CANINE ESTROUS CYCLE

Canine estrous cycle stages, PEDA

Proestrus, Estrus, Diestrus, Anestrus

What does PEDA stand for

Proestrus, Estrus, Diestrus, Anestrus

Proestrus average duration

Approximately 9 days

Proestrus duration range

0–27 days

Proestrus behavior

Male is attracted, but the female is NOT receptive

Proestrus hormonal changes

Estrogen peaks and follicles develop

Proestrus physical changes

Swollen vulva and bloody discharge

Proestrus vaginal cytology

Mixed cell population with many RBCs

Estrus average duration

Approximately 9 days

Estrus duration range

4–24 days

Estrus behavior

Female accepts the male and this is the fertile period

Estrus hormonal changes

Estrogen decreases while progesterone begins increasing

Estrus physical changes

Vulva remains enlarged, becomes softer, and has less blood

Estrus vaginal cytology

Predominantly cornified epithelial cells

Diestrus duration

Approximately 2 months

Diestrus behavior

Female no longer accepts the male

Diestrus hormonal changes

Estrogen is low, while progesterone peaks then gradually falls

Does diestrus occur whether or not pregnancy happens

Yes, diestrus occurs whether or not pregnancy happens

Diestrus vaginal cytology

Returns to basal cells with few RBCs

Anestrus duration

The longest phase, approximately 4 months, with some breeds having a longer duration

Anestrus function

Allows uterine repair and preparation for the next reproductive cycle

Anestrus physical findings

No vulvar swelling and no discharge

Anestrus vaginal cytology

Basal cells

Which stage has the highest estrogen

Proestrus

Which stage has decreasing estrogen and increasing progesterone

Estrus

Which stage has low estrogen and peak progesterone

Diestrus

Which stage has basal hormonal activity

Anestrus

Which stage is the fertile period

Estrus

Which stage is the female receptive to the male

Estrus

Which stage has a swollen vulva and bloody discharge

Proestrus

Which stage has predominantly cornified epithelial cells

Estrus

Which stage has mixed cells and many RBCs

Proestrus

Which stage has basal cells and few RBCs

Diestrus

Which stage has no vulvar swelling or discharge

Anestrus

Which stage has the longest duration

Anestrus

Which stage lasts approximately 2 months

Diestrus

Which stage lasts approximately 4 months

Anestrus

What happens to the vulva during estrus

It remains enlarged, becomes softer, and has less blood

What happens to progesterone during estrus

Progesterone begins increasing

What happens to progesterone during diestrus

Progesterone peaks then gradually falls

What happens to estrogen during proestrus

Estrogen peaks

What happens to estrogen during estrus

Estrogen decreases

What happens to estrogen during diestrus

Estrogen is low

What happens to estrogen and progesterone during anestrus

Both remain at basal levels

Proestrus quick identification

9 days, female not receptive, estrogen highest, swollen vulva, bloody discharge, mixed cells + RBCs

Estrus quick identification

9 days, female receptive, fertile period, estrogen decreasing, progesterone increasing, cornified cells

Diestrus quick identification

2 months, female not receptive, estrogen low, progesterone peaks then falls, basal cells

Anestrus quick identification

4 months, female not receptive, no swelling or discharge, basal cells

Canine estrous cycle order

Proestrus → Estrus → Diestrus → Anestrus

Receptive stage of the canine estrous cycle

Estrus only

Non-receptive stages of the canine estrous cycle

Proestrus, Diestrus, and Anestrus