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Theriogenology VCS862 > Estrous Cycle > Flashcards

Estrous Cycle Flashcards

1
Q

Estrus (noun)

A

Period of sexual excitability when a female will accept the male for breeding

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2
Q

Estrous (Adjective)

A

relating to or a characteristic of estrus

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3
Q

Estrous Cycle

Continually polyestrous

A

Regular estrous cycles throughout the year

NOT responsive to photperiod

Bovine, Porcine, Some Ovine breeds

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4
Q

Estrous Cycle

Seasonal Polyestrous

A

Regular estrous cycles during part of the year

Responsive to photoperiod

Short Day Breeders: ovine, caprine, cervids

Long-day Breeders: Equine, Feline, Hamsters

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5
Q

Estrous Cycle

Diestrous

A

Two estrus per year

Domestic Canine

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6
Q

Estrous Cycle

Seasonally Monoestrous

A

One cycle per year

African breed dogs, bears, wolves, foxes

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7
Q

Bovine Estrous Cycle Periods

A

Estrus

Metestrus

Diestrus

Proestrus

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8
Q
A

Bovine Estrous Cycle

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9
Q

Bovine

Estrus

A

Standing ot be mounted

Lasts 20 hours

Progesterone levels are low

Estrogen levels are falling

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10
Q

Bovine

Metestrus

A

No longer “Standing”

Ovulation 10-15 hrs after estrus ends

Lasts 3-5 days

CL is being developed

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11
Q

Follicle Growth

1 day after onset of estrus

A

Concentrations fo FSH decrease after initial surge

Growth of numerous follicles contine

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12
Q

Bovine

Metestrus

Follicle growth Day 2 post estrus

A

Progesterone concentrations begin to increase

FSH concentrations remain above basal levels

Dominance of growing follicles begin to affect smallest follicles (inhibin)

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13
Q

Bovine Follicle Growth

Day 3 post estrus

A

Dominant and subordinate follicles secreting estradiol and inhibin

These two compounds are suppressing the growth of other follicles

If the largest follicle was ablated or aspirated, the largest subordinate would continue to grwo and become dominant

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14
Q

Bovine Follicle Growth

Day 4 post estrus

A

CL size and progesterone concentrations increase substantially

Divergence of largest follicle form subordinates between day 3-4

Subordiante follicles become atretic

Dominant follicle acquires LH receptors

GnRH (exogenous - injected by human) induced LH surge can ovulate the domiant follicle

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15
Q

Bovine Follicle Growth

Day 5 post estrus

A

Few Corpora Lutea responsive to exogenous PGF2a

GnRH induced LH surge can ovulate the dominant follicle

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16
Q

Diestrus

A

Period of the CL

Lasts about 12 days

High levels of Progesterone

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17
Q

Bovine Follicle Growth

Days 6-14 post estrus

A

Neally all Corpora Lutea are responsive to exogenous PGF2a

GnRH induced LH surge can ovulate the dominant follicle if follicle is not too mature

FSH suppressed

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18
Q

Bovine Follicle Growth

Days 15-17

A

Nearlly all Corpora Lutea are responsive to exogenous PGF2a

GnRH induced LH surge will ovulate the new dominant follicle

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19
Q

Bovine Proestus

A

CL is regressing

Lasts 2-3 days

Progesterone levels decreaseing

Estrogen levels Increasing

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20
Q

Bovine Follicle Growth

Day 18

A

CL regression induced endogneously

GnRH induced LH surge will ovulate the new dominant follicle

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21
Q

Bovine Follicle Growth

Day 19 & 20

A

CL regression induced endogneously

GnRH induced LH surge will ovlulate the new dominant follicle

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22
Q

Equine Cycle is divided into two parts

A

Estrus

Diestrus

*Anestrus

23
Q

Anestrus

A

Complete absence of estrous cycles during short days

24
Q

Equine

Estrus

A

Aka “Heat” or “in heat”

Aka Follicular phase of the estrous cycle

Lasts 7 days

THe mare is receptive to the stallions advances

Progesterone levels in blood are low

Estrogen levels in blood are high

LH surge leasts longer in the mare than other species

Estrus Ends abotu 24-48 hours after ovulation

25
Q

Equine Estrus

Vaginal Speculum Examinaition

A

During Estrus, progesterone levels are low and the cervix is swollen with relaxed folds which hang down over hte open orifice

26
Q

Equine Estrus

Teasing

A

Obvious interest in the stallion, urination, vulva eversion, and squatting

27
Q

Equine Diestrus

A

Aka Luteal Phase of the Estrous Cycle

Time of progesterone dominance

Lasts 14-15 days

The mare refuses the stallion

Progesterone comes from the CL

Endogenous PGF2a is secreted by uterus if no maternal recognition of pregnancy by day 13-14

PGF2a causes CL lysis and a rapid decline in progesterone production the last few days of diestrus

28
Q

Equine Diestrus

Vaginal Speculum Examination

A

During diestrus, progesterone levels are high and the os cervix is tightly closed and surrounded by firm, well-defined folds

29
Q

Equine Diestrus

Teasing

A

Obvious hostility to the stallion, ears back, striking, biting, squealing

30
Q

Canine cycle is divided into 4 parts

A

Anestrus

Proestus

Estrus

Diestrus

Interestrus = diestrus + anestrus

31
Q

Canine Vaginal Cyctology

A

Evaluating vaginal cytology is an important clinical skill in canine repro management

Use cotton-tipped swab to gently exfoliate cells form the vaginal vault

Decrease estrogen means the bitch is not interested in breeding and the vaginal lining is thin. Vaginal cells are close to the blood supply and very healthy looking

Increased estrogen means the bithc is interested in mating and the vagina needs to “toughen up” and become thicker. The vaginal cells on the surface are now far from the blood supply and are dead

32
Q

Canine Anestrus

A

Lasts for a variable amount of time after diestrus ~ 90-150 days

Anestrus is a time of mandatory endometrial repair

Neither male nor female shows sexual interest

the vulva appears normal, not swollen or edematous

Progesterone is at baseline concentrations <1ng/ml

Prolactin secretion by the pituitary may promote anestrus, becuase prolactin inhibitors can be used to terminate anestrus

33
Q

Canine Anestrus

Vaginal Cytology

A

Relatively constant

One sees primarily proabasal and small intermediate epithelial vaginal cells

Neutrophils may or may not be present and RBCs are usually absent

Bacteria may or may not be seen

34
Q

Canine Proestrus

A

Averages 5-10 days

Males are interested in the female, but female is not interested in males

The vulva is swollen because of estrogen secretion by the growing follicles

THere is serosanguinous discharge form the vulva that results form diapedesis of RBCs through urterine vessels

The most reliable clinical sign of hte onset of proestrus is noting the first day of a bloody vaginal discharge

LH has an increased pulse-frequency

FSH suppressed

Estrogen comes from the growing follicles and peaks at end of proestrus

Testosterone is relatively high at the end of proestrus. This may result from a “backup” in estrogen synthesis. This may result in some masculine behavior by the bitch such as mounting other dogs

35
Q

Canine Early Proestrus

A

Similar to bithc in anestrus except, for the presence of varying ninbers of red blood cells

RBCs numerous parabasal cella nd intermediate cells

Neutrophils are common although usually not abundant and bacterai

the background is granual or “dirty”

36
Q

Canine Mid-proestrus

A

THe first evidence of continued estrogen effect on the vaginal cytology is the disappearance of neutrophils

Fewer parabasal and small intermediate cells, more large intermediate and superficial intermediate cells

RBC may ro may not be present

The background is dirty or clear

37
Q

Canine Late proestrus

A

No neutrophils, RBC are variable background is clear

Greather than 80% of the vagianl cells are superficial cells, with pyknotic nuclei or anuclear superficial celsl

38
Q

Canine Estrus

A

Average 9 days

THe make and female are both interested in each other

The estrous behavior results from the abrupt decline of estrogen following the peak in leat proestrus

39
Q

Canine Diestrus

A

Time of progesterone dominance

the hormonal events of diestrus are essentially the same in both pregnant and non-pregnant bitches

The female refuses male advances

Progesterone comes form the CL and rises through the first half of diestrus

Endongenous PGF does not appear to be luteolytic in the bitch

Exogenous prostaglandins are luteolytic in the bitch as early as 5 days after the beginning of diestrus

40
Q

Canine Diestrus

Vaginal cytology

A

clearly demarcated from that from a bitch that is nearing the end of estrus

within 24-48 hours at the end of estrus the percentage of superficial cells falls to approxiamately 20%, with the remainder of cells usually being intermediate cells

neutrophils occasionally reappear

ovulation happend 6 days ago

41
Q

Feline

Proestrus

A

averages 1 day or less

rejects males, but displays rolling, head rubbing, vocalization, crouching

42
Q

feline

estrus

A

averages 6 to 7 days

accepts male - deviation of tail to one side and allows male to grasp dorsum of neck

Intestsification of proestrus behavior: rolling, head rubbing, vocalizing, crouching

INDUCED OVULATOR

43
Q

Induced ovulator

A

if mating does not occur, LH is not released

Multiple matings results in higher and more prolonged LH release

Ovulation occurs about 50 hours after LH peak

44
Q

Feline Metestrus

A

lasts about 1-2 weeks

if not mated and LH is not released - no ovulation occurs and follicles regress during metestrus

If queen does not ovulate - progesterone does not rise above base-line

45
Q

Stage of Estrous Cycle Determination

Bovine

A

One time palpation of ovarian structures will NOT determine chates of cycle

Uterine tone differs based on dominate steroid homrone: relaxed with progesterone, turgid with estrogen; not reliable

Progesterone concentration in milk

Estrus detection - standing to be mounted

46
Q

Stages of estrous cycle determination

bovine

Estrus detection

A

breed AI 12 hours after first detection in estrus

secondary signs: riding other cows, mud on back, increased activity

Gomer (penile deviation) bull, androgenized cows

Color-change patches or tail-head paint ot indicate riding

Electronic mounting detector

Electronic behavior monitoring

47
Q

Stage of Estrous Cycle determination

Ovine

A

Estrus detection:

Ewes are subtle - difficult to detect in estrus

To detect estrus in order to utilize AI - need a vasectomized ram

48
Q

Stage of estrous Cycle determination

Caprine

A

Estrus Detection

Does will vocalize more and increased tail wagging

Vulva becomes reddened and vaginal discharge may be noted

To detect estrus in order to utilize AI - need a vasectomized buck

49
Q

Stages of Estrous Cycle Determination

Equine

A

One-time palpation of ovarian structures will NOT determine stages of cycle

Serial ovarian palpation of folicle size can be used to determine timing of ovulation

Cervical tone differs based on dominate steroid hormone

Estrus detection - teasing witha stallion

50
Q

Stages of Estrous Cycle Determination

Equine

Estrus Detection

A

daily during breeding season

take at least 15-20 minutes

Estrus behavior may be suppressed in: maiden mares, timid mares, mares with foals, during inclement weather, or early in the breeding season

51
Q

Stage of Estrous Cycle Determination

Porcine

A

Standing to be mounted

Twice daily is recommended

Boars and females brought to neutral pen or boar is walked next to femal pen

Boar-odor sprays or audio recordings of boar “chant” can be used in absence of a live boar

Handler applies pressure to females back in the presence of a boar - females in heat will stand firmly

52
Q

Stage of Estrous Cycle Determination

Canine

A

Estrus detection - most common method for natural mating

Vaginal Cytolog - NOT precise enough to use alone for AI

Serum Progesterone

53
Q

Stage of Estrous Cycle determination

canine

serum progesterone levels

A

First rise in P4 >1ng/ml is correleated with LH peak

Ovulation begins 24-48 hours later, and oocytes are fertile 24-48 hours after ovulation

Measure every 2 days starting on day 5 of proestrus

Breed 4-6 days after first rise in P4

Breed first day P4>5-7.5ng/ml

Breed 72hrs after first day P4 >5-7.5ng/ml Frozen semen)

54
Q

Stage of Estrous cycle determination

Canine

Serum LH

A

used in conjunction with P4 measurments

Typically measured every day starting on Day 5 of proestrus

There are several rises in LH prior to the ovulatory peak

This assay is not always used

Theriogenology VCS862 (13 decks)

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