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Female Reproduction: Cyclicity and Pregnancy

Female Reproduction: Cyclicity and Pregnancy. Dr. N. Matthew Ellinwood, D.V.M., Ph.D. January 29, 2014. Iowa State University College of Agriculture and Life Sciences. http://www.ivis.org/signin.asp?url=http://www.ivis.org/home.asp. The Bitch and the Queen. Historical Aspects

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Female Reproduction: Cyclicity and Pregnancy

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  1. Female Reproduction: Cyclicity and Pregnancy Dr. N. Matthew Ellinwood, D.V.M., Ph.D. January 29, 2014 Iowa State University College of Agriculture and Life Sciences

  2. http://www.ivis.org/signin.asp?url=http://www.ivis.org/home.asphttp://www.ivis.org/signin.asp?url=http://www.ivis.org/home.asp

  3. The Bitch and the Queen • Historical Aspects - Bitch vs. queen • Driving forces of research with dogs and cats • Practical aspects • Under ideal situations, neither have difficulty becoming pregnant • A variety of issues favor greater attention to the bitch for managed reproduction • Reproductive physiology • Breed characteristics • English bulldogs can’t naturally reproduce successfully • Management

  4. Canine and Feline Estrous Cycle • Estrus – period of sexual receptivity • heat, season, standing • Bitch • Monestrous • Queen • Seasonally polyestrous: multiple estrus cycles depending on the season

  5. Endocrinology of Estrous Cycle • Hypothalamic-pituitary-gonadal axis • Positive feedback loop • Pulsatile secretion of GnRH • Pituitary release of FSH and LH • Recruitment of ovarian follicles • Gonadatrope independent • haven’t developed LH and FSH receptors • Gonadatrope dependent • possessing receptors for LH and FSH

  6. Estrus • Beginning is influenced by estrogen and FSH • Escalation of positive feedback loop between ovary hypothalamus and pituitary leads to • LH surge • Ovulation: 24-48 hours after LH peak • Decline of estrogen and rise of progesterone • Triggers behavioral estrus in bitch; receptivity

  7. Trigger for Estrous Cycle • Canine • Unknown • Domestic dog cycle length is about every 6 months • Exception – Basenji, which is about every 12 months • Feline • Light/Day length • Long day breeders • ~ Feb – Sept • Induced ovulators • No spontaneous LH surge • Ovulation induced by the penile spines of the tom

  8. BasenjiAfrican Barkless Dog http://www.puppyfind.com/basenji.php

  9. Feline Estrous Cycle • Anestrus • October – January • Estrus occurs • February – September • Polyestrous • Proestrus 1-2 days • Estrus ~ 7 days • Behavioural change - Lordosis • External track shows no change • Bred or Not Bred

  10. Feline Cycle Continued • Not bred • Interestrus ~ 4 days • Cycle total ~ 14 days • Non fertile breeding or stimulated to ovulate • LH surge, CL forms • Metestrus/diestrus/psuedopregnacy ~ 36 days • Progesterone remains high • Cycle total ~ 45 days

  11. Feline Pregnancy • Luteotrophic factors produced by conceptus • Maintains CL function throughout pregnancy • Fertilization in oviduct (remain 5-6 days) • Implantation 11-14 days • Palpation 17-25 • Parturition 66 days after first breeding • Dystocia • Rare in the queen

  12. Reproductive Cycle of the BitchThe Vocabulary and Calendar • First Cycle • 6 to 18 months of age • Proestrus • Bloody vaginal discharge to standing heat • Estrus • Standing heat to refusal • Diestrus • Refusal of breeding to whelping or until luteolysis • Anestrus • Whelping to onset of next cycle

  13. Canine Estrous Cycle • Anestrus ~ 4 months • Proestrus ~ 9 days (25-3) • Turgid swelling of vulva, bloody discharge, attractive to male, will not “flag” or stand to be bred

  14. tovet.blogspot.com/2007/11/pyometra-in-cat.html Canine Estrous CycleContinued • Estrus ~ 9 days • Diestrus/Metestrus/Psuedopregnancy • ~ 45-60 days • High progesterone • Pregnancy associated behavioral and physiological responses • Pyometra risk • Pregnancy = 65 days from LH surge (+/- 1 day) • ~9 weeks

  15. Vaginal cytology • Parabasal cells • Intermediate cells • Superficial cells

  16. Endocrinology of the Cycle:Why we see what we see • Proestrus • Estrogen is increasing, produced by follicles, which are the functional unit of the ovary that matures the egg • Estrogen causes • growth and bleeding in the uterus, which results in bloody vaginal discharge • cellular thickening of the wall of the vaginal canal with increases of sloughed cells seen on cytology as superficial cells

  17. http://www.vivo.colostate.edu/hbooks/pathphys/reprod/vc/proestrus.jpghttp://www.vivo.colostate.edu/hbooks/pathphys/reprod/vc/proestrus.jpg Cytology of Proestrus Increasing cornification of epithelial cells of the vaginal wall

  18. Endocrinology of the Cycle:Why we see what we see • Estrus • Estrogen is decreasing, while progesterone is increasing • This combination causes onset of “standing heat”, which is the hallmark of estrus • 48 hours after the spike in luetenizing hormone • Roughly consistent with ovulation • Cytological estrus is ~95% superficial cells

  19. http://bakerinstitute.vet.cornell.edu/contentimages/library/fac-meyers-canine_image2.gifhttp://bakerinstitute.vet.cornell.edu/contentimages/library/fac-meyers-canine_image2.gif Cytology of Estrus

  20. Endocrinology of the Cycle:Why we see what we see • Diestrus • Period of pregnancy and pseudopregnancy with progesterone being the dominant hormone • Onset of diestrus is probably caused by a decline of estrogen below a threshold level • Onset is evaluated in two ways • Behavior: The bitch refuses to stand for breeding • Cytology: Sharp decline in % of superficial cells on vaginal cytology. May see a “neutrophil spike”

  21. http://www.vet.uga.edu/vpp/clerk/Beimborn/Fig4.jpg Cytology of Diestrus

  22. Overview of the cycle http://arbl.cvmbs.colostate.edu/hbooks/pathphys/reprod/vc/

  23. Canine Pregnancy and Parturition • Timing • Parturition can be 55-70 days from first breeding • Endocrinology • 65 days +/- 1 day from LH surge • Why the difference?

  24. Peculiarities of the Bitch and Stud • Ovulation of immature oocyte • Has not completed meiosis • Fertilization can occur over 5 days • Canine sperm can be long lived in tract • Variability in sub-cycle lengths • Proestrus (3-25 days) • Estrus (5-12 days) • Chemistry

  25. Canine Pregnancy(days relative to LH surge) • Ovulation (day 2) • Fertilization in the oviduct (day 3 – 8) • Maturation of ova (day 5) • 4- 8 cell embryo (bred early and late) in oviduct (day 9) • Uterine horns (day 12) • Migration (day 13-17) • Implantation (day 22) • Palpation (day 25-35)

  26. Canine Pregnancy Continued(days relative to LH surge) • X-rays of skull and spine (day 46) • X-rays of teeth (day 60) • Beginning of progesterone decline and nesting behavior (day 62) • Decline of progesterone to below 2 ng/ml (day 64) • Decline of body temp by 2.5 degree C (day 64) • Parturition (day 65)

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