Equine Pregnancy: Physiology and Diagnosis Flashcards
Embryo enters uterus ______ days after ovulation
- 5-6 days
- embryo secretes prostaglandins which stimulate myometrial contractions
Spherical vesicle is very mobile until _____
Day 16
- sticks to base of one horn
Maternal recognition of pregnancy occurs around ______
Days 14-16
Interference with _____ can lead to pregnancy loss
Mobility
Presence of excessive tone in uterus is due to
Elevated progesterone and estrogen produced by the embryo
- keeps early embryo in close apposition to endometrium until attachment
Embryo begins attaching to endometrium at _____
40-45 days
Endometrial cups
Trophoblastic cells invade uterine epithelium around day 40 of gestation
- horseshoe arrangement of pale irregular outgrowths on luminal surface of pregnant horn
Endometrial cup progression
- appear at day 40
- max size at day 70
- regress/sloughed by day 130
- produce eCG
- assist in formation of supplementary CLs and maintenance CLs
Why do we need to know if a mare is pregnant?
- identify open mare
- get mare re-bred
- eliminate twin pregnancy by 14 days
- evaluate pregnancy loss at 15, 30, 42, 60, and 120 days
- for vaccine strategies –> rhino vacc at 5, 7, and 9 mos gestation
What are non-specific indicators of pregnancy?
- behavior assessment
- serum/milk progesterone assay
- vaginal speculum exam
What are specific indicators of pregnancy?
- palpation of repro tract per rectum
- US
- eCG levels
- estrogen in blood, urine, feces
Why use indirect methods
- supports diagnosis of pregnancy
- when other tests are inconclusive
- poor facilities
- vicious or non-domestic equids
- mini’s or ponies
- previous rectal tear
- inexperience of practitioner
Absence of estrus
Mare is teased
- non pregnant mare estrus should be detected 16-19 days after last visible signs of estrus were seen
- failure to return to estrus is suggestive of pregnancy
- not reliable
- 10% of pregnant mares continue to show estrus
Mare may not be pregnant, but shows _______
- early embryonic death following maternal recognition
- prolonged maintenance of CL
- silent estrus
- rarely do mares have lactational anestrus after foal heat
Progesterone testing
High progesterone levels 18-20 days post ovulation implies pregnancy due to functional CL
False positives are frequent
- presence of progesterone does not equal pregnancy
- absence of progesterone equals non pregnancy
Progesterone testing is _____
Non-specific sign of pregnancy
Progesterone only indicates _____
Presence of luteal tissue
Absence of P4 (<1 ng/ml) at 18-20 days is good indication that mare ______
Is not pregnant!
- best way to utilize this hormone is in detecting non-pregnant mares
P4 progression
- secondary CLs elevate P4 levels after 40 days
- P4 declines around 85 days and is negligible by 150-180 days
If the vagina is pregnant, the cervix should be _______
Tight, dry and dull, pale pink and centrally located
Its common to spec a mare at _____ days post ovulation or breeding
18-21 days
Palpation - cervix
16-18 days after ovulation cervix is closed, tight, firm and elongated
- caused by elevated P4
- remains closed until late in gestation
Do you do a vaginal exam to palpate the cervix?
NO, causes abortion
