Lochial and endometrial cytological changes during the first 10 days post-partum with special reference to the nature of foaling and puerperium in equine

During the puerperium, pregnancy-associated changes of the uterus need to be reversed. The duration of this process is of importance in terms of breeding efficiency and thus monitoring and treatment of the disturbed puerperium are essential. Aim of this investigation was to identify changes over time in the cellular composition of samples from endometrium and lochia in 120 mares with different obstetrical and puerperal history. In regular examinations up to 10 days post-partum the uterine involution was assessed by transrectal palpation and ultrasound. The vagina and cervix were examined using a speculum. Mares were classified as having an undisturbed or disturbed puerperium based on history and clinical findings. Uterine cytology samples were obtained with a cytology brush and lochia were obtained by manual withdrawal. Smears were done by rolling the brush or the swab on slides. They were stained using Hemacolor®-staining. In total, 238 cytology and 150 lochia smears were examined. Endometrial cells, neutrophils, and erythrocytes were distinguished by light-microscopy. Changes in the neutrophil granulocyte count in cytology and lochia smears were determined. The correlation between the number of neutrophils in cytology and lochia smears was not significant (p = 0.22). There was a significant influence of the puerperium on the percentage of neutrophils in the cytology samples (p = 0.001) but not in the lochia smears (p = 0.83). A significant decline of erythrocytes was detected in cytologies (p