Quantitative and qualitative echographic characteristics of ovaries in dogs during estrus

The article is devoted to the quantitative and qualitative echographic characteristics of ovarian structures in dogs during the estrus of the sexual cycle, the significance of the follicular echogenicity index in detecting ovulation. The object of the study was 27 sexually mature female dogs of different breeds, from the period of proestrus to diestrus. The animals were divided into 3 groups: the first group - dogs weighing up to 5 kg (n = 12), the second group – dogs weighing 6-20 kg (n = 8), the third group - dogs weighing more than 20 kg (n = 7). The studies were carried out at the Pirogov Veterinary Center in Stavropol on a SIUI Apogee 1100 Omni scanner (Shantou Institute of Ultrasonic Instruments Co., Ltd., Guangdong, China) according to the generally accepted technique using a multi-frequency linear sensor with a frequency of 7.5-12 MHz in B-mode. The quantitative parameters of the echogenicity of the ovaries and follicles were determined using the techniques of Silina T.L. et al. (2010) and Tsygansky R.A. (2020). Specific echographic markers of the ovulation process have been established, in the form of an increase in the hyperechoic border of follicles by 0.1-0.2 cm or loss of clarity of the follicle contour with a decrease in their size, loss of follicle symmetry, a decrease in the number of follicles by 30-40%. During estrus, the follicular echogenicity index (FEI – the ratio of quantitative units of echogenicity of the stroma and follicles). At the beginning of proestrus, this index is 1.5-1.7, by the end of proestrus 2.0-2.5, which indicates a decrease in the echogenicity of the follicles during folliculogenesis, after ovulation, this index decreased below 2.0. Dynamic changes in the echographic parameters of the ovaries were accompanied by an increase in the concentration of progesterone in the blood serum of dogs. The obtained qualitative and quantitative sonographic data of the ovaries of dogs in the process of folliculogenesis can serve as a basis for identifying various stages of the active phase of the sexual cycle during ultrasound examination.

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