Ch.43.DzesofReproductiveSystem Flashcards
During the breeding season, mares ovulate every how many days?
every 21 days
How long is estrus in the mare?
5 to 7 days
What is estrus characterized by in the mare?
-presence of ovarian follicle
-serum progesterone less than 1 ng/ml
-sexual receptivity
-cervix palpably relaxed
-uterus is edematous
When does ovulation occur?
24 to 48 hours before the end of estrus
- may be accompanied by ovarian sensitivity
The first postpartum estrus (“foal heat”) occurs in what time period after foaling?
1 week after foaling
–ovulation between 7 to 15 days
When does diestrus occur?
**luteal phase
regression of CL, caued by released of endometrial prostaglandin F2alpha (PGF2alpha) occurs 14 to 15 days after ovulation
What is the estrous cycle of cows?
ave 21 days (17 to 25 days)
What is the duration of estrus in cows?
12 to 16 hours ( range 6 to 24 hours)
In the absence of a bull, estrus can be detected in cows by:
Signs of homosexual (bisexual) activity
-restlessness
-increased activity
-vulvar hyperemia
-edema
-clear mucous discharge
When is the optimum time for insemination of cows?
between 16 to 24 hours after onset of estrus
Well managed dairy cows with uncomplicated periparturient experiences may ovulate how many days after calving?
how about in beef cows?
approx. 20 to 25 days after calving
–beef cows with nursing calves– 40 or more days after calving
Coarse wooled breeds of ewes are seasonally polyestrous in what seasons? in temperate climates
autumn and winter (short photoperiod)
Ewes of fine wooled breeds are are polyestrous in what seasons?
year round
**if adequately nourished
When does lambing typically occur in ewes, in relation to their reproductive cycle?
during anestrous season
**do not return to estrus until the next breeding season
In what seasons are goats in estrous?
polyestrous from late summer until early spring (short photoperiod)
How long is the estrous cycle in goats?
ave 21 days
**lasts 18 to 26 hours
When does ovulation occur in goats?
in 24 hours after onset of estrous
Do South American camelids bred in North America have a breeding season? and when?
Nonseasonal
– bred in a seasonal manner to avoid newborn crias born in the hottest and coldest months of year
Why do South American camelids have nonseasonal breeding season?
because they are induced ovulators
Define ovarian cysts
follicle-like ovarian structures that arise because of failure of ovulation of a dominant follicle
–persist in absence of a CL for 10 days or more
What is the mechanism of ovarian cyst development?
unknown
What is the percentage of cows that are affected by cystic follicular development?
70 to 80% of cows affected by CFD are anestrus, whereas 20 to 30% display frequent or intense estrus (nymphomania)
**affects 10 to 30% of dairy cows
Why is cystic follicular degeneration not seen in beef cattle?
b/c commercial beef cows are culled for reproductive failure
Diagnosis of cystic follicular degeneration is based on:
-accurate history
-constant or frequent estrus
-short interestrous intervals
-anestrus may suggest CFD
-clinical exam
-evaluation of ovary via rectal palpation– presence of enlarged fluid-filled structures
Ultrasonography can help differentiate cystic follicular degeneration from what other diseases
salpingitis
hydrosalpinx
oophoritis
ovarian abscesses
ovarian neoplasms
cysts of fimbria
Other causes of ovary enlargement
Clinical pathology changes in cattle with cystic follicular degeneration?
-low plasma progesterone levels (lower than cows with normal CLs)
-variable estrogen levels
What is the goal of treating cystic follicular degeneration in cows?
induces luteinization and reestablish normal etorus cycles
Spontaneous recovery from cystic follicular degeneration occurs in what percentage of cows?
up to 60% of cows that develop CFD
What are possible treatment options for cystic follicular degeneration in cows? (without spontaneous recovery
human chorionic gonadotropin (luteinizing hormone)– retrun to norm estrous cycle w/in 3 to 4 wks
Gonadotropin-Releasing Hormone (ovarian cysts), followed by luteolytic dose of prostaglandin 10 to 14 days later
Prostaglandin F2alpha (luteal cysts)
Manual rupture (thin walled follicular cysts): complications of hemorrhage with adhesion formation between ovary and system
Poor nutrition affects reproduction in what ways?
poor or weak signs of estrus
depressed ovulation
abnormal cycle
delayed puberty
What nutritional deficiencies are commonly associated with irregular estrous cycles?
energy
protein
Vitamins A and E
phosphorus
many trace minerals (iodine, copper)
Anti-Mullerian Hormone is produced by what cells? and functions in?
-granulosa cells in developing follicles
functions:
-regulation of primordial follicular recruitment and development into primary follicles, preserving the ovarian reserve
-role in folliculogenesis (unknown role)
-reliable marker for presence of granulosa cell tumors
Sheep are sensitive to the effects of phytoestrogens. What clinical observations are seen?
infertility
irregular and prolonged heat cycles
lower conception rates
early embryonic death
heat stress has what effect on reproduction?
decreases estrus detection
impair follicular development
disrupt funciton of repro tract
affect oocyte competence
lead to early embryonic death
While embryos are developing, they develop resistance to heat shock? what bovine embyro stages are unaffected by heat shock?
morulae to blastocyst stages
What are differentials for anestrus in mares?
pregnancy
prolonged diestrus
seasonal anestrus
unobserved estrus
pyometra
undernutrition
granulosa-theca cell tumor
gonadal dsygenesis
When does the mare go through puberty?
between 12 to 24 months
Transitional mares exhibit signs of estrus such as:
clitoral “winking”
tail flagging
urination in presence of stallion
Anestrous mares on rectal palpation/ultrasound
-ovaries- small and firm
-uterus-flaccid wiht a thin endomterium
-cervix with mild tone
-specumulum: caginal mucosa is pale and dry, cervox usu closed
Artificial lighting can be used in mares to move vernal transition. What typical regiment is implemented
-expose mares to 16 hours of light and 8 hours of dark by extending the photoperiod in the evening starting in late November to initiate ovulation by February
– light added toe nd of day
-or split ebetween beginning and end of teh day
What can be performed/administered to alter mares anestrus cycle?
-artificial lighting
-exposure to stallions (several times a week, ovulated sooner than not)
-Gonadotropin releasing hormone (GnRH)- induced ovulation in 2 to 3 weeks
-dopamine antagonists
-steroids
-follicular aspiration in follicles <35 mm in diameter– hasten onset of cyclicity in transitional mares
Describe pseudopregnancy
-mares embryonic lossin presence of endometrial cups (d 35 to 150 of gestation)
-condition in which a conceptus was lost after maternal recognition of pregnancy and before development of endometrial cups, resulting in prolonged luteal life
What occurs in Pseudopregnancy, despite the loss of the fetus and placental tissue, what occurs?
endometrial cups remain in palce and continue to sevrete equine chorionic gonadotropin (eCG) for similar period in pregnant mare: 100 to 150 days
What is the treatment of Pseudopegnancy?
repeated daily injections of PGF2alpha– CL older than 5 days respond to tx
What are differentials for prolonged or irregular behavioral estrus in mares?
transitional period
Granulosa-theca cell tumor
Gonadal dysgenesis
Behavioral nymphomania
Normal mare
When approached by stallion what is normal estrus behavior in mare?
-ears held forward
-elevate tail
-rhythmically evert the clitoris (“winking”)
-assume squating posture
-urinate
-lean against teasing chute toward stallion
When approached by stallion, what is normal diestrus behavior in a mare?
hold ears back
strike, kick, squeal, swish tails and forcefully void small amount of urine
Behavioral nymphomania or abnormal estrous behavior and aggression may be seen in mares when?
at any stage of estrous cycle
**ovarian tumours considered an important differential
What are differential diagnosis of anestrus in cows?
Pregnancy
unobserved estrus
cystic follicular degeneration
pyometra
mummified
fetus
undernutrition
granulosa theca cel tumor
freemartinism
ovarian hypolasia
Dairy herds in which infertility is caused by inaccurate estrus detection are usually characterized by:
-prolonged intervals from calving to first breeding and between services
-insemination intervals of 10 to 15 days and 30 to 25 days
-records of examinations that confirm cyclic ovarian changes but in which observation of estrus is not recorded
-finding more than 15% cows presented for pregnancy examination to be nonpregnant
What is the treatment of the silent estrus in cattle? and what are the limitations?
PGF2alpha
-inaccurate palpation of the temporary ovarian structures
-injection during the wrong phase of the cycle
-failure of manager to observe estrus in treated cows (timed AI can be used to overcome this problem)
Sexual differentiation occurs in what three stages?
each stage is dependent on the previous one
- Chromosomal sex
- Gonadal sex
- Phenotypic sex
When is chromosomal sex determined?
at fertilization in mammals by the type of sex chromosome contributed by the sperm (X or Y). In mammals, females are XX and males XY
Gonadal sex is regulated by what gene?
Sry (sex determining region of the Y chromosome gene– produces a protein called the HY antigen
activation of this pathway induces testis formation in the bipotential gonads and X-linked Dax1 gene suppresses testis formation
What is phenotypic sex regulated by?
substances produced in the male testes to cause regression of the female tract and formation of the male tract
or, in the absence of a testis, formation of the female tract
abnormalities in chromosomal sex occurs because of:
nondisjunctional errors during either mitosis or meiosis
Monosomy X is known as what syndrome and is due to what genetic abnormalities?
Turner syndrome
lack of a Y chromosome and consequent Sry genethe phenotype is female
What is the most common reported chromosomal abnormalities in mares
Monosomy X
(turner syndrome)
Mares with monosomy X (Turners syndrome) have what characteristic C/S
-history of poor performance
-lack of or sporadic repro cyclicity
-ovaries small, inactive, smooth and firm
-uterus and cervix- usu hypoplastic
-externally mares genitalia may appear normal or underdeveloped
XXY Syndrome is part of Klinefelter syndrome because of what genetic abnormality?
presence of a Y chromosome and the consequent Sry gene, phenotypically male– generally have hypoplastic genitalia and repro organs
factor on X chromosome must escape the inactivation process, which happens early in development
What clinical signs are seen with the XXY syndrome?
testicular development and spermatogenesis are inhibited–> small, flaccid testes and azoospermia
+/- retained/descended testes
-normal libido & sexual behavior
+/-low testosterone concentrations
**infertility always accompanies this syndrome
What is seen with XXX genetic makeup?
report of an infertile mare– bilat small, inactive ovaries and a hypoplastic uterus and cevix
Define mosaics genetically
individuals that have at least two cell lines with different karyotypes arising from the same zygote
Define true hermaphrodites
mosaics that have mixed gonadal dysgenesis, with an ovary and a testis, or ovotestes, owing to sex chromosome mosaic cell lines
Define chimeras
individuals having cell lines from two different embryonic sources
Cause of chimeras?
-natural fusion of blastocysts in utero
-suspected double ovulation and fertilization followed by blastomere fusion (suspect in a horse)
What is the effect of chimerism seen in ruminants?
freemartinism– resulting in chimeric twins
Define freemartinism
phenomenon in ruminants in which an infertile female is twin to a male
What abnormal development results in freemartins?
-dizygotic occurrence happens when the blastodermic vesicles of 2 zygotes fuse early in development (cattle: d 18 to 20) and share embryonic tissue
-placentas fuse (day 30 to 50) and share blood through gestation
**occurs before gonadal differentiation at day 40 to 50
What is the genetic makeup of a freemartin?
XX/XY– both individuals
What are the effects of freemartinism in the female?
-lacks a cervix, uterus, uterine tubules and cranial vagina
-vulva is normal
-yearling free martin fails to exhibit estrus, udder and teats remain small and free martin externally resembles a steer (only with a vulva)
How can clinical diagnosis of free martinism be made?
-establish a blind end to the vagina (no cranial vagina, no cervix)
-confirm with genotyping or use of PCR to detect Y chromosome in a phenotypic female
what number of fetuses are seen with ovine free martinism?
-rare with twins or triplets
-common quadruplets or quintuplets
What genes act downstream of Sry to support gonadal differentiation?
Sox9
Gata4
Wt1
Sf1
synergistically promote testicular differentiation
When do sex reversals occur?
When chromosomal and gonadal sex do not agree with each other
ie: XX: sex reversed males, XY sex reversed females or true hermaphrodites (both ovarian and testicular tissue on separate gonads)
What cells secrete testosterone?
Leydig cells
What two steroids promote the differentiation of male genitalia?
Testosterone
dihydrotestosterone
The tissues that form the round ligament of the uterus are analogous to what male body part?
the male gubernaculum
Abnormalities of phenotypic sex occur because of:
when chromosomal and gonadal sex agree (XX with ovaries and XY with testes), but the xxternal and/or internal genitalia do not correlate or are amibiguous
**male or female pseudohermaphrodites
What are the most common causes of bilaterally small ovaries in the mare?
- seasonal anestrus
- Hypothalamopituitary dysfunction
- severe malnutrition
- Immaturity
- Advanced age
- Use of anabolic ssteroids
- gonadal dysgenesis
What is the affect of anabolic steroid administration in mares reproductively?
-Suppression of gonadotropin secretion
-effect on both estrous behavior and ovarian size and function
-low doses (aggressive or stallion-like behavior)
-high doses (inhibit ovarian activity, failure of follicular development & ovulation)
Mares with gonadal dysgenesis result in what characteristics of the reproductive tract?
-ovaries are small, firm, smooth & inactive
-tubular tract thin and flaccid
-endometrial hypoplasia
-mares are sterile & NO TX
What is the effect of PPID on the equine productive cycle?
-abnormal estrous cycles
-infertility
-possibly both
PPID causing decreased fertility is due to?
unknown mechanisms
-destruction of gonadotrophs of anterior pituitary
-insulin resistance– suspect role in ovarian steroidogenesis & follicular development
PPID mares that are pregnant, what is important to remember about their treatment with pergolide?
D/C 30 days before expected foaling until 1 month postpartum and mares should be monitored for decreased milk production
What are the most common causes of enlarged ovaries in the mare?
- tumors
- anovulatory follicles
- ovarian hematomas
- pregnancy
Most equine ovarian tumors are categorized as:
- sex cordstromal tumors (granulosa-theca cell tumors)
- epithelial tumors (cystadenomas)
- germ cell tumors (dysgerminomas and teratomas)
What is the most common ovarian tumor in the mare?
Granulosa- theca cell tumor (GCT)
Granulosa theca cell tumors develop from what cells?
steroidogenic cells of the follical- resultin gin abnormal secretion of inhibin and testosterone
What are characteristics on ultrasound of the reproductive tract of a mare with granulosa theca cell tumors?
-affected ovary: multi-cystic or honeycombed structure, solid mass or single larger cyst
-contralateral ovary: small & inactive
Granulosa theca cell tumors are hormonally active, what clinical diagnostic assay can be used for the detection of GCT tumors?
alpha inhibin: INC in 90% of mares with GCT
serum testosterone: elevated in 50 to 60% of affected mares
Progesterone: always below 1 ng/mL, b/c normal follicular development, ovulation and CL formation does not occur
Antimullarian hormone: GCTs consistently higher than normal cyclic & pregnant mares– excellent tool in dx of GCT
Granulosa theca cell tumors: clinical signs
-enlarged clitoris
-INC mm mass
-crested neck
other C/S: colic, lameness and weight loss
Granulosa theca cell tumors: treatment
Surgical removal:
-colpotomy
-flank and ventral midline laparotomy
-laparoscopy
What is the most common tumor of the surface of epithelium of the equine ovary?
cystadenoma
what are equine ovarian cystadenomas?
rare, benign
hormonally inactive tumors from surface of epithelium of the ovulation fossa
-tumor unilateral
-contralateral ovary is normal
Treatment of cystadenomas in the mare?
Benign tumors
– usu surgically removed
What are ovarian tumors of germ cell origin?
dysgerminomas and teratomas– rare ovarian tumors
**both tumors are unilateral & hormonally inactive
What are Dysgerminomas?
germ cell tumors
-affected ovary unilaterally enalrged & multicystic
-malignant
-often metastasize to peritoneal and thoracic cavity
What are ovarian teratomas?
arise from 3 germinal layers
-neoplastic ovary may contain bone, cartilage, teeth, hair, muscle and nerves
Ovarian teratomas effect reproductively?
Do not cause C/S, interrupt the estrous cycle or alter the behavior of the mare