Vaginal Cytology in the Bitch

Vaginal cytology is microscopic examination method which is used to evaluation phases of oestrus cycle and possibility of result time the best date for successful breeding. Substance of the examination is subjective evaluation of the epithelium and cell morphology. Vaginal cytology is influenced by levels of sexual hormones which are typical for individual phases of oestrus cycle. Regular physiologic changes on internal and external sexual organs happen during oestrus cycle. Canine behaviour, espacially with regard on refusal or accept dogs, is depending on phases of interval. Oestrus is in the bitch usually twice a year, in 5 to 12 month cycles. Oestrus cycle is devided into individual phases: proestrus, estrus, metestrus and anestrus. In terms of sexual behavior of females the whole estrous cycle can be distinguished into a period of sexual willingness (proestrus, estrus) and the period of sexual reluctance (metestrus, anestrus). Proestrus begins as a regression of the corpus luteum and finishes with onset of estrus. At the end of proestrus LH surge occurs after which further 24 to 48 hours ovulation follows. Proestrus is characterized by progressively increasing size of the vulva, vaginal epithelial proliferation, cornification epithelum of vagina and vulva swelling. For this stage parabasal and intermedial cells, erythrocytes and leukocytes are typical in the cytological smear of vagina. Estrus is the period of sexual willingness. In this period matured follicle burst and subsequent egg ovulation. In this cytology smear dominating superficial squamous cells are typical for this period. There can observed erytrocytes. In initial period of estrus too large intermediate cells often appear. In the next period, metestrus, the corpus luteum is gradually developing. Cytology smear from vagina is characterized by the presence of large numbers of neutrophils, typical are parabasal and small intermediate cells. In anestrus manifests luteal activity of the corpus luteum. Vaginal cytology is characterized by finding parabasal, small intermediate cells and leukocytes. Vaginal cytology is a simple, quick, noninvasive and inexpensive procedure that allows us to identify the stage of the reproductive cycle of bitches and to diagnose some pathologic conditions of the genital tract (hormonal dysfunctions, inflammatory or neoplastic diseases). More than other domestic animals vaginal cytologic changes are expressed in the bitch which correlate with each phase of the estrous cycle