At birth, a foal exhibits behavior patterns that have developed during the in utero period of approximately 340 days. By 90 days, when the fetus is approximately 12 cm, the legs and hooves are well formed. From the third month of gestation onward, fetal movements can be detected by ultrasonic study; these movements become more complex as gestation continues and the fetus matures. Bouts of in utero activity and rest occur. The peak of fetal activity occurs about three days prior to parturition and appears to lead to the attainment of the birth posture (Fraser et al. 1975).
In free-roaming herds, births typically occur in late spring. Some foal-ings do occur at other times of the year—in all seasons. Yet, under most feral conditions foaling is rare during winter. Under management conditions winter births are not as uncommon when parturition can occur in a stall. In fact, to coincide with the custom of recording a horse one year old at the beginning of the next January, some horse associations, for growth advan-tage in competitive events involving young horses, encourage foaling to occur early in the calendar year—out of phase with natural tendencies.
During parturition the forefeet of the foal appear shortly after the rup-ture of the chorio-allantoic membrane. At this time, stimulation of the fore-limbs may cause some motor response from the foal. But as the body of the foal passes through the maternal pelvis by additional uterine contractions,
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reactions by the foal cease, even to painful stimuli, until the hips are deliv-ered (Rossdale 1967a). With delivery past the mare’s pelvis, straining by the mare ceases, and the foal is officially born. The hooves are usually pig-mented, although temporarily capped by the blunt, soft, unpigmented hoof material (called the perinychium) present throughout much of the gestation period (Pollitt 1995).
Within seconds after the pelvic girdle of the foal leaves the maternal reproductive tract, the foal lifts its head and neck and assumes sternal recumbency. If intact, the amnion is thus ruptured, and breathing can com-mence unhindered by fetal membranes. The head is unsteady as the foal regulates its upright posture. The eyes are open. The ears remain back or protrude passively to the side. The tail is tucked, covering the perianal region.
Newborn Thoroughbred foals weigh between 38–62 kg (84–137 lb), breathe at a rate of 65±6.5 breaths per minute during the first minute of age, and have a rectal temperature of 37.1˚ to 38.9˚C (98.8˚–102.0˚F) and a heart rate of approximately 69 beats per minute. During the process of trying to stand, the heart rate can be as high as 200 beats per minute before stabilizing at about 96 (double the adult rate). By one hour of age, the res-piration frequency has dropped to 34 breaths per minute (as an adult it will be approximately 12). Body temperature averages about 38˚C (100˚F) after the first hour in healthy horses (Rossdale 1967b; 1968a; 1969).
In addition to the righting reflex shown in the first moments after birth, the foal’s initial movements appear to be a reaction to restraint by fetal mem-branes and to the hindlegs being not yet free of the maternal reproductive tract. If the mare remains recumbent, crawling movements by the foal, using the anteriorly extended forelegs assisted by motions of the head and neck, cause the neonate to move away from the mare. These locomotor move-ments drag the foal’s hindlimbs free of the mare’s vagina and usually cause the umbilical cord to sever as the distance increases (Waring 1970a).
Movements of the foal continue, usually in bouts. Once free from restraint, movements appear to be attempts at getting up. Often at 15 min-utes postpartum the foal has begun to raise its sternum off the substrate by pushing with forelegs extended anteriorly, maintaining its forehooves in con-tact with the substrate. The hindlegs during the initial efforts appear inert;
nevertheless, repeated attempts to stand occur. Usually not until after another 30 minutes do the hindlegs finally flex sufficiently to assist in lifting the body free of the ground. If disturbed, the foal and the mare stand sooner than they would otherwise.
Meanwhile the eyes of the foal, accompanied by appropriate head move-ments, begin to show distinct binocular orientation by 25 minutes of age. Ten minutes after birth, Rossdale (1967a) was able to elicit the pupillary light reflex, and head jerking was inadvertently induced by the flash of photo-graphic bulbs. Usually auditory orientation becomes evident about 40 min-utes postpartum when the ears begin to show distinct and independent orientation toward ambient sounds. Even before standing, the foal investigates its immediate surroundings using its eyes, ears, and nose. Periodic tactile and vocal stimulation by the mother begin soon after parturition (Waring 1970a).
Using data on 249 Thoroughbred foals, Rossdale (1967a) concluded the average time taken by neonates to stand was 57 minutes. The data ranged from 15 to 165 minutes, with more foals standing in the 40–60 minute inter-val than in any other period (Figure 4.1). Among the 127 foals observed by Campitelli et al. (1982), neonatal females first stood at 56.3 minutes whereas males stood at 70.6 minutes, on average. Stop-motion film analysis (War-ing 1970a) has shown the initial stance of the foal is unsteady with the legs spread laterally, hindlimbs extended posteriorly, and the forelegs positioned well forward with a slope of nearly 50˚. The crest of the neck is held with a slope of about 40˚ and the dorsal surface of the muzzle at 45˚. The foal shifts its neck and feet frequently to maintain its balance.
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Figure 4.1: Time from birth to first standing for 249 Thoroughbred foals.
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Locomotion forward, laterally, or backward is first accomplished by shuffling motions of the spread legs. These motions soon approximate a walking gait with little leg flexion. During the next hour, the leg flexion and walking pattern are perfected until coordination is achieved and the foal moves along easily.
The sucking reflex can be induced within minutes after birth by objects in contact with the mouth. Tactile stimulation along the anterior half of the head triggers and maintains searching and sucking activity. When sucking has not yet been induced by tactile simulation, I have observed standing foals as well as those in sternal recumbency exhibit spontaneous sucking motions in mid air 31–60 minutes postpartum. The lips and tongue were characteristi-cally shaped and sucking sounds could be heard; the head was extended and swayed from side to side as the mouth was elevated.
Nosing, sniffing, and licking of nearby objects occurs during the foal’s pre-nursing investigations. For example, the mare’s forearm, girth, gaskin, and perianal region are thus investigated if contacted.
Successful nursing is dependent upon the mare’s willingness to stand motionless and the foal’s ability first to stand and then to carry out nipple searching activities. Some mares subtly position themselves in a way that all the foal needs to do is extend its head and begin sucking. Such fortunate foals nurse soon after standing. Often foals inadvertently delay nursing by search-ing for long periods around the mare’s forelegs. In other cases, the restless mare may move away each time the foal probes the apparently tender udder region. In the latter instances, human attendants often intervene to restrain the mare and guide the foal to the milk source. Rossdale (1967a) found that foals born in box stalls nursed between 35–420 minutes following birth. The average was 111 minutes (Figure 4.2). Attendants facilitated some of the ini-tial nursing bouts; yet, other studies of confined and free-ranging horses have found similar results (e.g., see Tyler 1969; Waring 1970a; Boyd 1980).
Once nursing has occurred successfully the first time, the foal returns progressively more easily to the flank area and teats when attempting sub-sequent nursings. A foal will often suckle from one teat and then the other without changing its position beside the mother. The common stance is with the foal’s head tucked between the mare’s flank and hindleg, causing the foal to orient posteriorly relative to the mare with one shoulder close to the mother’s side. Inter-nursing intervals generally vary between 10 and 90 minutes for the first 24 hours. Drummond et al. (1973) found germ-free foals (fed ad libitum with milk formulated to approximate mare’s milk) drank 300-400 ml per feeding.
Defecation may occur prior to one hour of age in foals standing suc-cessfully; urination follows a few hours later with posture typical of the sex of the foal. Defecation occurs with the foal spreading the hindlegs, raising the tail 40˚ or higher above horizontal, and depressing the croup protrud-ing the anal area posteriorly. Strainprotrud-ing in an attempt to pass firm pellets is not uncommon.
The first few attempts to lie down often end in rough collapses, although the foal during the second hour postpartum, may try to slowly flex its closely placed legs to go down steadily first to its knees. Unsuccessful attempts to go down are often made at this early age, only to return instead to standing or walking. Resting may eventually be done by fatigued foals while standing. Not until after several tries does a foal lie down with coordination and ease. Having once gotten to its feet unassisted, subsequent standing is usually done readily and with success.
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Figure 4.2: The time of first nursing from the mare. Data from 245 foals.
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Vocalization is rare from newborn foals. Weak whinnies and squeals may be emitted during the first hour by foals when distressed or restless.
Yet it is during the second hour postpartum that the mare and foal overtly respond to each other’s sounds. The mare is the more vocal member of the pair.
At the end of one hour of age, the foal shows basic abilities in righting itself, maintaining its posture, investigative behavior, standing and moving about, care-seeking behavior, agonistic withdrawal when restrained, and sometimes other behaviors, such as ingestion, vocalization, and defecation (Figure 4.3).
During the second hour postpartum, the foal begins to follow and remain close to the mother, nuzzles her, and seeks her side upon the approach of others. The foal seems to show concern for the mother when she struggles with discomfort, such as when trying to expel the placenta and fetal mem-branes. When the mare is down and exhibits discomfort, the foal may cir-cle her restlessly and may whinny loudly following her groans. These behaviors are used as indicators that primary socialization (social imprint-ing) is occurring at this early age (Waring 1970a; 1970b).
Figure 4.3: Progression in the onset of behavior patterns of neonatal foals.
(Adapted from Waring 1970a and Reed 1980)
Sleep behavior begins as brief naps in the second hour of age and pro-gresses thereafter until deep sleep and drowsiness occupy much of the foal’s early life. Sleeping commonly occurs while completely prone or in a relaxed sternal recumbency, but when unable to lie down a foal will stand and doze with eyes mostly closed and neck nearly horizontal. In a study of Welsh ponies, Crowell-Davis (1994) noted foals spent 32 percent of the day-light period in lateral recumbency during their first week.
Fear of new objects begins as early as the end of the second hour of age;
but with the security provided by the close proximity of the mother, the foal continues to investigate its surroundings. Foals resist restraint from the early minutes of age; however, learning to adapt to restraint-type handling can occur in these early hours. Foals receiving such early handling sepa-rate from their mothers to greater distances and show more self-confidence in exploratory behavior. They also tolerate restraint better when older (War-ing 1970b).
At the end of two hours of age, the typical foal has perfected its earlier abilities until it can now walk easily, nurse, follow its mother, vocalize, inter-act socially with the mother, and seek shelter beside her. Fear and sleep have also appeared.
After several more hours the foal can, in addition, combat insects by nip-ping at its side and also by moving its tail and legs. It urinates typical of its sex, and it can trot and gallop with ease. It shows brief spells of exuberant play and has begun mouthing various objects, such as hay, grass, twigs, and feces. Some ingestion of these solids may occur. Tyler (1969) once observed a newborn nibble grass for a total of 15 minutes while the mare struggled for 40 minutes to expel the afterbirth. Foals have also been observed to exhibit in the first 24 hours the behavioral patterns of rolling, scratching, rub-bing, flehmen, yawn, and snapping (Unterlegenheitsgebärde). Swimming, too, is possible. Ron Keiper witnessed a day-old foal swim a four-foot-deep tidal stream to keep up with its mother (Ford and Keiper 1979).