Foals: The First Hours of Life
In the short time involved in the birth of a foal, the baby undergoes tremendous physical changes. The foal leaves the protected environment of the uterus where everything is provided and enters a world of light, cold and noise. In her new environment she must change her circulation, breathe air and seek out her own nutrition.
The lungs of the foal undergo the most dramatic transformation at birth. Previously bathed in fluid with no airspaces, and possessing a limited blood supply, the lungs suddenly transform into the oxygen-absorbing organ of the body through which the entire blood volume must flow several thousands of times each day. Several events must come together for this to occur.
- During parturition (birth), the foal's chest is compressed as she passes through the pelvic canal of the dam. This mechanical action helps express fluid from the lungs.
- The placental blood flow decreases, and the drop in oxygen stimulates the foal to gasp for air. These deep breaths generate a vacuum that sucks air into the lower airways and air sacs for the first time. During the foal's first few breaths, the lungs expand, encouraging fluid to move from the air sacs in the lungs to the pulmonary blood vessels, leaving room for more air than fluid to fill the lungs in subsequent breaths.
- While these changes are occurring in the lungs, blood flow is redirected to the blood vessels in the lungs. Before the foal is born, most of the blood flow bypasses the lungs through a detour between the aorta and the main pulmonary artery, called the ductus arteriosus. But the heart has been remodeled so that it can deliver all the blood to the lungs after birth. The ventricular septum, the wall between the left and right side of the heart, was completed by the 38th day of gestation and the foramen ovale, a connection between the left and right atria, should close a few hours after birth.
At birth the initial lung expansion causes a drop in pulmonary blood pressure, allowing the blood to flow from the pulmonary arteries through the capillaries of the lung. Complete closure of the ductus arteriosus should occur by 72 hours after birth. Until that time it is normal to hear a soft heart murmur in the newborn foal.
All of these steps are important for the development of a healthy newborn foal. And they generally take place in the first moments after birth. Problems can develop anywhere along this path, although most foals do this very well. Nevertheless, some need our help.
In human neonatology a system called the Apgar test has been developed to evaluate a newborn's condition after delivery. Newborns are rated at one minute, five minutes and 10 minutes after delivery on five qualities: appearance (color), pulse (heartbeat), grimace (reflex), activity (muscle tone), and respiration (breathing). Veterinarians have modified this system to fit the foal. It is a good guideline for assessing problems and for determining whether aggressive resuscitation is necessary.
Four parameters are measured in the foal system: heart rate, respiratory rate and pattern, muscle tone, and the reaction to nasal stimulation with a straw. The test is performed immediately after birth. A value of 0 to 2 is assigned to each measurement and a final score is determined by adding up the values. A total score of 7 to 8 indicates a normal foal; a score of 4 to 6 suggests that intervention is needed; and scores of 0 to 3 represent severe problems with likelihood of not surviving.
Assigned Value: 0
Heart and pulse rate: Undetectable
Respiration (rate and pattern): Undetectable
Muscle tone: Lateral recumbency, or lying on her side and unable to rise
Suckle reflex: Absent
Assigned Value: 1
Heart and pulse rate: Less than 60 beats/min
Respiration (rate and pattern): Slow, irregular
Muscle tone: Lateral recumbency, evidence of some muscle tone
Suckle reflex: Weak suckle
Assigned Value: 2
Heart and pulse rate: Greater than 60 beats/min
Respiration (rate and pattern): Greater than 60 breaths/min, regular
Muscle tone: Able to maintain sternal recumbency, which is sitting up on the brisket with the legs tucked under the body
Suckle reflex: Strong suckle
Normal foals have a heart rate of greater than 60 beats/minute. You can usually feel the heart beat of a newborn foal by placing the palm of your hand on the left side of the chest just behind the elbow. Each time you feel a vibration or thump, this counts as one heart beat. Alternatively, you can listen with a stethoscope if you have received training. If you count the beats for 15 seconds and multiply by four, you get the heart rate per minute.
The respiratory rate of the newborn foal can vary greatly but it is usually over 60 breaths per minute. This can be determined by counting the number of times the foal's chest rises over 15 seconds, and again, multiplying it by four to get the breaths per minute. A range from 60 to 100 breaths/min is acceptable. Assessing the respiratory effort is equally important . The normal foal has a regular, gentle rising and falling of the chest wall. If the foal has a breathing problem the effort increases so that the foal's ribs and /or abdominal muscles contractwith each breath. In severe respiratory problems, the foal resorts to aggressive movement of the abdomen, a sign the diaphragm is working to extreme. This may be a sign that the foal is having trouble clearing the normal fluids from the lung.
Soon after birth, foals begin to right themselves and sit sternally with the sternum on the ground. They should be actively moving their legs and holding their head up. Lateral recumbency, or lying on the side, is abnormal for the newborn. Although foals normally lie on their side when sleeping, they will go sternal or stand if stimulated. A foal that does not respond in this way is abnormal.
The suckle reflex is generally present within five minutes of birth. It may be weak at first, but it should continually strengthen over the first hour of life. Absence of a suckle or the persistence of a weak suckle may indicate that the foal was deprived of oxygen during the birth process.
Newborn foals should be stimulated by rubbing them briskly with a dry towel. This causes the normal foal to shake her head and move around. More aggressive intervention is needed if the foal presents with a score of less than 6. If the foal is not breathing then you need to help clear the lungs of fluid. To aid in clearing excess fluid from the lungs, the lying foal's hind quarters can be elevated over the level of the head, and the chest gently patted with a cupped hand (coupage). This loosens mucus in the lungs and provides drainage. Mouth-to-nose resuscitation can be performed by holding one nostril and the mouth of the foal closed while you blow into the other nostril. You should be able to see the chest moving if you are filling the lungs. Cardiac massage may be needed until the veterinarian can provide more effective treatment.
Immediately after parturition (birth) the mare turns and sees the foal. One of the first behaviors that you may notice is a soft nickering that is reserved for her foal. Soon the dam will sniff and lick the fetal membranes and the foal. It is thought that this behavior helps the mare to discriminate between her foal and others. The first half hour after birth is probably the most important time to establish this bond, although foals may not bond to their mothers for several days. If the foal appears normal on your Apgar test, then it is important to give mare and foal this time to become acquainted.
Normal foal behavior during the first three hours after birth should follow the guidelines listed below. The adaptive response is followed by the time elapsed since birth.
Normal respiratory and cardiac rhythms: Within 1 minute
Righting reflexes established: Within 5 minutes
Suck reflex established: Within 5 minutes
Attempts to stand: Within 30 minutes
Ability to stand unassisted: Within 60 to 120 minutes
Nursing from udder: Within 60 to 180 minutes
These guidelines are fairly strict. Failure to meet them may be the first indication that there is something medically wrong with the neonate and a veterinarian should be consulted immediately.
The most important observation concerns suckling. A foal will try to nurse on many parts of the mare before finding the udder. It is important that you actually see the foal attach to the udder and wrap her tongue around the teat. Sometimes the foal is actually sucking on the inner thigh of the mare or other parts of the udder but not the teat, so it important to watch closely, and see that the foal is swallowing milk. During the first week of life, foals nurse at a frequency of approximately four to five times each hour. The average length of time of nursing is one minute. This may range from a few seconds to several minutes.
If the foal is attempting to suckle more frequently, you should suspect that the mare may not be producing enough milk, as the foal's hunger may not be satisfied. If the mare's udder seems enlarged and milk is dripping without stimulation from the foal, it may mean that the foal is not eating enough. This may be an early sign of depression and illness in the foal. Your veterinarian should be consulted immediately.
If there is any question about the success of the foal to suckle enough colostrum, your veterinarian should be consulted. In most cases, the veterinarian will want to draw blood to see if colostrum was absorbed. The test can be performed between 12 and 24 hours after birth.
The foal will generally defecate for the first time about 30 minutes after nursing. The first manure that the foal passes is called meconium and is made up of cellular debris and amniotic fluid that has been ingested over pregnancy. It generally consists of dark brown hard balls. Sometimes the newborn foal will have difficulty passing his meconium, called meconium impaction. The foal may posture and strain to defecate with his back arched (humped). The foal's first urination occurs between three to five hours after birth. Sometimes owners confuse the signs of straining to defecate (arching the back) with the signs of straining to urinate (lowering the back).
Foals are fast learners. In the wild they need to be able to run from predators as quickly as possible after birth. The foal becomes steady on his feet about 4 to 5 hours after birth. He should be able to lie down, stand and nurse with ease. Mares and their foals can be turned out into a small paddock by themselves within the first 24 hours after birth. Mares should be very attentive of their foal's location at all times. Maternal protectiveness will cause the mare to try to place herself between her foal and anything that may threaten him. Foals should follow their mares. First the first few days of life the foals will stay within a 10-foot radius of the dams. As they become more secure with their environment they will widen the safety zone between themselves and their dams.
Sometimes a mare will reject her foal. The most common and least severe form of rejection usually involves mares that are having their first foal. These mares appear to be afraid of their foals and the behavior is one of avoidance and intolerance to nursing. The more severe forms involve actual aggression toward the foal. This may be a chronic problem that occurs with every foal.
Foal rejection should be treated immediately. Causes for pain such as a swollen udder or mastitis should be evaluated. Mild restraint of the mare is often sufficient to allow the foal a chance to nurse. A mild tranquilizer may be needed in the beginning. Do not inflict pain on the mare while the foal is nursing because she may associate the pain with the foal. If the mare is actually aggressive toward the foal then the pair should be watched very carefully. The mare should be milked out and the foal fed the colostrum (antibody rich milk) if there is any suspicion that the foal has not ingested enough milk.
Even the nicest mare can change her behavior toward humans after the birth of her foal, and you should be cautious when entering a stall with a mare and foal. It is best to acknowledge the mare first by talking quietly to her and stroking her forehead and neck. She will be normally anxious about her foal and may exhibit protective behavior by placing herself between you and the foal.
It is usually safest and easiest to have two people present when attempting to catch the foal. One person should be holding the mare with a lead shank while the other person approaches the foal. It is best to approach the foal in a slightly crouched position with arms held out wide. A normal foal will attempt to run away and hide behind his dam. The person holding the mare can aid in catching the foal by backing the mare into a corner so that the foal can't run behind her. If he does then the mare holder can block his movement while the foal catcher approaches from the other side.
Once the foal is caught it is important to hold onto him. The best method for controlling the foal is to place one arm under and around the base of his neck and one hand on the tail. By encircling the foal like this you are able to control his forward and backward movement. Leverage on the tail will add more restraint for more rambunctious foals. If too much restraint is applied, the foal may react by collapsing in your arms. This is normal. All you need to do is lighten up on your pressure. Once the foal realizes that you are not going to hold him up, he will jump up. Continue to encircle the foal with your arms as you lighten your pressure so that you can continue to restrain the foal as necessary.
Once you are though handling the foal, his normal reaction is to run back to his dam and begin to seek the udder and nurse. The security of knowing that the milk is still available is comforting to the foal. This is also a good method to evaluate whether the foal is nursing well or not. If the foal does not run back to the dam or suckle, your foal may be depressed. Depression and anorexia are two early signs that the foal is sick.