Ultrasonographic computer-assisted quantification of the intraluminal uterine content in female dogs

In dogs, the characterization of intraluminal uterine contents has been subjectively carried out by the operators. The aims of this study were: 1) To ultrasonographically describe and compare the echogenicity and heterogeneity of the intraluminal uterine contents in bitches using digital analysis; 2) To assess the cytology of the uterine contents; 3) To evaluate the effect of clinical, ultrasonographic, bacteriological and cytological parameters on intraluminal contents echogenicity and heterogeneity. Twenty-one intact, 3-24 kg, 1-12 years of age, female dogs with ultrasonographically detected uterine content were included. According to the gross evaluation, the contents were classified as purulent (PC; n = 8), mucous (MC; n = 4), serous (SC; n = 9). Ultrasonographic images of the contents were digitally analyzed to measure echogenicity and heterogeneity, represented as the mean gray value (MGV) and the standard deviation of the gray value (SDG), respectively. Endometrial cytology samples were collected post-ovariohysterectomy. Clinical, ultrasonographic, bacteriological and cytological parameters were compared among groups using one way ANOVA and Chi-square tests. A generalized linear model was performed to analyze their effect on MGV and SDG. Uterine diagnoses included cystic endometrial hyperplasia - pyometra, cystic endometrial hyperplasia, cystic endometrial hyperplasia - mucometra, endometritis and normal uteruses. MGV was higher in PC and MC than in SC (P < 0.01), did not differ between PC and MC (P > 0.1). SDG was higher in PC than in SC (P < 0.01) and MC (P < 0.05). Digital analysis distinguished among purulent, mucous and serous fluids. Cytology revealed higher inflammation-related parameters in PC than in MC and SC. Cytological parameters, such as cellularity and bacterial presence, were associated with echogenicity and heterogeneity of uterine contents.