Pure Science - Fifth Year, Fourth Delivery - THERIOGENOLOGY (PDF)

# Pure Science ## Fifth year ## 5.00 ## Fourth delivery ## THERIOGENOLOGY ### Stages of Parturition **Def.** Previously, parturition was considered 4 stages, but the **preparatory stage** was deleted because of its long duration and because only three stages of parturition are considered (Active...

# Pure Science ## Fifth year ## 5.00 ## Fourth delivery ## THERIOGENOLOGY ### Stages of Parturition **Def.** Previously, parturition was considered 4 stages, but the **preparatory stage** was deleted because of its long duration and because only three stages of parturition are considered (Active Stages) since there is no clear boundary between each stage, but there are specific signs that indicate the end of the stage. **1st Stage (Opening or Dilatation stage)** - Starts from the onset of birth pain until cervical dilatation or the appearance of fetal sacs. - It also starts from the onset of labor until the appearance of the fetal membranes and the fetal sacs in the cervix and vagina. **2nd Stage (Expulsive stage)** - Starts from cervical dilatation or appearance of fetal sacs (CA) until expulsion of the fetus. - In cattle, it typically occurs in a lateral recumbent position **External Changes** - Restlessness - Stop eating - Frequent urination and defecation of soft feces (due to increased peristaltic movement) - Lying and rising up frequently - Pawing the ground, raising tail and muscle tremors - Mares and cows lay in a recumbent position to move the fetus from the abdominal cavity to the pelvis. - Straining (abdominal contraction) may be evident externally **Internal Changes** **Cervix:** - Relaxation and dilatation of the cervix → Cervix cannot be felt by vaginal examination as cervix & vagina become one tube. **Contraction:** - Initial myometrial contraction of the inner circular muscle only → The fetus adopts its birth position (PPP) and pushes the fetus and fetal sacs toward the cervix - Regular intermitted contraction → 30 seconds contraction then 120 seconds rest **Contraction:** - Expulsive myometrial contraction of the outer longitudinal muscle (due to ↑ E2, ↑ PGF2a & Oxytocin) - Abdominal contraction supplements the uterine contraction - Animal inspiration and closes epiglottis → ↑ chest pressure → ↑ abdominal pressure → ↑ abdominal contraction - Regular intermitted contraction → 120 seconds contraction then 30 seconds rest **Contraction is from uterus only due to P4,↑ E2, ↑PGF2a** - Contraction → pressure on the umbilical cord against the pelvic brim →stop of circulation → continued contraction without rest → asphyxia and death of the fetus **Fetal Membrane** - Chorioallantoic enters the vagina → intact CA appears from the vulva as a bluish vascular semitransparent membrane (contains watery amber yellowish fluid) - Rupture of fetal membrane can occur after complete dilation of cervix - Rupture of fetal membrane by → twisting of the tail and rubbing against a hard object → dampness بلل around the maternal perineum - Avoid rupture of fetal sacs by yourself (manual rupture → stop of cervical dilatation. - 1st water bag is Chorioallantoic (ruptures first) & 2nd water bag is Amniotic (second to rupture) - Although the term water bag refers to the amniotic membrane **Duration** * **Cow:** 4-6 hours in pluriparous and 6-12 hours in primiparous (heifer) * **Duration generally is long due to the nature of cervix (fibrous collagen)** **Synergistic with the dam - rest** - The greater maternal effort is associated with the passage of the fetal head through the vulva, at which the fetal thorax enters the maternal pelvis. **Fetal Membrane** - Amnion enters the vagina → Before rupture the amnion appears as a grayish-white avascular and opaque sac at the vulva (contains viscus transparent fluid) - After rupture of fecal sacs and exposure of any fetal parts to the external environment → stimulation of inspiration **Expulsion of the fetus** - Points at which birth pain is replicated: - During expulsion of the head, shoulder, and pelvis of the fetus - During bypass of the fetus through the cervix, pelvis, and hymen of the dam **Duration** * **Cow:** 0.5-3 hours **3rd Stage (After birth stage)** - Starts with fetal expulsion and ends with expulsion of fetal membranes and placenta - Placental circulation lost - Placental dehiscence and separation - Uterine and abdominal contraction continue - Drop of placenta - Separation of placenta during the expulsive stage, so it is considered a retained placenta. - In equines, we must intervene and remove it because it is a diffuse placenta and any infection (especially tetanus) will spread throughout the body within a short period. **Duration** * **Mare:** 2 hours * **Cow:** 2-8 hours, up to 12 hours in summer and 24 hours in winter. * **Longer than 24 hours is considered retained.** * **Sheep & goat:** 3-4 hours after last lambing * **Saw:** Within 2 hours after last piglet * **Bitch and queen:** No afterbirth stage. **In Cow:** - The fetus is expelled wrapped in its membranes, which the dam eats. - 80% Allantoic sac rupture occurs first, and 20% Amniotic sac ruptures first (as allantoic covers 80% of the amniotic sac). **In Mare** - Profuse patchy sweating as the fetus enters the birth canal - Teat waxing (bead-like deposition at the end of teats) - Separation of placenta (simple diffuse) during the expulsive stage, so the fetus must be delivered within 0.5 hours, unless it dies. - Once the foal is delivered, it is often still enclosed in the amnion (intact amnion). - Allantoic sac completely covers the amniotic sac. - Umbilical cord is ruptured at a well-demarcated point when the mare rises or the foal moves vigorously - Mare lies still temporarily exhausted in a recumbent position for 1/2 hour after expulsion of the fetus until transferring 1/3 of the fetus's blood to the foal - Avoid disturbing the dam immediately postpartum, as premature rupture of the umbilical cord increases the risk of neonatal maladjustment and after problems (approximately 1/3 of the fetal blood is still in the placenta) **Why mare & cow give birth in recumbent position?** - In Mare, to avoid premature rupture of the umbilical cord - In Cow, to move the fetus from the abdominal cavity to the pelvic region. - In Mare, lay in lateral recumbency to facilitate expulsion of the shoulders of the fetus. If there is dystocia (difficult labor) and we need to intervene, it is ideal if the cow is standing to give us more room to work. - If the cow is unable to stand, then lay her in sternal recumbency, not lateral, because the weight of the upper leg in lateral recumbency can compress our hand as we are working. **In Ewe** - 50% of lambs and kids are born with intact amnion. **In Sow:** - Older sows → Excessive Relaxation of pelvic ligament may cause → vaginal & rectal prolapse - 50% of piglets are still enclosed within their amnion, and those born early in the litter have intact umbilical cord. - Piglets are born at intervals of approximately 15 minutes. - Portions of the placenta may be passed after each piglet, after a number of piglets, or at the end of furrowing - The chorionic surface of the last pieces of placenta from each horn may be darker red color than the remainder of this tissue. **In Bitch** - The most reliable sign of parturition is body temperature by 2°C within 24 hours of whelping. - The puppies come in posterior presentation → breech birth - The interval between puppies is (5-60) minutes (average 30 minutes). - A dark green discharge (Nitrofurantoin stain) during delivery arises from the breakdown of the marginal hematomas of the zonary placenta. **In Queen:** - Body temperature by 0.1-1°C 12 hours before birth - A dark brown discharge during delivery arises from the breakdown of the marginal hematomas of the placenta. - The bitch severs the umbilical cord with her teeth about 2 cm from the puppy/kitten. - The placenta may be delivered after each puppy/kitten or after a group of puppies, or at the end of parturition. - The dam will eat each placenta as it passes, but this may cause vomiting. **O In Monotocus animals (Caw & Mare)** - All uterus contracted from the apex to the base. So contraindicated to use Oxytocin during parturition in dystocia → rupture for uterus **In Polytocous animals (dog & cat)** - The uterus is divided into many chambers, each chamber is separated from the other by a muscular band. - So the contraction is from a single muscular band to the base & after expulsion of one fetus → contraction in barrel chambers in the alternative horn (alternative contraction). - This means we can use Oxytocin in polytocous during parturition and repeat the dose every 2 hours (As half-life of Oxytocin is 40 min.) - Contraindicated to use Oxytocin in a monotocus animal during the expulsive stage for dystocia → rupture of uterus.