn period. It is important to use a drench effective against the larval stages of the small strongyles for all three treatments.
Where pastures are highly contaminated, where there are large numbers of horses on the property, and where the drenching program has been much more frequent, it is very important that any change to a lower frequency of drenching is made gradually over several seasons and with veterinary supervision. Twice weekly dung removal may also be necessary. Your veterinarian should monitor progress using egg counts on dung samples, and possibly drench resistance testing.
Mares visiting studs should be treated on arrival, regardless of recent drenching, and kept apart from other horses for 1-2 days. All dung passed should be collected and disposed of. The effectiveness of the arrival drench can be checked by egg counts after a few days if necessary.
*source: Charleston, Tony. "Parasites and Horses", revised edition. NZERF, March 2001.
How do I take care of my mare during pregnancy?
Health and Well-Being of the Pregnant Mare
We often think of pregnancy as a delicate and fragile condition. When it comes to horses, this perception is perhaps due to the mare's relatively poor reproductive performance in comparison to other domestic animals. However, in a natural setting, the mare does comparatively well reproductively. Therefore, this seemingly poor performance is due as much to improper management as to any reproductive deficiency. Fortunately, management is something we can control.
As a conscientious owner, you probably have many questions about caring for your expectant mare. In truth, you may be a little worried. Relax. With a little TLC, your mare should progress through her pregnancy without mishap. Proper nutrition, deworming, exercise, and vaccinations will help ensure a healthy pregnancy, and you can look forward to the birth of your foal with greater confidence.
Precarious Beginnings
The earliest days of an embryo's existence are perhaps the most precarious. During the first 30 days, there is a 10-15% chance that the embryo will be resorbed. Stress, illness, uterine infection, hormonal abnormalities, the presence of twins, and other factors have been implicated in early embryonic loss. Often, the cause remains undetermined.
When the mare conceives, the fertilized egg (zygote) travels down the fallopian tubes and enters the uterus around day 6-7. It migrates throughout the uterus until about day 16 and typically implants into the uterine wall at 6-8 weeks. By day 12-13, the embryonic vesicle is usually large enough to be detected by ultrasonic examinations, during which an image is made by bouncing sound waves off tissues. For practical reasons, some breeding farms simply tease the mare 14-20 days after her last breeding date to see if she comes back into oestrus (heat). If she does not, the pregnancy may then be confirmed by ultrasound or trans-rectal palpation at approximately 30-35 days post-breeding.
Neither teasing, palpation, nor ultrasound has been shown to harm the developing embryo or endanger the pregnancy. However, because of the embryo's uncertain beginning, it may be wise to have the pregnancy reconfirmed at 45, 60 or 90 days.
The Trouble With Twins
Twins are invariably the result of double ovulations. If the two ovulations occurred on the same day the embryonic vesicles are of similar diameter. More commonly ovulations are separated by one or more days and the vesicles are of different diameters. Some reproductive specialists recommend an ultrasound exam at 13-15 days post-ovulation to detect twins. Early detection of twins provides an opportunity to eliminate one embryo, thus allowing the other to develop normally. This is commonly done because twins pose a number of risks:
Helping Nature Take Its Course
Good broodmare management is the best aid for helping the mare make it through the critical first 30-60 days of pregnancy. The mare should go into the breeding season fit and perhaps gaining weight. Severely underweight mares will have more trouble conceiving than will mares of appropriate weight.
Avoid stressing the mare as much as possible. Stress can cause a drop in progesterone, a hormone which helps maintain pregnancy. Illness and/or fever can cause the mare's system to secrete prostaglandins, which may cause abortion.
Use Good Judgement
Middle Pregnancy
Unless there are special circumstances, during the first 7 months of pregnancy, treat your mare as you would a non-pregnant one. She will benefit from moderate riding or exercise.
The ration should be composed primarily of high-quality forage in approximately the same as pre-pregnancy amounts. Extremes in weather can alter her nutritional requirements and should be taken into account when formulating the ration. She should always have plenty of clean, fresh water. The mare will also benefit from routine hoof and dental care, standard vaccinations, and regular deworming.
Vaccines
Vaccinations should be current, since infectious diseases can trigger abortions. An inoculations for tetanus are recommended at the beginning of pregnancy. A booster should be given one month prior to foaling to increase the antibody level in the mare's colostrum (first milk) and help protect the newborn foal from disease. Also, the mare should be vaccinated for equine rhinopneumonitis (commonly called virus abortion or rhino) at five, seven, and nine months' gestation. Consult with your local veterinarian regarding other vaccines that may be advisable in your area.
Deworming
Most deworming agents available today are relatively safe for pregnant mares. Consult your veterinarian to establish an effective and safe deworming schedule for your mare. It is especially important to deworm the mare within several weeks of foaling, because the mare will be the primary source for infecting her foal with parasites. Of course, manure should always be properly disposed of.
Changing Needs
During the last four months of pregnancy, the foal will grow rapidly. To accommodate this growth, the mare's energy needs will increase. Even so, special nutritional supplements are probably unnecessary. Good-quality hay and forage should remain the bulk of the expectant mare's diet. Concentrated feeds, such as grains, may be added to the ration to bolster energy intake without adding excess bulk.
Use the mare's body condition as your guide to how she's faring. Adjust the ration accordingly. The mare should not become obese. Your veterinarian can advise you regarding a proper nutritional program for your mare.
Exercise during the last four months of the mare's pregnancy should be light to moderate. In fact, a pastured mare will get as much exercise as she needs just grazing. Vigorous exercise is not recommended.
Home Stretch
The average length of pregnancy in the mare is 338-343 days. However, normal gestation can range from 320-380 days. You needn't become overly concerned if your mare is past due. Prolonged gestation is not generally associated with problems or extra large foals. If your mare's pregnancy extends much past 340 days or you're concerned, ask your veterinarian to examine her to determine if the mare is still pregnant and confirm that all is well.
Suspected Abortion
Mares do occasionally abort. If you notice a vaginal discharge or dripping milk during pregnancy, contact your veterinarian. If you find the remains of a placenta or fetus, save it for your veterinarian to examine. It may be possible to ascertain the cause of abortion and treat the mare accordingly. Mares can and do abort without ill effects. However, it's always a good idea to have her checked by your veterinarian, because some complications of abortion, such as a retained placenta, can be life-threatening to your horse.
Impending Birth
There are obvious as well as subtle signs of impending birth. The time frame during which they occur varies from mare to mare. The most obvious and reliable are:
More subtle signs include:
*source: Equine Reproduction notes by Dr. Nigel Perkins, 2002; Bayer AG 2003; American Assn. Equine Practitioners
What can I expect when my mare is foaling?
Preparing for a Safe and Successful Foal Delivery
If your mare has made it through 11 months of pregnancy, you're almost home free. Labour and delivery, while momentous, are generally uneventful. In most cases, you will simply need to be a quiet observer--if, that is, you are lucky enough to witness the birth. Mares seem to prefer to foal at night in privacy, and apparently have some control over their delivery. Despite your frequent visits to the barn, your mare may give birth the minute you step away. While this is disappointing, don't worry. She is unlikely to need your help anyway. However, in case problems arise, it is advisable to have your veterinarian's telephone number nearby.
A Safe Place to Foal
What your mare will need, however, is a clean, safe, quiet place to foal. Horses have been giving birth on the open range for eons, and this is still an acceptable choice. Allowing the mare to foal in the pasture even has some advantages. An open grassy area is likely to be cleaner than a stall and provides a healthy environment with adequate room to foal. You won't have to worry about the mare crowding into a corner or foaling too close to a wall. However, many owners prefer to confine the mare to observe her progress.
Should you choose to foal your mare in a stall, provide one that is a minimum of 14' x 14'. If possible, the stall should have a floor that can be readily cleaned and disinfected. Dirt or day floors make hygiene more difficult. Also, provide adequate clean bedding. Straw (particularly wheat straw) is preferable to shavings, as it won't cling to the wet newborn or mare the way small wood particles can. Remove manure and soiled bedding promptly, and disinfect the stall between deliveries.
The Countdown
Mares provide clues that they will soon give birth. However, the timetable is far from absolute. Some mares may show all the signs like clockwork, others show practically none. The following is a general guideline, but be prepared for surprises:
Preparing for Birth
Most mares foal without difficulty. It usually is best to allow the mare to foal undisturbed and unassisted. If a problem becomes apparent, contact your veterinarian immediately.
What you can do:
Labour and Delivery
Labour is divided into three stages:
Stage one begins with the onset of contractions and generally lasts 1-2 hours. During this phase, contractions move the foal through the cervix and into position in the birth canal. The foetal membranes (allantois) may become visible at the mare's vulva. When the sac breaks, signaled by a rush of fluid, stage one ends.
Stage two is the actual expulsion of the foal. This phase moves relatively quickly. If it takes more than 30 minutes for the mare to deliver, there could be a problem. Call your veterinarian immediately. If labour seems to be progressing, wait and watch. Even in a normal delivery, the mare may stand up, lie down, and roll several times in an effort to properly position the foal for delivery.
Normal presentation of the foal resembles a diving position, with front feet first, one slightly ahead of the other, hooves down, followed closely by the nose, head, neck, shoulders, and hindquarters. If you notice hoof soles up, the foal may be backwards or upside down, and you should call your veterinarian immediately. If you suspect any deviation from the normal delivery position, call your equine practitioner.
Stage three labour begins after delivery and is the phase during which the afterbirth (placenta) is expelled. Most placentas are passed within 1-3 hours after the foal is delivered. If the placenta has not passed within 3 hours, call your veterinarian. A retained placenta can cause serious problems, including massive infection and laminitis.
Postpartum Care for Mare and Foal
In the excitement of birth, it is important to remember some tried and true guidelines:
Importance of Observation
Following birth of the foal, the mare and foal should be monitored for the following:
Importance of Colostrum
It is essential that the foal receive an adequate supply of colostrum. Colostrum, the mare's first milk, is extremely rich in antibodies. It provides the foal with passive immunity to help prevent disease until its own immune system kicks in.
A foal must receive colostrum within the first 8-12 hours of life in order to absorb the antibodies. If a foal is too weak to nurse, it may be necessary to milk the mare and give the colostrum to the foal via a stomach tube.
If a mare appears to be leaking an excessive amount of milk prior to birth, consult your veterinarian. This pre-foaling milk is not typically colostrums-rich. However, depending on your veterinarian's recommendation, the mare may be milked and the colostrum frozen to give to the foal shortly after birth. For orphan foals, or mares without an adequate supply of colostrum, it is important to locate a back-up supply. Without it, the foal is at an increased risk of infections. Your veterinarian can test the colostrum to determine whether it is rich in antibodies. Also, the foal's serum can be tested at 18-24 hours of age to evaluate IgG antibody levels. If IgG is inadequate, treatment for Failure of Passive Transfer (FPT) should be instituted by your veterinarian.
Other Foaling Caveats
*source: Equine Reproduction notes by Dr. Nigel Perkins, 2002; Bayer AG 2003; American Assn. Equine Practitioners
What does a foal need to be fed for optimum growth and development?
Special Care and Nutrition
A healthy foal will grow rapidly, gaining in height, weight and strength almost before your very eyes. From birth to age two, a young horse will achieve 90 percent or more of its full adult size, sometimes putting on more than a kilogram per day.
Genetics and environment play significant roles in determining individual growth patterns. Through research, we also know we can influence a foal's growth and development - for better or worse - by the nutrition we supply.
Strive for Balance
Feeding young horses is a careful balancing act. The interplay between genetics, management and nutrition is complex. While we can do nothing to change the genetic road map, we can alter its course via proper management.
The nutritional start a foal gets can have a profound effect on its health and soundness for the rest of its life. We can accelerate growth if we choose. However, research suggests that a balanced dietary approach which supports moderate growth is less likely to cause developmental problems. Some conditions which have been associated with rapid growth rates include contracted tendons, epiphysitis, angular limb deformities, and osteochondrosis.
The Nursing Foal
One of the foal's first missions in life is to stand and nurse. In doing so, it receives the antibody-rich colostrum which helps protect it from disease. During the first weeks of life, the mare's milk provides everything a rapidly growing foal needs for sustenance. The burden then gradually shifts to other sources. To produce adequate milk during lactation, mares must receive adequate feed and water. Lactation can be a severe strain on a mare in poor condition. Observe the foal's nursing habits. If it suckles for more than 30 minutes at a time, it may not be receiving enough milk. Supplemental feed or milk replacer may be required.
Peak lactation generally occurs during the second and third month of a foal's life. At this time a mare will need almost double the amount of feed she required during her early pregnancy. In addition to extra energy, her diet must include adequate protein, vitamins and minerals to keep from depleting her own body reserves. Increases or decreases in feed should be made gradually over a 7 to 10-day period.
The Foal's Changing Diet
As early as 10-14 days of age, a foal may begin to show an interest in feed. By nibbling and sampling, the youngster learns to eat solid food. Its digestive system quickly adapts to the dietary changes.
At 8-10 weeks of age, mare's milk alone may not adequately meet the foal's nutritional needs. High quality grains and forage should be added to the foal's diet. It is essential the ration be properly balanced for vitamins and minerals. Deficits, excesses or imbalances of calcium, phosphorous, copper, zinc, selenium and vitamin E are of particular concern in the growing foal. Improper amounts or ratios can lead to skeletal problems.
Foal Feeding Guidelines
As the foal's dietary requirements shift from milk to feed and forage, your role in providing the proper nutrition gains in importance. Here are some guidelines to help you meet the young horse's needs:
Weaning
Foals are commonly weaned at 5 to 6 months of age. Beginning about the third month, the mare's milk supply gradually declines and a natural weaning process begins.
To prepare the foal for complete weaning, its ration should be increased over a 2-3 week period to make up for the nutrients being lost in the diminishing milk supply. The mare's grain should be reduced and/or gradually eliminated to further limit milk production. Once it is no longer nursing, a weanling should be eating approximately 2.5% of its body weight in feed and forage a day.
Sustaining Growth
Weanlings and yearlings continue to build bone, muscle and mass at a remarkable rate. From weaning to two years of age, the horse may nearly double its weight again. Weanlings and yearlings benefit from a diet containing 14-16 percent protein. They also require readily available sources of energy to meet the demands of growth and activity.
A good rule of thumb is to provide 60-70 percent of the ration as concentrates and 30-40 percent of the ration as roughage-measured by weight. The diet must also provide ample fiber to keep the digestive tract functioning properly. Some of the new "complete feeds" have the ration already balanced.
Weight gain and development taper off as the horse matures. As growth slows, you will need to adjust the ration to approximately 1.5-2% of the yearling's body weight. The grain to roughage ratio should also be adjusted so by the time the horse is a 2-year-old, half of its daily diet (by weight) is coming from grain sources and the other half from hay and pasture. Breed type, maturity and level of activity will affect the horse's exact nutritional requirements.
Total Care & Management
Work with your equine practitioner to develop a total health care plan for your foals, weanlings and yearlings. A regular deworming, vaccination and examination schedule is essential to ensure your foal is getting the care it needs. Consult your equine practitioner for exact recommendations.
Here are some other management tips:
The reward for providing excellent nutrition, conscientious care and a safe environment will be a healthy foal that grows into a sound and useful horse.
*source: Equine Reproduction notes by Dr. Nigel Perkins, 2002; Bayer AG 2003; American Assn. Equine Practitioners
What do I need to know about equine artifical insemination and breeding with transported semen?
Breeding With Transported Semen
Today's breeding technology provides horse owners with more options than were available in the past. Artificial insemination and semen preservation techniques make it possible to ship stallion semen to mares nearly anywhere in the country. Success with transported semen will depend on the careful reproductive management of both stallion and mare. Only three registries do not currently allow AI: Thoroughbred, Miniature Horse, and Standard Jack and Jennet Registry.
Why Ship Semen?
Even under the best conditions, transporting horses long distances can be stressful and costly. Mares with foals are of special concern, since foals are particularly vulnerable to disease and injury when exposed to new horses and environments. Older or injured mares, or those requiring special care, may also benefit from staying closer to home during breeding season. The ability to ship cooled semen makes it possible for breeders to arrange matings that might otherwise be impractical due to distance, economics, or health.
AI allows more efficient use of stallions by dividing each ejaculate into multiple insemination doses. More mares can be bred in one season. Semen extenders mixed with sperm after collection have beneficial effects on sperm longevity and on eliminating contaminating bacteria, and can even improve the fertility of subfertile stallions. Use of AI prevents transmission of most venereal diseases. Regular collection of semen for AI allows close monitoring of semen quality throughout the breeding season.
Good Candidates
Many -- but not all -- horses are good candidates for the use of cooled transported semen. Both mares and stallions should be in excellent reproductive health, since fertility problems tend to be compounded when transported semen is added to the breeding equation.
With shipped semen, there is generally only one opportunity per cycle to breed a mare. Problem breeders may fare better at the stud farm, where they can be monitored and serviced at regular intervals throughout their heat cycles.
Also be aware that not every stallion's semen cools or ships well. Therefore, it is critical for a stallion's sperm viability to be checked after a dose has been extended and cooled for 24 to 36 hours. This is generally the interval between collection and the time the transported semen is placed in the mare.
Intensive Management
Breeding with cooled transported semen is more management-intensive than with on-site matings. Timing is critical. For the greatest chance of pregnancy, a mare must be bred from 12-24 hours before ovulation to up to six hours after ovulation. From a practical standpoint, however, once the mare has ovulated, it may be difficult to determine whether you are still within an acceptable time frame for fertility. Also, remember cooled stallion semen only has a shelf life of 24-48 hours.
The Mare
Prior to breeding season, a mare should have a full reproductive examination. A uterine biopsy and culture may be indicated to get a clearer picture of the mare's overall reproductive health. During breeding season, the mare should be kept where she can be teased by a stallion on a regular basis in order to detect onset of oestrus reliably.
Once the mare comes into heat, your equine practitioner will need to predict the onset of ovulation accurately -- -allowing time for the semen shipment to arrive. The veterinarian will monitor the mare daily or every other day via rectal palpation and ultrasound throughout her heat cycle to determine the appropriate time to breed her.
Pregnancy rates with transported semen are somewhat lower than with on-the-farm breedings. This means it may take more than one cycle to get a mare successfully in foal. The mare owner absorbs the cost of additional semen shipments, veterinary procedures and mare care.
The Stallion
The stallion should also be evaluated for fertility prior to the breeding season. Semen should be tested by extending, cooling and storing it in the same way it will be handled for shipping. Commercial extenders have different formulations. The stallion manager or veterinarian may want to experiment to see which extenders promote the greatest viability. Proper handling is also important. Here are some considerations:
Communication & Cooperation
Good communication between stallion and mare managers is essential. Coordinating semen shipments will take planning and cooperation. Most stallion managers plan collection schedules so as not to overtax a stallion's fertility or reproductive performance. Collections made 3-4 times per week will accommodate most cooled transported semen requirements without negatively affecting fertility, while allowing breeders to meet on-site demands as well.
The mare should be on a regular teasing and examination schedule to reliably ascertain the proper time to breed. This will allow planning and timely shipment of cooled semen. Many overnight shipping services provide prompt, reliable deliveries and can reduce the need for last minute trips to the airport.
Costs
Transporting semen may have some cost saving benefits. However, they can be offset by increased management costs. Additional costs may include:
A Team Effort
Breeding with cooled transported semen is a team effort requiring the expertise of qualified professionals. The goal is to produce a healthy foal in the most efficient, effective way. To prevent disappointment, undue expense and loss of valuable time, you must do your part to ensure success.
*source: Equine Reproduction notes by Dr. Nigel Perkins, 2002; Bayer AG 2003; American Assn. Equine Practitioners