engleski

Diagnosis of the Reproductive Disorders in Dairy Cows by Ultrasound

In veterinary medicine, utilization of the ultrasound as a diagnostic tool is considered as a safe, non-invasive procedure either for the animal or the operator. It is well accepted in animals, offering a great variety of examinations, mainly in research area or in animals with chronical diseases. In dairy cattle, transrectal B-mode realtime ultrasongraphy is rutunely used either for early pregnacy diagostics (>day 25. after AI) or for determination of the stage of the estrous cycle by visualization and measurement of the ovarian structures. While follicles, appears as spherical, anechoic (black) areas, from 3-to18 mm in diameter, the spherical shaped corpora lutea (CL) in diestrus, are easily recognizable as distinctly less echogenic regions then the ovarian stroma, with the diameter >25mm. Sometimes, a centrally located anechoic area in the middle of the CL could be found, named Central Luteal Cavity, representing a non-pathological structure, appearing frequently in both pregnant and non- pregnant cows. Static ovaries (true anestrus), defined as absence of CL and follicles larger than 8 mm in diameter on both ovaries, could be diagnosed by ultrasound, after day 45 postpartum. Treatment with GnRH, eCG or progesterone-releasing devices are usually less effective in comparison to the improvement of the nutritional status of the cows. Ovarian cysts (OC), during the US examination are visualized as a uniformly non- echogenic ovarian structure >25 mm in diameter, persisting more than 10 days on one or both ovaries, in an absence of an active luteal tissue. OC could be classified according to the thickness of the wall as luteal cyst having thick (≥ 3 mm) and more echogenic wall that appear as a gray layer of the inner wall and follicular cyst having thinner wall (<3mm), showing uninterrupted anehogenic antrum. When the fate of spontaneous generated ovarian cysts was investigated by ultrasound, it was found that ovarian cysts are dynamic structures and should not always be considered as a severe pathological condition. While, the single ovarian cyst have partial capability for spontaneous self-recovery in short period of time, (probably undergoes to the process of luteinization), the multiple follicular cysts have tendency for persistency for more than three weeks, and therefore, acquire a hormonal treatment (Dovenski et al., 2002). Early embryonic mortality (EM) could be detected by serial ultrasound examination between d. 25 and d.42 after AI, when an embryonic sac, previously diagnosed, could not be detected in the consecutive scanning. Incidences of EM vary from 7% to 40% in farms with different housing conditions, nutritional and epidemiological status. Different pathological conditions of the uterus, such as the endometritis, pyometra, fetal maceration and mummification could be recognized by ultrasound, characterized by expanded lumen and presence of varying degrees of echogenic fluid inside.

ultrasound diagnostics, ovary, follicle, corpus luteum, cyst, cow

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