The last few days prior to foaling can be especially tedious for the owner, farm manager or foaling staff. Late-term pregnant mares should be monitored closely to optimize services of farm or veterinary personnel, maximize use of foaling space, and to assist with the safe delivery of the foal if needed.
Prediction of Foaling
Clinical signs of impending foaling begin subtly a month or so prior to the expected due date. Changes become more dramatic and occur more rapidly as the day of foaling approaches. The first noticeable change is in the mammary gland, which begins to enlarge 2 to 6 weeks prior to term. Some mares may develop a large amount of edema around the udder before the gland itself becomes enlarged. Mammary gland development will be much more pronounced in mares that have previously had foals than in maiden mares. The teats or nipples will remain relatively flat until the last few days prior to foaling, at which time they will engorge with colostrum. The secretion by the mammary gland changes from a clear straw-colored fluid to a more turbid milk-like fluid as the due date draws near. The mammary secretion becomes thick and honey-like as colostrum develops within the last day or two prior to foaling.
A thick, waxy exudate of dried colostrum often accumulates at the ends of the teats 24 to 48 hours prior to foaling. “Waxing” of the teat ends is a classic sign that foaling is imminent. The extent of waxing can range from tiny droplets to elongated candle wax-like formations that project a half-inch or more from the teat ends. However, not all mares wax up and the duration from onset of waxing to foaling can be quite variable. In addition, some mares will transiently develop wax at the teat ends 1 to 2 weeks prior to foaling. Approximately 70% of mares wax up prior to foaling and about 70 % of the mares that wax give birth within the next 24 to 48 hours.
In the last 2 to 3 weeks of pregnancy the abdominal muscles relax causing a pronounced “dropping” of the abdomen, which is especially noticeable in older mares. During the last week prior to foaling, the ligaments, muscles and other structures surrounding the mare’s pelvis and perineum soften in preparation for birth. The vulva becomes relaxed, elongated and edematous in the hours immediately prior to foaling. The behavior of the mare often changes during the last few days or hours preceding foaling. Mares near term may tend to isolate themselves, go off feed and pass small amounts of manure or urine frequently. A majority of mares foal out at night, although a low percentage of mares will give birth during daylight hours.
Prediction of foaling based on changes in calcium concentrations in mammary secretions has been used successfully for many years. Calcium concentration in milk increases sharply as the mare approaches the time of foaling. It is recommended that testing be initiated several days prior to the expected due date and performed once daily in the evening. Testing in mares with an unknown breeding date should begin when significant udder development is noted and a small amount of secretion can be obtained.
Evaluation of calcium levels in mammary gland secretions is useful in prediction of when mares are likely to foal and are also useful in predicting that a given mare is unlikely to foal in the next few days. Calcium testing may not be necessary on farms if trained foal-watch personnel are available. However, the tests may be quite valuable on smaller operations with limited staff.
The pH of a mare’s milk often decreases markedly within the 24 hour period prior to foaling. The normal pH of mare’s milk in the week prior to foaling is typically 7.0 to 7.4. A drop in pH to ≤ 6.4 is associated with foaling within the subsequent 24 hours. The most accurate method to measure milk pH is a commercial pH meter, but cost of the device may preclude routine use on a breeding farm or ranch. An alternative is to use commercial pH test strips calibrated in the range of 6.0 to 8.0.
Labor alert devices are intended to signal an owner or foaling attendant that the mare is in the process of giving birth. The design of the devices vary between units. The Foalert system utilizes a transmitter sutured to the vulva of the mare. Separation of the vulva lips at foaling pulls a magnet out of the transmitter, which activates the transmitter to send a signal to receiver which has an audible alarm. The receiver can also be attached to an auto-dialing device which can be programmed to activate a pager or send a message to one or more phones pre-programmed into the unit. Labor alert devices are beneficial in that mares can be monitored continuously without constant or periodic observations. Labor alert devices may be most effective in allowing farm personnel to go about their routine chores or business during the daytime when one does not necessarily expect a mare to foal.
Video systems, either direct or web-based, are becoming common on broodmare farms to monitor late-term mares. These systems allow for close supervision of mares without the necessity of the foaling attendant to wait by the stall or to make repeated visits to the stall every 15 to 30 minutes throughout the night. An added benefit is that video systems minimize disturbances to the nervous mare by decreasing stall visits. However, in the end someone still needs to monitor the mare and positioning of the mare relative to the camera may limit visibility.
Normal Foaling
A key concept regarding the onset of foaling is that the fetus initiates or triggers the birth process. Parturition will generally occur when the fetus is physiologically ready to survive outside of the mare. The pregnant mare may control, to a limited degree, the specific time that foaling occurs (i.e. foaling may be delayed slightly if the mare is stressed or disturbed).
The average normal gestation length for an equine pregnancy is 340 days, with a range from 320 to 360 days. Foals born prior to 320 days are considered to be premature and foal health may be compromised. Clinical signs of a premature foal typically include low birth weight, soft silky hair coat, delayed interval from birth to standing, muscular weakness, tendon laxity, decreased suckle response and other issues.
Mares that carry longer than 360 days are considered to have a “prolonged gestation”. It is not considered to be prudent to induce labor in a mare that is “beyond her due date” and not showing signs of eminent foaling. The outcome of such an endeavor is likely to be the delivery of a dysmature foal that will have a difficult time surviving. It is wiser to let the mare carry until a spontaneous delivery occurs or wait to induce labor until the cardinal signs of an eminent foaling are present and the induction is medically indicated.
Preparation of the Mare for Birth
A series of brief tasks should be completed as the time of foaling approaches. The vulva of the mare should be checked for the presence of a Caslick episioplasty. If a Caslick is present, it is recommended that the vulva be opened completely 7 to 14 days prior to the calculated due date. The Caslick should be opened earlier if the mare bags up significantly prior to her due date. Failure to completely open a Caslick could result in severe trauma to the vulva and perineal body, with the possibility of a 3rd degree perineal laceration. A third-degree laceration is a tear that extends from the vaginal through the perineal body into the rectum.
It is recommended that the tail of the mare be wrapped prior to foaling, primarily for cleanliness and to prevent tail hairs from getting in the way in the event that assistance is required during delivery. A variety of materials may be used to wrap the tail, including Vet-wrap, rolled gauze, polo wraps, neoprene wraps, etc.
The perineum and udder of the mare should be washed with soap and water as the hour of foaling nears. Cleaning the perineum and udder of the mare prior to foaling or immediately after foaling may reduce the incidence of septicemia and diarrhea in newborn foals by decreasing the number of bacteria the foal is exposed to early in life.
The foaling site should be clean, dry, and visible (i.e. able to be monitored). Mares housed in paddocks with other mares or housed in traditional 12’ x 12’ stalls should be moved to a large foaling stall or moved to the foaling pasture as parturition approaches. Mares on many ranches in the western United States are bred (live cover), maintained and foal out on large tracts of open pasture. It is recommended that observations be performed on the herd at least once daily during the foaling season to identify mares that may have reproductive problems.
Foaling is a continuous process that has been categorized into three stages. Prior to the onset of labor the equine fetus is positioned with its back toward the mare’s abdomen and the head toward the mare’s pelvis prior to foaling. During Stage 1 of labor, the head and forelimbs extend and rotate into a dorsal position for delivery. In Stage 2 of labor, the fetal head, forelimbs and shoulders enter the birth canal and the fetus is delivered. Stage 3 consists of passage of the fetal membranes or placenta.
Stage 1
The first stage of labor begins with the onset of uterine contractions and ends with rupture of the chorioallantoic membrane or outer placental membrane (i.e. the mare “breaks her water”). The start of Stage 1 is difficult to determine since the initial mild uterine contractions may occur without overt clinical signs. The mare may be restless or nervous, lie down and stand up frequently, paw at the ground, nibble a little hay or grass, pass small amounts of urine or feces, look at her flanks and/or show signs of abdominal discomfort. She may exhibit patchy sweating behind the elbows, in the flanks and along the neck. Milk may begin to squirt from her teats as a result of oxytocin secretion.
The force of the uterine contractions eventually exerts enough pressure to push the placenta through the cervix where the chorioallantoic membrane ruptures at the “cervical star,” releasing allantoic fluid. This is visible as an outpouring of fluid from the vulva (i.e. the mare has “broken her water”). The duration of Stage 1 is usually 1 to 4 hours. Stage 1 may be shorter and less obvious in mares that have had several foals (i.e. multiparous mares). If the chorioallantoic membrane fails to rupture, it may pass through the cervix and vagina and be visible outside of the vulva (see the section on Premature Separation of the Placenta or “Red Bag”).
Stage 2
The second stage of labor begins with rupture of the chorioallantoic membrane and ends with delivery of the foal Contraction of the uterus pushes the fetus into the birth canal. Cervical stimulation triggers a neuroendocrine reflex (Ferguson’s reflex) which results in release of oxytocin from the posterior pituitary of the mare. Oxytocin stimulates additional uterine contractions which begin to expel the fetus.
The first structure normally visible at the vulva is the amnion or inner placental membrane. The amnion is recognized as a translucent, light gray to white membrane and is filled with amnionic fluid. The amnion is usually visible within 5 to 10 minutes after rupture of the chorioallantoic membrane. As uterine contractions continue, the front feet and nose of the fetus protrude through the vulva. The soles of the front feet are normally directed downward if the foal is in normal orientation in the birth canal (i.e. anterior presentation, dorsal sacral position with both front feet and the head extended).
One forelimb usually precedes the other by 4 to 6 inches. This results in slight staggering of the shoulders and thereby reduces the width of this area as it passes through the mare’s pelvis. The nose of the fetus should appear by the time the carpal joints are observed. If not, intervention may be indicated as the head may be in an abnormal position and a normal unassisted foaling may be difficult or impossible.
The amnion typically covers the front feet and head of the fetus as Stage 2 of labor progresses. Spontaneous rupture of the amnion often occurs once the fetus is at least midway through the birth canal. There is no need to manually remove the amnion from the head of the foal until after the chest has passed through the birth canal. The amnion should be manually removed from over the head if the membrane remains intact after the foal has been delivered to prevent the foal from suffocating.
The mare usually lies down for the final contractions that push the fetus completely out. Straining usually decreases markedly when the foal’s hips clear the vagina. It is best if the mare is allowed to lie quietly with a minimum of disturbance for several minutes after foaling. This allows the foal orient to its new environment and may potentially allow for transfer of blood from the placenta into the foals circulatory system prior to rupture of the umbilical cord. The amount of blood that is actually transferred from the placenta to the foal after birth is somewhat controversial.
The average duration of Stage 2 of labor is 17 minutes and the normal range is between 10 to 20 minutes. Stage 2 is typically shorter in mares that have previously delivered a foal. No assistance is needed or recommended in most equine births. If labor is progressing normally, it may actually be detrimental to step into the foaling stall since many mares will become anxious, stand up and foaling is delayed. However, in some instances during an otherwise normal foaling, it may be beneficial to provide gentle traction on the front legs of the foal in synchrony with the mare’s contractions to help facilitate delivery of the foal.
The mare should be examined if the fetus has not been delivered within 15 to 20 minutes after the mare has broken her water, if labor has stopped completely, or if the normal progression of foaling has been interrupted. A delay in labor may result in compromise to the health of the fetus when oxygen delivery is decreased as the placenta begins to separate from the uterus of the mare.
If the foaling attendant is experienced, he or she should quickly but effectively clean the perineal area with soap and water and then perform a vaginal examination. The position of the foal within the pelvic canal should be determined and a judgment made as to the ability of the mare to deliver the foal with minimal or no assistance. If it is determined that the mare cannot deliver the foal without assistance, the foaling attendant should start to implement the dystocia/emergency foaling plan that should be in place prior to the foaling season on every farm. The plan may consist of calling for additional help from the farm or a neighboring farm, calling a local veterinarian to come to the farm, or transporting the mare to a veterinary clinic.
If the foaling attendant is not experienced, help should be summoned if the mare has not made significant progress or delivered a foal within 15 to 20 minutes from the time the water broke. Knowing when to call for help is one the most critical and time-sensitive decisions that can be made on a broodmare farm. In general, the only bad decision is not calling for help or taking action. Failure to take action may put the life of the foal at risk within a few valuable minutes. Any factor that slows the delivery process is detrimental, because the placenta may separate rapidly and the supply of oxygen to the fetus can be subsequently reduced. The risk of fetal or neonatal death increases as the duration of Stage 2 increases.
It is common on some breeding farms to vigorously rub down a foal with a towel in the first few minutes after it has been born. The purported goals of the “toweling-off” procedure are to dry the foal (especially on very cold winter nights) and to stimulate the foal to promote normal breathing, etc. In many instances the foal does not actually need the drying or the manual stimulation. However, the procedure does promote interaction with the foaling attendant which may help with early identification of congenital abnormalities.
Once the foal is determined to be stable and breathing, it is recommended that the foaling attendant leave the stall and allow the mare to interact with the foal and begin to establish the maternal-foal bond. If the mare is exhausted and seemingly unable to stand and turn around to interact with her new foal, it may be reasonable to carefully move the foal to the front of the mare.
The mare should be monitored in the immediate post-foaling period as well. Some mares remain recumbent for a prolonged period of time due to exhaustion while other mares exhibit mild colic signs presumably due to continued uterine contractions. Administration of a non-steroidal anti-inflammatory drug such as flunixin meglumine may be beneficial in reducing pot-foaling discomfort which may allow the mare to bond better with her foal.
It is usually not necessary or recommended to routinely cut or manually break the umbilical cord. The cord normally breaks when the mare stands or the foal attempts to rise. If necessary, manual breakage of the cord can be accomplished by grasping the cord with one hand on each side of the natural point of breakage, which is usually 1 to 2 inches from the foal’s abdomen. Direct tension on the cord attachment to the abdominal wall should be avoided. This may result in rupture of the cord at the level of the abdomen or even below skin level (i.e. without an umbilical stump) and will increase the likelihood of an infection in the umbilical cord (i.e. “navel ill”).
If it is necessary to cut the umbilical cord, it is recommended that the cord be tied with umbilical tape or an umbilical clamp be placed 1 to 2 inches from the abdominal wall. The cord can then be cut on the side of the tape or clamp away from the foal. Failure to tie or clamp the cord prior to cutting with a sharp knife or scissors may result in excessive hemorrhage. The umbilical stump should be disinfected with chlorhexadine (i.e. 2% Nolvasan solution diluted 1:1 with distilled water) immediately after the cord breaks.
Stage 3
Expulsion of the placenta or fetal membranes is the final stage of parturition. After the foal is delivered, the amnion may be tied to itself so it hangs just above the hocks. This prevents the mare from stepping on it and yet provides sufficient weight and traction on the umbilical cord to aid in the separation of the chorioallantois from the uterus. When separation is complete the entire placenta is expelled. The placenta is usually passed within 45 to 90 minutes after an uncomplicated foaling. The range of normal passage of the placenta ranges from immediately after foaling to up to three hours after foaling. The equine placenta is considered to be abnormally retained after 3 hours.
Foaling Kit
Mare owners are encouraged to keep basic critical supplies on hand during the foaling season. A list of such supplies is provided in the Table below. It is recommended that owners receive specific instructions or training from their veterinarian regarding appropriate use of obstetrical equipment, recognition of complications of the foaling process, and routine medical care of the newborn foal. In the event of a complication, the person attending the foaling is encouraged to immediately call the farm manager, owner and/or veterinarian for additional help or instructions.
| Item | Use |
|---|---|
| General Use | |
| Thermometer (fast-reading) | Evaluation of body temperature of mare and/or newborn foal |
| Stethoscope | Evaluation of heart rate and respiratory rate in mare and/or newborn foal |
| Scissors | Multiple uses, including opening a placenta in a ‘red-bag’ birth, cutting umbilical tape, tail wrap material, or occasionally cutting the umbilical cord |
| Flashlight with batteries | Most mares foal out at night; a small flashlight may be very handy at that time. |
| Syringes (3 ml; x 3) | Used to collect blood: 1) from mare prior to foaling to test for antibodies against other equine red blood cell types as a screening test for potential neonatal isoerythrolysis (Jaundice Foal Syndrome) and 2) from foal to evaluate passive transfer of antibodies after nursing (at approximately 24 to 36 hours of age |
| Needles (20 gauge; x3) | Used to collect blood from mare and foal |
| Blood tubes | Red-top tube for NI testing and purple top tube for foal IgG testing. |
| Plastic screw-top vial (1.8 ml) | Serum is stored in this vial and sent to a diagnostic laboratory for NI testing |
| Transfer pipette (plastic) | Used to move serum from Red-Top tube into small 1.8 ml plastic storage tube. |
| Mailing box | Pre-labeled box and Styrofoam container used to send blood sample from mare for NI testing |
| NI Test Submission Form | Fill out owner and mare information and send with blood sample from mare prior to foaling for evaluation of antibodies against other horse red blood cell antigens. |
| Pre-Foaling Supplies | |
| Milk calcium test kit | As aid in the prediction of foaling date |
| De-ionized water | Used in the milk calcium test |
| Milk cup (30 ml; 1 ounce) | Small plastic cup to collect a small amount of milk for calcium testing (pre-foaling) or testing of colostrum (post-foaling) |
| Tail wrap (Vet-Wrap) | To get tail hairs out of the way prior to and during foaling |
| Obstetrical sleeves (sterile) | Used if needed to check the position of the fetus during the foaling process. |
| Obstetrical lubricant (tube; sterile) | Applied to sleeve prior to checking position of fetus (if needed) |
| Exam gloves (2 pairs of medium; 2 pairs of large) | General purpose, non-latex gloves used when washing mare prior to foaling, handling placenta, etc. |
| Liquid soap (Ivory®) | Used to wash udder and perineum of mare prior to foaling. |
| Foal Supplies | |
| Umbilical tape (x 2) | To tie off the umbilical cord immediately after foaling (if needed; used as an alternative to an umbilical clamp) |
| Umbilical clamps (x 2) | To clamp off the umbilical cord immediately after foaling (if needed; used as an alternative to umbilical tape); usually removed or will fall off after 2 to 3 days |
| Umbilical cord disinfectant (Chlorhexadine, 1 %) | Used to dip the stump of the umbilical cord (navel) immediately after foaling to help seal the vessels within the cord and disinfect the area to reduce the probability of a bacterial infection (navel ill) |
| Towel | To dry off and stimulate respiration in newborn foal |
| Enema (Sodium Phosphate-type) | Administered to newborn foal at 1 to 2 hours of life to prevent or treat a meconium impaction |
| Colostrum refract meter | Used to evaluate the quality of the colostrum of the mare after foaling |
| Foal IgG Test | The Snap Test is a convenient semi-quantitative on-farm test used to determine if adequate passive transfer of antibodies has occurred once the foal has had an opportunity to nurse colostrum from the mare. The test is usually performed at 12 or 24 hours of age. A quantitative antibody test (ARS IgG Test) is available for larger farms when an accurate assessment of passive transfer is desired. |
| Measuring cup (600 ml; 20 ounce) plastic cup with handle | Convenient when collecting a larger volume of colostrum from a mare immediately after foaling for freezing. |
| Plastic bottle | Used for storage of colostrum in freezer. Convenient size and pre-labeled. |
| Cotton gauze 4x4’s | Used to strain colostrum to remove dirt and debris. |
| Plastic bag with drawstring | Used to dispose of placenta. The placenta may be weighed as part of a routine evaluation. A typical placenta weighs approximately 11 % of the foal’s body weight. |
| Nylon cord | Used to tie placenta above hocks of the mare after foaling; prevents mare from stepping on and tearing placenta. |
| Catheter-tip syringe (60 mls) | A dose syringe that may be used to administer oral medications to foal under supervision or instruction of a veterinarian. |