Estrous Cycle Flashcards

Question

How can mares be tested for estrus?

Answer 1

* Vaginal Speculum Examination * During estrus, progesterone is low and the cervix is swollen w/ relaxed folds which hang down over the open orifice (external uterine ostium) * Teasing * Obvious interest in the stallion, urination, vulva eversion (winking), and squatting

Answer 2

* “Luteal Phase of the Estrous Cycle” * Time of progesterone dominance * Lasts 14 - 15 days (fairly consistent) * The mare refuses the stallion * Progesterone comes from the CL * Endogenous PGF_2a is secreted by uterus if no maternal regognition of pregnancy by day 13-14 * PGF_2a causes CL lysis and rapid decline in progesterone production the last few days of diestrus

Answer 3

* Vaginal Speculum Examination * During diestrus, progesterone levels are high and the os cervix (external uterine ostium) is tightly closed and surrounded by firm, will-defined folds * Teasing * obvious hostility to the stallion

Answer 4

* Anestrus * Proestrus * Estrus * Diestrus * \*Interestrus = diestrus + anestrus

Answer 5

* Evaluating vaginal cytology * Use cotton-tipped swab to gently exfoliate cells from the vaginal vault (stain w/ Diff-quick) * ⇣ Estrogen means bitch is not interested in breeding * Vaginal lining is thin. * Cells are close to the blood supply and "healthy looking' * ⇡ Estrogen means bitch IS interested in mating * Vaginal lining becomes thicker * Cells on the surface are now far from the blood supply and are dead

Answer 6

* Lasts for a variable amount of time after diestrus (or whelping) ~90 - 150 days * Time of manatory endometrail repair * Neither male nor female shows sexual interest * Vulva appears normal - NOT swollen or edematous * Progesterone is at baseline concentrations (\< 1 ng/ml) * Prolactin secretion by pituitary may promote anestrus, because prolactin inhibitors can be used to terminate anestus

Answer 7

* Relatively constant * Primarily parabasal and small intermediate epithelial vaginal ells * Neutrophils may or may not be present and RBC's are usually absent * Bacterial may or may not be seen

Answer 8

* Averages 5 - 10 days (range 2-22) * Males are interested in the females, but female is not interested in males * The vulva is swollen because of estrogen secretion by growing follicles * There is serosanguinous discharge from the vulva that results from diapedesis of RBCs through uterine vessels * The most reliable clinical sign of the onset of proestrus is noting the first day of a bloody vaginal discharge * LH has an increased pulse-frequency * FSH is suppressed * Estrogen comes from the growing follicles and peaks at the end of proestrus * actually the decline in estrogen at the end of proestrus that causes the bitch to show clinical signs of estrus * Testosterone is relatively high at the end of proestrus. May result from a ‘backup’ in estrogen synthesis. May result in some masculine behavior by the bitch, such as mounting other dogs

Answer 9

* Similar to anestrus except for the presence of varying numbers of red blood cells * RBC's, numerous parabasal cell and intermediate cells * Neutrophils are common, although usually not abundant, and bacteria may be present in small to large numbers * background is granular or “dirty”

Answer 10

* 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 * RBCs may or may not be present * Background is dirty or clear

Answer 11

* No neutrophils * RBCs variable * background is clear * Greater than 80% of the vaginal cells are superficial cells, with pyknotic nuclei or anuclear superficial cells

Answer 12

* Average 9 days (range 3 - 21 days) * Male and female both interested in each other * behavior results in abrupt decline of estrogen following the peak in late proestrus * if decline is prevented (exogenous estrogen) bitch will not show signs of estrus

Answer 13

* Throughout standing heat the vaginal cytology remains relatively constant * No changes to suggest the day of the LH peak or ovulation or the timing of fertilization * Superficial cells and anuclear squames account for greater than 80% of the total vaginal cells, often reaching 100% * No neutrophils are seen on cytology throughout this phase, RBCs may or may not be present

Answer 14

* Hormonal events of diestrus are essentially the same in both pregnant and non-pregnant bitches * Female refuses male advances * **Progesterone dominates** * Progesterone comes from the CL and rises through the first half of diestrus * Endogenous 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

Answer 15

* Clearly demarcated from that of a bitch nearing the end of estrus * Within 24 - 48 hour period at the end of estrus, the percentage of superficial cells falls to approximately 20% with the remainder of cells usually being intermediate cells * Neutrophils occasionally reappear * Ovulation is estimated to have occurred 6 days before the onset of diestrus

Answer 16

* Proestrus * Estrus * Metestrus

Answer 17

* Averages 1 day or less * Rejects male, but displays: rolling, head rubbing, vocalizing, crouching, etc

Answer 18

* Averages 6 - 7 days * Accepts male * deviates tail to one side, allows male to grasp dorsum of neck * Intensification of proestrus behavior * rolling, head rubbing, vocalizing, crouching * Queen is an **induced ovulator** * If no mating - LH is not released * Multiple matings result in **higher and more prolonged LH release (**single mating may not be sufficient to induce LH release) * **Ovulation occurs about 50 hours after LH peak**

Answer 19

* Lasts about 1 - 2 weeks * If not mated and LH is not released: * no ovulation * follicles regress during metestrus * No ovulation - progesterone does not rise above base-line * Therefore, not the typical progesterone-dominated diestrus characteristic of the non-ovulating portion of mammalian cycles

Answer 20

* One-time palpation of ovarian structures will NOT determine stage * CL and CA are present continually * Large follicle present most days * serial palpation would be useful - not done clinically * Uterine tone differs based on dominate steroid hormone * Progesterone - relaxed * Estrogen - turgid * Not Reliably accurate * Progesterone concentration in milk (dairy) * P₄ high(\>1 ng/ml) = NOT estrus * Estrus detection aids - standing to be mounted * Breed (AI) 12 hours after first detected in estrus * Secondary signs: riding other cows, mud on back, ⤒ activity * Gomer (penile deviated) bull, androgenized cows * Color-change patches or tail-head paint to indicate riding * Electronic mounting detector * Electronic behavior monitoring

Answer 21

* Estrus detection - very subtle * TO detect for AI - nee vasectomized ram * Doe will vocalize more and increase tail wagging * Vulva becomes reddened and vaginal discharge may be noted * One-time palpation of ovarian structures will NOT determine stage of cycle * CL not palpable * Large follicle present many days of the cycle

Answer 22

* One-time palpation of ovarian structures will NOT determine stage of cycle * Serial ovarian palpation of follicle size can be used to determine timing of ovulation * Cervical tone differs based on dominate steroid hormone * Progesterone - closed * Estrogen - relaxed * Teasing * Daily during breeding season * Take 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

Answer 23

* Estrus detection - standing to be mounted * 2x daily recommended * Boars and females brought to neutral pen or boar is walked next to female pen * Boar-odor sprays or audio recordings of boar “chant” can be used in absence of live boar * Handler applies pressure to female's back * females in heat will stand firmly

Answer 24

* **Estrus detection** - most common method for natural mating * bring female to male (male's territory) * **Vaginal cytology** * used with other methods * Not precise enough to use alone * Onset of diestrus is most precise classification possible w/cytology * **Serum Progesterone** * First rise in P₄ \> 1 ng/ml is correlated with LH peak * Ovulation begins 24-48 hours later (ovulating for 24-48 hours) and oocytes are fertile 24-48 hours after ovulation * Measure every 2 days on day 5 of proestrus * breed 4-6 d after first rise * breed first day P₄ \>5-7.5 ng/mL (& again 24-48 hours later) * breed 72 hours after first day P₄ \> 5-7.5 ng/mL (frozen semen) * **Serum LH** * used in conjunction with P₄ measurements * Typically measured every day starting on day 5 of proestrus (vaginal cytology or bitch behavior) * Several rises in LH prior to ovulatory peak * Not always used - $$

Answer 25

If ovulation does not occur follicles regress during metestrus