How to Recognize Critical Illness in Foals
By Madison Seamans, DVM, MS
Few things in nature are more inspiring than new foals frolicking around their mothers on a crisp spring morning. The fact that a foal can be up and running within a few short hours after birth is but one in a long series of miracles. Conception is miraculous in itself. Development in utero, or in the womb, begins with the formation of all of the organ systems and is followed by their maturation. During the entire process, the foal is completely dependent on the mother’s blood supply for eating, breathing, and eliminating metabolic waste products. Many of the organ systems function differently in utero than they do after birth. Parturition, or birthing, initiates changes in the foal’s heart, lungs, liver, and urinary bladder which must occur almost instantly. These changes are essential for adaptation to life on the outside.
Many of the foal’s organ systems function differently in utero than they do after birth. Parturition, or birthing, initiates changes in the heart, lungs, liver, and urinary bladder which must occur almost instantly and are essential adaptations for life outside the womb. Photo: Pam MacKenzie Photography
Fortunately, things proceed normally almost all of the time. Foals have survived the cold, cruel world much longer than there have been foal-watch teams to worry about them. That being said, how do we know when things are not right? What are the signs? What can and should be done? In order to understand how things can go wrong, it is important to review the normal physiological processes taking place around the time of birth.
During gestation, the foal in utero is dependent on the mother for eating, breathing, and eliminating metabolic waste products while its organ systems develop and mature. Oxygen and nutrients from the mother’s blood are transferred through the placenta and umbilical cord to the foal, and waste products from the fetal circulatory system are passed back to the mother’s blood supply to be eliminated. Photo: Branko Habjan/Photos.com
Normal Transition from Prenatal Life to Neonatal Life
When the foal is still in utero, he does not breathe or eat. Oxygen and nutrients in the mare’s blood are transferred directly to the blood supply of the developing fetus through an elaborate system of membranes called the placenta, which is attached to the foal through his belly button, or umbilicus, via the umbilical cord. Waste products from the foal’s blood are then transferred back across the placenta to the mare’s blood to be eliminated. Shunts in the fetal foal’s circulatory system serve as little detours which direct blood away from the lungs and liver, as these organs are not needed until the beginning of life on the outside. Immediately after birth, since the foal can no longer rely on his mother for oxygen, nutrients, and waste elimination, these shunts must change to allow normal function of all body systems.
Cardiovascular and respiratory (heart, blood vessels, and lungs) changes occur first and the blood is instantly directed to flow through the lungs so they can inflate, absorb oxygen, and expel carbon dioxide. Other changes involving the liver, urinary bladder, intestinal lining, and immune system occur in the hours after birth and are critical to the foal’s survival. The urachus (the channel between the bladder and umbilicus) is normally closed at birth so urine starts flowing through the appropriate pathway. The intestinal lining, or epithelium, remains very porous during the first six to eight hours of life to allow absorption of some very large molecules called antibodies ingested in the first milk, or colostrum. These antibodies provide the foal with immunity from bacteria, viruses, and other potentially life-threatening infectious diseases. This “passive immunity” is essential for the life of the foal until his immune system matures and he is capable of making his own antibodies through “active immunity” at about six months of age. For this reason, foals are not routinely vaccinated for most diseases before about six months, as they may not be capable of producing an immune response to vaccines. If the mare is vaccinated about 30 days prior to her due date, she will pass the immunity on to her foal when he nurses the colostrum during his first day of life.
When Things Go Wrong
Appreciation of the transition from prenatal life in utero to neonatal life on the outside helps us understand the processes that occur when things go wrong. When a foal becomes ill, many of his body systems want to revert back to the warm, safe confines he had in the womb. However, the prenatal function of most organ systems is not compatible with life on the outside. In the absence of normal physiological function of these organ systems, the invasion of bacteria, viruses, and fungi can cause illness in foals leading to a serious infection in the bloodstream, or “neonatal sepsis.”
When a foal becomes ill, many of his body systems will attempt to revert back to their prenatal function, which in most cases is not compatible with life outside the womb. The retreat to prenatal life can occur rapidly, and can lead to neonatal sepsis, a serious infection in the foal’s bloodstream. Photo: Sini Merikallio/Flickr
In sick foals, the metabolic retreat to prenatal life can occur rapidly, within just a few hours of birth. The passage that allows blood to flow through the lungs begins to close, and so respiratory symptoms are common in “at risk” foals. Among the first symptoms noticed are cough, runny nose, high fever, and lethargy. The urachus opens again, urine dribbles from the umbilicus and “my colt is peeing out his belly button” is an alarming report. Gastric ulcers are also seen in these patients, and may cause rolling, teeth grinding, and increased salivation. A foal with gastric ulceration may roll up next to a fence or wall so he is lying directly on his back with his feet in the air. In addition, the passage that opened after birth to allow blood to flow through the liver begins to close again, and metabolic waste products that are normally cleared from circulation by the liver begin to increase in the blood. This build-up soon becomes toxic, the life-sustaining mechanisms cease functioning, and other potentially fatal events arise.
There are several things that suggest a foal is at risk for developing neonatal sepsis. Some of these can be quite subtle, so a routine neonatal examination by a veterinarian during the first 24 hours of life is strongly advised even if everything looks okay. Foals that fail to stand and nurse within two hours or have urine dribbling or swelling at the umbilicus are suspect. Joint swelling, extreme lethargy (sometimes indicated by general weakness), and “floppy” ears are also cause for concern. (It is interesting to note that before the foal can stand for the first time, he must have good control of his ears.) Diarrhea, cough, nasal discharge, and fever (a temperature over 38.6 degrees C (101.5 degrees F) suggest the presence of a serious problem. Lethargy can be difficult to assess as a normal foal will exhibit a cycle of nursing, playing, and “power napping” throughout the day. However, a foal that is not easily aroused by human or maternal stimulus, or has any of the other symptoms mentioned here, should be examined by a veterinarian immediately.
Nursing – Normal Behaviour & Problems
Failure to stand and nurse normally within two hours after birth may be a sign that the foal is at risk for developing neonatal sepsis. Photo: Alison McKellar/Wikimedia Commons
Normal nursing behaviour is the most important indicator of good health. Failure to stand and nurse normally within two hours after birth or wandering around the stall “nursing” foreign objects are clear indicators that the foal is in trouble. As the typical mare produces about four gallons of milk per day, a foal needs to nurse frequently to ingest this volume. The new foal should be observed closely to be certain that he actually has the teat in his mouth. Even though the foal’s head may be seen under the mare’s flank and sucking noises heard, sometimes he still has not “latched on.” The presence of milk on the newborn’s face is an indication that he may be getting close, but not actually nursing. This should be cause for concern. If the mare’s udder is being nursed regularly, the teats will look clean and be pointing downward.
If the foal has not latched on, directing him towards the teat and squirting milk on his nose can help him locate his breakfast. In some cases, however, a stomach tube must be passed by a veterinarian and the first colostrum delivered in this manner. This will ensure the presence of essential antibodies in his system, and provide the immediate nutrition needed until normal nursing patterns can be established. Normal nursing consists of episodes lasting 15 to 30 seconds or longer repeated two to six times per hour. Nursing activity for three or four seconds is not adequate and assistance is warranted. The importance of normal nursing cannot be overemphasized as it may be the most critical aspect of a foal’s survival.
It is important to ascertain that the foal has the teat in his mouth and is actually nursing. Some foals may make appropriate sucking noises under the mare’s flank but have not “latched on.” Photo: Sini Merikallio/Flickr
As the gut remains porous for the first 12 to 24 hours to absorb antibodies from colostrum, these holes can also allow the passage of bacteria. This is probably the cause of neonatal sepsis rather than the old wives’ tale of it coming from the umbilicus, traditionally called “navel ill.” The presence of milk in the intestine triggers the mechanism which closes the large pores in the lining and allows normal absorption of water and other nutrients. The closure of intestinal pores will guard against the introduction of bacteria into the bloodstream, and the antibodies present afford protection against those that may have tried to sneak in uninvited.
Premature & Dysmature Foals
Although normal gestation or length of pregnancy in a mare is 345 days (the average is 333 to 357 days), some foals prefer their own calendar. Although premature births are relatively uncommon in horses, as is the case in humans, they present severe challenges to survival. Clinical characteristics of prematurity in foals include low birth weight, a short velvety hair coat, domed forehead, floppy ears, lax tendons, and general muscle weakness. Foals that are born post-term or after their expected due date, but exhibit the physical characteristics of prematurity, are called “dysmature.” While we may be tempted to induce labour in pregnancies exceeding 400 days, this is very seldom advisable, as these foals aren’t “done” yet. Forcing their delivery will commonly result in a dysmature foal. Time sufficient for the maturation of all body systems is imperative for neonatal survival.
The production of surfactant, a substance that allows the lung to inflate properly, is among the last components to mature in the prenatal horse. This miraculous compound reduces surface tension in the alveoli, the microscopic spaces in the lung that are the location for exchange of oxygen, carbon dioxide, and other gases. When you blow up a toy balloon, you will notice that it is fairly difficult in the beginning; however, at some critical point, it gets easy. This is what surfactant does in the lungs – makes it easy to inflate the alveoli. Once the lungs are properly inflated and the foal is absorbing oxygen, life without the placenta is possible. Premature and dysmature foals often lack adequate surfactant, and severe respiratory problems with sepsis are common.
The amazing phenomenon of new life usually proceeds without difficulty. However, if a foal presents with any of the symptoms discussed here, veterinary attention is advised. Most of these cases should be treated as an emergency, so waiting for normal office hours is seldom an option. Many at risk foals can be saved with some simple mare-side techniques that can avoid major problems later. Above all, when in doubt, call your veterinarian.
This article was reprinted with permission from the American Association of Equine Practitioners.
Main Photo: Nigel Dowsett/Stock Photos/Photos.com