EVSSAR

Canine vaginal cytology is widely used for estrous cycle staging, but its predictive value for the estrus- diestrus transition and its correlation with serum progesterone levels require further val idation. This study aimed to evaluate whether neutrophils can serve as reliable cytological markers of diestrus and whether their fluctuations correspond with serum progesterone levels. Materials and Methods: Vaginal cytology samples were col lected from 13 bitches (n = 13) at different estrous cycle stages, including proestrus, estrus, and early diestrus. Serial samples were obtained to confirm intra- day progesterone consistency, with a focus on evaluating the percentage of parabasal, inter mediate, superficial, anucleated, neutrophil, and erythrocyte cells. Cytological samples were prepared using Diff- Quik stain ing and analysed under light microscopy (1). Serum progester one concentrations were determined using an enzyme- linked immunosorbent assay (ELISA) (2). Statistical analysis was per formed using Pearson's correlation and one- way ANOVA, with a significance threshold of p < 0.05. Neutrophils were highly correlated with diestrus (r = 0.81, p = 0.03) and showed a significant increase in this stage (80.67% in early diestrus, 19.33% in late diestrus, and 0% in estrus), con firming their role as a predictive marker for the estrus- diestrus transition. Superficial cells were the dominant cell type in estrus, comprising 23.19% and 29.07% across different sub sets, while anucleated cells accounted for 55.19% and 24.63%. Intermediate cells were most frequent in late diestrus (43.29%) and proestrus (26.36%), while parabasal cells were largely con fined to proestrus (82.4%). Diestrus samples had significantly higher progesterone levels compared to estrus (p = 0.02). No sig nificant correlation was found between erythrocyte percentage and any estrous stage (p > 0.05). This study confirms that neutrophil influx is an important pre dictive marker for the estrus- diestrus transition, with a strong correlation to serum progesterone levels. Superficial cells are the dominant cytological cell type in estrus, further supporting their role in estrous cycle monitoring. The use of ELISA for pro gesterone determination provides reliable hormonal validation of cytological changes. These findings validate vaginal cytology as a cost- effective diagnostic tool, particularly in settings where hormonal assays are unavailable. Future research should refine cytological progesterone estimation models to improve breeding and reproductive management strategies. References: 1) Davidson, Journal 2015. 2) Haji et al., Int J Livest Res 2018;8: 241.