Vet obst lecture 5 Parturition in domestic animals

The mechanism of parturition, theories of initiation of parturition, and the stages of parturition are described for the domestic animal species. Useful for students in veterinary science, practitioners, and researchers.

1. Parturition in Domestic Animals Prof G N PUROHIT Head, Department of Veterinary Gynecology and Obstetrics, College of Veterinary and Animal Science, Rajasthan University of Veterinary and Animal Sciences, Bikaner, Rajasthan, India

2. Parturition: Delivery of fetus through the birth canal on completion of gestation period Birth canal is formed by the uterus, cervix and vagina within the pelvic bones and their attachments The muscular canal that forms from the uterus to the outside of the body through which the fetus passes during birth.

3. Pre-parturient Care Shifting to calving boxes 1-2 months before calving Mares need a quiet environment Feeding Cows should be given a low energy high fiber diet during gestation and anionic salts should be given if they are fed fodder to which high K+ fertilizer has been added Sheep twin fetus carrying animals should be fed high energy feed. Bitches 1.0 to 1.8% Ca and 0.8-1.6 % P in diet of late pregnant bitches Vaccines Tetanus vaccination of foaling mares

4. Vaccination of pregnant bitches Never use a live vaccine in a pregnant bitch: only use registered 'safe' killed vaccines and registered 'safe' intranasal vaccines.  Keep up to date with live vaccines in non-pregnant bitches to avoid having to give vaccines to pregnant bitches. 

5. Killed parvovirus vaccines can be given 2 weeks or more before the pups are due to be born (they should not be given any closer to the time of birth than this) to increase the levels of parvovirus antibodies in the colostrum . Maternal antibody levels may persist in these antibody-enriched pups for up to 14 weeks and, depending on the vaccine type being given to these pups, they may require preventative vaccinations for up to 16-18 weeks of age before they are considered safe to socialise.

6. Newer vaccines are now available that overcome this issue of maternal immunity, achieving full protection within 12 weeks of age.  If using vaccination therapeutically, in order to achieve high levels of immunoglobulin's (antibodies)in the colostrum , vaccinate the pregnant bitch 2-3 weeks before the pups are due to be born.

7. Vaccination of pregnant mares Vaccinations should be current, since infectious diseases can trigger abortions. It is recommended that mares be vaccinated against EHV-1 in the 5th, 7th and 9th month of her pregnancy. In higher risk situations first Rhinopneumonitis immunization be given at 3 months. Currently, there are two killed virus vaccines approved for use in pregnant mares to prevent EHV-1 abortion: Pneumabort -K® (Fort Dodge Animal Health, Ft. Dodge, IA) and Prodigy® ( Intervet , Inc., Millsboro, DE).

8. Pregnant mares previously vaccinated against tetanus:  Vaccinate annually 4 to 6 weeks before foaling, both to protect the mare should foaling-induced trauma or retained placenta occur and to enhance concentrations of colostral immunoglobulins . Pregnant mares unvaccinated against tetanus or of unknown vaccinal history:  Administer a 2-dose primary series of tetanus toxoid with a 4- to 6-week interval between doses. Revaccinate 4 to 6 weeks before foaling. TT 25-40 Lf Units IM

9. Sheep and goats Pregnant ewes should be vaccinated for clostridial diseases (usually  clostridium perfringins type C & D and tetanus) 4 to 6 weeks prior to parturition. Vaccinated females will pass antibodies in their colostrum to their newborn lambs via the colostrum. Ewes that have never been vaccinated or whose vaccination status is unknown will require two vaccinations during late gestation, 4 weeks apart. Ewes should not be vaccinated within two weeks of lambing. This is not enough time to get antibodies in the colostrum. If the dam was not vaccinated for tetanus, the tetanus Antitoxin should be given at the time of docking.  

10. Can pregnant cows be dewormed ? In the vast majority of cases, it is safe to deworm pregnant cattle . ... There are a few exceptions; an example is albendazole ( Valbazen ), which restricts use in  cattle  during the first 45 days of pregnancy . Pyrantel pamoate is safe to use in pregnancy and lactation and is frequently used in these situations to minimize the worm burdens of neonatal animals.

11. Deworming mares Most commercially available dewormers are safe for use in pregnant mares, however, it is always recommended to check the product label before administering a dewormer or any other product to a pregnant mare. Last treatment should occur 4-6 weeks before her due date Many vets suggest to administer ivermectin dewormer to the mare within 12 h or foaling to avoid the passage of strongyles in milk that may cause diarrhea in new born foals.

12. Dogs Deworm the bitch prior to mating and then at 5 weeks and 8 weeks gestation. Make sure you use a good quality wormer that is SAFE for pregnant/lactating bitches. Fenbendazole is considered a safe  dewormer against roundworms, hookworms, whipworms and giardia . This may not stop the puppies from getting worms, but at least It may decrease the amount

13. Sheep and goats It is a good idea to feed a coccidiostat to ewes during late gestation. All sheep have coccidia in their GI tracts. Coccidiostats disrupt the life cycle of coccidia ; therefore, feeding a coccidiostat will reduce the number of coccidia oocytes being shed into the lambing environment.  Deworming with an effective anthelmintic will help the ewe expel the worms and reduce the exposure of newborn lambs to infective worm larvae.  Albendazole should not be given to pregnant ewes during first trimester of pregnancy.

14. Symptoms of approaching parturition Cow Udder enlargement 4 months in heifers and 1-2 weeks before parturition in cows Vaginal discharge 7 months Relaxed ligaments 24 - 48 h prepartum, raised tail head, anorexia, Bitch Vomition, drop in 1-2 rectal temp 24 h prepartum, nesting behavior. Mare Drop in mammary secretion electrolytes Waxing of teats

15. Symptoms of approaching Parturition

16. Theories of parturition initiation Physical factors 1. Increase in fetal size: this increases uterine irritability 2. Uterine distension : reversal of progesterone block 3. Fatty degeneration of placenta and presence of infarcts: leads to interference in fetal nutrition Biochemical factors: 1. Increase in CO 2 tension in maternal blood due to increased fetal activity : this ↑uterine contractility 2. Release of fetal antigens: →serotonin →release of collagenase and stoppage of blood supply to cotyledons.

17. Neuroendocrine factors: FETAL factors 1. ↑ in cortisol in adrenals →convert P 4 to E 2 & release of PG 2. ↑ in ACTH by pituitary →stimulate cortisol release 3. ↑ in CRH in hypothalamus →stimulate ACTH 4. ↑ in endogenous opiods →stimulate ACTH

18. MATERNAL factors 1. Reversal of P4 block → ↑ myometrial contactility 2. Release of relaxin → dilation of the birth canal 3. Placental estrogen rise →release of PG ↑ myometrial contactility 4. Pro- inflamatory cytokines → dilation of the birth canal 5. Release of PG → softening of cervix, contractions ↑ 6. Release of Oxytocin → ↑ myometrial contactions

19. Fetal hypothalamus ↓ Fetal Pituitary ↓ ACTH ↓ Fetal adrenal ↓ Adrenal corticosteroids ↓ Convert progesterone to estrogen ← Feto placental estrogens → Relaxin ↓ ↓ → →→ → →→→ → →→↓ Cervical softening ← ← ← ← ↓ Cotyledons / Myometrium ↑ Proinflamatory cytokines ↓ Luteolysis ← Release of PGF →oxytocin ↓ ↓ ↓ ↓ Decrease in serum progesterone ↓ ↓→ ↓ ↑ Abdominal contractions Myometrial contractions → Fetal Expulsion ↑ Oxytocin ↑ Posterior Pituitary Possible endocrine changes that occur during the periparturient period in the sow, ewe, cow and their effects

20. Parturition Fetal Nutritional Demands Placental Insufficiency Hypothalamus Anterior Pituitary Adrenal Cortex CRH ACTH Fetal Corticosteroids (Cortisol) Lung (surfactant) Liver (glycogen) Thyroid (metabolism) Progesterone Estrogen PGF 2 a Uterine Contractions PGF 2 a Relaxin Oxytocin Uterine Endometrium Oxytocin receptors Uterine Myometrium Gap junctions Ovary (CL) Cow, Sow Triggers CL Regression Placentome Cervical Ripening

21. Final Role of Oxytocin Sensory Neurons in Cervix Oxytocin from Posterior Pituitary Myometrial Contractions

22. Orientation of Fetus Fetus must reorient prior to parturition Initially on back Reorient so feet and head will exit first Breech Rear of fetus comes first Orientation not important in pig Abnormal orientation results in dystocia

23. Fetal Orientation

24. Fetal Orientation

25. Placenta Liver Left Atrium Lungs Right Atrium Foramen Ovale Ductus Venosus Ductus Arteriosus Aorta Umbilical Arteries Umbilical Vein Portal Vein Vena Cava Head and Heart Tissues Fetal Circulatory System

26. Liver Left Atrium Lungs Right Atrium Foramen Ovale Ductus Arteriosus Aorta Portal Vein Vena Cava Head and Heart Tissues Adult Circulatory System Ductus Venosus

27. Perinatal Fetal Changes Immune status Has no antibodies to protect Gets passive immunity from mother Gut permeable to antibodies in colostrum Only first 1 - 2 days Rabbit, rat, man get some antibodies absorbed through placenta

28. Prepartum fetal changes: Changes do occur in the fetus before delivery and these are essential because the fetus has to prepare itself for the external environment outside the uterus. The changes include Maturation of fetal lungs: The surfactants in the lungs increase which reduce the surface tension within the alveoli. Increased output of tri- iodothyronine and catecholamines to meet the increased metabolic demands Closure of the ductus arteriosus and the closure of the foramen ovale Increased glycogen reserves in the liver to meet the demands on delivery by the production of glucose as a source of energy post delivery.

29. Stages of Labor Preparative (2 to 12 hours) 1 st stage Myometrial contractions Uterine pressure Abdominal discomfort Cervical dilation Appearance and rupture of first water bag ( Chorio -allantois)

30. Stages of Labor Expulsion of fetus (30 to 180 min) (2 nd stage) Strong uterine contractions Rupture of the allantochorion Appearance of the fetus wrapped in amnion Maternal recumbence and straining Not only uterine but abdominal contractions as well Rupture of the amnion and fetal delivery

31. Stages of Labor (cont.) Expulsion of the placenta (1 to 12 hours) and uterine involution (3 rd stage) Uterine contractions Chorionic villi loosen Expulsion of the placenta Delayed in ruminants due to presence of cotyledons separating independently Suckling induces oxytocin release which triggers further uterine contractions

32. Species First stage of labor Second stage Third stage (Placental expulsion) Cow 4-24 h (Bluish vascular semitransparent chorio-allantois appears & ruptures 0.5 – 3 h (Amnion appears with the fetus. Fetus is delivered) 12-16 h (Placenta is expelled) Buffalo 1-12 h 45-90 min 7-12 h Mare 1-12 h 30 min Within 3 h Ewe/Doe 6-12 h 0.5-1 h Within 3-6 h Sow 12-24 h 0.5-4 h After 2-3 piglets or 4 h post farrowing Bitch 4-24 h 1 st puppy within 2 h of 2 nd stage of labor. 5-60 min between puppies. Total time upto 24 h After each puppy or within 2 h of last puppy Cat 2-12 h 1 st kitten within 5-60 min of labor. Subsequent kittens every 5-60 min Within 2 h of last kitten Camel 3-48 h 5-80 min Within 4 h Duration of different stages of labor in domestic animals

33. Sequence of parturition events in the cow

34. Parturition in the buffalo

35. 1 2 Sequence of parturition events in the mare 2 second stage and 3 third stage 2 2 3

36. Stages of labor in a goat 1 2 3 1. The first water bag( allantochorion ) is protruded 2. The second water bag (amnion) and the fetus are protruding through the vulvar lips. 3. The placenta is being dropped in the third stage of labor

37. A pregnant cat about to kitten and a sow in delivery

38. Maternal behaviour

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