Female Reproduction: Cyclicity and Pregnancy

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Female Reproduction Cyclicity and Pregnancy

• N. Matthew Ellinwood, D.V.M., Ph.D.
• AnS 224
• Spring 2009

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http//www.ivis.org/signin.asp?urlhttp//www.ivis
.org/home.asp
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The Bitch and the Queen

• Historical Aspects
• - Bitch vs. queen
• Driving force of research
• Practical aspects
• Under ideal situations, neither have difficulty
  becoming pregnant
• A variety of issues favor greater attention to
  the bitch
• Reproductive physiology
• Breed characteristics
• English bulldogs cant naturally reproduce
  successfully
• Management

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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

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Endocrinology of Estrous Cycle

• Hypothalamic-pituitary-gonadal axis
• Positive feedback loop
• Pulsatile pituitary secretion of GnRH
• Release of FSH and LH
• Recruitment of ovarian follicles
• Gonadatrope independent
• havent developed LH and FSH receptors
• Gonadatrope dependent
• possessing receptors for LH and FSH

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Feedback Loops of the Female
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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

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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

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BasenjiAfrican Barkless Dog
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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

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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

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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

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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

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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

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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

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Vaginal cytology

• Parabasal cells
• Intermediate cells
• Superficial cells

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Endocrinology of the CycleWhy 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

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Cytology of Proestrus

• Increasing cornification of epithelial cells of
  the vaginal wall

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Endocrinology of the CycleWhy 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

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Cytology of Estrus
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Endocrinology of the CycleWhy 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

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Cytology of Diestrus
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Overview of the cycle
http//arbl.cvmbs.colostate.edu/hbooks/pathphys/re
prod/vc/
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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?

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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

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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)

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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)