A necessary characteristic indicating the survival ability of a cow carcass is the hypoechoic nature of fetal fluids. Between day 10 and day 50, up to 15% of pregnancies experience embryo death. In the case of absorption, slight to moderate reflexes will appear relatively quickly in the liquid of embryonic vesicles. In a complete pregnancy, the interface between the embryonic vesicle and its surrounding environment is smooth. When this line becomes wavy, it may indicate that the embryo is about to die. In the complete pregnancy detection of cattle using B-ultrasound machine, the carcass remains strictly spherical until the 15th day of pregnancy. If the embryonic vesicle takes on any other shape before this day, it should be suspected that it has died. In the later stages, changes in shape can no longer be used as a reliable indicator. No heartbeat is a reliable sign of embryonic death. In intact embryos, the heart rate is usually above 150 beats per minute. Another sign that embryonic death may be ongoing is due to the volume of embryonic fluid being lower than normal and the size of vesicles (small date) being insufficient. The embryo resorption that occurs in the first three weeks of pregnancy is usually a rapid process.

Using B-ultrasound to detect uterine diseases in cows

The absence of signs of estrus and manual determination of increased uterine tension may indicate pregnancy. However, these same findings may also exist in cases where the corpus luteum persists after early embryonic death. In the mid to late stages of ovulation, cows do not show signs of estrus at the expected time, and uterine tension increases. The difference between pregnancy and these forms of false pregnancy can only be made with the help of ultrasound examinations aimed at detecting the presence or absence of embryonic vesicles.

The accumulation of fluid in the uterine cavity, especially during estrus, is a characteristic of cows with chronic endometritis. The accumulation of fluids discovered during estrus may be physiological, but in many cases it can also be an early sign of endometritis. Whenever liquid secretion is found in the uterus during the estrus period, it should be considered abnormal. The contour of fluid accumulation in endometritis cases is usually star shaped in cross-section. The interface between secretions and the surrounding uterine wall is wavy. In the case of endometritis, a typical feature of uterine secretions is the enhanced echogenicity of the fluid. It should be pointed out that during the second and third stages of pregnancy, amniotic fluid may also exhibit echogenicity. This also applies to the urine in the first three months of pregnancy. The ultrasound differentiation between the secretions of endometritis and other types of fluids in the uterus (such as placental fluid or fluid in endometrial cysts) must be evaluated in conjunction with other criteria, such as the echogenicity of the fluid, the position and shape of its internal uterus. The appropriate time for ultrasound diagnosis of endometritis seems to be in the mid to late stage of estrus.

Uterine pyometra is considered a major and severe endometritis. The ultrasound image shows extreme dilation of the uterus. In this way, the folds of the endometrium are stretched, and the interface between the uterine contents and the wall becomes smooth. In the secretion of pyometra, there is usually a strong reflex and an increase in abdominal density. The ultrasound image of the bladder looks very similar to pyometra.

Ultrasound image of bovine pyometra detected by B-ultrasound

Endometrial cysts in cows can occur in the uterine body and uterine horns, and these cysts may affect the fertility of cows. However, they do not constitute a * * barrier to the establishment of pregnancy, as many pregnancies develop very normally in the presence of endometrial cysts. In isolated situations, when cysts are particularly large or numerous, they appear to cause embryo death by interfering with the normal implantation process of the embryo. In ultrasound examination, cysts appear as fluid filled vesicles, ranging in shape from spherical to elongated elliptical. Their lumen can be composed of one lumen or divided into several lumens. The cystic fluid is lymphatic fluid, which has no echo and appears almost black on ultrasound examination. The size of these cysts can range from a few millimeters to a few centimeters. Some cysts ranging in size from 10 to 30 millimeters can sometimes be difficult to distinguish between the 10th and 25th day of pregnancy. From the fourth week of pregnancy, differentiation becomes easier as the embryo exhibits a beating heart. Spherical shape, diameter consistent with the last reported service date, and central position of the uterine cavity are all favorable symptoms for diagnosing pregnancy. The fluidity of vesicles or detectable heartbeat within the embryo will confirm pregnancy. The activity of the embryo is usually evident before the 15th or 16th day, and in most cases can be observed by scanning the vesicles for a few minutes. The indications for cysts include irregularity or ovality, the presence of multiple compartments within their lumen, or multiple occurrences in the uterus. Eccentric vesicles located within the uterus should be considered as cysts. The detected vesicles may be further signs of a cyst, including a difference between the observed vesicle diameter and the expected vesicle diameter, or an inability to grow in size. If there are still doubts about the identity of the vesicles, it indicates that the examination will be repeated a few days later. If a cow is pregnant, the size of the embryo vesicles will significantly increase at the next examination.

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