This document discusses vaginal cytology, which is the study of the structure, shape, and contour of exfoliated vaginal epithelial cells using staining techniques. Vaginal cytology can help characterize a bitch's estrus cycle to determine the best time for breeding, evaluate any diseases of the genital tract like vaginitis or pyometra, and identify some neoplastic conditions of the vagina and urethra such as transmissible vaginal tumors.