Pregnancy Diagnosis up to 60 Days

Pregnancy Diagnosis up to 60 Days



Basic Information image



Synonym(s)


Pregnancy check, early pregnancy monitoring



Overview and Goal(s)




• Accurate early diagnosis and evaluation of pregnancy and nonpregnancy are essential for optimal reproductive efficiency.


• Determination of pregnancy is critical for the establishment of effective veterinary management of broodmares. Not only does early detection of pregnancy provide information on whether the mare is pregnant and for arranging rebreeding of nonpregnant mares, it also helps establish a medical approach for abnormal pregnancy (eg, twinning) in the most advantageous manner.


• Several methods of pregnancy detection (behavior, transrectal palpation, ultrasonography, hormonal tests) are available. The choice of technique ultimately depends on the stage of pregnancy.



Indications


All mares included in a breeding program



Contraindications




• Mare with a disease that could compromise the integrity of the rectal mucosa


• Mare with an explosive temperament



Equipment, Anesthesia




• The mare must be adequately restrained. Depending on the mare’s temperament, stocks, lip chain, twitch, or sedation should be used before the reproductive tract is examined. In general, mares tolerate the procedure without major restraint.


• The veterinarian can, while wearing a glove, palpate the internal genital organs of the mare per rectum.


• A B-mode real-time ultrasound system consisting of a monitor and a linear array 5 to 7 MHz transducer is adequate for most needs encountered in equine reproduction.



Anticipated Time




• Days 12 to 25 of pregnancy: Objective is to confirm the pregnancy status


image Monitoring sexual behavior by daily teasing with a stallion can be performed. Failure to return to estrus between days 16 and 20 suggests the mare is pregnant. Estrous behavior occasionally may be displayed in pregnant mares around days 14 to 18 after ovulation. Furthermore, absence of estrous behavior may occur in nonpregnant mares: those with a persistent corpus luteum, early embryonic death, or a diestrus ovulation (1% to 2% of mares). Young or dominant mares may also not show estrous behavior as well as mares with a foal at foot.

image Transrectal palpation is the most common means of early pregnancy testing. Since pregnancy in the mare is associated with a tonic and tubular uterus and a tight, firm, and elongated cervix, transrectal palpation of both structures between days 17 and 20 can indirectly determine pregnancy status. The embryonic vesicle is usually not detectable by transrectal palpation between days 16 and 20 (15–24 mm in diameter). Because of possible false-negative results, reexamination is always necessary to confirm pregnancy.

image Transrectal ultrasonography is the most sensitive and specific pregnancy test. The ultrasound machine allows visualization of the embryonic vesicle as early as day 9.5 (3 mm in diameter), with an accuracy rate reaching 99% by days 14 to 15 after ovulation with a vesicle of 17 to 22 mm in diameter. Ultrasonography also allows assessment of the growth of the embryonic vesicle and early detection of multiple pregnancies (twins). In ultrasonographic images from a cross-section of a uterine horn, the vesicle appears as a spherical, anechoic (dark) structure surrounded by a lighter area of uterine tissue. Between days 10 and 15, the embryonic vesicle progresses from 6 to 22 mm in diameter (~3.0 mm/day). At day 17 to 18, the vesicle has a triangular shape like a guitar pick. The embryo itself can first be seen in the ventral portion of the yolk sac at day 21. Presence of a corpus luteum with an elevated progesterone concentration in the blood of the mare beyond day 15 of the estrous cycle is associated with pregnancy. Blood progesterone levels cannot be used as the sole diagnostic method of pregnancy. Nonetheless, a progesterone concentration less than 1 ng/mL of serum between 18 and 21 days after ovulation points to nonpregnant status.
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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Pregnancy Diagnosis up to 60 Days

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