Ultrasonic echography in the mare.

This paper presents a study of the use of ultrasonic echography for the early diagnosis of pregnancy and the detection of unusual pregnancy conditions in mares. The research demonstrates high accuracy rates in both positive and negative pregnancy detection, and provides insight into identifying abnormalities that may indicate different pregnancy states, as well as exploring early pregnancy loss and embryonic death rates.

Methodology and Overall Findings

• The research conducted used ultrasonic echography to diagnose pregnancy in mares, as early as 14 days after ovulation.
• A total of 7438 examinations were performed on 4688 mares across several farms, using the same apparatus, during the 1980 and 1981 breeding seasons.
• The findings suggest that this method of ultrasonic echography is highly accurate, with positive pregnancy diagnosis accuracy over 95%, and non-pregnancy diagnosis accuracy over 84%.

Detecting Abnormalities and Twins

• When abnormalities were found in ultrasound images, the researchers had to discern whether they were viewing a conceptus (an early stage of embryo development) or a cystic structure.
• The study also identified certain indicators to differentiate a normal pregnancy from an abnormal one, such as abnormal vesicle shapes, presence of echoes, divisions inside the vesicle, and the comparison of small and large vesicles.
• The researchers found that most small vesicles do not develop, whereas large or deformed vesicles, or those with echoes or divisions, often represent a growing conceptus or possibly twins.
• The rate of twin conception in early pregnancy stages was estimated between 2.6 and 2.8%. Factors such as two vesicles of equal size, one large vesicle or one of an irregular shape, or a divided vesicle could indicate twin pregnancies.

Results on Early Pregnancy and Embryonic Loss

• The study also looked into early pregnancy loss (between mean days 23 and 43), which was estimated at 5.3%, and a total embryonic loss (early and late) at 9%.
• It was observed that the rate of embryonic death increased in proportion to the interval between the two successive diagnoses.
• The research did not find any significant effects from the month of mating on the rate of twin conceptions. Similarly, no impact of the reproductive status on embryonic or fetal mortality was found.