Pregnancy Diagnosis in Cattle

Question 1

describe observation as a method of pregnancy detection

Answer 1

1. non return to estrus within 18-24days
   -false postive: cystic ovarian disease, hydrometra, metritis, pyometra, mummies, nutritional anestrus, poor heat detection
   -false negative: some pregnant females show behavioral estrus, can lead to unnecessary PGF2a use or AI
2. weight gain
3. udder development

-just gives a presumptive diagnosis

pros: easy, non-invasive, little training
cons: lacks sensitivity and specificity, not reliable

Question 2

describe trans-rectal palpation

Answer 2

1. most common and accurate method in cows
   -sensitive, specific, economic, immediate results, allows aging of fetus
2. useful as early as 32d depending on:
   -DVM experience, age and size of dam
3. cardinal signs:
   -membrane slip
   -amniotic vesicle
   -placentomes
   -fetus

Question 3

describe the chorioallantoic membrane slip

Answer 3

find by compressing the horn between the thumb and forefingers, will feel a pop

-lifting the uterus allows the membrane to slowly slip from the grasped uterine wall (35-100d)

-feel at 35d in gravid horn
-feel at 60d in nongravid horn

Question 4

describe the amniotic vesicle

Answer 4

1. contains the developing conceptus and amniotic fluid
2. palpable at 28 days post conception (dpc) in heifers and 32dpc in cows (30-60d)
3. spherical, turgid, fluid filled structure, free floating
4. detected by encircling the uterine horn between thumb and fingers
   -make grasp shape with hand and slide down horn
5. by day 60-65: less turgid and difficult to recognize (starts to elongate), fetus becomes palpable
6. be careful before 40dpc because heart is external and can be ruptured!

Question 5

describe placentomes

Answer 5

1. endometrial caruncles and fetal cotyledons
   -75-120 placentomes
2. formed early in gestation and palpable by 75-80d
3. size increases as gestation advances and varies with location
   -larger in the middle of gravid horn (closer to fetus)
   -more consistent in size immediately cranial to the cervix (focus on these size)
4. false positive:
   -after fetal death, remain palpable for a variable time
   -mistaken ovaries: similar size in 4-5 mo of preg (systematic exam = key!)
   -palpate >3 placentomes during exam!
5. false negative:
   -when uterus is completely descended (5-7 months)
   -search for other signs of pregnancy
   -identify nongravid uterus before saying non pregnant

Question 6

describe feeling the fetus

Answer 6

1. palpable at 60d (amniotic vesicle loses turgidity and increases size)
   -call it a fetus at 42 days bc organogenesis
2. early: fetus can be grasped
   later: fetus can be balloted (re-bounce)
3. 2nd-4th month: free floating, firm object within the fluid filled uterus

-5th-6th month: fetus increases weight, fluids pull uterus ventrally and cranially, fetus rests on abdomen floor (descending)

-7th-9th months: fetus continues growing, positions closer to the maternal pelvis (ascending)

4. fetus size used for determining the age of gestation
   -rat: 3 mo
   -cat: 4 mo
   beagle: 5 mo
   -brittany: 6 mo
   german: 7 mo
5. false positive: another structure is mistaken for a fetus:
   -dorsal sac of rumen (if push, will leave an impression), left kidney, uterine tumors, enlarge lymph nodes, CT after surgery or obstetric trauma, fat necrosis (fescue toxicosis), mummified or macerated fetuses
6. false negative: more likely at 5-7months

Question 7

what are secondary signs of pregnancy? (5)

Answer 7

1. asymmetry of uterine horns
2. fluctuance of uterine wall (fluids)
   -false positive: hydrometra, mucometra, pyometra, delayed postpartum uterine involution
3. fixation of cervix: uterus retraction possible until 70-75d; at 90d is difficult to retract
   -false positive: hydrometra, mucometra, pyometra, maceration and mummification, adhesion after C-section, large uterine or ovarian tumors (lymphosarc or GCT)
4. fremitus of middle uterine artery:
   -as gestation advances, blood supply to uterus increases
   -increased size detectable in heifers 75d and cows at 90d
   -increased blood flow, increased size and thinning of the wall (1500mmHg)
   -persists for several days after abortion or parturition
   -present on other conditions (mummies and fetal macerations
5. presence of a CL:
   -do not palpate the ovaries if the cow is pregnant
   -in some cases, is useful to examine ovaries if uncertain after palpating the uterus
   -CL always in ovary ipsilateral to gravid horn
   -pyometra: persistence of a CL and fluid accumulation within the horse

Question 8

describe what would feel at 32d, 37d, and 45d preg

Answer 8

32d: 1 finger AV

37d: 1 finger AV and membrane slip

45d: 2 finger AV and membrane slip

Question 9

describe what would feel at 48d, 52d, and 60d preg

Answer 9

48: 3 finger AV, membrane slip

52: 4 finger AV, membrane slip

60: softened AV, membrane slip, mouse sized fetus

Question 10

describe what would feel at 75d, 80d, and 90d preg

Answer 10

75: no AV, membrane slip, fetus, 0.5cm placentome

80: no AV, membrane slip, fetus, 0.5-1cm placentome

90: no AV, membrane slip, rat sized fetus, dime sized placentome

Question 11

describe what would feel at 120d, 150d, and 180d preg

Answer 11

120: no AV or membrane slip, cat sized fetus, 2cm and 1/4 sized palcentome

150: no AV, no membrane slip, descending beagle sized fetus, 3cm and 1/2 sized placentome

180: no AV, no membrane slip, descending brittany sized fetus, 4cm placentome

Question 12

describe what would feel at 210d, 240d, and 270d preg

Answer 12

210: ascending GS sized fetus, 5 cm placentome

240: rottie sized fetus, 6-8 cm placentome

270: cow sized fetus, 8-12 cm placentomes

Question 13

describe transrectal ultrasound

Answer 13

1. min invasive, accurate, effective, quick
2. accurate at 24-26 dpc, HB detectable in viable embryos
3. heifers 3d earlier than cows
4. pros: earlier than palpation by around 7d
   -accurate, Se, Sp
   -not implicated as a direct cause of preg loss
5. assess defects:
   -separation of chorioallantois
   -flocculent amniotic fluid
   -no heart beat
   -amorphous appearance
6. sexing:
   -genital tubercle in males by 59-80d

Question 14

describe indirect methods of preg detections

Answer 14

1. progesterone test
   -many false positives! any time CL present and producing will get a positive
   -but P4 stays high during preg
   -in blood or milk
   -detected 24d after AI
   -reliable ID in non-preg cows
   -low Se and PPV for preg, expensive
2. preg-associated glycoproteins
   -produced by multinucleated giant cells in placenta
   -labeled for >28d in cows and 25d in virgin heifers
   -detected until 73 days post partum
   -low cost, fast turn around
   -high accuracy in ID non-preg cows!
   -false positive: preg loss

Question 15

describe a practical protocol for chemical test + palpation for preg diagnosis

Answer 15

1. AI = day 0
2. d28: blood sample to see who NOT preg (no PSPB)
3. d35: re-synch open cows, GnRH
4. d60: US/palpation

allows for faster resynch, helps to reduce calving intervals (<110d to reconception)