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physiology of reproduction in canine.pptx
- 2. Why………? To know…. The stages of estrus cycle and corresponding clinical signs The changes in hormonal profiles and physiological changes By knowing these, one can intervene successfully in the process of reproduction.
- 3. Neonate Adult Puberty Oestrous Cycle Successful Breeding or Mating Pregnancy Whelping Life cycle of Bitch
- 4. Reproductive Hormones originate from…. Maternal Hypothalamus Pituitary Gland Ovary Placenta Fetal Adrenal Cortex
- 5. Anatomy of typical mammalian hypothalamus and pituitary
- 6. HYPOTHALAMUS
- 10. OVARY
- 11. OVARY E2 E2 E2 / P4 P4 Estrous behavior Pregnancy maintenance upto 35 days of LH surge Then who is there to save the fetus after 35th day ?
- 12. FETUS
- 13. P4 to E2 in mother unit PGF2α from feto- placental unit unit Fetus under stress at end of Gestation Cortisols from fetus to mother
- 14. PLACENTA
- 15. PLACENTA PGF2α from feto- placental unit unit Relaxin Pelvis & Uterine muscles relaxation Whelping process
- 16. Puberty
- 17. Average age of puberty in males and females Canine Male: 5-12 months Female: 6-24 months
- 18. Puberty in biches has breed variation…. Small breeds- Earlier Large breeds- Later Why…….
- 19. Female must reach threshold body size before puberty can be achieved
- 20. Gn RH neurons detect “Moment – to-moment” changes in Blood glucose & FA
- 21. Blood FA may stimulate neurons that in-turn stimulate GnRH neurons Blood FA would be an indicator of nutritional status of the animal
- 22. Leptin Adipocytes produce leptin that enters the blood. Leptin may stimulate GnRH neurons Blood leptin reflects the nutritional status of the animal because the greater the amount of fat the greater the amount of leptin
- 24. Adult
- 25. Oestrous Cycle
- 26. Bitches - monoestrus non-seasonal Majority show signs of heat within a limited season (seasonality) Contradiction is probably due to the effect of “Pheramones” Pheramones from the fellow estrus bitch can induce cycle in an anestrus one This influences the intervention of pharmacological agents
- 27. Reproductive Cycle in Bitch Proestrus Estrus Diestrus Anestrus
- 28. Stage Duration in days External signs Proestrus 9 days Enlarged Vulva w/ bloody discharge, restlessness, no courtship w/ male Estrus 9 days Clear to pink vulva discharge, female turns hindquarters towards him, raises pelvic region, waves tail, male acceptance and courtship Diestrus 60 days Vulva shrinks, no discharge, non- acceptance of male, terminates with parturition Anestrus 100 + days Inactive ovaries, no vulval discharge, low steroids Canine Estrous Cycle
- 29. Swollen vulva & sero-sanguinous vulvar discharge characteristic of proestrus
- 30. Softer vulva & tan - coloured discharge characteristic of Estrus
- 31. LH surge be taken as a centre point for the incidents take place during a cycle
- 32. Ovulation takes place- 2 days after LH surge Maturation ovum-2 days after ovulation Implantation of zygote-18-20days from LH surge Whelping takes place 63 days from LH surge
- 33. Reproductive cycle in bitch Implantation Fertilization Ovulation Prolactin
- 34. Changes During Estrus of Bitch Vulva Swollen and Enlarged -8 -4 0 +4 +8 +12 Indicates Day of Peak in LH Proestrus Estrus Passive Aggressive towards Male Provides sexual posturing to male for copulation Bloody discharge from vulva Copulation
- 35. FSH & LH 2-3 weeks prior to proestrus, the ant.pituitary secretes FSH in pulses of increasing frequency FSH controls the development of the ovarian follicles, which in turn secrete principally oestrogen, but also, as they reach maturity, progesterone. Low conc of oestrogen exert +ve feedback on the ant.pituitary that stimulate more FSH to be released, resulting in further follicle growth and increased oestrogen concentrations. Process continues until the follicles are mature & about to rupture. At this stage, the higher concentrations of oestrogen have a -ve feedback effect that inhibit FSH secretion and trigger the release of LH from the ant.pituitary in a large pulse, which causes ovulation
- 39. -10 -6 -4 -2 0 2 4 8 12 14 Hormonal Patterns During Estrous Cycle of Bitch Arbitrary Plasma Concentrations Days from LH Peak Estrogen LH Progesterone Ovulation Fertile Period Completion of Meiosis I Fertilization
- 41. “Copulatory Tie” is not necessary for conception
- 42. Bitch - unusual in …… Low prog. conc produced by pre-ovulatory follicles are present prior to ovulation & these, in conjunction with falling levels of oestrogen, are probably responsible for the initiation of standing oestrus The signal that marks the end of proestrus & the beginning of oestrus are progesterone conc. above the critical plateau of 0.5ng/ml in conjunction with declining oestrogen conc. There is a long period of progesterone dominance, probably because the canine uterus produces no luteolytic factor
- 43. Unique hormonal changes -in oestrous cycle lead to two distinct phenomena: False pregnancy & cystic endometrial hyperplasia (CEH)- pyometra complex Long exposure to high progesterone conc. during each oestrous cycle may result in a syndrome of excessive GH production from the mammary gland resulting in acromegaly in some dogs
- 44. Pregnancy
- 45. Spermatozoa unite with the matured Ovum and forms zygote Zygote gets implanted in the uterus at about 18-20 days after LH surge
- 46. 3 stages of Pregnancy I.Fertilization to Implantation II. Implantation to Ossification III. Ossification to whelping
- 47. Development of CL is initiated in response to LH & is maintained by luteotrophic factor(s)-prolactin CL secrete progesterone, which, at high conc has a -ve feedback effect on production of LH, which maintains these secretory bodies until day 35 As LH levels dropped down, the P4 levels comes down Falling levels of progesterone have a +ve feedback effect on prolactin that maintains luteal function after day 35. Prolactin is the gonadotrophin secreted from Ant. Pituitary
- 49. OVARY E2 E2 E2 / P4 P4 Estrous behavior Pregnancy maintenance upto 35 days of LH surge Then who is there to save the fetus after 35th day ?
- 50. Arbitrary Plasma Concentrations 0 10 20 30 40 50 60 70 Days of Pregnancy Mating Parturition Progesterone Prolactin Corticosteroids Total Estrogens Hormone Concentrations During Pregnancy and Parturition
- 51. Whelping
- 52. Size of foetus increases Pressure on foetus gets elevated Pressure causes release of cortisols in fetus Cortisols from fetus enters mother’s circulation through placenta Cortisols lead to conversion of P4 to E2 in mother Cortisols also cause release of PGF2α from feto- placental unit PGF2α induces production of Relaxin from placenta Relaxin results in relaxation of pelvis and uterine contractions Contractions of uterus will be longitudinal and circular movements alternatively
- 53. These movements push the fetus towards the cervix The pressure produced by the entry of fetus at cervix stimulates the release of Oxytocin from Posterior Pituiary gland This Oxytocin further aggravates the uterine contractions
- 54. P4 to E2 in mother unit PGF2α from feto- placental unit unit Fetus under stress at end of Gestation Cortisols from fetus to mother
- 55. PLACENTA PGF2α from feto- placental unit unit Relaxin Pelvis & Uterine muscles relaxation Whelping process
- 57. The bitches with single fetus are more prone for whelping difficulties than those with multiple fetuses.
- 59. Common clinical conditions in bitches i. Pre-pubertal-Delayed maturity ii. Mature-Mismating Pseudopregnancy Pyometra Prolonged anestrus iii. Pregnant-Dystocia iv. Postpartum-Agalactia v. Ovariectomised-Urinary incontinence vi. Ageing-Mammary tumors
- 60. THANK YOU