11. therio- pregnancy diagnosis in cattle

what makes an ideal pregnancy test?

-rapid/instant results

-sensitive (ability to detect all pregnancies)

-specific (negatives are truly not pregnant(

-safe to fetus and dam

-low in cost

what methods are used to diagnose pregnancy in cattle?

1. transrectal palpation

2. transrectal U/S

3. hormonal tests on blood or milk

what are the advantages of transrectal palpation to diagnose pregnancy?

-diagnosis is reliable and accurate

-results are immediate

-can provide results before the second estrus following breeding

what is the technique used to diagnose pregnancy via transrectal palpation?

1. retract uterus into pelvic cavity

2. explore both horns for general changes of pregnancy

-asymmetry of uterine horns

-fluctuation of fluid in horn

*what are the positive (cardinal) signs of pregnancy?

1. fetal membrane slip

2. amniotic vesicle (feels like a grape)

3. placentomes

4. fetus

what is the fetal membrane slip?

-connective tissue cord on concave surface

-starts in the gravid horn at days 30-34

-will be in non-gravid horn after 50days

when is the amniotic vesicle palpable?

after 28 days, is turgid, spherical until day 55

what may occur if the amniotic vesicle is roughly palpated between days 32-44?

may be associated with atresia coli of fetus

what are placentomes?

cotyledon (fetal portion) + caruncle (maternal portion)

when are placentomes palpable?

may be palpated as early as 70 days, but more often palpated between 80-90days

when can the fetus be palpated?

fetus and fetal parts can be palpated/balloted after 60 days

can usually retract uterus up to day 60

when is fremitus in the middle uterine artery (on gravid side) palpable?

by days 120-150

will feel on both sides by 180 days

how can gestation stage be determined by palpation from 2-6 months?

2 months: size of mouse

3 months: size of rat

4 months: size of small cat

5 months: size of large cat

6 months: size of beagle

how is the middle uterine artery differentiated from the external iliac artery via rectal palpation?

middle uterine artery: freely movable when palpated (4)

external iliac artery: not freely movable, fremitus felt when compressed

how is pregnancy diagnosed via ultrasound?

using b-mode, real time, and a linear probe

-use 7.5MHz for early diagnosis >26 days

-use 5MHz for later diagnosis >35 days

embryo is observed by day 26-29

when can fetal sexing be performed via ultrasound?

at about 60 days gestation (image is of 61d - female)

what are the ultrasonographic signs used for determining fetal sex of calves?

by observing where the genital tubercle is:

-near umbilicus= male

-under tail= female

what is the basis for endocrine/hormone based pregnancy tests?

based on pregnancy-associated molecules (pregnancy associated glycoproteins- PAGS)

-better at diagnosing open cows than pregnant cows

-generally confirmed by another method a few weeks later

what is pregnancy specific protein-B?

bovine pregnancy associated glycoprotein

secreted by binucleate giant trophoblast cells throughout gestation

how does the pregnancy specific protein-B hormone test detect pregnancy?

test is reliable after 29days, and is detectable until 100 days after parturition (ie may still be positive even if cow is no longer pregnant)

protein-B will be higher in twin pregnancies

using dam’s blood/milk