What type of cells are predominant in uterine cytology when a bitch is in estrus?

During estrus in a female dog, the predominant type of cells observed in uterine cytology is cornified epithelium. This is due to the hormonal changes that occur in the reproductive cycle, specifically the elevation of estrogen levels that happens during estrus.

Estrogen causes the superficial layers of the vaginal epithelium to undergo cornification, which results in the shedding of the outer layers of the cells that are flat and keratinized. This characteristic appearance is commonly assessed in cytological evaluations during the estrous cycle to confirm the stage a female dog is in. The presence of these cornified cells indicates a readiness for mating and potential conception.

In contrast, during other phases such as proestrus or anestrus, different types of cells would be predominant, which could include non-cornified epithelial cells or various types of leukocytes, but during estrus, it is the cornified epithelium that is definitively noted.