Ultrasonographic and elastographic evaluation of the canine cervix across oestrous cycle stages

Abstract

This study evaluated B-mode ultrasonography and ultrasound elastography (UEl) for detecting structural and consistency changes in the canine cervix across the oestrous cycle, as the use of ultrasonographic techniques for this purpose remains underexplored. The present study aims to assess cervical features via ultrasound, acknowledging the critical role of the cervix in the canine oestrus cycle. Thirty-five bitches were evaluated during pro-oestrus, pre-ovulatory oestrus, peri-ovulatory oestrus, dioestrus and anoestrus. Progesterone levels, clinical signs, vaginoscopy and cytology were used to define the oestrous cycle phase. Cervical length, diameter, and the elastographic index (ElI) were measured, and the elastographic ratio (ElR) was calculated to compare cervical stiffness to the surrounding tissue. Cervical length and diameter values were observed to be higher during the pre-ovulatory and peri-ovulatory phases of oestrus (p < 0.05). ElI values in anoestrus were similar to dioestrus and significantly higher than pro-oestrus and pre-ovulatory oestrus (p < 0.05), reflecting greater cervical stiffness in anoestrus and dioestrus, while pro-oestrus and pre-ovulatory phases showed softer tissues. These findings underscore the utility of elastography in quantifying cervical tissue consistency and its correlation with hormonal influences, providing a novel diagnostic perspective for a more comprehensive understanding of reproductive health.