Pregnancy Detection

Question 1

In general how is pregnancy detected?

Answer 1

• Palpation of the reproductive tract (trans-rectal or abdominal)
• Imaging of the reproductive tract (radiograph or ultrasound)
• Measurement of hormone concentrations (blood or other fluids)

Question 2

How is pregnancy detected in beef cattle herds?

Answer 2

• Have a controlled breeding season - 60-90 days
• Done through a herd assessment:
  
  • Goal - get a lot of cows pregnant (most in the first 20 days of breeding)
  • Determine success of proceeding breeding season
  • Provide diagnostic information
  • Identify open cows for alternate management

Question 3

How is pregnancy detected in Dairy Cattle herds?

Answer 3

• Some dairies are seasonal - controlled 60 day breeding season similar to beef herds
• Most dairies breed year-around
  
  • Results in steady milk supply
• Mostly an individual cow assessment
  
  • Determine dry-off date (40-60 day prior to lactation)
  • Determine if cow should continue in breeding pool
  • Assess herd breeding program

Question 4

What types of pregnancy tests exist for cattle?

Answer 4

• Milk or blood progesterone assay
  
  • Milk progesterone values correlate with blood values
  • Remember the fluctuation of progesterone concentrations over an estrous cycle
    
    • Must know breeding date - and test at specific time after that breeding date (21-24 days post breeding)
    • If progesterone is found to be low = Not pregnant
    • If progesterone is found to be high = pregnant or in diestrus
• PSPB - Pregnancy specific protein B
  
  • Can be detected as early as 25 days of gestation
  • Remains in blood for up to 3 months after parturition (or abortion)
• Early Conception Factor (ECF)
  
  • Can be detected as early as 6 days of gestation
  • Although promoted by advertisements and anecdotal testimonials
  • Results of studies have shown unacceptable accuracy (48-96% false-positive, 14-95% false negative)
• Detection of Estrus
• Ultrasonography
  
  • Routinely accurate at 28day gestation
  • Can determine sex of fetus between 55-65 day gestation (up to 75day - but more difficult)
    
    • very difficult as fetus grows and uterus pulled over pelvis (~ day 90)
• Uterine palpation per rectum
  
  • Routinely accurate by 35 day gestation (possible by 28 days)
  • Fast and accurate with experience
  • Less information than ultrasound
    
    • ovarian structures, fetal sex, fetal viability

Question 5

How can the age of gestation in cattle be determined?

Answer 5

• Fluid Volume:
  
  • 35 days = slight amount of fluid in the uterus
    
    • able to “slip” fetal membranes
  • 40 days = 75mL
    
    • slightly more fluid than 35 days
    • Uterine wall is thinning
  • 60 days = 300mL
    
    • Pregnant horn is size of a banana
    • Still able to hold the entire tract in hand
  • 90 days = 1000mL
    
    • Can still reach around entire tract - but just barely
    • Routinely “bump” the calf
    • Routinely feel placentomes
  • 120 days = 3000mL
    
    • Cannot reach around entire tract
    • Placentomes are prominent - neckel-sized
    • Fremitus in mid-uterine artery on pregnant side

Question 6

What structures can cause confusion when trying to determine the age of gestion in cattle?

Answer 6

• Bladder
• Back of Rumen
• Left Kidney
• Gas bubble in intestine
• Pyometra
• Lymphoma
• Uterine involution (post calving)

Question 7

What are the different ways Ultrasound can be utilized in pregnancy detection and gestation determination in cattle?

Answer 7

• Pregnancy Diagnosis
  
  • a little earlier preg detection
    
    • 28 days vs 35 days
  • Able to assess fetal viability
  • Able to determine sex
  • Little slower than palpation
  • “Wow” factor
• Sex determination:
  
  • Genital tubercle is in noticeably different position by about 55 days of gestation
    
    • located immediately caudal to umbilicus in male
    • located just ventral to tail in female
  • Much past 70 days - difficult to consistently get right area of fetus on the screen
• Recognize early embryonic loss
  
  • ~17% of 28-day embryos are lost by day 56
  • Early pregnancy detection (US or palpation ) does not Cause embryo loss (unless very rough)
• Embryo Transfer
  
  • Identify recipients with CL
  • Follow follicular dynamic of donor cow - count CLs at flushing
• Dairy - Early non-pregnancy determination coupled with re-synchronization protocol
  
  • coupled with timed insemination to optimize use of labor
  • reduces “days open”

Question 8

How does an Integrated Reproductive Program in cattle work?

Answer 8

• All reproductive activities are on Tues and Thurs
• Ultrasound every Tuesday
• AI every Thursday
• 35 day interval between AI breeding

Question 9

How is Pregnancy detected in Horses?

Answer 9

• Equine Chorionic Gonadotropin (eCG)
  
  • At 36-38 days of gestation, fetal chorionic tissue invades the endometrium and forms endometrial cups - these cups secrete eCG (aka PMSG)
  • eCG acts to luteinize the normal follicular waves tat are occurring and results in the formation of secondary (accessory) CLs
  • eCG levels peak about day 60-80 of gestation
  • eCG assays will detect a high percentge (>90%) of pregnancies by day 42 (may be a good alternative for miniature horses)
  • But, eCG remains elevated if the pregnancy is lost - therefore a non-pregnant mare can have high serum eCG values
• Estrogens
  
  • Cuboni Test
  • Fluorescence of urine due to estrogen
  • Will accurately detect pregnancy by 100 - 150 days of gestation (also easily palpated per rectum)
• Estrone sulfate:
  
  • Present in serum, urine and even feces of the pregnant mare
  • Because non-invasive samples can be used - this test is utilized for assessing wild equine reproduction
  • After day 44 of gestation, high estrone sulfate is associated with fetal viability
• Early Pregnancy Factor (EPF)
  
  • Immunosuppressive protein secreted by the early embryo
  • Detected as early as 24-72 hours after mating and remains elevated through the second trimester of gestation (no present in 3rd trimester)
  • Poor test accuracy (sens 43% / spec 52%)
• Cervical Tone and appearance
  
  • Progesterone from CLs (primary and accessory) peak at day 80-90
  • High levels of progesterone cause the cervix and uterus to have exaggerated tone
  • From day 16 to the end of gestation the cervix is elongated and firm and the uterus has an increased tone
• Uterine palpation per rectum and transrectal ultrasound
  
  • Chorionic vesicle is distinctly spherical (early gestation)
  • Vesicle is palpable from d 18 to 60-70
  • Vesicle is visible via ultrasound beginning ~day 10

Question 10

Can ultrasound be used for fetal sexing in mares?

Answer 10

• Genital tubercle migrates toward the umbilicus in the male and the anus in the female
• Fetal sex is determine from day 59-68

Question 11

How can Pregnancy be detected in canines?

Answer 11

• Abdominal palpation
  
  • start at the dorsal abdomen and move your hand downward and squeeze thumb and fingers together gently - slip the uterus between the thumb and fingers
  • Day 21-31 (after the start of diestrus) the pregnancy can be palpated as small, firm, round vesicles (about the size of walnuts - 1.5-3.5cm)
  • Accurate counting of fetuses is not possible
  • Determining fetal viability is not possible
  • Palpation may be difficult in large dogs, dogs with tense abdomens, dogs with a lot of mammary development
  • From day 31-50 the vesicles lose their distinct round shape and are not detectable by palpation
  • After day 50 the puppies are palpable
• Trans-abdominal ultrasound
  
  • Fetal vesicles are visible by day 18-20 pat the LH peak as distinct, round black (fluid-filled) sacks
  • Fetal heartbeat (first seen day 23-25 after LH peak) & fetal movement (first seen 34-36days after LH peak) are indications of fetal viability
    
    • HR >20bpm is an indication of fetal stress (late in gestation)
  • Ultrasound s more accurate than palpation
  • Difficult to count fetuses (can differentiate between large and small litter
• Radiograph
  
  • fetal skeletons first seen 42 - 52 days after breeding 44-47 days after LH peak (20-21 days prior to parturition)
  • after day 50 fetal skeletons can be counted
• Relaxin - measure from blood sample
  
  • Detected by day 20-30 past LH peak
  • Commercial kit is available

Question 12

How is pregnancy detected in pigs?

Answer 12

• Detection of return to estrus
  
  • Non-pregnant sows should return to estrus 17-24 days after breeding
  • Sow’s behavior should be evaluated in the presence of a boar
  • False positive results are common (flalsely ID female as bred)
• A-Mode ultrasound
  
  • Use US waves to detect fluid-filled uterus
  • Output: audible signal or a series of lights
  • High accuracy 30-75 days
  • Number of false-negative results increases after day 75
• Doppler ultrasonography
  
  • Detects movement such as fetal heart and pulsing umbilical/uterine arteries
  • Output is an audible signal
  • High accuracy after 30-34 days
  • Risk of false-positive during proestrus or estrus
• Real-time ultrasonography
  
  • Expensive - so not used on small farms
  • Able to detect pregnancy sooner than with A-mode or Doppler US (d 23 vs d 30)

Question 13

How is pregnancy detected in ovines?

Answer 13

• Real-time US
  
  • Can detect pregnancy and assess fetal numbers as early as day 25 gestation
• Pregnancy-specific protein B
  
  • Can be detected as early as day 20 of gestation