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68 Cards in this Set

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GnRH

a. function
b. produced by...
c. clinical uses in cows
d. clinical uses in mares
a. causes ant. pituitary to synthesize & release gonadotropins (LH, FSH)
b. hypothalamus
c.
tx of cystic ovaries
synchronize ovulation in combo w/ progestagen & prostaglandin
superovulation in embryo transfer protocols
d. induction of ovulation
oxytocin

a. function
b. produced by...
c. clinical uses
a. stimulates smooth muscle contraction (mainly in genital & mammary tissues)
b. posterior pituitary
c.
milk letdown in females of all species
induction of parturition
induction of post partum uterine contractions/involution to promote emptying of uterus
LH

a. functions
b. produced by...
c. clinical uses
a.
stimulates tests to produce androgens (mainly testosterone)
stimulates ovaries to produce progesterone
causes oocyte maturation, ovulation of mature follicles, CL formation & maintenance
b. ant. pituitary
c. induction of ovulation of mature follicles
FSH

a. functions
b. produced by...
c. clinical uses
a.
stimulates follicular growth & estrogen production in females
promotes spermatogenesis in males
b. anterior pituitary
c. induction of estrus in pre-pubertal gilts & weaned sows
equine chorionic gonadotropin (eCG)

a. activity
b. produced by...
c. clinical uses in cows
a. FSH & LH bioactivity when administered to other mammals
b. endometrial cups of pregnant mare
c. superovulation protocols
human chorionic gonadotropin (hCG)

a. activity
b. clinical uses in cows
c. clinical uses in mares
a. major bioactivity is LH-like w/ a fairly long T1/2
b. tx of nymphomania caused by cystic ovaries
c. induction of ovulation of mature follicles (> 35 mm)
progesterone

a. functions
b. produced by...
c. clinical uses in cows
d. clinical uses in mares
a.
maintains pregnancy
suppresses uterine activity & promotes endometrial secretion
suppresses estrous cycle, ovulation, & usually estrus behavior
b. CL & placenta
c.
estrus synchronization (vaginal insert or delivered in food)
suppression of estrus in confined heifers in feedlots being fed to slaughter weights & not intended for breeding
d. estrus manipulation (seasonal transition, scheduled breeding)
estrogen

a. functions
b. produced by...
c. clinical uses in cows
d. clinical uses in mares
a.
responsible for behavioral estrus in females
acts w/ progestagens to stimulate growth of uterus & mammary glands
acts w/ oxytocin & PG to stimulate uterine contractions during parturition
ovarian follicle maturation
ovulatory surge of FSH & LH
b. ovarian follicle
c. superovulation protocols (compounded estrogens)
d.
enhance sexual receptivity of ovariectomized mares in semen collection programs
induction of labor prior to giving oxytocin
PGF-2a

a. functions
b. produced by...
c. clinical uses in cows & mares
a. luteolysis of CL & cessation of current cycle
b. endometrium
c. major use in estrous cycle control
What is impotentia coeundi?
either a lack of desire (libido) or an inability to copulate
What are some causes of lack of libido in males?
obesity
isolation
inexperience
age
poor BCS
systemic dz
psychic factors
pain
locomotor problems
genetics
What are some factors that cause inability to copulate in males?
genetics
balanoposthitis: inflammation of penis & prepuce
penile deviations: congenital or acquired
phimosis: inability to extend penis outside prepuce (dog most common)
paraphimosis: inability to withdraw penis into sheath (flaccid)
priapism: persistent erection (most common in dog & stallion)
hair rings: bulls
alterations of preputial process: bucks, rams
penile or preputial growths
What is impotentia generandi?
inability to fertilize ova
ddx for impotentia generandi assoc. w/ normal appearing semen
observed in certain infectious diseases

trichomoniasis, vibriosis, Mycoplasma in bull

Klebsiella, Psuedomonas, Taylorella equigenitalium in horse
ddx for impotentia generandi assoc. w/ abnormal appearing semen
1º sperm abnormalities: usually assoc. w/ testicular pathology (hypoplasia, degeneration, orchitis, epididymitis)

2º abnormalities assoc. w/ pathology of extra testicular ducts & 2º sex glands or can be d/t poor semen handling techniques (cold shock, agitation)
causes of testicular degeneration
temperature, pressure, trauma, infection, nutrition, sperm drainage blockage, noxious agents, vascular problems, age, chimerism
What are the parts of a male breeding soundness exam?
evaluation of general body condition
assessment of conformation as it relates to ability to breed
inspection of internal & external genitalia
examination of semen quality
What are the events of the luteal phase of the estrous cycle?
early (metestrus): CL formed from follicular cells

mid (diestrus): CL produces lots of P4

late
-CL lysed by PGF-2α (produced by uterine endometrium)
*lysis followed by marked ↓ in blood P4, which removes negative feedback on hypothalamus --> ↑ GnRH --> new follicular phase
*structural regression of CL --> corpus albicans (CA)
What are the events of the follicular phase of the estrous cycle?
gonadotropin release from anterior pituitary
follicular preparation for ovulation
sexual receptivity
ovulation
-estrogen controls onset of pre-ovulation LH surge which causes ovulation
-when follicle ruptures at ovulation, vessels w/in follicle wall also rupture --> corpus hemorrhagicum (CH)
What are some factors that affect onset of puberty?
considerable species, breed, & sex variation for onset of puberty
involves interaction of environment, nutrition, & genetics
What are the lengths of the estrous cycle & estrus in:

a. cows
b. ewes
a. 21 d. (17-24), 15 h. estrus (6-24)

b. 17 d. (13-19), 30 h. estrus (18-48)
What are behavior signs of estrus in:

a. cows
b. ewes
a. sort off from rest of group (sexually active group: SAG), females will mount other females
b. short period of restlessness, urination in presence of ram, immobile stance
What is the gestation length in:

a. cows
b. ewes
a. 282 d. (~9 mo.)
b. 150 d. (~ 5 mo.)
What factor may cause gestation length in ruminants to dec. by 5-10 days?
# of fetuses (twins)
What are the estrogen requirements during pregnancy for sheep & cattle?
ovary produces estrogen, but it is not required by the ovary to maintain pregnancy

fetal membranes produce estrogen, & it is required by fetal membranes throughout pregnancy
What are the progesterone requirements during pregnancy for sheep?
CL produces progesterone & requires it for the 1st 50-60 d. of pregnancy

fetal membranes produce progesterone & require it for last 100 d. of pregnancy
What are the progesterone requirements during pregnancy for cattle?
CL produces progesterone & requires it for the 1st 200-250 d. of pregnancy

fetal membranes produce progesterone & require some, esp. after day 200 of pregnancy
What are the 3 stages of parturition & how long does each last in the cow & ewe?
stage 1: preliminary (cow, ewe: 2-6 hrs)

stage 2: expulsion of fetus (cow: 0.5-1 hrs, ewe: 0.5-2 hrs)

stage 3: expulsion of fetal membranes (cow: 2-12 hrs, ewe: 5-8 hrs)
What are the preferred semen collection techniques for:

a. bulls?
b. stallions?
c. dogs?
a. electroejaculation
b. artificial vagina
c. manual
breeding soundness exam: bull

a. what % of normal sperm morphology does bull need to pass?
b. what scrotal circumference is considered too small?
a. 70%

b. < 32 cm
What are reasons to synchronize estrus in ruminants?
control time of AI
targeted breeding: cooler seasons
targeted milk production: highest prices
no heat detection needed: timed AI protocols
concentrate labor: breeding & calving
more uniform calf crop (beef)
control time of embryo collection & transfer
What hormones are used in ruminants to synchronize follicular growth?
GnRH, progesterone, follicle aspiration, estradiol (NOT approved)
What hormones are used in ruminants to regulate CL regression?
PGF-2a
progesterone
What is meant by "spring transition" in reference to horses?
mares show estrus behavior, but don’t ovulate

1st ovulation of year marks end of transition period: usually 1st week of April, then cycle regularly
What hormones are used in ruminants to induce ovulation?
GnRH
hCG
estradiol (not approved)
What are some estrus synchronization protocols used in cows when estrus is being detected?
2 PGF injections

MGA (synthetic progesterone) + PGF

CIDR (intravaginal progesterone) + PGF

CIDR + GnRH + PGF
What are some estrus synchronization protocols used in cows when using timed AI?
Ovsynch: GnRH + PGF + GnRH

Select Synch: GnRH + PGF

CO-Synch: GnRH + PGF + GnRH
What are 2 estrus synchronization protocols used in small ruminants?
2 PGF injections

MGA (synthetic progesterone) + PG600 (synthetic gonadotropin)
What is the average time of puberty & sexual maturity in horses?
puberty: 15-18 mo. depending on body weight, season

sexual maturity: ~4 yrs
Horses are _______ day breeds and are ______________ ______estrous.
long
seasonally polyestrous
horses: proestrus

a. length
b. P4 conc.
c. teasing
d. changes in repro anatomy
a. 12-48 hrs before behavioral estrus
b. decreasing/low
c. passive
d. uterine edema
horse: estrus

a. length
b. P4 conc.
c. teasing
d. changes in repro anatomy
a. 5-7 d.
b. low
c. mare “teases in” (shows signs of sexual receptivity): urinates, "winks"
d. cervix relaxes, uterine edema
When does ovulation occur in equine estrus? How is this related to LH conc?
ovulation occurs 1-2 d. before end of estrus

absence of well defined LH surge
-starts to inc. when mare comes into estrus
-LH highest in the day following ovulation
diestrus

a. length
b. P4 conc.
c. teasing
d. changes in repro anatomy
a. 15-16 d. (very consistent)
b. high (produced by CL)
c. “teasing out” (not wanting to mate): squeals, pins ears back, etc.
d. cervix tightens
What hormone assay is a good test for pregnancy in horses?

When is testing usually done & what do the results mean?
total estrogens

usually test around day 90-100
-if high, indicates viable fetus & placenta
-will decrease w/in 1-2 days if pregnancy is lost
What are the lengths of the 3 stages of parturition in the mare?
stage 1: ~ 4 h. (hard to identify)
stage 2: 20-60 min.
stage 3: 0.5-3 h.
What are the 2 main ways that estrus synchronization is accomplished in mares?
-termination of luteal phase w/ PGF-2α
-lengthening of luteal phase w/ exogenous progestins
What are some indications for termination of luteal phase w/ PGF-2a ("short cycling") in mares?
induction of estrus
after foal heat ovulation
tx of prolonged diestrus
estrus synchronization
following progestin therapy
elective termination of pregnancy
post-mating endometritis
What are some indication of lengthening the luteal phase w/ exogenous progestins in mares?
estrus synchronization
prevention of estrus
assist w/ pregnancy maintenance: mares w/ uterine cysts, poor cervical tone, embryo transfer
What is the ideal method to synchronize estrus & ovulation in mares?
progesterone & estradiol: daily tx for 10 days followed by PGF-2α injection

hCG when follicle > 35 mm

ovulation typically on day 9-10 after end of tx
What hormones are used to do the following in mares:

a. delay foal heat
b. induce estrus after foal heat ovulation
a. progestins +/- estradiol
b. PGF-2a
proestrus: dog

a. length
b. clinical signs
c. E2 conc.
d. vaginal cytology
a. 9-10 d.
b. swollen vulva, serosanguineous d/c
c. rising
d. % of cornified cells ↑ ~10-15% per day, reaching 90-100% by onset of estrus
estrus: dogs

a. length
b. clinical signs
c. E2 conc.
d. vaginal cytology
e. P4 conc.
a. 9-10 d.
b. vulvar swelling ↓ slightly, bloody d/c changes to straw colored or may remain bloody, vaginal folds shrink/wrinkle
c. decreasing
d. fully cornified, background of slide is clear
e. increasing, which coincides w/ LH surge that occurs w/in 2 days after full vaginal cornification
diestrus: dogs

a. length
b. vaginal cytology
a. 57-58 d.
b. typified by abrupt ↓ (overnight: ~50%) in % of cornified cells
anestrus: dogs

a. length
b. vaginal cytology
a. 2-5 mo.
b. parabasal cells
proestrus: cats

a. length
b. E2 conc.
a. 1-3 d. (may be inapparent)
b. increasing
estrus: cats

a. length
b. clinical signs
c. E2 conc.
a. 5-8 d.
b. rolling, exaggerated lordosis when petted
c. peak E2 causes behavioral estrus
What hormones are used for estrus prevention & suppression in dogs?
megestrol acetate (MGA): progestagen

androgens
What hormones are used to induce estrus in dogs?
eCG + hCG
FSH
GnRH analogs
estrogens (DES)
What hormones are used to shorten the interestrous interval in dogs?
PGF-2a
dopamine agonists
What hormone can be used to tx mismating in dogs?

What are potential risks of the tx?
estrogens

cystic endometrial hyperplasia & pyometra
BM suppression --> aplastic anemia
What is the preferred tx of a possible mismating?
confirm mismating has happened
-detect sperm heads w/in 24-48 hrs using special vaginal cytology technique

wait & preg check at 25-30 d.
-if pregnant, institute appropriate, safer therapy at > 30 d.
-if done < 30 d. --> fetal resorption
-abortion: PGF-2a, cabergoline (dopamine agonist): alone or w/ PGF-2a, dexamethasone, anti-progestins: not available in US
What hormone can be used to prevent abortion in dogs?
progesterone
What hormones can be used to tx psuedopregnancy in dogs?
progestagens, dopamine agonists (typically don’t do anything)
What hormones can be used to induce behavior estrus in cats:

a. w/ ovulation
b. w/o ovulation
a. estrogens
b. eCG, eCG + hCG, FSH +/- hCG, inc. photoperiod
What hormones/methods can be used to induce ovulation in cats?
glass rod for intravaginal stimulation, hCG, GnRH
What hormone can be used for estrus prevention/suppression in cats?
progesterone
What hormones can be used to tx mismating/induce abortion in cats?
estrogens, dopamine agonists

NOT PGF-2a (not luteolytic in early diestrus as it is in dogs)