Vaginal and cervical anatomic modifications during the oestrus cycle in relation to transcervical catheterization in the domestic cat.

In a previous study we observed that it is possible to reach the cervix in all queens with a 1 mm diameter probe only. So, we developed both a new technique and a catheter (1 mm diameter) to allow transcervical insemination [Zambelli and Castagnetti 2001]. The aims of this study were to investigate vaginal and cervical anatomic modifications during the various stages of the oestrus cycle and to test the previously described technique of transcervical catheterization during the various stages of the oestrus cycle. In experiment 1, silicon impression moulds were obtained from the reproductive tracts of 21 queens' cadavers and vaginal and cervical measures were taken. The results showed that there are some significant anatomic modifications during the various stages of the oestrus cycle in vaginal and cervical anatomy, principally related to the dorsal medial fold increase induced by the follicular phase. In experiment 2, transcervical catheterization was attempted in 95 queens at various stages of oestrus cycle both during reproductive and non-reproductive season. After catheterization, methylene blue solution was injected through the cervical catheter. Successful catheterization was assessed during surgery, when colour was observed in the uterine horns. It was possible to perform transcervical catheterization during non-reproductive season in 16 of 20 anoestrus queens and in 12 of 15 induced oestrus queens; during reproductive season in nine of 21 interoestrus queens, in eight of 13 dioestrus/pregnancy queens, in four of 18 oestrus queens and in seven of eight queens in first oestrus during lactation.