Lecture 7: Bovine Pregnancy Diagnosis

- ID open cows

- allow for tx of open cows (cycling, ART)

- allow for culling of non-productive cows

- help ID embryonic loss

- adjust management practices

Why do we pregnancy check cows?

- ID non-preg cows so they can be bred again

- usually performed around 40-35 days post AI/exposure

- consider milk production/voluntary waiting period

When and why do we do a preg check on dairy cattle?

- ID non-preg animals so they can be culled

- usually done at weaning

When and why do we do a preg check on beef cattle?

- cost for maintenance, keeping them open, breeding them, diagnosis them

What are the economic impacts of breeding for dairy cattle?

true

True or false

a pregnancy diagnosis will save bovine producers money

- history of exposure to bull

- clinical signs of anestrus at 18 - 24 days post mating (not seen cow in heat)

- NOT VERY RELIABLE AND SUBJECT TO ERROR OR MISINTERPRETATION

What are producer methods for detecting if a cow is open?

- used from about 35 days gestation to term

- cervix is the landmark for palpation

- must ID at least of positive sign of pregnancy

- look for 4 cardinal signs

When is a trans-rectal palpation used for preg checks? How is it done?

- fetal membrane slip

- amniotic vesicle

- placentomes **

- fetus ****

What are the 4 cardinal signs of pregnancy on palpation in cattle?

- direct

- indirect

- sweeper method

What are 3 methods to retract the uterus for a thorough exam early pregnancy (less than 90 days)?

- earliest sign of pregnancy

- palpable from 30 - 90 days (based on fluid fluctuations)

- slipping chorioallantois membrane through the the gravid uterine horn

What is a membrane slip when palpating for a pregnancy in a bovine?

- like you are strumming you fingers over a guitar string covered with a towel

- requires an experienced and delicate touch, since can mistake with fluid in the gravid horn

What does a chorioallantois or membrane slip in cattle feel like?

- turgid vesicles that are felt in the preg horn

- first palpable at about 32 - 35 days

- diameter is used to gauge gestational age

What is an amniotic vesicle? When can it be used to diagnose a pregnancy through palpation?

- 55 - 60 days

At what days are amniotic vesicles hard to palpation?

- maternal caruncle + fetal condyle

What is a placentome?

- palpable starting at about 80 days and at 120 days are in 4 rows

- size varies with stage of gestation and location

- they are larger closer to the fetus and smaller further away

When are placentomes first palpable when diagnosing a pregnancy through palpation? How do they vary with pregnancy?

- always feel at least 3 at the bifurcation of the cervix before coming to a conclusion about gestation length

- 90 days = US dime

- 120 days = US quarter

- 150 days = US half dollar

How do you use placentomes for pregnancy determination?

- 55 - 65 days

When is the fetus first palpable when trying determine a pregnancy in cattle?

a. 70 days

b. 150 days

c. 210 days

d. 240 days

What days to the following happen with the fetus of a cow?

a. descent begins

b. descent complete

c. ascent begins

d. ascent complete

- descent begins

This is a photo of a rectal exam of a pregnant cow at around 70 days. What is happening at this time?

- descent is complete

This is a photo of a rectal exam of a pregnant cow at around 150 days. What is happening at this time?

- ascent begins

This is a photo of a rectal exam of a pregnant cow at around 210 days (6 months). What is happening at this time?

- ascent complete

This is a photo of a rectal exam of a pregnant cow at around 240 days. What is happening at this time?

- 60 days

What day of gestation is a fetus the size of a mouse?

- 90 days

What day of gestation is a fetus the size of a rat?

- 120 days

What day of gestation is a fetus the size of a small cat?

- 150 days

What day of gestation is a fetus the size of a beagle?

- 210

What day of gestation is a fetus the size of a doberman?

- asymmetry of the uterine horns

- thinning of uterine wall

- fixation of cervix

- fremitus of middle uterine artery (vibration)

- presence of CL (requires record keeping)

- fluid in the uterus ***

What are supportive signs of pregnancy in cattle?

- in the broad ligament = moveable

- do not confuse with iliac artery = immovable

Where do you look for fremitus (vibration) in the middle uterine artery in a cow? What should it not be confused with?

- more vibration as preg progresses

- however often unremarkable

- can be variable with stress of the cow (HR)

How does fremitus of middle uterine artery (vibration) change throughout pregancy?

- first half of gestation where you use the diameter of pregnant horn and vesicle

What period of gestation is most accurate for staging the pregnancy?

- diameter of placentomes

- size of fetus

- middle uterine artery diameter

- crown-rump length

How can you estimate the stage of pregnancy in later gestation?

- best at 35-40 days for experienced palpator

- false positive

- false negatives

- role of EED

What is the accuracy of staging a bovine pregnancy?

1. normal variation in size and thickness of the uterus

2. heifers are easier than cows / thin cows easier than fat cows

3. some breeds are easier than others (jerseys are the worse)

4. parity

5. skill, experience, and frequency of palpator

What is early pregnancy diagnosis (3-35 days) dependent on?

- length of broad ligament

- length of tract

- location of uterus

Why can early diagnosis of pregnancy vary by difference in breeds?

- rectal perforation

- rupture of amniotic vesicle or fetal heart sac

- palpation of amniotic vesicles have been loosely associated with intestinal atresia in offspring

- aggressive membrane slip/palpation may terminate pregnancy via PGF2a release

What are the hazards of bovine palpation?

- most useful after 24 days

- look for heart beat

- gender at 55-80 days

- ID of EED is possible

How is trans-rectal ultrasound be used to determine pregnancy?

- most useful

- looking for

- 100 days

When is crown rump length 20-21 cm and best for estimating of age?

- often you are not able to see the entire fetus due to large crown rump length

Why are ages estimated in the red box often wrong?

- ~ 60 days

A what day can you reliable get the fetal sex in cattle?

- 22-30 (25.4) days

What is the first day you are able to detect a C-shaped embryo?

- first seen around 33 to 38 days (35.2)

- useful in early pregnancies up to 150 days

How are placentomes used for aging on ultrasound?

- inexpensive

- low tech

- immediate info

What are the pros bovine pregnancy detection with trans-rectal palpation?

- requires training

- subjective

- safety???

- not definitive to why said cow is open

What are the cons bovine pregnancy detection with trans-rectal palpation?

- definitive (tells us the why)

- objective

- CLEAR results that are digital

- professional

What are the pros bovine pregnancy detection with trans-rectal U/S?

- expensive

- requires training

- electricity???

What are the cons bovine pregnancy detection with trans-rectal U/S?

- bovine pregnancy specific protein B

- progesterone

- estrogen sulfate = not common

what are possible endocrine tests that can be run for diagnosis pregnancy in cattle?

- measures protein from trophoblastic cells

- detectable 30 days after breeding (>73 days post calving)

- levels remain high after delivery

What is the bovine pregnancy specific protein B endocrine pregnancy test in cattle?

- test blood or milk 20-24 days after breeding

- many false positive due to length of pregnancy

What is the progesterone endocrine pregnancy test in cattle?

- non-definitive for open cows

- does not answer why

What is the possible clients perspective for trans-rectal palpation>

- inexpensive

- low tech

- no "special" equipment

- quantitative

What are the pros to pregnancy specific protein B?

- time

- false positives

- requires client skill/training

What are the cons to pregnancy specific protein B?

- inexpensive

- easy

- low tech

What are the pros to milk/blood P4?

- timing

- record keeping by vet and O

- cow ID

- not quantitative

What are the cons to milk/blood P4?