Chapter 23 THE NEWBORN FOAL

The goal of any breeding program is a healthy, vibrant foal. After all the care taken to get the mare in foal and to maintain the pregnancy, proper attention to the management and care of the neonatal foal is imperative for a successful outcome. The majority of foalings are not attended by a veterinarian; this makes the experience and knowledge of caretakers (owner, groom, etc.) crucial to success. The more experienced the caretaker, the more likely he or she will be able to recognize problems early and will be better equipped to handle problems that occur. It will be the caretaker’s responsibility to determine when help and intervention are needed. Every normal foal should have a veterinary examination within the first 12–24 hours post-partum. In order to recognize abnormalities, it is important to know the normal condition and behavior of the neonatal foal.

A normal healthy full-term foal should be energetic and the following events should occur post-partum (Box 23-1). Foals are usually able to obtain sternal recumbency within about 5 minutes of birth. They should have a strong suckle reflex within 20 minutes and stand within an hour (range:15–165 minutes). They usually start to make attempts to stand within 15–30 minutes, but occasionally a normal foal may take as long as 2 hours to successfully get and stay standing and nurse. The first few attempts to stand may be uncoordinated and aimless, but they should figure it out with minimal assistance. The longer it takes, the greater the chance there is a problem with the foal and veterinary assistance will be required. If the foal has not suckled within 4 hours, it should be considered abnormal. Anything that varies from these guidelines should be considered abnormal and veterinary care should be sought prior to the routine veterinary check. The chance of a positive outcome increases the sooner veterinary intervention is made.

Box 23-1 Normal Post-Partum Foal Events

Sternal in 1–2 minutes

Standing within 15 minutes to 2 hours

Nursing 35 minutes to 4 hours

Consider the foal abnormal if it has not stood and suckled in 4 hours.

RISK ASSESSMENT

The use of risk categories can improve the outcome of serious complications in neonatal foals by allowing for early monitoring, assessment, and intervention. These categories can be used to guide management practices and determine the amount of intervention needed and the need for the presence of a veterinarian at the time of parturition. The three-category system (low, moderate, and high risk) has been used successfully.¹^–³ A two-category system has also been suggested that eliminates the moderate category and therefore allows more foals to be classified as high risk and receive more attention.⁴ In determining the risk category of the foal, several factors are assessed, including the mare’s reproductive history, maternal conditions during the pregnancy, ease of birth, management and environmental factors, and the foal’s condition (Table 23-1). The risk category of the foal can be changed at any stage such that a foal that was considered “low risk” pre-partum suddenly becomes a “high risk” foal if a dystocia is encountered, or the foal is found to have an abnormality on assessment.

Table 23-1 Risk Assessment

If the foal has only one factor in the high-risk group, it is classified as “moderate risk.” Foals classified as a “high-risk” prepartum can be decreased to moderate if the parturition is normal and the foal appears clinically normal. Increased observation is still warranted and many recommend placing these foals on broad-spectrum antibiotics with a good gram-negative spectrum (e.g., ceftiofur) for the first 48–72 hours of life.¹ Serial blood work should be performed in these foals over the first week of life. This would include testing for passive transfer of immunoglobulins (IgG), a complete blood count, and biochemistry profile. The foals should be monitored closely for energy, suckling, and weight gain. “Low-risk” foals are those with no identifiable abnormalities in any category and are basically normal foals in all regards.

Maternal factors include a combination of historical data regarding reproductive history, such as uterine infection, previous foalings, and illness of the mare during the pregnancy. Maternal risk factors include any factor that may interfere with the development or nourishment of the foal in utero or that interferes with the mare’s ability to supply an adequate amount of good quality colostrum.^1,⁵ Examples of such conditions would include prior foals with neonatal isoerythrolysis (NI), hypoxic ischemic encephalopathy, dysmaturity, congenital defects, or poor-performance of undetermined cause, prior dystocias, twin pregnancies, premature lactation, or illness in the mare, among other things. Placental abnormalities such as placentitis, edema, or other placental irregularities can be identified pre-partum via ultrasound examination or post-partum by examination of the placenta, and they will increase the risk for the foal. Foals that are determined pre-partum to be at a “high risk” may be foaled out at a center that provides close monitoring and immediate veterinary attention at the time of parturition.

Even though a mare and her gestation had seemed normal, any problems with the parturition process affect the foal’s risk category by potentially altering blood flow or causing direct trauma to the foal.^1,⁵ Some of the conditions affecting the foal may be very obvious, such as dystocia, whereas others may be more subtle or unobserved. Any foal resulting from an unobserved delivery should be treated as “high risk” until determined otherwise. The same holds true for premature deliveries, premature placental separation, cesarean sections, or induced parturitions.

If obvious abnormalities with the foal’s appearance or behavior are observed, the appropriate measures should be taken. Some foal factors that will result in a “high-risk” classification include congenital abnormalities, meconium aspiration, prematurity/dysmaturity, and failure of passive transfer (FPT). The environment that the foal is born into is also important in the risk of disease. If the environmental conditions are less than optimal, in terms of hygiene, climate, pathogen exposure, or the lack of observation, then the foal should be considered at higher risk of illness, especially sepsis.

INITIAL FOAL ASSESSMENT

All those attending foalings should be instructed on how to perform an immediate post-partum evaluation of the foal using the APGAR scoring system described in Table 23-2, or some modification thereof, to assist with recognition of early signs of problems and to determine the need for additional assistance and intervention.³ This scoring is easy to perform even by inexperienced staff and should be obtained within the first 10–15 minutes post-partum. Each parameter is scored from 0 to 2. An optimal total score is 10, with normal foals usually scoring 9 or 10. Foals that score between 6 and 8 are usually considered to have mild asphyxia and may improve with stimulation by rubbing the core and limb manipulation. Assisting the foal into sternal recumbency may also be of benefit. Foals that score between 3 and 5 usually require oxygen therapy and cardiovascular support in addition to stimulation and placement in sternal recumbency. Preparations for intervention with respiratory and cardiovascular resuscitation should also be made. Aggressive therapy is usually required for foals that score <3, since full resuscitation is usually required.³

Table 23-2 APGAR Scoring System

Foals that are considered “high risk” or that have questionable APGAR scores should be evaluated regularly over the first hour. If the foal is considered normal in all accounts and the foal has stood and suckled in the normal amount of time, they can be left undisturbed. Even though a foal has a normal APGAR score, this does not preclude a thorough veterinary examination within the first day of life (preferably 12–18 hours of age).

Vital Parameters

There are many immediate post-partum changes that will affect the foal’s physical examination findings (Table 23-3). Most of these changes are due to accommodation of the cardiovascular and respiratory systems to life outside of the uterus. The pulse (HR) should be 40–80 bpm soon after birth and then increase to >100 bpm within the first hour of life. This increase usually coincides with the foal attempting to stand. It should take its first breath rather quickly after delivery, usually within the first 30 seconds. There may be an initial series of gasps that quickly change to a more normal breathing pattern. The respiratory rate (RR) should be >30 breaths/min and shallow just after birth. A slow RR is of more concern than a more rapid rate and may indicate the need for intervention and possible resuscitation.

Table 23-3 Neonatal Vital Parameters

Foals should also be monitored for urine production. Colts usually first urinate within the first 5–6 hours whereas fillies can take as long as 10–11 hours. If they are suckling normally, they will then void diluted urine frequently. Not considered by the APGAR scoring system, but still quite relevant to the health of the foal, is the rectal temperature. The most likely detrimental situation with a neonatal foal is hypothermia (<37°C). This may occur due to ambient temperature or circulatory deficiencies in the foal. Therefore, a climate-controlled environment is important and attempts should be made to warm these foals. Hyperthermia may occur due to sepsis but is also commonly associated with a high ambient temperature or as a result of the energy expended while attempting to stand. Should there be any alterations in the normal temperature, the foals should be considered at greater risk and monitored appropriately.

Prematurity/Dysmaturity

An assessment of the foal’s readiness for birth is also important in its initial assessment. Caretakers should be familiar with the signs of prematurity/dysmaturity as described in Box 23-2 in order to address the problems and potential complications that these foals may encounter. Prematurity should be assessed in each foal with a combination of the clinical appearance of the foal and the length of gestation. The presence of such signs warrants that the foal be treated as a “high-risk” foal and should be examined by a veterinarian before the routinely scheduled examination. Problems with premature/dysmature foals may include a variety of respiratory, metabolic, and infectious diseases.

The definition of prematurity is any foal that is born <320 days of gestation and appears clinically immature. The gestational length should really be only one of several criteria used to define a premature foal. As well as having its limits in identifying prematurity, gestational age is a poor indication of a foal’s readiness for birth. A dysmature foal is generally considered to be a foal that is normal in terms of gestational age but immature in terms of size and physical appearance. The term immaturity is used to describe clinical signs despite the gestational age, whether it be premature or of the correct gestational age. These foals are not entirely ready for birth and may have difficulty maintaining homeostasis.

Foals with a body size that is too small for their gestational age have usually experienced some type of chronic derangement during gestation that interrupts the normal growth patterns in utero, resulting in intrauterine growth retardation. Such derangements would include in utero infections, twins, malnutrition, placentitis, severe uterine fibrosis, or other maternal illnesses. Symmetrical retardation results in all body parts proportionately decreased in size. This is thought to be due to diseases that inhibit mitosis, such as viral infections and prolonged compromise in the nutrient supply. Asymmetrical retardation is characterized by visceral and fat wasting with a relative preservation of fetal length and head circumference. This is most commonly due to uteroplacental vascular insufficiency late in gestation, sparing brain growth. Some of these small-for-gestational-age foals may actually exhibit more readiness for birth because of maturation of the adrenal glands with the chronic stress that results in normal cortisol levels and lung maturation at birth.

Premature/dysmature foals are usually smaller than would be expected and general weakness causes abnormally long times to stand and suckle, if they ever do get up. A combination of factors might contribute to their weakness (e.g., immature musculoskeletal system, hypoglycemia). They usually also have a decreased suckle reflex, which further increases the chances of FPT. Care must be taken with feeding immature foals, especially when they are being fed by feeding tube, since they tend to be more intolerant to enteral feeding. The cause of this is not completely understood but may be due to immaturity of the enterocytes leading to maldigestion and malabsorption. This may affect the foal’s ability to obtain adequate passive transfer, even if an adequate amount of good-quality colostrum has been fed by a nasogastric tube.

Immaturity in the musculoskeletal system includes joint laxity, flexor tendon laxity, and incomplete ossification of the cuboidal bones of the carpus and tarsus. Immature foals have a characteristic short, silky hair coat (Fig. 23-1). The hair matures from cranial to caudal and therefore the hair over the back and rear quarters will be the most immature. They can have a domed forehead, bulging eyes, soft lips, a deep red tongue, and floppy ears (Fig. 23-2). Immature foals will frequently have altered thermoregulation, so extra nursing care is required to prevent hypothermia (Fig. 23-3).

Figure 23-1 Short, silky hair coat of premature foal.

(Courtesy Dr. Keith Chaffin)

Figure 23-2 Floppy ears of premature foal.

(Courtesy Dr. Keith Chaffin)

Figure 23-3 Nursing care and thermoregulation of the neonate.

POST-PARTUM CARE

Resuscitation

Any facility that is foaling a considerable number of mares should be equipped and have staff available that is trained in foal resuscitation. This is especially important if “high-risk” pregnancies are foaling in the facility. A veterinarian should be present for the delivery of “high-risk” foals and should be prepared to perform resuscitation as needed. Of course any facility that is considering delivering foals by cesarean section should be fully prepared for resuscitation and care of a severely compromised foal. Cesarean sections hold many potential complications for both the mare and the foal. The foal is subjected to the depressive effects of the anesthetics used in addition to a high incidence of hypoxia. They will not have many of the natural events of a normal delivery that assist in the transition from intra-uterine to extra-uterine life. The action of compressing the foal through the pelvic canal expresses some of the amniotic fluid out of the lungs. The umbilical cord will be clamped, which brings about the concerns over the loss of blood and the increased risk of umbilical infection and patent urachus.

There are many causes of asphyxia in the foal, including maternal issues (e.g., systemic disease, hypotension, general anesthesia), placental abnormalities (e.g., placentitis, placental insufficiency), or fetal diseases (e.g., immaturity, infection, cardiac disease, umbilical cord compression). In addition, the delivery itself may be associated with asphyxia caused by dystocia, premature placental separation, or inappropriate positioning of the mare for delivery. When confronted with a lack of oxygen, the foal can start to breath in utero, which will result in complications such as meconium aspiration and reversion back to the fetal circulation. This will result in apnea when the foal is born. Resuscitation is required for any foals that are apneic or experiencing very low RRs (<10 breaths/min) or are gasping. Resuscitation is also in order should the pulse be absent or the foal flaccid and non-responsive. A prepared kit should be easily accessible that contains all that is required to allow for resuscitation (Box 23-3).

The approach to resuscitation should include a thorough assessment of the foal, followed by clearing of the airways. If the foal has just been delivered, the amniotic membranes must be removed from the nostrils. Any secretions in the airways should be removed by positioning the head down, gentle pressure on the chest, and suctioning of the fluid from the nasal passages and pharynx. Attempts should be made to stimulate the foal to breathe by rubbing the foal briskly with towels, tickling the nasal mucosa or ear canal, flexing the limbs, or gently compressing the chest wall. The controversial use of doxapram (0.5 mg/kg IV) may be attempted. If a veterinarian or trained staff is present, the foal should be intubated (7-9–mm nasotracheal tube). Alternatively, a mask can be used to administer oxygen and breaths safely. Positive-pressure ventilation can be administered with the use of several devices. Care must be taken when using an Ambubag since a full compression is about 1 L, which would be too much for most foals. With 100% oxygen attached to the system, the inspired air has about 21% oxygen. Another easy-to-use device that can be used with or without oxygen is the C.D. Foal Resuscitator (Fig. 23-4). This unit contains two plastic cylinders that draw air through the induction valves and then expel it to the foal via a face mask. It has a bi-directional mask that allows the foal to exhale without removing the mask. It also has an adapter so that it can be used to aspirate fluid from the airways before resuscitation. If no units are available, positive-pressure ventilation can also be achieved by mouth-to-tube/nostril. If a demand valve is used in a clinic setting, care must be taken not to apply too much pressure. A breath should be administered just long enough to see the chest start to rise before being released immediately.

Figure 23-4 C.D. Foal Resuscitator.

(Courtesy Dr. Sylvia Hall-Andrews.)

In addition to addressing respiration, resuscitation should also involve improvement of the foal’s circulation. External chest compressions should be administered 60–120 times each minute. The pulse and color of the mucous membranes should be re-evaluated frequently. If there is no improvement, intravenous fluids should be administered (lactated Ringer’s solution with 5% dextrose, 7.5% hypertonic saline, Dextran, etc.). If this also fails to correct the situation, the administration of vasoconstrictors should be considered, along with the application of abdominal counter pressure or intermittent abdominal compressions.

Umbilical Care

The umbilicus usually ruptures within 6–8 minutes of birth about 3–5 cm from the body wall. Concern over premature rupture of the chord and the loss of blood were not clinically significant.⁶ Using umbilical clamps can increase the chances of urachal and umbilical infections. The stump should be treated as soon as possible after the chord has ruptured. The use of chlorhexidine (0.5%) solution is preferred and appears to be superior to 2% iodine or povidone-iodine in decreasing the incidence of umbilical infection.^1,⁷ The stump should be treated every 6 hours for the first 24 hours and then continued based on need (e.g., recumbent foals may require prolonged treatment). The use of 7% iodine is discouraged since it is too caustic and can cause necrosis of the surrounding skin predisposing the foal to infections and patent urachus. The powdered preparations do not likely penetrate into pits in the skin and are not as effective as a solution. Therefore, dipping the stump into the solution is preferable. Solutions should not be used on multiple foals; each foal should have its own dip. To make the chlorhexidine solution add 1 part 2% chlorhexidine solution to 3 parts sterile water. This solution will not dry up the stump as quick as the iodine solutions. If more desiccation is desired, a small amount of alcohol can be added to the mixture (about 10% of the total volume).

Prophylactic Enemas

Meconium is the first feces that the foal must pass and is usually dark, firm, and pellet like. It can also appear as tarry, soft, sticky feces that can vary from dark brown to green. It is made up of digested amniotic fluid, mucus, epithelial cells, and bile. Should it be passed in utero, it is an indicator of fetal stress and the risk of pneumonia resulting from meconium aspiration is great and these foals should be treated as “high-risk” foals. All the meconium should normally be passed within 24 hours post-partum. The majority of foals pass it within 4 hours. Once the yellow milk feces are passed, the meconium can be deemed completely eliminated from the intestinal tract. Meconium impactions are the most common cause of colic in neonatal foals, and colts have a higher incidence than fillies, especially when considering impactions in the pelvic inlet.¹ Foals that have had prolonged gestations tend to have a higher incidence of meconium impactions.

Colostrum stimulates gastrointestinal motility and has some laxative properties. The act of suckling itself also stimulates gastrointestinal motility. Prophylactic enemas can be given to the foal soon after birth. The most frequently used are 100–120 ml of phosphate-buffered solution (Fleet) or mild soapy water. It is important for the caretaker to know how to administer the enema and how much and how frequently it may be given to avoid negative potential side effects. A precautionary measure is to leave instructions for the caretakers to administer the enema only once; if the foal fails to pass all the meconium or is showing signs of colic or straining, veterinary assistance should be sought. Veterinarians should use a soft tube when administering enemas while being careful not to irritate or rupture the rectum. Repeated enemas can cause mucosal irritation and may result in hemorrhage and edema that will then result in more straining and possibly further exacerbating the impaction. This makes it difficult to determine if the initial straining caused by the impaction has resolved. Persistent impactions can be treated with a retention enema with acetylcysteine diluted in water.

Colostrum Intake

Foals are born agammaglobulinemic and immunologically naïve but are immunocompetent.⁸ Therefore, they rely on the immunity imparted by the colostrum to fight infection for the first 4–9 weeks of life. The foal’s IgG concentration is a major factor in preventing infection in the neonates and therefore much attention is paid to ensure that the foal receives and absorbs adequate amounts.⁹^–¹¹ When a foal fails to absorb sufficient maternal antibodies, it results in FPT. The commonly accepted value for FPT is any serum concentration that is below 400 mg/dL, while concentrations between 400 and 800 mg/dl are considered partial FPT.^12,¹³ Foals with FPT have an increased risk of morbidity and mortality because of septicemia, and early intervention and treatment with antibody supplementation helps to improve the outcome.^11,¹⁴

Any foal that fails to suckle colostrum within the first 4 hours should be considered abnormal, and immediate intervention is recommended to get the colostrum into the foal (tube/bowl/bottle). Each foal should suckle at least 1 L of good-quality colostrum to provide adequate protection. Intervention is also in order should the colostrum itself not appear normal in character or quantity. Therefore, checking the colostrum and double-checking the foal’s IgG absorption are imperative. Normal colostrum is creamy yellow and sticky. The quality of the colostrum depends on the IgG content. Generally an IgG concentration in the colostrum >70 g/L is considered adequate. This concentration of IgG is associated with a specific gravity >1.060 on a colostrometer or refractometer.¹⁵ On a refractometer for measuring sugar concentrations, it should be at least 20%.¹⁶ Special attention should be paid to the colostrum of maiden or older mares, mares with a history of poor colostrum production in the past, premature deliveries, or if the mare has been leaking colostrum before foaling. The easiest, although not very accurate, way to assess the colostrum is with its physical appearance. If it is white or dilute, it is definitely not adequate.

Simple, quick, commercial kits are available that allow the caretaker to identify poor-quality colostrum prior to the foal suckling. A semiquantitative glutaraldehyde precipitation (Gamma-Check-C, Veterinary Immunogenics Ltd., Cumbria, UK) test is one such test. Colostrum samples that clot within 3 minutes contain more than 60 g/L of immunoglobulins; if the sample clots in 3–10 minutes, it has ≥40 g/L of immunoglobulins. If the sample takes more than 10 minutes to clot or does not clot at all, an alternative source should definitely be sought for the foal. Another simple test that requires 20 minutes and can be done stall side is the Colostrum Equine IgG Midland Quick Test Kit (Midland BioProducts Corp, Boone, IA). This test uses 50 g/L of IgG as adequate colostral IgG concentration. Other tests are available that take longer for results and require a laboratory, like the single radial immuno-diffusion test (RID). These tests are very accurate but are better suited to test colostrum that is destined for a frozen colostrum bank as opposed to testing colostrum that is to be consumed by a newborn foal. When storing colostrum for a colostrum bank, it may be stored in a normal domestic freezer. Although the nutritional components and some other immune proteins may be lost with this freezing, the colostrum should retain its IgG concentration for 12 months. The use of a −70°C freezer should result in the preservation of almost all the colostral components permanently.