Exam 2 - Canine Estrus Cycle Flashcards

1
Q

What is puberty?

A

The ability of the hypothalamic neurons to produce sufficient GnRH

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2
Q

What does the Proestrus stage of the canine cycle entail?

A

initiation of overt activity

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3
Q

What does the Estrus stage of the canine cycle entail?

A

time for breeding (acceptance of the male)

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4
Q

What is the Diestrus stage of the canine cycle? (AKA what?)

A

AKA - Luteal phase

This is the stage in which either prenancy or pseudopregnancy occurs

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5
Q

What is the Anestrus stage of the canine cycle

A

period of quiescence & repair

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6
Q

What are the average lengths of the proestrus & estrus stages

A

Average duration is 7-9 d (total 14-18d)

actual range can be 2-21d

Each bitch is unique, needs individual breeding plan

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7
Q

How long is Anestrus in the canine

A

anestrus is usually 90 - 150+ d

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8
Q

how long is Diestrus in the canine cycle?

A

Fixed at 60 days whether pregnant or not!

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9
Q

what is the interestrus period?

A

the time from beginning of one estrus to the beginning of the next estrus

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10
Q

what is the minimum cycle length?

A

absolute requirement of 4 m

  • fertility is low if < 90d anestrus is not achived*
  • Diestrus is the canine luteal phase/progesterone phase -*

pregnancy or pseudopregnancy occurs in this phase!

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11
Q

what is the max cycle length?

A

normal = 12 mos

breed predispositions: Basenji, sight hounds

if >12 m then investiation indicated for cause (e.g. hyperprolactemia)

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12
Q

what is the vaginal cytology pattern during cycle?

A

normal thin: 2-4 cell layers in anestrus

under influence of estrogens = 20-40 cells thick by end of proestrus

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13
Q

What purpose does the thickening of the vaginal epithelium serve?

A

protect vagina against trauma

prevent bacterial entry

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14
Q

what can’t cytology of the cornification of vaginal epithelial cells tell us?

A

doesn’t accurately predict time of receptivity, LH surge or ovulation

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15
Q

what can cytology of the cornification of vaginal epithelial cells help with?

A

predict if the bitch is progressing & still in her fertile period

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16
Q

What is the best way to use cytology of vaginal epithelial cells when examining the bitch?

A

coordinate cytology with hormone concentrations & speculum examination!

17
Q

What are the physical changes seen in proestrus?

what causes the physical changes?

A

turgid swelling of vulva

hemorrhagic vulvar discharge

Diapedesis of RBC’s through uterine vessels - varies in individuals

18
Q

What would the vaginal cytology look like in proestrus?

A

Cornification of squamous epithelial lining of vagina,

by mid to late proestrus parabasal & small intermediate cells decrease, superficial & large intermdiate cells increase,

erythrocytes, neutrophils present

19
Q

during proestrus stage what changes can be seen by vaginal speculum?

A

early = vaginal mucosa edematous

late = starts shrinking, less edema

20
Q

what is a bitches behavior like during proestrus?

A

attracts males, but non receptive!

21
Q

which hormone dominates the proestrus stage?

A

Estrogen dominates!

Gonadotropins LH & FSH are low

Progesterone low (< 1 ng/mL)

22
Q

what are the physical changes in estrus stage?

A

softening of vulvar swelling

scant blood discharge

23
Q

what will vaginal cytology during estrus show?

A

cornification continues

24
Q

looking through vaginal speculum during estrus what is seen?

A

early = more shrinking of mucosa

late = max shrinkage called crenulation. angled mucosa

25
what is a bitches behavior like during estrus stage?
stands to be mounted & bred
26
What hormones are doing what during estrus stage?
progesterone rising estrogen falling LH & FSH peaks
27
describe hormone activity (profile) during estrus
**estrogen** begins to fall progesterone starts to rise - ***_first sharp rise of P4 is correlated with LH peak!_*** **Both estrogen & progesterone** necessary for standing behavior LH & FSH both peak at onset of estrus - may need both for ovulation
28
The bitch isn't pregnant yet! What is the rise in progesterone due to during estrus?
**Preovulatory rise is due to follicular estrual luteinization** When estrus ends, P4 is already greatly elevated over baseline
29
What is diestrus all about?
non acceptance of mating, but may still be attractive progesterone dominated - luteal phase vaginal cytology = superficial cells decrease, parabasal/small intermediate cells increase rounding/smoothing mucosa seen on vaginal speculum, may see variegated red/white areas pregnancy (pseuopregnancy) normal in bitch uterine tone develops 60 d duration (45-90 d range) mammary development in non preg. bitch subtle but reflects Prolactin levels
30
how does diestrus cease?
We don't know! No known luteolytc PGF2a from uterus in non pregnant bitch
31
And back to anestrus goes the bitch! How might that look?
Male shows no sexual interest in the female Female shows no sexual interest in male Vulva appears not swollen Vaginal cytology few cells and non-cornified * Superficial cells absent * ± Neutrophils & bacteria (low numbers) Vaginal wall is very thin and appears pale on vaginal speculum Progesterone is baseline (\<1ng/mL)
32