Bovine Pregnancy Flashcards
Modalities for pregnancy diagnosis:
How many offspring do cows usually have? Do their embryos have mobility?
one - monotocous
no, remains ipsilateral to the side of ovulation
What is the average length of gestation of cows? What kind of placenta do they have?
280 (279-287)
cotyledonary synepitheliochorial - placetomes connect fetus to mother, not as many layers as horses and more than other species
What are the 2 major sources of progesterone during bovine pregnancy?
- throughout gestation = CL
- 4th/5th to 8th month = placenta
What are the 4 cardinal signs of bovine pregnancy? When are they seen?
- amniotic vesicle - day 28-60
- chorioallantoic membrane slip - day 30-90
- placentomes (caruncles + cotyledons) - day 75-120
- fetus - day 60 until term
Why is behavior not the sole determinant as a sign of pregnancy?
not reliable - failure to return to estrus 18-22 days after service or artificial insemination + pregnant cows may show estrual behavior
What setup is recommended for transrectal palpation of the bovine reproductive tract? In what 3 ways can trauma to the cow be minimized?
chute, headlock, palpation rail +/- backup bar (can harm palpator if cow decides to lie down
- lubricant
- keep fingers together
- don’t fight the cow = observes for an arched back and wait out peristalsis
How can trauma to the palpator be avoided when performing reproductive exams on cows?
don’t palpate with arm above your shoulder
- get a stool if need be!
What is the earliest time that transrectal palpation can be helpful for reproductive exams?
30-45 days of gestation
What are 6 additional supportive findings of pregnancy in cows?
- presence of CL indicates where the fetus will be
- inability to retract the cervix, likely due to heavy fetus
- fluid within or fluctuance of the uterus
- enlarged diameter and asymmetru of the uterine horns (could be due to pyometra)
- enlargement and fremitus of the uterine artery
- fetus ballottement
What is the first step in transrectal palpation of the reproductive tract?
retraction - grasp the cervix or intercornual ligament and pull uterus into the pelvic floor
How does the membrane slip feel as gestation progresses?
- day 30 = thread in gravid horn
- day 60 = string in both horns
- day 90 = large string in both horns
How does bovine fetal size progress further into gestation?
- day 60 = mouse
- day 90 = rat
- day 120 = small cat
How does placentome size progress further into gestation?
- day 30-80 = not palpable or extremely small
- day 90 = dime
- day 120 = nickel/quarter
When is fremitus palpable?
day 120 - on side of pregnant horn (6 mm)
- day 150 - side of pregnant horn (9 mm)
- day 180 - both horns (10-12 mm)
Size of reproductive organs over bovine gestation:
When is the amniotic vesicle palpable? What is it?
days 30-60
turgid, fluid-filled sac surrounding the fetus that can be palpated as a small knot or bump within the uterine horn
Where can the chorioallantoic membrane be palpated at different stages of bovine gestation? How can it be palpated?
- day 30 = gravid horn
- day 60 = both horns
identify the cervix and retract the uterus —> grasp each horn gently between fingers and thumb and lift slightly resulting in a distinct popping sensation
What is considered the best method for definitively diagnosing pregnancy after mid-gestation? Where is palpation most consistent?
placentomes —> palpate at least 3 to confirm ovaries are not being palpated, size increases with fetal age
just anterior to the cervix
Uterine horn asymmetry:
fetus growth becomes more apparent as time progresses, non-gravid horn commonly becomes hidden
What is fremitus? How/when is it palpated?
buzzing/vibrating sensation from the uterine artery due to increased diameter during pregnancy
traverse the broad ligament to differentiate from internal iliac arteries
110-120 days, corresponding with increased blood delivery to the uterus
When is bilateral fremitus palpated?
six months into pregnancy (180 days)
- can persist post-abortion or post partum
What are the 3 ways of estimating how many days of gestation has passed?
- length of amniotic vesicle (30-60 days)
- fetal size - crown to nose, crown to rump (after 90 days)
- placentome size at uterine bifurcation (after 90 days)
What are 3 hazards associated with transrectal palpation of the bovine reproductive tract?
- rectal perforation
- rupture of amniotic vesicle or fetal heart sac
- aggressive membrane slip may release PGF2α, which causes luteolysis and abortion
What is the earliest a bovine fetus can be seen on ultrasound? What is the main purpose?
as early as day 24
estimate gestation age and fetal well being
When can a bovine fetus be sexed? How is it determined?
day 55-60
location of genital tubercle, which seens bilobulated closer to the anus (precursor clitoris) or on the abdomen (precursor penis)
Ovarian and uterine horn ultrasound:
- corpus luteum = hyperechoic
- follicle = hypoechoic
- small anechoic structure = beginning of fetus (fluid of amniotic vesicle)
Uterine horn ultrasound, day 26:
more prominent anechoic portion = fetal fluid
Uterine horn ultrasound, day 27:
fetus!
Uterine horn ultrasound, day 37:
larger fetus
Uterine horn ultrasound, day 59:
What are the genders of the fetus in the attached ultrasounds?
L = male, genital tubercle between hindlimbs
R = female, genital tubercle at base of tail
What is occurring in this ultrasound?
fetal mummy —> fetus observed without fluid surrounding it
Uterine ultrasound, day 200:
placentome
What tests are used to confirm pregnancy of cows? When can they be used?
pregnancy-associated glycoproteins (PAGs) secreted by binucleate trophoblastic cells produced in response to fetal presence, using milk or blood samples
28 days post-breeding —> allows for early detection of open cows and pregnancy confirmation at dry-off
What are 2 options for PAG detecting pregnancy tests in cows?
- Alertys - 28 days post-breeding and 60-70 days post-calving
- BioPRYN - biotracking pregnancy specific protein B 73 days post-calving
Detection of which substances offer limited value for confirming bovine pregnancy? What are 2 emerging research topics?
progesterone and estrone sulfate after 100 days of gestation —> levels tend to fluctuate during pregnancy, while PAGs are only produced with the presence of a fetus
- early pregnancy factor - days 2-140
- interferon-tau stimulated genes - days 14-26
