Veterinary · Clinical · also MSVE VGO-421
Pregnancy accidents, normal birth, dystocia and the operations that relieve it, and the complications of the post-partum period and the newborn.
In the exams: ICAR AICE-JRF core group 07; ICAR AIEEA-PG 13 (ARGO); Nepal NLEV Theriogenology 8
Veterinary obstetrics is the study of pregnancy after it is established, of birth, of the difficulties of birth and the operations that relieve them, and of the dam and newborn in the days after birth. It is taught across species: the cow and buffalo, the ewe and doe, the sow, the mare, and the bitch and queen. The same principles apply to all, but each species has its own anatomy, its own hormonal control of birth and its own common emergencies, and this manual points out those differences as it goes.
The subject is examined everywhere. In India it forms part of Animal Reproduction, Gynaecology and Obstetrics in the ICAR Master's and PhD entrance examinations and the state Veterinary Officer papers; in Nepal it falls under Theriogenology in the licensing examination; in China it is the obstetrics part of the clinical paper; and in North America, the United Kingdom, Australasia and South Africa it appears in licensing examinations as clinical reasoning about real cases. Drug doses in this manual are given only where they are standard textbook values, and every one must be checked against the product label and national formulary, because products, approvals and withdrawal periods differ between countries.
The placenta is the organ of exchange between dam and fetus. Its shape and the number of tissue layers between the two blood supplies differ by species, and both affect obstetric practice. Ruminants (cow, buffalo, ewe, doe) have a cotyledonary placenta: the fetal cotyledons interlock with maternal caruncles to form placentomes, the button-like structures that can be felt per rectum in pregnancy. Because separation has to happen at many discrete attachment points, ruminants, and the cow in particular, are prone to retained fetal membranes. The mare and sow have a diffuse epitheliochorial placenta attached over the whole endometrial surface; the mare's placenta normally ruptures at the cervical star, the thin avillous area over the internal os. The bitch and queen have a zonary endotheliochorial placenta, a band around the middle of each fetal sac, and haemorrhage from the zone's marginal haematoma gives the bitch's birth fluids their dark green colour (uteroverdin). The fetal membranes are the amnion, which encloses the fetus in amniotic fluid, and the allantochorion, which lies against the endometrium and holds allantoic fluid. At birth the allantochorion usually ruptures first ("first water bag") and the amnion appears at the vulva as the second bag, often around the fetal feet.
Gestation length is the interval from fertile service or ovulation to birth. Values vary with breed, sex of fetus, litter size and environment, so treat the following as typical figures rather than fixed numbers. Cattle average about 280 to 285 days, with dairy and some beef breeds differing by a week or more. River buffalo average about 310 days, and swamp buffalo run longer, roughly 320 to 330 days. The ewe and doe average about 147 to 150 days. The sow averages about 114 to 115 days, remembered as three months, three weeks and three days. The mare averages about 340 days with a wide normal range, commonly quoted as 320 to 360 days, and a live foal born outside that range is not in itself abnormal. The bitch whelps about 63 days after ovulation, which is about 65 days after the pre-ovulatory luteinising hormone surge; timed from mating the interval looks far more variable (roughly 57 to 72 days) because sperm survive for days in the bitch's tract. The queen averages about 63 to 65 days. Prolonged gestation in cattle can indicate fetal pituitary or adrenal failure, since the fetus triggers birth; this is why a fetus with an absent pituitary may remain in utero well beyond term.
Presentation is the relationship between the long axis of the fetus and the long axis of the dam's birth canal, together with the part of the fetus that enters first: anterior (cranial) longitudinal, posterior (caudal) longitudinal, transverse (dorsal or ventral, depending on which surface of the fetus faces the inlet) or vertical. Position is the surface of the maternal birth canal against which the fetal vertebral column lies: dorsal (dorso-sacral, the normal position, fetal back under the dam's sacrum), ventral (dorso-pubic, fetus upside down) and right or left lateral (dorso-iliac). Posture is the disposition of the fetal head, neck and limbs relative to the fetal body: extended or flexed. The normal disposition for a calf, lamb, kid or foal is anterior longitudinal presentation, dorsal position, with both forelimbs and head extended, the head resting on the forelimbs. Posterior presentation with both hindlimbs extended is also compatible with unassisted birth in cattle and sheep, though it carries more risk because the umbilical cord is compressed early. In the bitch, queen and sow, posterior presentation is common and normal; in the bitch it is often quoted at around 40 per cent of pups.
Abortion is the expulsion of a dead fetus, or of a live fetus too immature to survive, before the end of normal gestation. Loss before the end of the embryonic period (organogenesis, roughly the first 42 to 45 days in cattle) is called early embryonic death and usually passes unseen as a return to oestrus. In any abortion, handle the fetus and membranes with gloves and treat them as infectious until proven otherwise. Several abortifacient agents are zoonotic (Brucella, Chlamydia abortus, Coxiella burnetii, Toxoplasma gondii, Listeria), so pregnant women should not handle aborted material, and many are notifiable to the national veterinary authority under lists that differ by country. The best submission is the fresh fetus with its placenta, plus a serum sample from the dam and, ideally, paired sera from other dams in the group. Non-infectious abortion has many causes. Nutritional causes include severe energy deficit and deficiencies of iodine, selenium and vitamin A. Toxic causes include nitrate, ergot alkaloids, and in cattle the needles of certain pines, which can cause late-gestation abortion with retained placenta. Drugs are an important iatrogenic cause: prostaglandin F2 alpha and its analogues cause luteolysis and therefore abortion in species whose pregnancy depends on the corpus luteum at that stage, and corticosteroids given in late gestation can induce premature birth in ruminants. Every practitioner must check pregnancy status before giving these drugs to a breeding female.
Brucella abortus causes abortion mainly in the last trimester, with a necrotic placentitis in which the intercotyledonary placenta becomes thickened and leathery and cotyledons are necrotic; retained placenta and infertility follow, and it is a serious zoonosis. Leptospira species cause abortion, stillbirth and weak calves, often weeks after the dam's infection. Bovine herpesvirus 1 (the agent of infectious bovine rhinotracheitis) usually causes abortion in the second half of gestation with a markedly autolysed fetus. Bovine viral diarrhoea virus can cause early embryonic death, abortion, mummification, congenital defects such as cerebellar hypoplasia, and persistently infected calves when infection occurs in roughly the first four months of gestation. Neospora caninum, a protozoan whose definitive host is the dog, is one of the most frequently diagnosed causes of bovine abortion worldwide, typically from mid-gestation, and passes vertically from dam to fetus. The venereal agents Tritrichomonas foetus and Campylobacter fetus subspecies venerealis cause mostly early embryonic death and early abortion, seen as irregular returns to service in naturally bred herds; trichomonosis can also cause pyometra.
In ewes and does, enzootic abortion caused by Chlamydia abortus typically produces abortion or stillbirth in the last two to three weeks of pregnancy with a thickened, reddish-brown placenta; ewes that abort are usually immune afterwards. Toxoplasma gondii, whose definitive host is the cat, causes early fetal death and resorption, mummified fetuses, abortion and weak lambs, with small white necrotic foci in the cotyledons. Campylobacter fetus subspecies fetus and Campylobacter jejuni cause late abortion in ewes, and Brucella melitensis, Coxiella burnetii and Listeria are important in goats and sheep, especially where they are zoonotic hazards. In pigs, porcine parvovirus causes the syndrome remembered as SMEDI (stillbirth, mummification, embryonic death and infertility), and porcine reproductive and respiratory syndrome virus causes late-term abortion, premature farrowing and weak piglets; Leptospira, Aujeszky's disease virus, classical swine fever virus and Brucella suis are other causes. In the mare, equine herpesvirus 1 causes late-gestation abortion, sometimes in outbreaks, typically without warning signs and with a fresh fetus. Bacterial placentitis, often ascending through the cervix, causes premature udder development, vulval discharge and abortion; twin pregnancy is the classic non-infectious cause of late abortion in the mare because the placentas compete for space. In the bitch, Brucella canis causes abortion, typically in the last third of gestation, and canine herpesvirus causes fetal and neonatal death.
Foetal mummification is the death of a fetus in utero after the formation of bone, without bacterial invasion, with resorption of the fetal fluids and dehydration of the fetus and membranes into a firm, dry, brown mass. Because the cervix remains closed and no bacteria enter, the fetus is preserved rather than decomposed. In cattle the corpus luteum usually persists, so the cow does not return to oestrus and the owner often assumes she is simply carrying a long pregnancy. It is usually discovered when the cow passes her due date without udder development, or at rectal examination, which finds a firm mass in a uterus smaller than expected, with no fluid, no fremitus in the middle uterine artery and no placentomes. The traditional description in cattle is papyraceous (paper-like) mummification. Causes include twin pregnancy where one fetus dies, bovine viral diarrhoea virus, umbilical cord torsion and genetic factors; in many cases no cause is found. Treatment in the cow is luteolysis with a prostaglandin F2 alpha analogue, after which the mummy is usually expelled into the vagina within a few days and can be removed manually with lubrication; occasionally it lodges in the cervix or vagina and needs traction or, rarely, hysterotomy. In the sow and in carnivores mummified fetuses are common within otherwise normal litters, and in the sow a high proportion of mummies of varying sizes points to porcine parvovirus. Foetal maceration is the bacterial decomposition of a dead fetus within the uterus. It usually follows abortion or dystocia in which the cervix opens partly and bacteria enter but the fetus is not expelled. The soft tissues liquefy, leaving fetal bones in a thick, foul-smelling pus. Emphysema (gas formation) often precedes maceration when the fetus dies at term. On rectal examination the bones grate against each other within a thickened uterus, and there is a fetid discharge from the vulva. Systemic illness, chronic endometritis and adhesions are common. The prognosis for future fertility is poor, and culling is often the economic choice in food animals.
Hydrops means an abnormal accumulation of fluid in the fetal membranes. Two forms are recognised. Hydrallantois (hydrops allantois) is excess fluid in the allantoic sac. It accounts for the great majority of bovine cases, commonly quoted as around 85 to 90 per cent. It is associated with disease of the placenta itself: fewer functional placentomes, compensatory accessory (adventitial) placentation, and abnormal fluid transport. It develops rapidly, usually over a few days to a few weeks in the last trimester, and the fluid is a watery, clear transudate that can exceed 100 litres in severe cases. The abdomen enlarges bilaterally, the cow becomes dull, anorexic and may have difficulty breathing and standing, and per rectum the uterus is tense and greatly distended so that neither the fetus nor the placentomes can be palpated. Hydramnios (hydrops amnii) is excess fluid in the amniotic sac. It is usually associated with a fetal defect that prevents normal swallowing of amniotic fluid, such as abnormalities of the head and pharynx or the inherited achondroplastic "bulldog" calf. It develops slowly over months, the fluid is more viscous and syrupy, the abdomen is pear-shaped rather than tensely rounded, and per rectum the uterus is less tense so that the fetus and placentomes can usually be felt.
The decision is between terminating the pregnancy and slaughter. In hydrallantois the calf is often small or abnormal and rarely survives, the dam is at risk of recumbency, rupture of the prepubic tendon, ventral hernia and uterine rupture, and future fertility is uncertain because the placental defect may recur. Salvage for slaughter, where legal and where the carcass passes inspection, is often recommended in advanced cases. If the pregnancy is terminated, induction with a corticosteroid combined with prostaglandin F2 alpha is used in cattle, but uterine inertia is common because the myometrium is overstretched, so the cow needs assistance and close supervision; retained placenta and metritis often follow. Caesarean section is an alternative, but the fluid must be released slowly, in stages, while intravenous fluid therapy supports the circulation, because sudden decompression of the abdomen causes pooling of blood in the splanchnic vessels and hypovolaemic shock. Hydramnios has a better outlook for the dam, because the underlying problem is fetal rather than placental, and fertility afterwards is usually unaffected unless the fetal defect is hereditary; with a known genetic defect the sire should not be used again on related females.
Uterine torsion is rotation of the pregnant uterus about its long axis. It is most important in cattle and buffalo, occurs in the mare, and is uncommon in small ruminants, the sow and carnivores; in the bitch and queen one horn may twist on itself. In ruminants most torsions develop at the end of gestation, usually during the first stage of labour, when the fetus becomes active and the uterus is least stable. Torsion is described by direction, degree and site. Direction is named as seen by an observer standing behind the dam: clockwise (to the right) or anticlockwise (to the left). Site is post-cervical when the twist includes the anterior vagina, which is the usual form, or pre-cervical when the twist lies in front of the cervix and the vagina is normal. Predisposing factors include the unstable suspension of the gravid uterus from its lesser curvature by the broad ligaments, a large single fetus, a small non-gravid horn, and sudden falls or rolling. Torsion is strikingly common in the buffalo, where it is reported in many South Asian clinical surveys as the leading cause of dystocia. Reported proportions of clockwise versus anticlockwise torsion differ between studies and species, so direction must be determined in every case rather than assumed.
The dam is usually at or near term, shows signs of first-stage labour that fail to progress, with restlessness, intermittent mild colic, kicking at the abdomen, anorexia and sometimes straining. The water bag does not appear. Where the torsion is severe or long-standing, the uterine blood supply is compromised, the fetus dies and the dam becomes toxaemic and shocked. Diagnosis is by vaginal and rectal examination. In a post-cervical torsion, the vaginal wall shows spiral folds that narrow toward the cervix; the direction of the folds indicates the direction of the torsion, and in severe torsion the hand cannot pass to the cervix. Per rectum, the broad ligaments are felt crossing each other: in a clockwise torsion, the left broad ligament is pulled tightly over the top of the uterus toward the right, and the right ligament passes down beneath it. Pre-cervical torsion is diagnosed per rectum only, since the vagina is normal. In the mare, torsion occurs mostly in the last months of pregnancy rather than at term and presents as colic; diagnosis is by rectal palpation of the broad ligaments.
Correction aims to untwist the uterus and then deliver the fetus. Four approaches are used, alone or in sequence. First, rotation of the fetus per vaginam: with a small torsion and a partly open cervix, the fetus is grasped under the shoulder and rocked over, carrying the uterus with it. Second, rolling the dam: the dam is cast on the side toward which the torsion is directed and rolled rapidly in the same direction, so that her body turns faster than the heavy uterus and catches up with it. For a clockwise (right) torsion she is cast on her right side and rolled to the right. A modification widely used in India and elsewhere places a plank across the upper flank with a person standing on it while the dam is rolled slowly, fixing the uterus while the body turns around it. After each roll the vagina is checked: success is shown by disappearance of the spiral folds. Rolling in the wrong direction increases the torsion. Third, laparotomy: through the flank, the uterus is rotated by hand, and caesarean section is often done at the same time. Fourth, caesarean section without correction when the uterus cannot be untwisted or is devitalised. In the buffalo, the cervix often fails to dilate after successful correction, especially when the torsion was long-standing; clinicians then wait a limited time with supportive therapy and proceed to caesarean section if dilation does not follow. Prognosis depends mostly on duration: early cases do well, while late buffalo cases with a dead emphysematous fetus, uterine necrosis or rupture have a high dam mortality.
In ruminants the fetus decides when birth begins. As the fetus matures, its hypothalamus and pituitary increase secretion of adrenocorticotrophic hormone, and the fetal adrenal cortex releases a surge of cortisol. Fetal cortisol induces placental enzymes, including 17 alpha-hydroxylase, that divert the placental synthesis of progesterone toward oestrogens. Falling progesterone and rising oestrogens change the myometrium from a quiet to an excitable tissue: gap junctions and oxytocin receptors increase, and the uterus becomes able to contract in a coordinated way. Oestrogens also promote synthesis of prostaglandin F2 alpha by the endometrium and cotyledons. In species that depend on the corpus luteum for progesterone at term, such as the cow, goat, sow and bitch, this prostaglandin causes luteolysis, removing the main source of progesterone. In species where the placenta maintains pregnancy late on, such as the ewe and mare, the switch in placental steroid synthesis is the key step. Relaxin, from the corpus luteum or placenta depending on the species, softens the cervix and pelvic ligaments. Once the fetus begins to press into the cervix and vagina, sensory nerves stimulate the release of oxytocin from the posterior pituitary, which increases uterine contractions and so pushes the fetus further, a positive feedback loop called the Ferguson reflex. The same understanding explains how parturition is induced: corticosteroids mimic the fetal signal in ruminants, and prostaglandin F2 alpha causes luteolysis where the corpus luteum is essential. Signs of approaching birth are useful for planning supervision but none predicts the hour. The udder enlarges, and in the mare and cow the teats fill; waxing, a bead of dried colostrum at the teat end, appears in many mares one to two days before foaling, though some foal without it and some leak milk for days. The pelvic ligaments relax, so the tailhead appears raised and the area beside it sinks; in the cow, relaxation of the sacrosciatic ligaments is a useful sign. The vulva swells and becomes flaccid, and the cervical seal liquefies to a stringy mucus. In the bitch, the rectal temperature falls by about 1 degree Celsius, often below about 37.5 degrees, roughly 12 to 24 hours before whelping starts, following the fall of plasma progesterone; the bitch also becomes restless, seeks a nest and may refuse food.
Labour is divided into three stages. Stage one is preparatory: the cervix dilates and the fetus rotates into the correct position and posture, driven by uterine contractions that the dam does not visibly strain against. The dam is restless, looks at her flank, lies down and gets up, and may sweat (mare) or stop eating. In the cow the first stage typically lasts about 2 to 6 hours, longer in heifers; in the mare it is often 1 to 4 hours; in the bitch it is commonly 6 to 12 hours and can be longer in a first whelping. Stage two is expulsion of the fetus. It starts when the fetus enters the pelvic canal and abdominal straining begins, and ends with delivery. In the cow it usually lasts from about half an hour to 1 hour, and up to 2 to 4 hours in heifers; in the ewe it is usually under 1 hour for a single lamb; in the mare it is short and forceful, usually 10 to 30 minutes, and any delay beyond about 30 minutes is an emergency because the foal's placental oxygen supply fails quickly after the allantochorion separates. In the sow, piglets are born at intervals, commonly around 15 to 20 minutes, over a total of a few hours. In the bitch, pups usually follow at intervals of 30 minutes to 2 hours. Stage three is expulsion of the fetal membranes. In the cow it usually occurs within about 6 to 12 hours; failure within 12 to 24 hours defines retained placenta. In the mare the placenta is normally passed within about 3 hours, and often within an hour. In litter-bearing species, membranes are passed with or soon after each fetus, so the second and third stages alternate.
Most births need no help. Intervention is justified when stage one or two fails to progress in the expected time (in the cow and ewe, about 30 minutes of strong straining without progress), when the fetus is visibly malpresented, when the dam is exhausted or ill, and in the mare as soon as the second stage stalls. In the bitch, recognised criteria include strong, persistent straining for more than about 20 to 30 minutes without a pup, more than about 2 to 4 hours between pups, green discharge without a pup within a few hours, and gestation clearly beyond term from a known ovulation date. The obstetric examination begins with the history (duration, straining, fluids, previous assistance), a general clinical examination, and then a clean vaginal examination with the tail held aside, the perineum washed and the arm or gloved hand well lubricated. The clinician determines the state of the birth canal and cervix, the presentation, position and posture, the relative size of the fetus to the canal, and whether the fetus is alive. Signs of life include the pedal (withdrawal) reflex, the suck reflex, the corneal reflex, the anal reflex in posterior presentation and a palpable umbilical pulse. An emphysematous fetus, with crepitus under the skin and hair that pulls away easily, has been dead for at least a day.
Dystocia means difficult birth: birth that is prolonged or impossible without help. It is classified by origin into maternal causes and fetal causes, and within each into failure of the expulsive force and obstruction of the birth canal. Frequency varies greatly by species, breed and management. It is commonest in first-calf heifers, in beef breeds with heavy muscling, in some breeds of sheep carrying large singles, and in brachycephalic and toy breeds of dog. The most frequent single cause differs by species: fetomaternal disproportion (a fetus too large for the dam's pelvis) dominates in heifers; faulty fetal disposition is prominent in the mare, because of the foal's long limbs and neck; uterine torsion is leading in buffalo in many surveys; malpresentation, twins and incomplete cervical dilation (ringwomb) are important in the ewe and doe; and primary uterine inertia is the commonest maternal cause in the bitch. Each species therefore needs its own checklist.
Uterine inertia is failure of the myometrium to contract strongly enough to deliver the fetus. Primary inertia is present from the start of labour. Causes include hypocalcaemia, overstretching of the uterus by twins, a large litter or hydrops, obesity, systemic disease and, in the bitch, a litter too small to stimulate labour or large enough to overstretch the uterus. Secondary inertia is exhaustion of the myometrium after prolonged, unproductive contraction against an obstruction, and it is therefore a consequence of another dystocia rather than a cause. The distinction matters because primary inertia may respond to correction of calcium deficit and, when the canal is open and the fetus correctly disposed, to oxytocin, whereas secondary inertia will not respond until the obstruction is removed, and giving oxytocin against an obstruction risks uterine rupture. In the bitch, oxytocin should be given only after an obstruction has been ruled out by digital examination and, where available, radiography or ultrasonography; calcium is sometimes combined in practice.
The maternal birth canal is the bony pelvis and the soft passages: cervix, vagina and vulva. A narrow bony pelvis is the commonest maternal obstruction in cattle and is the maternal half of fetomaternal disproportion. It follows breeding heifers at too low a body weight, and poor growth; pelvic measurement before breeding is used in some beef systems, though it predicts dystocia imperfectly. In the soft canal, incomplete cervical dilation is the key problem. In the ewe and doe it is called ringwomb: the cervix dilates only to a small ring, and some cases respond to gentle manual dilation over a period, while others need caesarean section; forcing the cervix causes tears and severe haemorrhage. In the cow incomplete dilation can follow premature intervention, uterine torsion or hypocalcaemia. In the buffalo it frequently follows correction of a torsion. A small or poorly relaxed vulva is common in heifers and may need patient stretching or an episiotomy, an incision made dorsolaterally from the vulval lip to avoid tearing into the rectum. Other obstructions include uterine torsion (chapter 4), vaginal cystocele (the urinary bladder prolapsed through a vaginal tear or retroverted), tumours, fibrous bands, and in the bitch inguinal herniation of the gravid uterus.
Fetal oversize can be absolute, when the fetus is abnormally large for its breed, or relative, when a fetus of normal size meets a dam that is too small. Risk factors for a large calf include sire breed and individual sire, male sex, singletons, a long gestation, and in some breeds inherited muscular hypertrophy (double muscling). A heifer bred too young or too light is the classic relative case. Fetal oversize also occurs with a dead fetus that has become emphysematous, because gas inflates the tissues and the skin loses its slipperiness. In the ewe, a large single lamb is a common problem in flocks that usually carry twins. A fetal monster is a grossly malformed fetus. Monsters are uncommon but important because they usually need fetotomy or caesarean section. In cattle, schistosomus reflexus is the most important: the spine is sharply flexed so that the head and tail approach each other, the body wall fails to close and the abdominal organs lie exposed. On vaginal examination the clinician may feel viscera first, or four limbs and head together. Perosomus elumbis is a fetus lacking lumbar and sacral spinal segments, with rigid, fixed hindlimbs. Fetal ascites (fluid in the abdomen), anasarca (generalised subcutaneous oedema), hydrocephalus and limb contracture, as seen after Akabane or Schmallenberg virus infection in ruminants, also obstruct birth. Ascites and anasarca can sometimes be relieved by puncturing the fetal abdomen or skin to release fluid; hydrocephalus by incising the skull. Where the monster is dead and the canal is large enough, fetotomy is often preferred; otherwise caesarean section.
Faulty disposition is any presentation, position or posture that prevents normal delivery. Postural defects are the most common. In anterior presentation they include carpal flexion (one or both forelimbs flexed at the knee), shoulder flexion (the whole limb retained alongside the body, so only the head appears), lateral deviation of the head (the head turned back alongside the fetal chest) and downward deviation of the head (the nose pointing down beneath the pelvic brim), and elbow flexion, in which the elbow is caught at the pelvic brim and the feet appear level with or behind the muzzle. In posterior presentation, hock flexion and hip flexion occur; bilateral hip flexion is called breech presentation, in which only the tail is felt in the passage. Positional defects include ventral (dorso-pubic) and lateral positions, which in the cow often accompany uterine torsion. Presentational defects include transverse presentation, in which the fetus lies across the canal with either its back (dorsal transverse) or its four limbs (ventral transverse) toward the inlet, and vertical presentation, which is rare. In litter-bearing species, two fetuses may enter the canal together, and in the bitch lateral deviation of the head is a recognised cause of obstruction. In twin calvings, both calves may present at once, often one anterior and one posterior, and the clinician must identify which limbs belong to which calf before any traction.
The cow is best examined standing, restrained in a crush or by a halter, with the tail tied aside. Caudal epidural anaesthesia is widely used: local anaesthetic is injected into the epidural space at the sacrococcygeal or first intercoccygeal space. It stops abdominal straining, which makes repulsion possible, and desensitises the perineum, but it does not stop uterine contractions. In an adult cow of about 500 kg, a commonly used volume is about 5 to 6 millilitres of 2 per cent lidocaine by caudal epidural injection — confirm against the product label and your national formulary. Larger volumes spread cranially and can cause hindlimb weakness and recumbency, which is dangerous in a cow that must stand. Mutation is the set of manoeuvres that returns the fetus to a normal presentation, position and posture. Repulsion means pushing the fetus back out of the pelvis into the uterus to create space. It is done between contractions, with the hand or a padded repeller placed on the chest or between shoulder and neck in anterior presentation, or below the tail and perineum in posterior presentation. Epidural anaesthesia makes it easier. Rotation means turning the fetus about its long axis to correct position, for example from ventral or lateral to dorsal; crossed limbs can be used as a lever, and rotation is often easier with the fetus partly repelled. Version means turning the fetus about its transverse axis to convert a transverse or vertical presentation into a longitudinal one; the fetus is usually converted to posterior presentation because the hindlimbs are generally nearer the inlet and easier to bring up. Extension or adjustment of the extremities corrects flexed limbs and a deviated head. The rule for a flexed limb is to repel the proximal part, rotate the distal part outward, and bring the foot up in an arc while the hand cups the hoof or claws to protect the uterine wall. For carpal flexion, the carpus is pushed up and back while the foot is drawn medially and forward. For hip flexion, the hindlimb is first converted to hock flexion by repelling the rump and drawing the hock back, and then the hock is flexed and the foot brought up. A deviated head is brought round by holding the muzzle or the lower jaw, or with a head snare or eye hooks; the orbits must not be used for heavy traction on a live fetus.
Forced extraction is delivery by traction applied to the fetus, and it is only appropriate when the fetus is correctly disposed and there is room for it to pass. Obstetric chains or ropes are looped above the fetlock with a half hitch below it, which spreads the force across two points; a head rope or snare behind the ears and through the mouth keeps the head aligned. Traction is applied in time with the dam's straining and relaxed between. In anterior presentation, pull first upward and backward to lift the head and forelimbs over the pelvic brim, then straight back, then downward toward the dam's hocks as the chest emerges. A practical guide used in cattle is that if the head and forelimbs can be brought into the canal and the fetlocks drawn clear of the vulva by moderate traction, delivery per vaginam is likely; if not, an alternative should be chosen. A hip lock, in which the fetal pelvis catches at the maternal pelvic inlet, is relieved by stopping traction, repelling slightly and rotating the calf by about 45 to 90 degrees so that its widest hip diameter meets the widest diameter of the dam's pelvis, then pulling downward. In posterior presentation, once the calf's umbilical cord is trapped against the pelvic brim, delivery should be completed quickly because the calf will attempt to breathe in fluid. A mechanical calf puller multiplies force greatly and must be used with care, in the direction of the birth canal and synchronised with straining, since excessive force causes fractures of the calf's ribs and limbs, vaginal lacerations and maternal nerve injury. Traction beyond that of two or three people is generally considered excessive in the cow.
Fetotomy (also called embryotomy) is the division of a fetus within the birth canal or uterus so that it can be removed in parts. It is used almost always on a dead fetus. Indications include a dead fetus that is too large to deliver whole, faulty dispositions that cannot be corrected by mutation because of fetal rigidity or lack of room, monsters such as schistosomus reflexus, and an emphysematous fetus that cannot be extracted. Contraindications include a live fetus, a canal too narrow for the parts to pass, an incompletely dilated cervix, uterine rupture, and a dam too ill for a long procedure, where caesarean section is safer. Fetotomy is performed mostly in cattle and buffalo, less often in the mare, where the cervix and vagina are easily damaged and the number of cuts should be kept to a minimum, and rarely in small ruminants. It is not used in the sow, bitch or queen. Two methods exist. Subcutaneous fetotomy uses knives and hooks to cut beneath the skin, so the skin remains to cover sharp edges; it is older and now little used. Percutaneous fetotomy uses a tubular wire-saw fetotome through which an obstetric wire saw is threaded around the part to be removed; the tubes protect the maternal tissues from the wire, and the cut passes through skin, muscle and bone together. Percutaneous fetotomy is now the standard method in most countries.
The dam is restrained standing if possible and given caudal epidural anaesthesia; copious lubricant is used throughout. The wire is placed around the part, the fetotome head is held against the fetus at the level of the cut, and an assistant saws with long, even strokes. Commonly described cuts for a calf in anterior presentation include removal of the head at the atlanto-occipital joint when the head is deviated and cannot be corrected, removal of a forelimb together with the scapula when the shoulders are too large, and a transverse cut through the thorax or abdomen behind the ribs to divide the fetus into front and hind parts. The hindquarters are then divided by splitting the pelvis in the midline, and each half is removed with a hindlimb. In posterior presentation, a hindlimb can be removed through the hip joint, or the fetus divided transversely. A complete fetotomy requires several cuts; a partial fetotomy, often a single cut, is frequently enough. Complications include lacerations of the vagina and cervix, uterine rupture, haemorrhage, retained placenta, metritis, and obturator nerve paralysis if extraction was forceful.
Caesarean section (hysterotomy through a laparotomy) is the surgical delivery of a fetus through an incision in the abdominal wall and uterus. Indications in cattle and buffalo include fetomaternal disproportion that traction cannot overcome, incomplete cervical dilation, uterine torsion that cannot be corrected per vaginam or by rolling, some monsters, an uncorrectable faulty disposition with a live calf, uterine rupture, and elective delivery of valuable or oversized calves. In small ruminants ringwomb and fetal oversize are the main indications. In the mare, it is indicated when controlled vaginal delivery fails within minutes. In the bitch and queen it is indicated for obstructive dystocia, primary inertia unresponsive to medical treatment, a fetus in distress, and electively in breeds that commonly cannot whelp naturally, particularly brachycephalic dogs. The result depends above all on timing: the longer the dystocia, the worse the fetus and the more contaminated the uterus. Delay is the commonest avoidable cause of failure.
The standard approach in cattle is the left flank laparotomy with the cow standing, under regional anaesthesia such as a proximal or distal paravertebral block of the thirteenth thoracic and first and second lumbar spinal nerves, or an inverted-L block. A vertical incision is made in the middle of the left paralumbar fossa, long enough to exteriorise the uterus, usually 30 to 40 centimetres. The left flank is used because the rumen holds the intestines away from the incision. After exploration, the pregnant horn is exteriorised, and the uterine incision is made along the greater curvature over the fetal limbs, away from the placentomes and major vessels, long enough to avoid tearing as the calf is delivered. Loose membranes are removed but adherent ones are left. The uterus is closed with an absorbable suture in one or two continuous inverting layers, such as the Utrecht pattern, Cushing or Lembert, which bury the cut edges and reduce adhesions. In the buffalo, many cases arrive late after a torsion with a dead, emphysematous fetus and a friable uterus; a ventrolateral or ventral approach in lateral recumbency is often chosen, and the outcome is poorer than in the cow.
In the ewe and doe, a left flank approach with local or regional anaesthesia is standard, with the animal in right lateral recumbency or standing. In the sow, a flank approach in lateral recumbency is common, and several piglets can often be milked to one uterine incision near the bifurcation. In the mare, caesarean section is done under general anaesthesia through a ventral midline incision with the mare in dorsal recumbency. The mare's uterus bleeds more than the cow's, so a continuous haemostatic suture is placed around the edge of the uterine incision before closure, and the mare is at higher risk of retained placenta afterwards. In the bitch and queen, the approach is a ventral midline laparotomy, and the uterus is opened in the body or proximal horn so that fetuses can be milked to one incision. Anaesthesia is chosen to limit depression of the pups and kittens: short-acting induction agents, inhalational maintenance and a local anaesthetic line block are commonly combined, and drugs with long neonatal depressant effects are avoided. Ovariohysterectomy can be done at the same time, including an en bloc technique in which the whole gravid uterus is removed and the fetuses delivered rapidly by assistants, but owners who want future litters need a conserving procedure.
Vaginal prolapse is eversion of part or all of the vaginal wall through the vulva, often with the cervix. It occurs mostly in the last trimester of pregnancy, and is common in the ewe, the cow and particularly the buffalo, in which pre-partum prolapse is a major field problem in South Asia. Contributing factors include relaxation of the pelvic tissues under late-pregnancy oestrogens, raised abdominal pressure from the uterus, rumen fill and fat, standing with the hind end downhill, hypocalcaemia and a heritable tendency in some breeds. Prolapses are graded by severity. In the mildest grade, a mass of vaginal floor protrudes only when the animal lies down and returns when it stands. In more severe grades, the prolapse persists when standing, the bladder may be retroverted into it so the animal cannot urinate, the cervix is included, and in chronic cases the tissues become dry, lacerated, infected and necrotic. Treatment is to clean the prolapse, give caudal epidural anaesthesia, drain the bladder by lifting the mass, replace the tissue, and retain it. Retention methods include a buried purse-string suture of wide tape around the vulva (Buhner's method), mattress or quill sutures across the vulva, and in ewes an external retainer or harness. Any retention suture must be released at the onset of labour, or the dam will tear. Because of recurrence and heritability, affected ewes and cattle are often culled after the current pregnancy.
Uterine prolapse is eversion of the uterus through the cervix and vulva. It is almost always a post-partum event, occurring within hours of delivery while the cervix is still open, and is seen most often in the cow, buffalo and ewe, less often in the sow and mare, and rarely in carnivores. In the cow, risk factors include hypocalcaemia, dystocia, forced extraction, retained placenta and uterine atony. It is an emergency because of haemorrhage, shock, trauma and contamination; in the mare, rupture of the uterine vessels can be rapidly fatal. First aid is to keep the dam quiet, prevent her trampling the uterus, and support the uterus in a clean wet sheet at vulval level. Replacement is done under caudal epidural anaesthesia. The uterus is washed, large pieces of detached membranes are removed, and tears are sutured. Replacement is easiest with the cow in sternal recumbency with both hindlimbs drawn out behind her, which tilts the pelvis forward, or with the cow standing. The uterus is lifted to vulval level and returned by pressing from the cervical end first, with the palms rather than the fingertips. The horns must then be fully everted to their tips by hand or with a bottle, since a partly inverted horn causes straining and recurrence. Calcium is given if hypocalcaemia is likely, and oxytocin is commonly given after replacement to contract the uterus. Recurrence after a complete replacement is uncommon. Amputation is reserved for a uterus too damaged to save. In the sow, the prognosis is often poor.
Retained placenta (retained fetal membranes) is failure to expel the fetal membranes within the normal time after birth. In the cow it is usually defined as failure within 12 to 24 hours, with 24 hours the most common field definition. In the mare, membranes not passed within about 3 hours are regarded as retained, and the condition is more dangerous because it can lead quickly to metritis, endotoxaemia and laminitis. In the bovine, the basic defect is failure of separation of the fetal cotyledon from the maternal caruncle, which normally depends on maturation of the placentome and on an immune process that includes the recruitment of neutrophils. Risk factors include abortion and premature birth, induced parturition (particularly with corticosteroids), twins, dystocia, caesarean section, hypocalcaemia, deficiencies of selenium and vitamin E, and placentitis, especially brucellosis. In the cow, routine manual removal is not supported by current evidence: it damages caruncles and does not improve fertility, so the membranes are left to separate while the cow is monitored for fever, depression and a fetid discharge, which indicate metritis and need systemic treatment. Intrauterine medication is still used in some countries but its value is disputed. In the mare, treatment with repeated low doses of oxytocin is standard, and gentle traction or distension of the allantochorion with fluid can help; the passed membranes should be laid out to confirm they are complete, as a missing tip of the non-pregnant horn is a common finding. In the ewe, doe, sow and carnivores, retained membranes are less common and usually accompany a retained fetus.
The puerperium is the period after birth in which the uterus involutes and the endometrium regenerates; in the cow it lasts several weeks, whereas the mare often shows foal heat within the first two weeks. Uterine disease in the dairy cow is classified in a widely used scheme. Puerperal metritis occurs within 21 days, usually within 10 days, of calving, with an enlarged uterus, a fetid, watery red-brown discharge and systemic illness such as fever above about 39.5 degrees Celsius; clinical metritis has the uterine signs without systemic illness. Clinical endometritis is purulent uterine discharge detectable in the vagina 21 days or more after calving, or mucopurulent discharge after about 26 days. Subclinical endometritis is inflammation detected only by cytology. Parturient paresis (milk fever), hypocalcaemia around calving, is common in older dairy cows and can cause uterine inertia, prolapse and retained placenta. Injuries of birth include vulval, vaginal and perineal lacerations. Perineal lacerations are graded as first degree (mucosa and skin), second degree (into the muscle of the perineal body) and third degree (through the rectovaginal shelf, making a common opening of rectum and vagina); a rectovaginal fistula leaves the perineal body intact. Third-degree lacerations are common in primiparous mares and are usually repaired after several weeks when inflammation has settled. Obturator nerve paralysis, from compression of the nerve in the pelvis by a large calf, causes inability to adduct the hindlimbs; peroneal paralysis causes knuckling of the fetlock. Haemorrhage, uterine rupture and vaginal haematoma occur; in older multiparous mares rupture of the uterine artery can cause fatal haemorrhage. In the sow, post-partum dysgalactia syndrome (formerly called mastitis-metritis-agalactia) causes poor milk supply and piglet starvation. In the bitch, puerperal tetany (eclampsia) is hypocalcaemia typically in the first weeks of lactation in small breeds nursing large litters; a common treatment is 10 per cent calcium gluconate at about 0.5 to 1.5 millilitres per kilogram by slow intravenous injection over 10 to 30 minutes, with heart monitoring and the injection stopped if bradycardia or arrhythmia appears — confirm against the product label and your national formulary.
The first minutes after birth decide many newborn lives, especially after dystocia. For the calf, lamb, kid and foal, the airway is cleared first: membranes are removed from the nose and mouth, and fluid is cleared by suction or by wiping. The newborn is placed in sternal recumbency, which improves lung expansion; hanging calves upside down drains mainly stomach fluid rather than lung fluid and is no longer recommended. Breathing can be stimulated by rubbing the body briskly, by a straw inserted in the nostril, and by cold water poured into the ear. If the newborn does not breathe, ventilation with a mask and bag or by intubation is started. In the foal, the usual guide is the one-two-three rule: the foal should stand within about 1 hour, suck within about 2 hours, and the mare should pass the placenta within about 3 hours. In pups and kittens delivered by caesarean section or after dystocia, the membranes are removed at once, fluid is cleared from the airway with gentle suction, the neonate is rubbed with a warm towel, and the umbilical cord is clamped or ligated about 1 centimetre from the body. Newborns of all species need warmth; hypothermia and hypoglycaemia are closely linked and are major causes of early death in lambs, piglets, pups and kittens.
Ruminant, pig and horse neonates are born almost without circulating antibodies, because their placentas do not transfer immunoglobulins from the dam. They depend on colostrum, the first secretion of the mammary gland, which is rich in immunoglobulin G. The intestine absorbs intact immunoglobulins only for a short period after birth, and absorption falls steadily to near zero by about 24 hours, a process called gut closure. Colostrum should therefore be fed early: for the calf, a common recommendation is about 10 per cent of body weight at the first feed within the first 2 hours or so, for example about 4 litres for a 40 kilogram calf, of good-quality colostrum. Colostral quality can be estimated with a Brix refractometer; a reading of about 22 per cent is widely used as the cut-off corresponding to roughly 50 grams of immunoglobulin G per litre. Failure of passive transfer in calves is traditionally defined as serum immunoglobulin G below 10 grams per litre at 24 to 48 hours of age; serum total protein measured by refractometer is used as a field estimate. In foals, a serum immunoglobulin G below 400 milligrams per decilitre indicates failure of passive transfer, 400 to 800 partial failure, and above 800 adequate transfer. Puppies and kittens receive a small fraction of their immunity across the placenta and the rest from colostrum. Thresholds and recommended volumes vary between sources and systems, so local guidance should be followed.
The umbilicus is a route of infection in all farm neonates. Dipping the navel in an antiseptic such as chlorhexidine or an iodine solution soon after birth is widely practised, although its effectiveness varies between studies; clean, dry bedding and adequate colostrum matter more. In the foal, meconium retention, the most common cause of colic in newborn foals, shows as straining and tail swishing in the first day and is treated with enemas. Neonatal isoerythrolysis in the foal occurs when a mare lacking a red cell antigen, most often Aa or Qa, has been sensitised and produces antibodies against her foal's cells, which the foal absorbs from colostrum, causing haemolysis and jaundice within days of birth; it is prevented by testing and by withholding the dam's colostrum for the first day or two and feeding safe colostrum instead. In cats, blood type B queens have strong natural anti-A antibodies, and type A or AB kittens nursing from them can develop neonatal isoerythrolysis; type B is common in some breeds, so blood typing before breeding is advised. Piglets are born with low iron reserves and sow milk is poor in iron, so iron-deficiency anaemia develops within weeks in indoor piglets unless they receive supplementary iron, usually as an injectable iron preparation in the first days of life. Neonatal lambs die mainly from the starvation-hypothermia complex, which is prevented by shelter, early colostrum and management of mismothering.
As a student you must be able to name the stages of labour and their normal durations in each species, describe presentation, position and posture precisely, and recognise the common malpostures by feel on an obstetric model. Practise the order of the obstetric examination: history, general examination, vaginal examination, fetal viability, decision. Learn the distinctions examiners love: hydrallantois versus hydramnios, mummification versus maceration, primary versus secondary inertia, vaginal versus uterine prolapse, rotation versus version. On rotations, take every calving and lambing you can, and write up each one with the fetal disposition, what you did and the outcome.
At five years in practice you will be expected to handle a dystocia alone and decide quickly. The key decision is whether vaginal delivery is safe: after correcting the disposition and giving epidural anaesthesia, does moderate traction advance the fetus? If not, move to caesarean section or, with a dead fetus and enough room, a partial fetotomy, rather than escalating force. You will correct torsions by rolling, replace uterine prolapses, manage retained placenta without routine manual removal, and advise on heifer calving ease sires, colostrum management and prolapse culling. In small animal work, you will decide when a whelping needs oxytocin and when it needs surgery.
With twenty-five years' experience the work shifts to systems and teaching. You will audit a herd's or region's dystocia, stillbirth and retained placenta rates, identify the causes (heifer growth, sire selection, transition cow nutrition, hypocalcaemia, supervision at calving) and set targets. In buffalo regions you will organise training of para-veterinarians in early recognition of torsion and prompt referral, since delay is the main cause of death. You will set practice protocols for caesarean section, epidural technique, analgesia and antimicrobial use, and mentor younger colleagues through their first fetotomies and caesareans, knowing when to step in.
A PhD researcher with long field experience asks why and how much. Open questions include the endocrine and immunological mechanisms of placental separation and retention, the causes of the buffalo's susceptibility to uterine torsion, predictors of dystocia from pelvic and fetal measurements, the value of intrauterine and systemic therapies for post-partum uterine disease, the welfare and pain management of obstetric procedures, and the genetics of calving ease and prolapse. Such work needs well-designed field trials with defined case definitions, adequate sample sizes and honest reporting of negative results, and it shapes guidelines used by practitioners worldwide.
This manual does not give doses for oxytocin, prostaglandins, corticosteroids, calcium borogluconate in cattle, tocolytics or antimicrobials, because products, approvals and withdrawal periods differ by country; use the national formulary. It gives the direction frequencies of uterine torsion only as variable, because published proportions disagree. It does not yet cover camelid, deer or exotic-species obstetrics, detailed fetotomy sequences for every malposture, equine and canine neonatal intensive care, or the full surgical technique for third-degree perineal laceration repair. Figures on incidence of dystocia and retained placenta are left out because they vary widely by herd and country.
Original practice questions written to the syllabus and pattern of the exams named in each question's examTags. They are not past papers and do not reproduce any board's questions.
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