Gynae Gutka (Combined) - Maternal Recognition of Pregnancy Lecture Notes PDF

LECTURE-1 MATERNAL RECOGNITION OF PREGNANCY DEFINITION It is an establishment of pregnancy involves interactions between two interdependent systems defined as Uterus and Conceptus (embryo and extra embryonic membranes. At the appropriate time, the c...

LECTURE-1 MATERNAL RECOGNITION OF PREGNANCY DEFINITION It is an establishment of pregnancy involves interactions between two interdependent systems defined as Uterus and Conceptus (embryo and extra embryonic membranes. At the appropriate time, the conceptus must produce steroid hormones and /or proteins to signal its presence to the maternal system. This signal is necessary for corpus luteum (CL) maintenance, production of progesterone and continued endometrial development and secretory activity. This phenomenon was described by Short (1969) as “Maternal Recognition of Pregnancy” MECHANISM OF MRP If the conceptus fails to signal its presence at exactly the correct time, the function of CL is terminated by the luteolytic action of prostaglandin F2 alpha (PGF2α) from the uterus. This ensures that the female will return to estrus and mate at frequent intervals until a successful pregnancy is established. Uterine PGF2 alpha, is produced by endometrium of cows, ewes, mares and sows and causes morphologic regression of CL and cessation of progesterone production. The effect of conceptus is luteostatic, since progesterone production is maintained at a level comparable to that of dioestrus during pregnancy. Basal secretion of luteinizing hormone (LH) from the anterior pituitary is also essential for CL maintenance and function during pregnancy Non pregnant:- PGF2α is released in an endocrine direction during estrus cycle (non pregnant) to cause regression of CL. Pregnant:- Secretion is however, in an exocrine direction during pregnancy and PGF2α is, therefore, unable to exert its luteolytic effect on the CL. TIME OF MATERNAL RECOGNITION OF PREGNANCY (MRP) IN DOMESTIC ANIMALS Species Day of MRP Day of definite Attachment Cow 16-17 18-22 Ewe 12-13 16 Mare 14-16 36-38 Sow 12 18 The farm animal species are spontaneous ovulators and exhibit uterine- dependent estrous cycles. A close coordination between dynamic processes in the uterine endometrium and the ovary is critical to the establishment of an appropriate uterine environment for pregnancy coincident with the timing of sexual receptivity and ovulation. Following successful mating and fertilization, the conceptus must signal its presence to the maternal system and block the regression of the corpus luteum (CL), a process termed luteolysis,in order to maintain luteal progesterone production. Maintenance of CL is essential for the establishment of pregnancy in all farm animals. The conceptus synthesizes and secretes steroids or protein in order to signal its presence to the maternal system. These molecules serve to modulate synthesis and release of luteolytic prostaglandin F2α (PGF2α) from the uterus and prevent CL regression. During the critical period of uterine PGF2α release, the conceptus must cover a large portion of the maternal endometrium to regulate the production of PGF2α. In the pig, this is accomplished by multiple conceptuses, in the horse, by conceptus migration. The critical period for signalling by the conceptus to block luteolysis and allow pregnancy to be established is called maternal recognition of pregnancy. In the absence of successful mating and fertilization, the uterus synthesizes and release luteolytic PGF2α to initiate morphological regression of the CL and the cessation of progesterone production. This process serves to initiate a new cycle of sexual receptivity ( return to estrus) in preparation for mating and fertilization in another attempt to establish pregnancy. MATERNAL RECOGNITION OF PREGNANCY IN SHEEP AND COW In case of ewe, proteins secreted by the conceptus between days 12 and 21 of pregnancy inhibit PGF2α production by the uterine endometrium. Luteolysis in the ewe involve episodic release of PGF2α between days 14 and 16 of the estrous cycle. These pulses increase in frequency until five pulses are released with in a 24-hour period, resulting in luteal regression. In pregnant ewe, episodic PGF2α release average 1.3 pulse between days 14 and 15 of pregnancy versus an average of 7.6 pulses in nonpregnant ewe during the same period. Expression of receptors for oxytocin in the uterine endometrium is stimulated by estrogen produced by preovulatory follicles on the ovary. Conceptus proteins have no effect on the CL lifespan when injected in to the utero-ovarian circulation or blood circulation. The antiluteolytic product in the homogenates is a low molecular weight, acidic protein produced by the sheep conceptus between days 12 and 21 of pregnancy, first termed ovine trophoblast protein 1 (oTP-1). This protein has high amino acid sequence homology to a class of proteins called interferons and is now classified as a unique interferon type called ovine interferon- tau. Incyclic ewes, numbersof endometrial estrogen and progesterone receptors are high between estrus and 12 of the cycle. Under the influence of progesterone, the uterine endometrium releases very little PGF2α and appears insensitive to estrogen or oxytocin stimulation. This period is referred to as the “progesterone blockˮ. In the cow, maternal recognition of pregnancy occurs between days 16 and 19 of pregnancy The model for maternal recognition of pregnancy in the cow is very similar to that for the sheep, although it is less clear that a direct relationship exists between oxytocin stimulation and release of PGF2α in the cow. The bovine conceptus produces a number of low molecular-weight acidic proteins which inclued bovine trophoblast protein-1 (bTP-1). Like OTP-1, this protein is classified as an IFN-tau and called bovine IFN-tau(bIFN-tau). Endometrium of pregnant cows produces an endometrial prostaglandin synthesis inhibitor(EPSI). which specifically depress synthesis of PGF2α. This inhibitor appears to be linoleic acid. The ratio of linoleic acid to arachidonic acid is much higher in pregnant cows than nonpregnant cows suggesting a critical role for alterations in lipid composition of the utetrine tissue in maternal recognition of pregnancy in the cow. There is no evidence for an EPSI in the ewe. MATERNAL RECOGNITION OF PREGNANCY IN PIG Production of estrogens by the developing conceptuses is the signal for maternal recognition of pregnancy in the pig. Periods of estrogen production between days 11 and 12 and days 14 to 30 of pregnancy allows for maintenance of the corpora lutea. Both period of estrogen stimulation of the uterine endometrium appear to be critical since estrogen stimulation in both phases is required to extend the lifespan of the CL. Injection of exogenous estrogens (estradiol benzoate) on days 11 and 14 of the estrous cycle result in extended CL lifespan. Utero-ovarian plasma concentrations of PGF2α are elevated between days 12 and 16 of the estrous cycle. Concentrations of PGF2α are significantly lower in utero-ovarian venous plasma between days 12 and 16 in pregnant and nonpregnant gilts. Conceptuses must be present in both uterine horns for pregnancy to be established, and at least two conceptuses must be present in each horn for a sufficient area of the uterine endometrium to be covered and PGF 2α release altered. Pigs generally can not maintain unilateral pregnancy because PGF2α released from one uterine horn may cause luteolysis and CL regression on both ovaries. MATERNAL RECOGNITION OF PREGNANCY IN HORSE In the cycling mare, PGF2α in uterine venous plasma and in uterine and uterine flushings increase from day 8 to day 16 when CL regression occurs and progesterone production ceases. Synthesis of PGF2α is reduced in the presence of the conceptus. Pregnant mares have only very low levels of PGF 2α in uterine venous plasma and in uterine flushings, and PGFM in peripheral blood plasma shows no episodic pattern of release. Endometrium from both pregnant and nonpregnant mares synthesizes considerable quantities of PGF2α in the absence of a conceptus and the CL of both pregnant and nonpregnant mares in sensitive to PGF2α. The conceptus migrates with in uterine lumen from one horn to the other 10 to 13 times per day between days 10 and 16 of pregnancy, likely in an effort to inhibit or modify endometrial PGF2α production. Between day 8 and 20 of pregnancy, the equine conceptus produces and secretes estrogen, including estradiol and estrone. The conceptus also produces several major secretory protein. It protein provide the signal for maternal recognition of pregnancy in the mare by inhibiting, directly or indirectly, endometrial PGF2α production.  APPLIED ENDOCRINOLOGY OF PREGNANCY Cow The main source of progesterone for the maintenance of pregnancy in the cow is the CL while the placenta produces only small amounts. Progesterone concentrations in the peripheral circulation during the first 14 days of gestation are similar to those of diestrus; thereafter, those of the non-pregnant cow decline sharply from about the 18th day after ovulation. Estrogen concentrations during early and mid-gestation are low, less than 100 pg/ml; however, towards the end of gestation, in particular after day 250, estrogen concentrations increase to reach peak. These rapidly decline about 8 hours prepartum to low levels immediately post-partum. Both FSH and LH concentrations remain low during gestation and show no significant fluctuations. Prolactin is low during pregnancy until just before calving, when it increases from basal concentrations of 50-60 ng/ml to peak values of 320 ng/ml 20 hours prepartum, until a subsequent decline to basal concentrations by 30 hours post-partum. Bovine placental lactogen can be detected in the peripheral circulation of the dam after the first month of gestation, increasing to maximum concentrations between 200 days and term. The role of this hormone appears to have prolactin and growth hormone-like activities. Mare The endocrine changes in the mare during pregnancy are particularly unusual when compared with other domestic species. After ovulation and the formation of the corpus haemorrhagicum followed by CL formation, plasma progesterone concentrations in the peripheral plasma rise to 7-8 ng/ml by 6 days. The level persist for the first 4 weeks of gestation but there is a transient fall at about 28 days after ovulation to 5 ng/ml followed by a later rise. In the early part of the second month of pregnancy, the endometrial cups are formed. These are discrete outgrowths of densely packed tissue within the gravid horn, derived of fetal trophoblast cells. Usually, there are about 12 cups present at the junction of the gravid horn and body as a circumferential band. The endometrial cups produce pregnant mare serum gonadotrophin (PMSG), also known as equine chorionic gonadotrophin or eCG. These are first evident in blood 38-42 days, reaches maximum at 60-65 days and disappears by 150 days. The eCG has both Follicle Stimulating Hormone (FSH)-like and Luteinizing hormone (LH)-like activity. It provides the stimulus for the formation of accessory CLs and regulates luteal steroidogenesis. Because of the presence of the accessory CLs, the progestogen concentration increases and then decline. By 180-200 days the concentrations are below 1 ng/ml, and they remain so until about 300 days of gestation. Concentrations of total estrogens in the peripheral circulation during the first 35 days of pregnancy are similar to those of diestrus. After this, they increase to reach a plateau between 40 and 60 day, the rise is due to the increased follicular development. After day 60 it is likely that the increase is due to the activity of the fetus or placenta. Maximum values are observed at about 210 days, the main source being the fetal gonads with a gradual decline towards the time of foaling. The main source of progesterone in early pregnancy is the 'true' CL and the accessory CLs. The placenta must take over the production of progesterone after the regression of the accessory corpora lutea and, although concentrations fall in the peripheral circulation, they remain high in the placental tissue and must maintain pregnancy by localized effect. Ewe In the non-pregnant cyclical ewe, progesterone concentrations in the peripheral blood fall rapidly just before the onset of estrus. Following conception, the CL persists and peak diestrus values are maintained and gradually increase to about 60 days of gestation. Levels remain high until the last days of pregnancy, when they decline rapidly to 1 ng/ml at parturition. The concentration of progesterone is significantly higher in multiple pregnancies since in late pregnancy the placenta produces progesterone. Maximum progesterone concentrations in the peripheral blood of ewes with a single lamb was 3.8 ng/ml between days 105 and 110, with twins 5.1 ng/ml between days 125 and 130, and with triplets 9.2 ng/ml between days 125 and 130. Bilateral ovariectomy after 55 days will not result in abortion because by this stage of gestation the placenta has taken over the major role of progesterone production. However, it should be remembered that the CLs persist for the duration of the pregnancy and regress only at the time of parturition. Estrogen concentrations in the peripheral circulation remain low throughout gestation. A few days before parturition they start to gradually rise, then suddenly increase to about 400 pg/ml at the time of lambing, followed by a rapid fall. Prolactin concentrations fluctuate during pregnancy between 20 and 80 ng/ml; towards the end, however, they start to increase and reach a peak of between 400 and 700 ng/ml on the day of lambing. Placental lactogen has been detected in maternal plasma from 48 days of gestation; it reaches a maximum by about 140 days, gradually decreasing until lambing. Goat Similar to ewe, progesterone concentrations increases until a plateau is reached, and then decline rapidly a few days before parturition. Bilateral ovariectomy at any stage of gestation will result in loss of the pregnancy. Total estrogens in the peripheral circulation are much higher than ewe. They increase gradually from 30 to 40 days of gestation, reaching a peak value 600 pg/ml just before parturition. Prolactin remains low during pregnancy but rises rapidly just before parturition. Sow In the non-pregnant sow the plasma progesterone concentration falls rapidly 15-16 days after the previous estrus, but if conception occurs the CLs persist and the peripheral progesterone concentrations remain elevated at between 30 and 35 ng/rnl. The ovaries and CLs are always necessary for the maintenance of pregnancy. The number of embryos present in utero does not influence the progesterone concentration. The minimum concentration of progesterone in the peripheral circulation for the maintenance of pregnancy is 6 ng/rnl. Total estrogen concentrations remain fairly constant in plasma during pregnancy but about 2- 3 weeks prepartum they begin to increase to about 100pg/ml with a sudden surge to values about 500 pg/ml a few days before farrowing. This is followed by a rapid decline after parturition. The early pig blastocyst synthesizes substantial amounts of estrogens. This can be exploited for the early diagnosing of pregnancy, using either plasma or faecal samples. Dog The bitch has a prolonged luteal phase with the CLs remaining active for 65-75 days in the non-pregnant animal. Progesterone concentrations in the peripheral circulation of pregnant bitches are similar to those of non-pregnant individuals and for this reason, unlike in other species, cannot be used to diagnose pregnancy. From about 30 days of gestation, there is a gradual decrease in progesterone so that by about day 60 values of 5 ng/ml are obtained, followed by a sudden decline just before parturition. Peripheral plasma estrogen values are slightly higher in the pregnant bitch than in the non-pregnant bitch. They remain fairly constant during the rest of gestation, before declining to basal values by the day of parturition. Prolactin is the main luteotrophic hormone, especially during the second half of gestation. Relaxin has been detected in the peripheral circulation of pregnant bitches at 20-30 days of gestation, whereas it was absent in non- pregnant bitches. The ovaries of the bitch are necessary for the maintenance of pregnancy; their removal even as late as 56 days resulted in abortion. The average gestation length in the bitch is normally 63-64 days. However, if gestation length is measured from the time of the preovulatory LH peak it is very constant at between 64 and 66 days.  Lecture no. 40-41 PREGNANCY DIAGNOSIS IN FARM AND COMPANION ANIMALS. Accurate and early pregnancy detection is an important part of monitoring or controlling herd fertility. Early pregnancy diagnosis will help to detect those that are not pregnant so that they can be inseminated again or culled from the herd. DIFFERENT METHODS OF PREGNANCY DIAGNOSIS Different methods of pregnancy diagnosis in Cattle, Sheep and Goats have been dealt with in detail under the following headings. PREGNANCY DIAGNOSIS IN CATTLE IN THE DIFFERENT METHEDS 1. MANAGEMENT METHOD 2. PHYSICAL METHED 3. LABORATORY METHED 4. ULTRASONOGRAPHY AND FETAL ELECTROCARDIOGRAPHY 5. PROSTAGLANDIN INDUCED MILK FLOW TEST(PGIMFT) ✓ Dairy cows should calve for the first time approximately 24 months of age and should deliver subsequent calves at intervals of approximately 13-13.5 months. Thus, dairy cows should conceive within approximately 4 months or less of calving in order to get the maximum economic returns.  ✓ An ideal test would accurately detect pregnancy before the first expected estrus after insemination (about 21 days) so the cow could be re- inseminated without further loss of time. ✓ Unfortunately no tests are currently available that are practical to use and allow detection of pregnancy in cows prior to the first expected estrus. 1. MANAGEMENT METHODS A presumptive pregnancy diagnosis by cattle owners is based on history and clinical signs. A. Exposure to a Bull or Artificial Insemination History of a cow with a bull or the observation of mating or AI is not a reliable indicator of pregnancy status and may sometimes be deceptive. Reasons are - a) even with high fertilization rates only about 50% of the inseminations result in detectable pregnancy b) due to unobserved, unplanned, or unrecorded matings, many cows presented with a complaint of infertility are found to be pregnant on rectal palpation B. Cessation of the Estrous Cycle Around day 15 to 17 after ovulation, bovine embryos signal their presence as a result the corpus luteum is maintained, and the maternal estrous cycle is suspended. Thus, failure to return to estrus approximately 18 - 24 days after mating, suggests that conception has occurred. 2. PHYSICAL METHODS 1) RECTAL PALPATION ✓ First palpation should be made between 35 - 42 days after artificial insemination.  ✓ All cows that have not returned to estrus by 60 days post breeding should be palpated a final time. ✓ After about 60 days, fetal death rates are low and most, but not all; cows that are found to be pregnant after this proceed to term and deliver calves. Palpable Changes Per Rectum ✓ Although number of changes occur in the size, texture, location and content of the uterus during pregnancy, there are four positive signs of pregnancy that are detectable by rectal palpation, and examiner must detect at least one of these four signs before declaring the cow pregnant. ✓ The four positive signs of pregnancy in cows are: i. Palpation of the fetal membrane slip ii. Palpation of amniotic vesicle iii. Palpation of placentomes iv. Palpation of fetus 1. PALPATION OF FETAL MEMBRANE SLIP ✓ It is best performed from 35-90 days of gestation. ✓ It is valuable in the differential diagnosis of pregnancy from uterine diseases characterized by fluids causing uterine distension, eg. pyometra or mucometra. 2. PALPATION OF AMNIOTIC VESICLE  ✓ The amnion contains the developing conceptus and the amniotic fluid and is palpable as early as 28 days after conception in heifers and by 32-35 days in pluriparous cows. ✓ The vesicle is recognized as a nearly spherical, turgid, fluid filled structure that is approximately 1 cm in diameter at 28 days and increases in size as pregnancy advances. ✓ It is detected by encircling the uterine horn with the thumb on one side and the fingers on the other. ✓ The vesicle is free floating within the uterus but is most commonly found at the cranial edge of the inter-cornual ligament. The amniotic vesicle becomes progressively less turgid and is difficult to recognize by about day 65 of gestation. At that time the vesicle softens and the fetus becomes palpable. ✓ In a bovine conceptus, the heart is external until approximately day 42; therefore, caution must be exercised when attempting to detect early pregnancies and undue pressure must not be applied to the amniotic vesicle, as rupture of the embryonic heart or other fragile organs may result. 3. PALPATION OF PLACENTOMES ✓ Placentomes begin to form early in gestation and are of sufficient size to be palpable by 75-80 days of gestation ✓ The size of the placentomes varies with the stage of gestation and their location in the uterus ✓ Placentomes are progressively larger near the middle of the gravid horn and are smaller at the cervical and ovarian poles ✓ They are most consistent in size immediately cranial to the cervix and are palpated at that location to estimate the stage of pregnancy  ✓ Placentomes are identified by grasping a longitudinal fold of the uterine wall and rolling it between the thumb and fingers ✓ In more advanced pregnancies, placentomes can be palpated by passing the flattened hand over the uterine wall 4. PALPATION OF FETUS ✓ Fetus becomes palpable at approximately 65 days when the amniotic membrane loses its turgidity and remains theoretically palpable for the balance of gestation. ✓ In early stages of gestation fetus can be grasped directly. Later, the fetus is detected by ballottement; the examiner sets the fetal fluids in motion by rocking the hand against the uterine wall and recognizes the fetus as it rebounds against the hand ✓ The fetus is easily palpable as a free floating firm object within the fluid-filled uterus during the first 4 months of gestation ✓ As pregnancy advances, increased weight of the fetus and fluids pulls the uterus ventrally and cranially until the fetus comes to rest on the abdominal floor during the fifth and sixth months. Continued growth of the fetus positions it closer to the maternal pelvis during the last trimester (period of ascent) and palpation of the fetus is facilitated. SUPPORTING SIGNS OF PREGNANCY 1) Asymmetry of the uterine horns 2) Resilience and fluctance of the uterine wall 3) Fixation of the cervix 4) Ovarian changes 3. LABORATORY METHOD A. Hormone Estimation :- a) Progesterone in milk and plasma b) Estrone sulfate in milk B. Proteins 1. Bovine Pregnancy Specific Protein -B 2. Immunosuppressive Early Pregnancy Factor a) PROGESTERONE IN MILK AND PLASMA ✓ Robertson and Sarda (1971) described a method of diagnosing pregnancy by determination of progesterone concentration in the plasma of cows. ✓ Measured using Radioimmunoassay (RIA) or by various assay kits that are available for on-farm use. ✓ In cows, progesterone (P4) from corpus luteum is required to maintain pregnancy. If pregnant, the cow does not return to estrus and P4 concentrations in blood and milk are elevated at 20-24 days post insemination. Conversely, if pregnancy fails, P4 concentration is elevated until approximately day 17 when luteolysis is followed by a sharp decline in P4 concentration by day 20 and return to estrus. ✓ Optimum time for collecting the milk sample: 24 days after breeding ✓ If P4 concentrations are low in blood or milk samples assumed to be non-pregnant, if elevated assumed to be pregnant. b) ESTRONE SULPHATE IN MILK  ✓ Estrone sulfate is a product of the placenta and is present in the milk of pregnant cows in concentrations sufficient to differentiate between the pregnant and non-pregnant cows after approximately day 100 of gestation. ✓ Practically, however, assays for estrone sulfate are not useful for early detection of pregnancy and offer no substantial advantage over other methods except in the case of a few cows in which rectal palpation cannot be performed. 1. BOVINE PREGNANCY SPECIFIC PROTEIN-B (bPSPB) ✓ In bovines a pregnancy-specific protein (bPSPB) secreted by the trophoblastic cells has been isolated and purified. ✓ RIA for measurement of bPSPB have been developed and used to differentiate pregnant from non-pregnant cows. ✓ Concentrations of bPSPB are detectable in a few cases as early as 15 days after insemination and in nearly all pregnant cows by 24 days after insemination. ✓ The protein increases in concentration as gestation advances and is detectable until parturition. ✓ Concentrations of bPSPB are higher in twin pregnancies than in single pregnancies, but individual variations did not permit accurate prediction of fetal numbers. 2. IMMUNOSUPPRESSIVE EARLY PREGNANCY FACTOR ✓ An assay has been developed for detection of a glycoprotein immunosuppressive early pregnancy factor in the serum of pregnant cows.  ✓ Blood samples collected from dairy cows within 24 h of ovulation can be assayed for presence of immunosuppressive early pregnancy factor. ✓ The assay is able to diagnose pregnancy in 87.5% cows at less than 24 hours of gestation and 12.5% inaccurate in the identification of non- pregnant cows. 4. ULTRASONOGRAPHY AND FETAL ECHOCARDIOGRAPHY ❖ ULTRASONOGRAPHY ✓ In animals, transducers of 5 MHz and 7.5 MHz frequencies are most widely used for transrectal ultrasonography. ✓ Lower frequency transducers are capable of penetrating greater depths of tissue but are not capable of resolving small structures. ✓ Higher frequency transducers are capable of resolving smaller structures but do not penetrate deeply through tissues. ✓ Under practical conditions, ultrasonography with 5 MHz transducer is an accurate method for pregnancy diagnosis after approximately day 24. A 3.5 MHz transducer is found to be reliable after day 30. ❖ FETAL ECHOCARDIOGRAPHY It is not applicable before 5 months of gestation, but might have application for the diagnosis of multiple pregnancies. ❖ SUMMARY OF DIFFERENT METHODS SUMMARY OF METHODS OF PREGNANCY DIAGNOSIS IN COW Methods Earliest time (in days) 1. Early pregnancy factor (EPF) / early conception factor 3 (ECF) 2. Real-time ultrasound (direct imaging) 13 3. Failure of return to estrus and persistence of corpus 21 luteum 4. Progesterone concentration in plasma and milk 21-24 5. Assay of pregnancy specific protein -B 24 6. Palpation of allantochorion (membrane slip) 33 7. Unilateral cornual enlargement and disparity in size, 35 thinning of the uterine wall, fluid filled fluctuation of enlarged horns 8. Palpation of the early fetus when the amnion loses its 45-60 turgidity 9. Palpation of the caruncles/cotyledons 80 10. Hypertrophy of the middle uterine artery until 85 presence of fremitus 11. Estrone sulphate in milk 105 12. Palpation of the fetus 120 ❖ DIFFERENTIAL DIAGNOSIS ✓ Uterine enlargement is usually associated with pregnancy. It should not be always construed that it is the only cause. ✓ The ability to make an accurate, early diagnosis is required of most successful large animal practitioners. Hence, it is imperative to differentiate physiological uterine enlargement (gravid) at each stage of pregnancy from that of one or more of the other causes. Pathological Characteristic features Stage of conditions pregnancy (in days) Pyometra: ✓ Uterine wall is thicker, 45-120 accumulation of spongy and less pus in a sealed resilient. uterus. ✓ Uterine horns unequal in size ✓ Absence of dorsal bulging ✓ Pus is more viscous than the fluid of pregnancy and frequently can be moved from one horn to the other. ✓ Absence of placentomes and fetus. ✓ Absence of fremitus. Endometritis: a ✓ Absence of pus. 30-45 non-specific ✓ Uterine wall thickened infection of the  endometrium and spongy. Metritis: a non- ✓ Presence of visible pus. 35-40 specific infection ✓ Uterine wall thickened of the uterus and spongy. Mummified fetus ✓ Absence of 90-240 placentomes and fetal fluids. ✓ Absence of fremitus. ✓ Thick uterine wall tightly contracted around a hard, firm fetus. ✓ Presence of Persistent corpus luteum Tumors ✓ Lymphocytoma, granulose 45-120 cell tumor of the ovary, and fat necrosis in the mesentry Mucometra or ✓ Mucus varies in consistency 45-120 Hydrometra ✓ Uterine wall fairly thin ✓ Absence of placentomes and fetal fluids. ✓ Absence of fremitus. ✓ Failure of double slipping ❖ PREGNANCY DIAGNOSIS IN SHEEP AND GOATS  There are different methods used for pregnancy in ovines i. External palpation ii. Abdominal ballotment iii. Recto-abdominal palpation technique (Hulet's technique) iv. Radiography v. Ultrasonography vi. Hormonal assays 1. BIMANUAL PALPATION TECHNIQUE ✓ This method involves digital palpation per rectum combined with abdominal manipulation ✓ Does are examined in the morning before feeding and watering ✓ Obese animals are fasted over night ✓ Restrain the animal in standing position by an attendant holding the head ✓ The urinary bladder is emptied before examination ✓ Sitting at the level of pelvic region on the right side of the animal, the examiner's pre lubricated, gloved index finger of the left hand is introduced in to the rectum ✓ Fecal pellets are removed and a distended urinary bladder is evacuated by gentle recto-abdominal pressure ✓ The right palm is held vertically, with the finger tips touching the ventral floor of the posterior abdomen; it is then lifted upwards to move abdominal organs forward ✓ Then, using regulated forward, upward, and backward movements, the reproductive tract within the pelvic cavity could be held in palm of the right hand ✓ Examination is performed per rectum using the left index finger assisted by the fingers of the right hand ✓ The size, shape, consistency and surface characteristics of the vagina, cervix, uterine horns and adjoining structures are then assessed ✓ Palpation of the ovaries is performed in the same manner, pressing the index finger per rectum against the right fingers ✓ Once the uterine horns are palpated, the ovaries are easily located and palpated lateral to the center of the coils as small oval bodies on each side ✓ Palpation is continued to assess their size, shape, mobility and any other gross structural abnormalities 2. RECTO-ABDOMINAL PALPATION ✓ This method was described by Hulet and hence the name, Hulet's Technique. ✓ This technique involves use of a glass or steel rod (50 cms long and 1.5 cms diameter) inserted in rectum. ✓ A soap enema is given 5 minutes before examination to evacuate the rectum. ✓ The ewe or doe is turned on her back. ✓ The probe is lubricated with paraffin oil and carefully inserted approximately 30 cms inside the rectum.  ✓ Left palm is placed on the abdominal wall and the rod is moved to and fro in a horizontal plane with the right hand. ✓ If the rod is palpable as it moves slowly with no obstruction to its passage across the abdomen from side to side, the ewe is considered non-pregnant. If a palpable mass is detected with the free hand through the abdominal wall on one or both sides, the ewe is pregnant and the number of fetuses assessed according to the size and position of masses, wherever possible. ✓ The rectum and uterus should be carefully examined for injury or damage following examination. 3. ULTRASONOGRAPHY Ultrasonographic determination of pregnancy has been well documented in sheep and has been reported to some extent in goats and has been discussed under the following headings Preparation and restraint Speed and accuracy of the procedure Transrectal ultrasonography Transabdominal ultrasonography PREPARATION AND RESTRAINT ✓ Sheep are most commonly scanned in the right inguinal wool-less area in the standing position. ✓ Goats have some hair in this area and may need to be clipped for best results. When large numbers of goats are being checked, acceptable scans can be obtained without clipping if a thick coupling lubricant is used. ✓ Dairy goats are usually restrained in stanchions or against wall.  TRANSRECTAL ULTRASONOGRAPHY ✓ A small amount of lubricant is applied to the end of the linear - array transducer, which is then inserted in to the rectum. ✓ The operator’s index finger maintains contact with the transducer and is used to orient the direction of the scan. ✓ The transducer is directed ventrally and then rotated approximately 45° to each side. ✓ Some operators like to stiffen the cord behind the transducer when it is used in this manner by taping a rigid tube around it to provide leverage. ✓ Urinary bladder is identified as a non-echogenic landmark. ✓ Gravid uteri are identified by non-echogenic areas, a fluid filled structure anterior and ventral to the urinary bladder. ✓ Transrectal imaging allows visualization of pregnancies as early as 15 days post-breeding; but routinely observed by 19-22 days post-breeding. TRANSABDOMINAL ULTRASONOGRAPHY ✓ Accurate estimations of gestation length can be made by measuring the biparietal diameter of fetuses between 40-100 days of gestation. ✓ Gestational age can be estimated within approximately one week by visualization of the diameter of the uterine lumen, crown-to-rump length of the embryo or young fetus or thoracic or skull size of the fetus up to approximately 90 days of gestation. ❖ PREGNANCY DIAGNOSIS IN MARE  i. Management ii. Clinical iii. Ultrasonography iv. Laboratory 1. Management ✓ Failure of return to estrus is a good sign that a mare is pregnant ✓ This requires the presence of a teaser stallion ✓ It is preferable that mares should be accustomed to the teasing routine ✓ Teasing should commence 16 days after service and continue for a further 6 days False Positives will Occur: ✓ If the mare has a silent heat, a common problem when the foal is with mother ✓ If the mare becomes anestrus as a result of lactation or environmental factors ✓ If the mare has a prolonged diestrus and yet has not conceived ✓ If the mare has a prolonged luteal phase associated with embryonic death; this is referred to as 'pseudopregnancy'. False Negatives will Occur: ✓ A few mares will show estrus although they are pregnant. 2. CLINICAL METHODS A) Rectal Palpation  ✓ Uterine tone is marked at 17-21 days of pregnancy when the cornua can be palpated as resilient tubular organs. ✓ Palpation of the conceptus is first possible at 17-21 days when it is a small soft swelling of 2.4-2.8 cm. ✓ At about 100 days it is often possible to ballot the fetus as it floats in the fetal fluids of the uterine body. A portion of the corpus luteum is only palpable for a few days after ovulation in the region of the ovulation fossa before it is covered by the dense fibrous ovarian tunic Ovulation occurs commonly, 52-63 % in the left ovary, about 60 % or more of the fetuses develop in the right horn Based on the ovarian changes the gestation period may be divided in to 4 periods as follows: Period-I: (ovulation to 40 days) characterized by the presence of a single CL of pregnancy and a number of various sized follicles on both ovaries. Period-II: (40-150 days) characterized by marked ovarian activity with as many as 10-15 follicles (over 1 cm in diameter) and formation of 3-5 or more accessory corpora lutea in each ovary. This ovarian activity with follicle and corpora lutea formation is probably produced by the high level of gonadotrophic hormones secreted by the uterine endometrium from 40-120 days of gestation. Period-III: (150-210 days) characterized by regression of the corpora lutea or absence of follicles. Period-VI: (210 days to foaling) no corpora lutea or follicles are present. During these latter two periods steroid hormones produced in the placenta maintain gestation. 3. ULTRASONIC METHOD  In mares, three types of ultrasound are used for pregnancy diagnosis. i. Ultrasonic fetal pulse detector ii. Ultrasonic amplitude depth analyser (A-Mode) iii. Brightness Mode (B-Mode) ultrasound 4. LABORATORY METHODS i. Milk or Blood Progesterone. ii. Blood Estrogens. iii. Immunologic-Gel Diffusion or Haemagglutination-Inhibition Techniques. Biological Methods There are two tests performed for detecting pregnancy in mares. 1. A-Z test :- Used for detecting the presence of gonadotrophic hormones in the mare serum. The gonadotrophic hormone from the endometrial cups is first found in the serum from 40-120 days of gestation, reaches its maximum between days 50-80, gradually declines and is absent after 150 days. 2. Mucin test Chemical Tests Chemical methods are used for detecting the presence of estrogenic hormone in the urine of pregnant mares. There are two tests:  1. Cuboni test :- Cuboni test performed after 150 days of pregnancy helps to detect estrogen in urine and correlates with fetal viability. From day 90, a radio-immunoassay may be performed using serum from the mare. 2. Lunaa test PREGNANCY DIAGNOSIS IN SOWS Different methods have been used to detect pregnancy in the sow. They are as follows: i. Management Methods ii. Clinical Method - Transrectal Palpation iii. Ultrasonographic Methods iv. Laboratory Methods a) Vaginal biopsy b) Plasma progesterone assay c) Plasma estrogen assay 1. MANAGEMENT METHOD ✓ Failure to return to estrus at 18-22 days after service or artificial insemination is considered as pregnant. ✓ This may also be due to a reluctance to show signs, anestrus or ovarian cysts. ✓ Early identification of pregnant sow or gilt is essential so that breeders can certify before sale, she can be served again, treated or culled 2.TRANSRECTAL PALPATION ✓ Need less restraint ✓ Preferably to be done when the animal is feeding ✓ Reliable on per rectum palpable changes of the cervix, uterus and middle uterine arteries 0-21 Days of Gestation ✓ Cervix and uterus feel very similar to their state at diestrus ✓ Bifurcation of the cornua becomes less distinct and the uterus becomes slightly enlarged, with soft walls ✓ Middle uterine artery (MUA) increases to approximately 5 mm in diameter towards the third week. 21-30 Days of Gestation ✓ Cornual bifurcation is less distinct, the cervix and uterine walls are flaccid and thin. ✓ MUA is 5-8 mm in diameter and more easily identified. 31-60 Days of Gestation ✓ Cervix feels like a soft-walled tubular structure. ✓ Uterus is ill defined and thin-walled. ✓ MUA enlarged to about the same size as the external iliac. Fremitus can be first identified at 35-37 days; the pulse pattern comparable with that of the external iliac artery. 60 Days to Term ✓ MUA is greater in diameter than the external iliac and it has strong fremitus; it crosses the external iliac artery more dorsally than before. ✓ Only towards the end of gestation it is possible to palpate piglets at the level of the cornual bifurcation. 3.ULTRASONOGRAPHIC METHODS Ultrasonic Amplitude-Depth Analysis (A-mode ultrasound)  ✓ More reliable B-Mode Direct Imaging ✓ B- mode direct imaging has proved to be Very successful in the sow ✓ The transducer probe is applied to the abdominal wall of the standing sow about 5 cm posterior to the umbilicus, to the right of the midline and just lateral to the teats, and is directed towards the posterior abdomen. 4.LABORATORY METHOD Laboratory methods include i. Vaginal Biopsy ii. Plasma Progesterone Assay iii. Plasma Estrogen Assay 1. Vaginal Biopsy ✓ Histological assessment of the number of layers of the stratified squamous epithelium of the vaginal mucosa obtained by biopsy can be used as a method of diagnosing pregnancy. ✓ Between 30-90 days of pregnancy, the accuracy is over 90%. 2. Plasma Progesterone Assay ✓ Sow bled 16-24 days after service and subjected to plasma progesterone estimations were diagnosed as pregnant when values in plasma were >7.5ng/ml. ✓ Accuracy of the test was 96% and because of irregularities of the interestrus interval, the test was more reliable in identifying those sows non pregnant. 3. Plasma Estrogen Assay ✓ In pregnant animals, estrogens are detectable from day 20 of gestation. ✓ A small volume of blood sufficient for the assay can be collected from the ear vein. ✓ Optimum time to perform the assay is about 24—28 days. DIFFERENT CLINICAL METHODS OF PREGNANCY DIAGNOSIS IN FARM ANIMALS SPECIES DIAGNOSTIC DAYS FROM TECHNIQUE MATING Cattle and buffalo EPF First week Buffalo Failure to return to estrus 21-14 Progesterone 22-24 Real-time ultrasonography 24 Bpspb 24-30 Rectal palpation 35-70 Estrone sulfate 72 Sheep and Goat EPF (sheep) Within 24h Return to esturs 16-21 Real-time ultrasonography 35-40 P4 (goat) 20 Horse Real-time ultrasonography 9-16 Return to estrus 16-21 P4 16-22 Rectal palpation 17-25  eCG 40-120 Estrone sulfate 40-100 Pig Return to esturs 18-25 P4 21 Real time ultrasonography 24 Esreone sulfate 26 Fremitus in middle uterine 28 A-mode ultrasonography 30-90  LECTURE NO. - 03 METHODS OF PREGNANCY DIAGNOSIS IN CANINE AND FELINES In most domestic species, pregnancy interrupts normal cyclicity by increasing the length of the luteal phase and delaying the return to estrus. However, in the bitch the length of luteal phase is similar in both pregnancy and non-pregnancy. This is the reason why pseudopregnancy is a common and normal event in bitches. Due to the peculiarities of the estrous cycle of the bitch, endocrinological methods of pregnancy diagnosis from other species cannot be simply extrapolated. OBJECTIVES a. To understand the importance of early pregnancy examinations. b. It compare and contrast the different methods used for pregnancy determination. c. Determine various clinical and laboratory methods available for pregnancy diagnosis in bitches and queens PREGNANCY DIAGNOSIS IN CANINES In canines, the following methods are used for pregnancy diagnosis: 1) Absence of Estrus 2) Behavioural Changes 3) Physical Changes 4) Abdominal Palpation 5) Identification of Fetal Heart Beats 6) Radiography 7) Endocrine Tests 8) Acute Phase Proteins 9) Ultrasonography 1. ABSENCE OF ESTRUS The failure to return to estrus is not a reliable indicator of pregnancy as the bitch is not polycyclic. The inter estrus interval is identical in pregnant and non-pregnant cycles 2. BEHAVIOURAL CHANGES Behavioural changes typical of pregnancy are observed in both pregnant and non-pregnant bitches. Changes not specific for pregnancy are associated with an increase in plasma prolactin concentration. During the second half of pregnancy, there is approximately 50% increase in food intake. Some bitches may show a brief period of reduced appetite approximately 3-4 weeks after mating. 3. PHYSICAL CHANGES OBSERVED AT DIFFERENT DAYS OF PREGNANCY Approximately one month A slight mucoid, vulval after mating discharge is noticed in pregnant, and also noticed in non-pregnant bitches  Teats become pink and erect. From day 35 onwards Body weight begins to increase and may go to up 50% of normal. From day 40 onwards Abdominal swelling may be noticed. Appreciable mammary gland enlargement and serous fluid can be expressed from the glands. Between primigravida and multigravida, changes may vary considerably. From day 50 onwards The abdominal swelling may progress to abdominal distension. In primigravida or bitches with small litters, changes not appreciable During the last 7 days of Colostrum may be present in the pregnancy teats. Exercise care while assessing changes in mammary size and secretion, since pseudopregnant bitches also exhibit similar features 4. ABDOMINAL PALPATION Technique of abdominal palpation can be highly accurate if performed between day 26 and 30 of pregnancy which is at a time when the uterine swellings are approximately 2 inches in length Beyond day 35, pregnancy diagnosis by abdominal palpation becomes difficult to perform as swellings become larger, more elongated, nearly confluent. Counting the number of fetuses by abdominal palpation is difficult except when performing an examination at approximately day 28 in a relaxed and thin bitch. Difficult to perform in obese or nervous animals, in bitches with tense abdomen, in bitches carrying single pup or a few pups in cranial abdomen. Changes Observed by Abdominal Palpation at Different Days of Pregnancy DAY CHANGES 26-30 Conceptuses are spherical in outline. Diameter varies between 15 and 30 mm.  They are tense fluid filled structures. Readily palpated in a relaxed bitch. 35 Conceptuses become elongated, and enlarged. Tend to lose their tenseness. Less easy to palpate at this time. 45 Uterine horns tend to fold upon themselves, so that the caudal portion of each horn gets positioned against the ventral abdominal wall, and the cranial portion of the same horn being positioned dorsally. 55 Fetuses can often be palpated with the forequarters of the bitch elevated and the uterus manipulated caudally towards the pelvis. Difficult to count accurately the number of conceptuses, except at approximately day 28 in a relaxed and thin bitch. 5. IDENTIFICATION OF FETAL HEART BEATS In late pregnancy, possible to auscultate fetal heart beats using a stethoscope. Fetal hearts may also be detected by recording a fetal ECG. 6. CHANGES OBSERVED BY RADIOGRAPHY AT DIFFERENT DAYS OF PREGNANCY STAGE CHANGES Day 30 Uterine enlargement can be detected. Readily identified in the caudal abdomen, originating dorsal to the bladder and ventral to the rectum; it frequently produces cranial displacement of the small intestine. Early pregnant uterus has soft tissue opacity and it cannot be differentiated from pyometra, which  occurs at the same stage of the estrous cycle. After day 45 Mineralization of the fetal skeleton is detectable, progressive mineralization results in an increasing number of bones that can be identified. It is unlikely that the fetuses will be damaged by ionizing radiation; however sedation or anesthesia of the dam may be required and is a potential risk. In late pregnancy Number of puppies can reliably be estimated by counting the number of fetal skulls 7. ENDOCRINE TESTS Plasma concentrations of progesterone are not useful for the diagnosis of pregnancy in the bitch.  A significant elevation of plasma prolactin occurs in pregnant bitches compared with non-pregnant bitches, and it is possible that prolactin assays may become useful as methods of pregnancy diagnosis. Measurement of the hormone relaxin is diagnostic of pregnancy. 8. ACUTE PHASE PROTEINS Approximately at the time of implantation, an acute phase response occurs, appears to be unique to the pregnant bitch. Measurement of fibrinogen, C-reactive protein, or other acute phase proteins is sensitive markers for pregnancy. The initial rise occurs from day 20 onwards with a peak at approximately day 40. Methods appear to be reliable, although false positive diagnoses may result from inflammatory conditions such as pyometra. The rise in fibrinogen concentration is the basis of commercial pregnancy test. Estimation of plasma fibrinogen level by 17 days after mating can be taken as an index for detecting pregnancy and pseudopregnancy in bitches 9. ULTRASONOGRAPHY Diagnostic B-mode ultrasonography can be used for early pregnancy diagnosis. It is a non-invasive imaging modality, which is safe both for the operator and the animal. Most accurate time to perform is generally one month after the last mating. Sound frequencies in the range of 2-10 MHz are commonly employed in diagnostic examinations.  Small dogs (< 10 Kg) : 7.5 or 10 MHz. Medium sized dogs : 5.0 MHz Large breed dogs : 3.0 MHz or lower frequencies. To visualize the entire reproductive tract, multiple positions and scanning planes may be required TECHNIQUE The dog should be placed in dorsal recumbency, including right or left lateral recumbency and scanned from the dependent or non-dependent side or with the animal standing. Standing on the floor is advantageous for large or giant-breed dogs. Clipping the ventral abdominal hair is the standard protocol to obtain the best image. Application of alcohol or other wetting agents prior to applying acoustic gel to an unclipped hair coat may improve image quality by reducing air between the transducer and skin. CHANGES OBSERVED BY ULTRASONOGRAPHY AT DIFFERENT DAYS OF PREGNANCY STAGE CHANGES From 15 days after ovulation Homogeneous uterus can be identified dorsal to the bladder. Conceptuses may be visualized, and appear as spherical anechoic structures approximately 2 mm in diameter.  From day 20 after ovulation Conceptus is approximately 7 mm in diameter and 15 mm in length and the embryo can be visualized. Approximately 22 days after Embryonic heart beat can be ovulation detected Between days 32-55 The limb buds become apparent and there is clear differentiation of the head, trunk and abdomen From 40 days onwards Fetal skeleton becomes evident, fetal bone appears hyperechoic, and casts acoustic shadows. In late pregnancy The head, spinal column and ribs produce intense reflections and become more easily identifiable PREGNANCY DIAGNOSIS IN FELINES 1. ABDOMINAL PALPATION Satisfactory time to perfom 16-26 days post breeding Conceptuses are readily identifiable as individual turgid spherical swellings  Conceptuses can be palpated as early as 13 days post breeding, but can be confused with fecal mass After 6 weeks - conceptus swelling increase markedly in size, elongate and merge, making palpation more difficult Abdominal enlargement at this stage will be appreciable 2. B-MODE ULTRASOUND Enlarged uterus can be confirmed as early as first week of pregnancy Gestational sacs can be identified from second week which is more reliable Fetal viability can be assessed by cardiac activity detected from third week onwards  Gestation Period In Domestic Animal The gestation period or pregnancy period is the period from fertilization or conception to parturition or the birth of young one. During this period single cells divide and develop in to highly organized individuals. This antenatal period is the least understood and probably one of the most important periods of life. The mortality rate of the ovum, embryo or fetus during this period is much greater than for any other period of equal length after birth. Because they are usually unrecognized, early death of the fertilized ovum or the small embryo with resulting resorption or abortion is often considered as sterility or infertility. PRE-NATAL DEVELOPMENT The pre-natal development of farm animals may be divided in to three main periods based on the size of the individual and the development of its tissues and organs. Period of embryo and Organogenesis Period of fetus and fetal growth Period of ovum or blastula PERIOD OF OVUM OR BLASTULA In cow it is about 10-12 days. It extends from the time of fertilization that usually occurs within a few hours after ovulation, to the development of the zygotes primitive fetal membranes in the uterus. In domestic animals, the size of the ovum not including the zona pellucida is about 120- 180 µm at the time of fertilization and the shedding of the second polar body. During this period, division of the fertilized ovum progresses in the region of the ampullary isthmic junction of the oviduct to the morula stage characterized by the inner and outer cell masses totalling about 16-32 cells. In sows, on the 3rd day and 4th to 5th day in other domestic animals the morula enters the uterus.  By 6-10 days after fertilization the zona pellucida fragments and a blastocyst is formed composed of the embryoblast or inner cell mass and trophoblast or outer cell mass and fluid. By 11 days in the ewe and 12 days in the cow, the blastocyst is about 1 and 1.5 mm in size. PERIOD OF EMBRYO AND ORGANOGENESIS It extends from 12-15 days to about 45 days of gestation in cow, 11-34 days in ewes, 12-55 to 60 days in horse. During this period the major tissues, organs and systems of body shape occur so that by the end of this period the species of the embryo is readily recognizable. This usually coincides with the development of the eyelids. The trophoblast elongates starting at 12 days in the ewe and 14 days in the cow. By 18-19 days of gestation in the cow, the trophoblast may extend in to the opposite horn. In horse, dog, and cat the trophoblast does not elongate but remains oval during this period causing a localized enlargement in the uterus helpful in early pregnancy diagnosis. By 22 days - heart is crudely formed and beating The allantois is well developed, anterior limb buds are formed, eye and brain development is well advanced. In the cow, as in other animals, attachment of the fetal membranes is a gradual process that begins with the formation of the first villi about 30 days of gestation and progresses to a primitive attachment of the chorioallantois to the endometrium in the caruncular areas about 33-36 days of gestation. Until the well- developed attachment of the chorion to the endometrium, the nourishment of the ovum and embryo is provided by the secretion of the uterine glands called "Uterine milk" a yellowish or whitish, thick, opaque secretion grossly resembling and occasionally mistaken as for a purulent exudate. During this period: Severe teratological defects or anomalies of development occur. Embryo may die and be expelled unnoticed at the next estrum.  Becomes macerated and absorbed without external signs. PERIOD OF FETUS AND FETAL GROWTH It extends from 34 days in sheep and goat, 45 days in cattle and 55 days in horse to parturition. During this period minor details in the differentiation of organs, tissues and systems occur along with the growth and maturation of the antenatal individual. Changes in the bovine fetus from 70 days to parturition are not radical. The increase in the size of bovine and equine fetus takes place very rapidly the last 2-3 months of gestation. From 210-270 days the increase in weight of bovine fetus is equal to 3 times the increase from the time of fertilization to 210 days. FETAL CIRCULATION Blood from the placenta is carried to the fetus by the umbilical vein. About less than a third of this enters the fetal ductus venosus and is carried to the inferior vena cava, while the rest enters the liver proper from the inferior border of the liver. The branch of the umbilical vein that supplies the right lobe of the liver first joins with the portal vein. The blood then moves to the right atrium of the heart. In the fetus, there is an opening between the right and left atrium (the foramen ovale), and most of the blood flows through this hole directly into the left atrium from the right atrium, thus bypassing pulmonary circulation. The continuation of this blood flow is into the left ventricle, and from there it is pumped through the aorta into the body. Some of the blood moves from the aorta through the internal iliac arteries to the umbilical arteries, and re-enters the placenta, where carbon dioxide and other waste products from the fetus are taken up and enter the maternal circulation. HORMONAL CONTROL OF GESTATION Nervous control of the uterus is not essential during gestation in man and other animals. Conception, gestation and possibly normal parturition can occur with complete paralysis and lack of nerves in the lower portion of the body. Gestation and the onset of parturition are entirely under hormonal control. In the cow, sheep and pig and probably the mare, about 12-16 days after estrum and fertile coitus, the trophoblast of the embryo grows very rapidly and its presence causes a persistence of the corpus luteum (CL) and cessation of the estrous cycle. This is accomplished by the effect of the trophoblast acting on the endometrium: To cause a continuing release of pituitary luteotrophin by means of a neuro- humoral mechanism acting on the hypothalamus and anterior pituitary gland, and To prevent the release or formation of uterine luteolysin and thus block the transport of this substance by the local utero-ovarian pathway to the CL. The progesterone from the CL or the fetal placenta during pregnancy is essential for Endometrial gland growth. Secretion of uterine milk. For endometrial growth. Attachment of placenta for the later nourishment of the fetus. For inhibiting the uterine motility to aid in placental attachment. A certain amount of ovarian or placental estrogen appears to enhance the effect of progesterone and in later pregnancy to produce udder development, relaxation of pelvic ligaments, initial uterine tonus and cervical relaxation and to sensitize the uterus to oxytocin. Other hormones essential in maintaining pregnancy are the gonadotropic or luteotrophic hormones from the anterior pituitary gland necessary for the persistence of the CL and its active secretion of progesterone. In the mare, the gonadotropins can be produced by the endometrial cups and in women by the chorion of the fetal placenta. The endocrine glands of the fetus, thyroid, adrenals, gonads, anterior pituitary gland and possibly others besides the fetal placenta play important roles in maintaining and terminating the pregnancy. The CL of pregnancy is required throughout gestation to maintain a normal gestation period and permit a normal parturition. It is reported that the normal CL in cows contains about 270 µg of progesterone. Levels below 100 µg were not conducive to embryo survival. In sows, ovaries are essential for the maintenance of gestation (pregnancy) throughout most of the gestation period. The ovaries or CL may be removed in the latter half of the gestation in the ewe, mare, and woman. DURATION OF PREGNANCY Duration of pregnancy is the period from implantation of the blastocyst in the endometrium until termination of pregnancy (pregnancy or gestation). The length of gestation is calculated as the interval from fertile service to parturition. Species Duration (in days) Cow 273 – 296 Horse 327 - 357 Sheep 140 - 155 Swine 111 - 116 Dog 60 - 63 Cat 56 – 65 Goat 148 – 156 Water buffalo 305 – 310 FACTORS INFLUENCING DURATION OF GESTATION The duration of gestation is genetically determined, although it can be modified by maternal, fetal and environmental factors. 1. Maternal factors In different species, the duration of pregnancy is influenced by the dam. A two day extension from the normal occurs in the 8 year old ewe. Young heifers carry their calves for a slightly shorter period than older heifers. 2. Foetal factors In polytoccus species with exception of pig there is an inverse relation between the duration of gestation and litter size. Monotocus species carrying multiple fetuses also have shorter gestation periods. Twin calves are carried 3-6 days less than single calves. Interaction between fetal and placental sizes may influence gestation in horse. The sex also determines the length of gestation; male calves are carried 1-2 days longer than females. Endocrine functions of the fetus may also influence the duration of pregnancy. 3. Genetic factors The small variations in duration of pregnancy among breeds may be due to genetic, seasonal or local effects. The extreme expression of genetically prolonged gestation is known among dairy cows that carry fetus homozygous for an autosomal recessive gene. Breed of embryo determines the length of gestation in cattle. This has been established by transferring the embryos from breeds with shorter gestation length than the donor's and vice-versa. Genetic factors are also responsible for differences in gestation length between mutton and wool breeds of sheep. 4. Environmental factors Season may influence the duration of gestation.  Foals conceived in late summer and autumn have significantly shorter gestation periods than those conceived at the start of the breeding season in early spring. SHORT GESTATION Abortions and premature births often lead to short gestation. The gestation period is 3-6 days shorter in cattle carrying twins and is 0.6 days shorter in sheep and goats. Adverse disease condition affecting the endometrium and placenta or the fetus may result in abortion and short gestation. Other adverse influences include: o Malnutrition. o Chronic debilitating diseases. o Deficiency diseases. o Starvation. o Severe stress. o Other conditions favouring abortion. PROLONGED GESTATION IN DOMESTIC ANIMALS In general, the length of gestation period varies depending upon the breed and certain hybrid. In domestic animals, the gestation period gets prolonged in a variety of conditions. PROLONGED GESTATION IN CATTLE Three types of prolonged gestations have been observed in a number of cattle breeds. a) Associated with premature, long haired fetal giants in Holstein and Ayrshires and in other breeds: Due to a homozygous recessive autosomal gene, Gestation prolonged by 20-90 days Characteristic features of premature fetuses Fetus weight 130-200lbs Long hooves Erupted incisors teeth Dehydration Hypoplastic adrenals b) Associated with cretin-like immature fetuses with cranial and CNS anomalies including hydrocephalous, anencephaly or cyclopia and short, deformed loose jointed legs with aplasia of anterior pituitary gland and a degree of hairlessness. Observed in Guernsey, Ayrshires, and Swedish Red cattle Due to autosomal recessive mode of inheritance Gestation gets prolonged from 20 to over 230 days over the normal period. Dystocia may occur, but not a serious problem c) Associated with cerebral hernia or Catlin mark is an opening of the frontal and parietal bones. Observed in Holsteins Results in dystocia Prolonged gestation: 20-60 days overtime In the last three conditions no pre-partum or post-partum changes are observed at the time of parturition and the udder in undeveloped until after the fetus has been removed. Parturition does not occur unless the fetus dies in-utero. Cattle carrying male fetus had one or two day’s longer gestation than female fetus. Gestation lengths in heifers and in second pregnancy carry one or two days less than parous cows. High doses and continued injection of progesterone or progestins delayed parturition. Most fetuses die the following month of normal parturition. PROLONGED GESTATION IN SOWS Iodine deficiency or the administration of thiouracil to produce hypothyroidism results in prolonged gestation by 4-10 days longer than normal with poorly viable, goitrous, and hairless piglets. Gestation period gets prolonged by 3-4 weeks in inbred sows. High doses and continued injection of progesterone or progestins delayed parturition. Most fetuses die the following month of normal parturition. PROLONGED GESTATION IN EWES  Ingestion of veratrum californicum about the 14th day of gestation caused severe deformities of the face, head with hypoplasia of the hypophysis resulted in prolonged gestation up to 230 days with fetal giantism and even rupture of prepubic tendon. Deficiency of Vitamin A resulted in prolonged gestation by 1-4 weeks. Decapitation of ovine fetuses resulted in overtime small, weak, edematous lambs with adrenals one fourth to one fifth the normal size. Destruction of pituitary glands of ovine fetuses by electro cautery at 90-142 days results in prolonged gestation. High doses and continued injection of progesterone or progestins delayed parturition. Most fetuses die the following month of normal parturition. PROLONGED GESTATION IN MARES Normal gestation in mares is considered to be 330 days, with a range of 320- 340 days. Pregnancies that extend well past this upper range have been reported. In most cases, the mares progress past the expected foaling date with no signs of impending parturition such as mammary development or pelvic ligament relaxation. Delivery of these offspring’s has spontaneously occurred from 365- 415 days following ovulation or breeding. Fetal oversize has not been typically associated with this condition as it has been in cattle. Etiology of prolonged gestation is not fully understood, but it is thought to involve a period of embryonic diapause. This has been suspected when mares have embryonic vesicles that do not grow normally in the first month of gestation and endometrial cup formation is delayed. This delay in endometrial cup formation has been reported to extend for up to 1 month in some cases. The idea of embryonic diapause is supported by the lack of fetal overgrowth with the extended gestation length. Ingestion of fescue infected with endophyte has also been associated with prolonged gestation. The average gestation length of mares consuming infected fescue past 300 days of gestation is 2 weeks to 20 days longer than mares not ingesting the endophyte. These mares also do not have mammary development prior to delivery and on occasion do not even develop the gland following parturition. Parturition in these mares is frequently associated with dystocia. This can result from fetal malformations, edema of placenta and premature placental separation without rupture of the chorioallantois at parturition, or "Red Bagging". Emaciated status of the fetus may be due to the decrease in the availability nutrients from across the placenta because of vasoconstriction. Vasoconstriction may also be partially responsible for the presence of edema in the fetal membranes at delivery. An ergot alkaloid is thought to be responsible for the associated complications of fescue ingestion because it causes vasoconstriction and decreased prolactin from increased dopaminergic activity and decreased serotoninergic activity. Gestation Period Dr. Chandra Prakash Dixit Assistant Professor Department of VGO Gestation or Pregnancy period  The gestation or pregnancy period is the period from fertilization or conception, to parturition or the birth of young.  Duration of pregnancy is the period from implantation of the blastocyst in the endometrium until termination of pregnancy (pregnancy or gestation).  The length of gestation is calculated as the interval from fertile service to parturition. Terminology  ABORTION The expulsion from the uterus of a living fetus before it reaches a viable age, or more commonly the expulsion of a dead fetus of recognizable size at any stage of gestation is called an abortion.  STILLBIRTH The fetus expelled dead at parturition are called stillbirths.  PREMATURE The fetus born before the end of the normal gestation period and is capable to survive in external enviroment are called premature  Gestational period  Based on the size of the individual and the development of tissues and organs.  Divided into three parts I Period of ovum or blastula II Period of embryo and organogenesis III Period of fetus and fetal growth I Period of ovum or blastula  This period of about 10 to 12 days in the cow extends from the time of fertilization.  Size of ovum in domestic animals not including the zona pellucida or granulosa cells is about 120 to 180 microns.  11 days in the Ewe and 12 days in the Cow/Mare.  During the period of the ovum progresses in the region of the ampullary- isthmic junction of the oviduct to the morula stage (16-32 cells) characterized by inner and outer cell mass.  Entry into uterus ✓ 3rd day in the sow. ✓ 4th to 5th day in domestic animals. ✓ 6th to 10th days after fertilization the zona pellucida has fragmented and blastocyst has formed.  During this period ❖ Defective ova died and are absorbed. ❖ Corpus luteum developing- producing progesterone- hormone necessary for the growth and preparation of the endometrium. ❖ Favorable environment for the ovum and embryo present in the uterus. II Period of embryo and organogenesis  The period extends from 12 to 15 days to about 45 days of gestation in the cow.  11 to 34 days in the ewe.  12 to 55 to 60 days in the horse.  II Period of embryo and organogenesis The major tissues, organs and systems of the body are formed and changes in the body shape occur so that by the end of this period the species of the embryo is readily recognizable.  Trophoblast elongation.  Positioning of embryos in the uterus (Swine).  In the horse, dog and cat trophoblast or blastodermic vesicles does not elongate but remain oval- Early pregnancy diagnosis.  By 20 days: In cow, amnion is completely formed and somites are forming.  By 22 days heart is crudely formed.  By 25 days neural tube.  In domestic animals the term attachment is preferred to the term implantation or nidation.  Implantation refers to the process in humans and rodents where the zygote erodes, penetrates and implants itself within the endometrium.  the nourishment of the ovum and embryo is provided by the secretion of the uterine glands called uterine milk. II Period of embryo and organogenesis  During this period nearly all of the more severe teratologic defects or anomalies of development occur.  The embryo may die, be expelled unnoticed at the next estrum, or become macerated and absorbed without external signs. III Period of the fetus and fetal growth  During this period extends from about 34 days of gestation in the sheep and dog, 45 days in cattle and 55 days in the horse to parturition.  During this period minor details in the differentiation of organs, tissues and systems occur along with the growth and maturation of the antenatal individual. Increase in the size of fetus takes place very rapidly the last 2-3 months of gestation. From 210-270 days the increase in weight of bovine fetus is equal to 3 times the increase from the time of fertilization to 210 days  Fetal venous circulation Blood from the placenta is carried to the fetus by umbilical vein About less than a third of this enters the fetal ductus venosus and is carried to the inferior vena cava while the rest enters the liver proper from the inferior border of the liver Branch of the umbilical vein that supplies the right lobe of the liver first joins with the portal vein The blood then moves to the right atrium of the heart In the fetus, there is an opening between the right and left atrium (the foramen ovale) Most of the blood flows through this hole directly into the left atrium from the right atrium, thus bypassing pulmonary circulation The continuation of this blood flow is into the left ventricle, and from there it is pumped through the aorta into the body Some of the blood moves from the aorta through the internal iliac arteries to the umbilical arteries, and re-enters the placenta, where carbon dioxide and other waste products from the fetus are taken up and enter the maternal circulation Fetal venous circulation  FACTORS AFFECTING DURATION OF GESTATION  The duration of gestation is genetically determined although it affected by maternal, fetal and environmental factors. Maternal factors ▪ In different species, the duration of pregnancy is influenced by the dam. ▪ Young heifers carry their calves for a slightly shorter period than older heifers. Foetal factors I. In polytoccus species except (pig) there is an inverse relation between the duration of gestation and litter size. II. Monotocus species carrying multiple fetuses also have shorter gestation periods. III. Twin calves are carried 3-6 days less than single calves. IV. The sex also determines the length of gestation; male calves are carried 1-2 days longer than females. V. Endocrine functions of the fetus may also influence the duration of pregnancy. Genetic factors  The small variations in duration of pregnancy among breeds may be due to genetic, seasonal or local effects.  The extreme expression of genetically prolonged gestation is known among dairy cows that carry fetus homozygous for an autosomal recessive gene.  Breed of embryo determines the length of gestation in cattle. This has been established by transferring the embryos from breeds with shorter gestation length than the donor's and vice-versa.  Genetic factors are also responsible for differences in gestation length between mutton and wool breeds of sheep. Environmental factors  Season may influence the duration of gestation.  Foals conceived in late summer and autumn have significantly shorter gestation periods than those conceived at the start of the breeding season in early spring. SHORT GESTATION  Abortions and premature births often lead to short gestation. The gestation period is 3-6 days shorter in cattle carrying twins and is 0.6 days shorter in sheep and goats.  Adverse diseases condition affecting the endometrium and placenta or the fetus may result in abortion and short gestation.  Other adverse influences include:  Malnutrition.  Chronic debilitating diseases.  Deficiency diseases.  Starvation.  Severe stress.  Other conditions favouring abortion PROLONGED GESTATION  Sow: Iodine deficiency or the administration of thiouracil to produce hypothyroidism results in prolonged gestation by 4- 10 days longer than normal with poorly viable, goitrous, and hairless piglets.  High doses and continued injection of progesterone or progestins delayed parturition. Most fetuses die the following month of normal parturition get macerated or mummified.  Ewe  Deficiency of Vitamin A resulted in prolonged gestation by 1-4 weeks.  Consumption of veratrum californicum about the 14th day of gestation caused severe deformities of the face, head with hypoplasia of the hypophysis resulted in prolonged gestation up to 230 days with fetal giantism and even rupture of prepubic tendon.  Destruction of pituitary glands of ovine fetuses by electro cautery at 90-142 days results in prolonged gestation. Cattle  Associated with premature, long haired fetal giants in Holstein and Ayrshires and in other breeds:  Due to a homozygous recessive autosomal gene  Gestation prolonged by 20-90 days  Characteristic features of premature fetuses ❖ Fetus weight 130-200lbs ❖ Long hooves ❖ Erupted incisors teeth ❖ Dehydration ❖ Hypoplastic adrenals  Associated with cerebral hernia or Catlin mark is an opening of the frontal and parietal bones. Observed Holsteins. Results in dystocia  Prolonged gestation: 20-60 days overtime  Associated with cretin-like immature fetuses with cranial and CNS anomalies including hydrocephalous, anencephaly or cyclopia and short, deformed loose jointed legs with aplasia of anterior pituitary gland and a degree of hairlessness. ✓ Observed in Guernsey, Ayrshires, and Swedish Red cattle ✓ Due to autosomal recessive mode of inheritance ✓ Gestation gets prolonged from 20 to over 230 days over the normal period. ✓ Dystocia may occur, but not a serious problem. THANK YOU  CARE OF PREGNANT AND POSTPARTUM ANIMAL 1. Identify pregnancy The pregnancy diagnosis should be 90 days following AI. The rectal examination or ultrasonography can be done to detect pregnancy. Rough handling while doing pregnancy diagnosis may result into abortion. 2. Feed Provide concentrate feed 3.5 kg per day. A 25 – 35 kg green fodder and 5 kg of paddy straw should be given on daily basis. 3. Dry period A minimum of 45 to 60 days dry period is essential. Therefore, it is recommended to keep the animal during last two months of gestation. 4. Avoid stress Avoid stress to pregnant animal especially animal in advanced gestation. Avoid long distance travel, chasing by dogs, bull or children. The stress in pregnant animal can lead into abortion. 5. Shed condition The shed should not be slippery. It should be well ventilated and clean. Avoid overcrowding in shed. 6. Avoid infighting between pregnant animals  Keep the animals in early pregnancy, mid pregnancy and in advanced gestation in separate shed. Further, animals during their last few days of gestation should be kept in individual barns. 7. Separate pregnant animals from diseased animal Keep the recently aborted or diseased animals segregated especially from those are pregnant. The placental fluid, fetal membrane or uterine discharge from aborted animal may act as source and can infect the other pregnant animals. The infection may occur via drinking of contaminated water, consuming contaminated feed or licking of perineal area of aborted animal. 8. Provide adequate clean drinking water There should be continuous supply of fresh and clean water to pregnant animals. The drinking water should be easily accessible to them. 9. Protect against extremes of climate The water sprinkler and fan should be installed in shed of pregnant animal in order to avoid stress due to hot and humid climate. Provision of covered shed during winter season would prevent direct effect of chill wind.  CARE OF PARTURIENT ANIMAL Mares approaching term should be put in a convenient paddock. As soon as the udder and teats become distended, or waxing occurs, the mare should be kept under continuous but unobtrusive observation. If the presentation is seen to be normal, i.e. two feet and muzzle at the vulva, then the mare is almost certain to deliver the foal. As soon as faulty presentation, position or posture is recognized, or if no progress occurs within 10 minutes of the onset of straining, a veterinary examination should be called for the early dehiscence of the allantochorion in equine dystocia makes stillbirth the rule. As soon as a cow shows complete relaxation of the posterior border of the sacrosciatic ligaments and a sudden enlargement of the udder she should be put in a clean, well-bedded box and kept under frequent observation. If after 12 hours of restlessness there is no straining, a veterinary examination should be made. Heavily pregnant ewes should be kept in a convenient paddock or in a lambing yard. Sows should be well washed and introduced to a farrowing crate several days before the expected farrowing. On industrial pig farms, where pregnancies are synchronized in groups because of the weaning management, this will take place according to an “all-in, all-out” system. The majority of sows farrow during the evening and at night, when there is fewer disturbances in the farrowing barn.  POSTPARTUM CARE OF DAM Immediate Postpartum Care In Cow ✓ Check for evidence of another fetus ✓ Check the entire birth passage to rule out any damage ✓ Check for signs of hemorrhage ✓ Check the udder for signs of mastitis ✓ Check for signs of metabolic disorders ✓ Administer antibiotics to prevent secondary infection ✓ Administer oxytocin 60–100 I.U. as a preventive measure of retained fetal membrane ✓ The roughage fed to cow should be of good quality. ✓ The grain ration should be laxative and light such as bran, oats. In Mare ✓ Evaluation of the mare’s behavior including attitude and interaction with her foal ✓ Her general condition including: Character of pulse and respiration Color of mucous membranes Degree of alertness ✓ Examine the udder for consistency of mammary secretions and patency of the teats ✓ Mares should foal in a clean, dry, draft-free area that has protection from excessive sun and wind. If the climate permits, a small, clean grass paddock is best; otherwise, a well-bedded dry stall will be good. ✓ The number of mares in the paddock should be minimal to decrease competition among the mares for food and space and to allow the mare to bond with her foal. ✓ During the postpartum period, mares need exercise to promote uterine involution. Leaving a mare in a stall for prolonged periods is detrimental, as the mare may accumulate intrauterine fluid leading to metritis. If fluid accumulates, lavaging her uterus with large volumes of warm saline until the efflux clear followed by administration of 10 to 20 units of oxytocin has been helpful in preventing metritis. ✓ For the first few days after foaling, feeding should be light to moderate, and laxative feeds such as bran mashes are appropriate to reduce the incidence of constipation. ✓ When vaccination history is vague or absent, the mare should be simultaneously vaccinated with tetanus antitoxin and toxoid. ✓ If the mare and has not been dewormed during the last 2 months of gestation, she should be dewormed within a few days of foaling. Broad-spectrum anti- parasitical compounds such as ivermectin are best. ✓ Mares with a history of a Caslick’s operation as an essential part of infertility management should be re-sutured as soon as practical. If performed within 15 minutes of parturition, local anesthesia is not required. If the mare tears the dorsal commissure of her vulva and it is not sutured immediately, it is best to keep the area clean until it is sutured in 3 to 4 days. If it is sutured when inflammation is maximal, 24 to 48 h after parturition, it will likely dehisce. In Goat ✓ Carefully perform abdominal ballottement of the doe immediately after parturition for the presence of additional fetuses. ✓ On abdominal palpation, a retained fetus may be detected as a firm mass, and can be confirmed by ultrasonographic examination. ✓ Examine the birth canal for any signs of trauma or hemorrhage. ✓ After parturition, assess the doe’s vital signs and muscle tone to detect hypocalcemia, as it may predispose to uterine prolapse. In Sow ✓ Farrowing is assumed to be complete, when the sow stops straining and begins to demonstrate an interest in her litter. ✓ Complete expulsion of fetal membranes and placentas is the final phase of parturition, however the time required for expulsion of the fetal membranes may range from 20 min to 12 h after the last pig is born. ✓ Retained placenta occurs rarely in sow. Failure to find placenta in farrowing crate 4-12 hrs postpartum suggests the presence of another fetus in the birth canal. Thus, vaginal examination is indicated. ✓ Sows that continue to strain, have malodorous and discolored vulvar discharge or show sign of depression should be vaginally examined for another fetus. ✓ Inspect the sow’s udder for color, consistency, heat and lesions likely to be associated with pain to determine if the sow is suffering from mastitis or any puerperal disease condition. ✓ The light grain ration should be continued for a week and then increased gradually. If increased too rapidly the piglets may get too much milk and diarrhea may develop. CARE OF NEW BORN The fetus during its development inside the uterus is maintained under constant, regulated and well protected stress free environment. Under the influence of hormonal changes during the latter part of gestation, a number of changes occur in the fetus so as to prepare it for survival in a free state. In spite of this in utero preparation, following delivery, the fetus has to quickly get adapted to the sudden change in its immediate environment. Generally, when the parturition is normal, the fetus easily overcomes this transition. However, from birth to variable period of time afterwards, a number of important events must occur. It is imperative that, the personnel supervising or assisting the parturition process has to exercise great care to recognize the changes in the new born so that it could be rectified quickly to enhance its survival. The following aspects have to be taken care of: Onset of spontaneous respiration Acidosis Thermoregulation Care of umbilicus Feeding of colostrum Protect the new born from an excitable dam Onset of respiration During normal calving, spontaneous respiratory movements of the offspring occur within 60 seconds. If there is a delay in calving, sometimes respiratory movements occur before expulsion of the fetus. During the parturition, the O2 and blood pH are falling and CO2 is rising due to start of placental separation, occlusion of the umbilicus, thus restricting gaseous exchange. These changes stimulate chemoreceptors in the carotid sinus for initiation of respiration. Tactile and thermal stimulation are also important for initiation of respiration. Immediately after delivery of the fetus, clear the upper respiratory tract of fluid and attached membranes using fingers. Elevating the rear of the calf will help in escape of copious volume of fluids. Brisk rubbing of the chest with straw and towels frequently, provide necessary tactile stimulus for respiration. If spontaneous respiration is not present it may be stimulated by pinching the fetal nose, tickling the nasal mucosa or by splashing cold water. Respiratory stimulants like coramine and adrenaline may be tried. Oxygen cylinder and resuscitator are useful. If resuscitation does not result in spontaneous respiration in two or three minutes, it is unlikely that new born will survive even though there is a strong pulse and heart beat. Acidosis During normal calving, fetus will usually have a mild metabolic acidosis, corrected within a few hours, and respiratory acidosis, which may last up to 48 hours. Dystocia is likely to cause a severe respiratory and metabolic acidosis and result in adverse effect on both respiratory and cardiac function, and in the case of the calf will reduce vigor, the suck reflex resulting in reduced colostrum intake and impaired passive immunity. METHODS OF ASSESSMENT: Presence of good muscle tone and a pedal reflex: a well-oxygenated calf with fairly normal acid-base status. Presence of scleral and conjunctival hemorrhages: hypoxia and acidosis TREATMENT: A calf requiring resuscitation is likely to be suffering from both a metabolic (low plasma bicarbonate concentration) and a respiratory (high PCO2) acidosis. The PCO2 will be reduced with improved alveolar gas exchange and tissue perfusion. Metabolic acidosis may be treated with sodium bicarbonate. Sodium bicarbonate at a dose rate of 1-2 mmol/kg as a bolus intravenous injection of 50-100 ml (35 gm in 400 ml of lukewarm water) can be used quite safely. Thermoregulation Immediately following birth, the newborn has to adjust to an environment and the temperature is also usually below that of the uterus. After birth, the body temperature of the newborn falls quickly from that of the dam before it eventually recovers. The degree of decline and speed of recovery vary from species to species and with the environmental temperature. In the foal and calf, the fall is transient; in the lamb recovery occurs within a few hours; the piglet takes up to 24 hours or even longer in cold conditions; while in the kitten and puppy the period before the temperature recovers to approximately that of birth is 7-9 days. Thermoregulation is controlled in two ways: Increased metabolic rate Reduce heat loss Ensure that there is adequate food available for new born. Reduce heat loss by ensuring that the coat is adequately and quickly dried. The neonates should be placed in a warm environment until they can be returned to the dam. Care of umbilicus If the bleeding occurs, the cord may be ligated with a suitable suture. It is important not to cut the cord too close to the abdomen. The umbilical cord should also be disinfected with mild antiseptic. In foals, premature severance should be prevented, since it has been shown that up to 9 minutes after expulsion pulsation occurs, thereby ensuring an adequate blood volume to the foal. It is advisable to administer prophylactic dose of tetanus antitoxin in foals. Clean, sanitary, well- bedded stalls for the calf and parturient cow help greatly in preventing navel infection. Feeding of colostrum The new born should receive colostrum from the dam. Colostrum should be made available to the new born within 1-2 hours of delivery. Feeding of colostrum to the young one provides antibodies. The great importance is of globulins in the colostrum, which are only absorbed from the gut 12-36 hours after birth. Premilking in cows, sometimes practiced to avoid severe edema of udder, may reduce immune globulins available to the newborn calf because of their dilutions in large quantity of milk stimulated by milking. Clipping of hairs around udder in heavily fleeced ewes may aid the lambs to find the teats and nurse promptly. Protection from an excitable or vicious dam In some instances, the dam may attack the new born. In such cases it needs to be provided with physical protection and resort to the use of tranquillizer drug.  Topic: Implantation and Placentation The terms embryo, conceptus and fetus are often used interchangeably to describe the developing organism. Embryo is defined as an organism in the early stages of development. In general, an embryo has not acquired an anatomical form that is readily recognizable in appearance as a member of the specific species. During early stages of development, it i