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The Birth of a Foal
The horse breeder must wait eleven months until his mare will hopefully give birth to a healthy foal. Because there may be great problems the time of foaling is also a time of sleepless nights for the owner, who may watch over the mare for days or even weeks in order not to miss the dicisive but short moment of birth. Parturition in the horse only takes about half an hour normally.
The fetus and the fetal membranes
To understand the process of parturition and to help in it if necessary, we must first look at the conditions in the motherīs womb (picture 1).
The uterus contains the fetus with the fetal membranes. We can distinquish between a gravid and a non gravid uterine horn. The placenta, the intimate union of the uterine mucous membrane and the outer fetal membrane, the allantochorion, fills the whole surface of the uterus. Here the respiratory and nutrient exchange occurs: from the maternal blood vessels via diffusion to the blood vessels of the allantochorion and hence via the umbilical cord to the fetus. The opposite way is taken by the fetal hormones, that show the mare the readyness of the foal for birth. Furthermore the placenta itself produces the gestational hormones like progesterone and others.
The inner fetal membrane, the allantoamnion, is a smooth and whitish sack. The outer membrane, the allantochorion forming part of the placenta, on itīs outer side is full of microscopic small processes, the so called microcotyledons, which give it a red and velvety appearence. The red colour comes from the many small blood vessels. Its inner surface is smooth and of a blue colour with the big blood vessels clearly visible. Only at the cervical area the allantochorion is white and without microcotyledons. Here the foal will pass the fetal membranes during parturition.
Both fetal membranes contain fetal fluids so that we can distinguish between two compartments: The inner compartment, the amnion with three to five liter of a mucous yellow fluid. And the outer compartment, the allantois with eight to 15 liter of a watery fluid composed of fetal urine and other secretion of the fetus and mare. The fetal membranes and fluids serve as a mechanical and immunological protection of the fetus during pregnancy. During parturition they widen and lubricate the passage through the birth canal.
The umbilical cord contains the blood vessels (two arteries and one vein) passing into the fetus from the placenta and also the urachus, a passage from the fetal bladder to the allantois. The fetus can move inside the uterus: After the 7th month it rotates around its own axis. Therefore the umbilical cord is always twisted to a certain degree, up to twelve windings have been found.
Preliminary symptoms of parturition
After a gestational time of 300 to 360 days parturition will begin. The mean time is 337 days. Gestation greatly differs in lenght depending on individuals and races. So thorough bred horses take less time than ponies. The Arabian takes 333 days in the mean. Male foals are normally born a few days later than female foals. If parturition happens before day 300 we call it abortion and the foal will not be able to live because of missing lung function. Between days 300 and 325 the foal must be considered as premature and a risk-foal.
How can the breeder know that parturition is at hand? In the last trimester the enlarged belly of the pregnant mare is evident only with the exception of many maiden mares. In the last two to three weeks we can find the following signs: The muscles of the belly relax and we see the more of a hanging belly the more pregnancies the mare had before. The paralumbar fossa hollows afterwards. And later the muscles of the croup and lateral of the tail-head soften.
Most important is to check the udder for signs of parturition. The mean mare shows an enlargement and edema of the udder two to three weeks before birth. This continues until four to six days before parturition the teats fill out.
The so called wax, dried secretions of the udder, can be found at the end of the teats some days before parturition. Admittedly it may take much more than one week in some cases. And maiden mares may show no wax at all. Some mares, especially confined mares, show ventral edema that may reach to the pectoral region.
In some cases the mare may loose milk before parturion (mostly on the day of but even up to one week before parturition). If this happens it is important to check if the foal has received enough coloctral antibodies after one day.
All of the above mentioned signs are very vage and do not allow to determine the exact day of foaling. The most acurate test is to check the amount of Calcium in the milk. If the test shows a significant increase parturition will happen in the next 24 hours in more than 90 % of the mares. A very good help for foal watching can be recommended in the apparatus of the Kegel company that reacts upon the sweating of the mare.
The mare shoul be dewormed some days before foaling. Vaccinations against Tetanus and Influenza should be done at least one month before. Against Herpes the time of vaccination is the third and ninth month of pregnancy.
The Stages of Parturition
Parturition is divided in three stages: opening, expulsion of the foal and expulsion of the membranes. In order to know if the process of foaling is normal or not also the owner of the mare should be informed about the normal proceedings and times of parturition.
In the 7th month of gestation the fetus turns itself in anterior presentation and ventral position, the back looking down and the front legs and head in a flexed position. About three days before foaling the fetus moves increasingly. It must turn into presentation for birth: it rotates to the dorsal position (the back is next to the mareīs back) and extends the head and legs. This takes place during the firts stage of labor (opening). At the same time the uterus rhythmically contracts beginning from the tips of the horn. So the fetus is moved to the pelvis and cervix.
The first stage of labor is characterised by uneasiness and nervousness of the mare. She will lie down, get up, nibble a little hay, move her tail and may sweat a little and urinate. Also mild signs of colic are not uncommon. The time intervall is usually two to three hours, but may also be much longer and interrupted by phases without signs.
The placenta is forced into the cervical canal by the increasing forces in the uterus and eventually breaks at the cervical star, the area without connection between the fetal membranes and the uterus. The end of the first stage is marked by the expulsion of one to three liters of fluid through the rupture in the allantochorion.
The second stage or expulsion only lasts 10 to 30 minutes in most cases. Following expulsion of the chorioallantoic fluid uterine contractions increase. The amniotic vesicle dilates the cervix and this leads to a release of oxytocin and stronger contractions and the front feet and nose of the foal are forced into the pelvis. Until this time the mare is usually standing and amnion and feet of the foal are visibly protruding through the vulva (Picture 2 and 3, these and the following pictures show the birth of Minza by Ansata Amir Zaman out of Musinnah by Montasar).
At this period corrections for malpresentations are most easily made. For instance if after 15 minutes after the expelling of large amounts of fluid no amnion or feet are visible. 98 to 99 % of all foals are born with front feet and head first, this is called anterior presentation. If the hind legs are born first - easily detectable by the soles of the hooves looking upward - it is called posterior presentation. In this case delivery must be speeded up by manuael extraction because aphyxia is likely.
For the expulsion of the fetus the mare will lie down, in most cases next to the wall (picture 4). Now actual labor begins. Inside the amniotic vesicle one leg can be seen with the other a little bit behind. In a normal presentation the sole is downward and the nose of the foal is at carpus level.
It takes another 15 minutes to expell the foal completely. First the foal will be expelled to the shoulders (picture 5). Here the labor stops for a pause. While pelvis and hind legs of the foal are still in the mare the foal begins to move head and front legs. So the amnion ruptures, the nostrils get free and breathing starts (picture 6). Further labor will expell the pelvis (picture 7).
At last, after about ten minutes of rest, the mare rises (picture 8). Thus the umbilical cord breaks at a certain point, about one to two centimeters from the belly (picture 9). You should not force the mare to get up to fast because important blood flows back from the placenta to the foal.
In the last stage of parturition, the expulsion of membranes, directly after delivery of the foal, the placental membranes, now called afterbirth, are born. This takes 15 minutes to one hour normally. Pains not unlike of a mild colic may be seen that can last even for hours after the expulsion of the membranes. The pain comes from the contractions of the uterus. By this the rests of fetal fluids are removed from the uterus.
If the placental membranes are not expelled after six to twelve hours the veterinarian must help. If not uterine infection, fever, laminitis and later infertility may occur.
The afterbirth
Because even smallest remnants of the fetal membranes remaining in the uterus will lead to serious diseases it is very important to controll the completeness of the placental membranes (picture 13). Furthermore any deviation from the normal condition may give important clues about the foalīs health.
The allantochorion (that had formed part of the placenta) is born inverse: by the traction of the umbilical cord the smooth inner layer is turned to the outside. It has a characteristic form with two horns of different size which correspond to the gravid and non-gravid horn of the uterus. Both tips of the afterbirth must be complete! The larger one sends out the umbilical cord which reaches the allantoamnion, that has been torn during birth. Exactly like the uterus the allantochorion also has a body which always shows a ruptured opening. Here the foal has passed during birth.
The end of the umbilical cord is composed of two umbilical arteries protruding some centimeter. The arteries rupture inside the foalīs abdomen.
In order to judge the velvety surface the afterbirth must be reversed. The veterinarian may see inflamatory, haemorhagic or other changes which give clues about the placental function. If abnormalities are noticed mare and foal must be checked.
The newborn foal
The breederīs attention is fixed on the foal immediatelly after delivery. Does it come up to the expectations? But first we should push aside those thoughts and keep an eye on both the foalīs and mareīs healt. Every foal should be checked under the following aspects.
First and most important condition for the life of the newborn is the establishment of breathing. During fetal life the placenta had served this purpose and now the lungs must function at the lastest one minute after delivery of the foalīs pelvis. The first and normally spontane breath unfolds the lung-tissue. An irregular breathing pattern starts within 30 seconds after birth and after 60 seconds a regular rhythm is established. Five minutes after birth the normal frequence of breathing is 20 to 40 breaths per minute. It is important that the airways are free of mucus or fetal fluids.
A healthy foal will always lie in a sternal position (picture 14)!
Asphyxia, the deficiency of oxygen, occurs if the foal will not breath regularly after one minute. Such a foal must be resuscitated in order to avoid irreversible damage to the brain. The nostrils must be cleaned of mucous and the lung must be inflated by blowing air into one nostril in a rate of about 25 times per minute - while the other nostril and the mouth must be closed.
The heart rate will usually be 40 to 80 beats per minute during the firts five minutes after birth. If the foal begins to try to rise it will increase to 130 to 150 beats or more. During the first days of life the heart rate should be between 70 and 100.
Within normally 20 minutes the reflex of sucking appears, sometimes only one minute after delivery. The time until standing is one hour in the mean, but also 15 minutes or two and a half hour may be normal (picture 16). The time until nursing is about two hours (35 minutes to seven hours) in healty foals (picture 17 and 18). The normal body temperature is between 37,2 and 38,9 degrees Celsius during the first week.
The umbilicus normally breaks at a certain point one to two centimeters from the abdominal wall of the foal when the mare gets up to lick the foal or the foal tries to rise. The stump should be treated with iodine to prevent infection at this side. If the umbilical cord does not break by itself, this only happens if the placenta is expelled prematurely, it must be severed by twisting at the correct and clearly visible place.
Furthermore the passage of meconium, black, hard and round feces from the intestine of the newborn, must occur. The colostral milk also serves as a laxative. Because of the relative high incidence of retained meconium I recommend the prophylactic use of an enema. It may prevent the pain associated with meconium impaction - the foal will try to fecate with its tail carried high in the air or even up to strong colic pain, so that the foal lies on its back, the front legs laid around the head and rolling in pain. Even death may occur and any other disease of the newborn foal will be accelerated.
In the end you should calculate the exact time of gestation. If it is less than 320 days the foal must be considered premature and at high risk. By means of all those criteria even a lay may know, if the foal is healty. If this is the case you need not call the veterinarian at an inhumane time in night. If not you should call him immediatelly for help. In the worst any help may be too late for a sick newborn soon.
The mare after parturition
Also the mare may suffer from complications during foaling and must be observed thoroughly. Does the mare behave normally against her foal? Does she accept it, lick and mother it? Is the afterbirth expelled in time? The fetal membranes must be checked and shown to the veterinarian. The vulva must be examined for lacerations. Major injuries must be sutured. Hematomas and large blood clots do not require prompt treatment.
Nursing of the foal may be critical. Some mares, especially maiden mares, show a painful reaction to their full udder and the harsh treatment by their foal: they cick against foal and men. A sedation by the veterinarian will help. The first milk, the colostral milk, is of special importance for the foal. The colostral antibodies of the mare will be taken up by the foalīs intestine only during the first day. Thereafter a transfer of antibodies via intestine is no more possible and the foal would be without protection against infections.
In order to check if the foal has taken up enough of the maternal antibodies its blood may be examined after twelve hours at the earliest. This should always be done if
1. the mare has lost milk for a longer period before parturition
2. the foal could not drink enough (weakness of the foal, different diseases of the neonatal period, mare did not let drink or did not have enough milk)
3. the mare already had foals which died from infection during the first months
4. diseases of the mare during parturition like severe colic, shock after severe blood loss and other.
(This article has been published in ARABER JOURNAL)
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The expulsion of the foal has begun
The front legs of the foal are presented in the amniotic sack
The head with the red tongue is visible
