1 Monitoring ovarian development for timely mating

B-ultrasound can monitor ovarian development, determine ovulation period, and provide the best time for mating or artificial insemination. When monitoring ovarian development, the number of mature follicles can be calculated from multiple sections. When there are too few mature follicles (less than 5) or the number of synchronously growing follicles is small and the speed is slow, gonadotropin can be used in appropriate amounts to promote ovarian development and ovulation, improve conception rate, and increase litter size.

2 Early pregnancy diagnosis application

B-ultrasound can be used for early pregnancy diagnosis, and can intuitively display pregnancy characteristics such as embryonic sac and embryo on the screen with high accuracy. The B-ultrasound judgment of early pregnancy in animals is mainly based on the observation of the circular liquid dark area of the gestational sac and the enlargement of the uterine horn section and the thickening of the uterine wall on the ultrasound section of the uterine area as indicators. The exploration method is to use a 5 or 7.5 MHz linear array or fan-scan probe to observe the horizontal, vertical and oblique planes after cutting the hair of the abdominal bottom wall or both sides. When one or more dark areas of the gestational sac are seen, it can be judged as pregnancy. The positive rate of B-ultrasound pregnancy diagnosis is 80% 20 to 24 days after dog mating; it can reach more than 90% at 25 to 30 days.

3 Monitoring of embryonic development, number of fetuses, gestational age, and stillbirth In pregnancy monitoring, predicting the number of fetuses is of great significance to feeding management.

In the late pregnancy, the nutritional level of the mother animal is directly related to the birth weight of the fetus. The application of B-ultrasound can observe the external structure, shape, and internal structure of the embryo. The number of embryos can be estimated based on the number of gestational sacs and embryos; the gestational age can be predicted based on the echo structure that can be identified on the B-ultrasound section; the fetal heartbeat and embryo structure can be used to distinguish between dead fetuses and emphysematous fetuses, and to judge embryo absorption and miscarriage.

4 Dynamic monitoring of transplanted embryos During embryo transplantation, B-ultrasound is mainly used for dynamic monitoring of the development of transplanted embryos.

B-ultrasound monitoring has achieved satisfactory results in the selection of donor and recipient sheep before embryo transplantation, the determination of pregnancy of prepared sheep, the estimation of ovulation of donor sheep after superovulation treatment, and the judgment of early pregnancy of recipient sheep after transplantation.

5 Diagnosis of obstetric diseases

5.1 Ovarian cyst Ovarian cyst refers to a pathological state in which there is a follicle-like structure on the ovary, with a diameter of more than 2.5 cm, and the existence time is more than 10 days. At the same time, there is no normal corpus luteum structure on the ovary and it is accompanied by abnormal estrus. It mainly occurs in large livestock. This disease is generally divided into follicular cyst and corpus luteum cyst. B-ultrasound results of cattle with follicular cysts showed that the ovarian volume was enlarged, the cystic follicles were anechoic and liquid dark areas, the follicle diameter was larger than the normal ovulation follicle diameter, the follicles were round and anechoic and liquid dark areas, the follicle walls were thin, and the borders were neat and smooth. B-ultrasound results of cattle with corpus luteum cysts showed that the corpus luteum cysts slightly protruded from the ovarian surface, the surface echo was smooth, liquid dark areas appeared in the cysts, the walls were thick, the edges of the corpus luteum cysts were smooth, and there were clear contours. Cotton-like echoes or irregular light masses were visible inside, the inner wall was not smooth, and faint light spots appeared.

5. 2 Uterine effusion Uterine effusion is a common uterine disease in dogs. According to the characteristics of B-ultrasound images combined with clinical diagnosis, uterine effusion can be roughly divided into two categories: hydrometra, the uterine wall is very thin, the fluid in the uterine cavity has a very low echo (dark area), and there are generally no clinical symptoms except for the increase of abdominal circumference in some cases; pyometra, the uterine wall is thicker, the uterus is an echo-free dark area of varying sizes and irregular shapes (long dark areas), the dark area is connected to the abdominal wall, or it is a uniform weak echo circular cavity.