Expression of prostaglandin F2 alpha receptors (PTGFR) and C-reactive protein (CRP) in the canine uterus and cervix with opened- and closed-cervix pyometra

Pyometra is a common reproductive disorder in female dogs. This study investigated the protein expression of prostaglandin F2 alpha receptors (PTGFR) and C-reactive protein (CRP) in responses to inflammatory events of uterine and cervical tissues in dogs. Uterus and cervix samples were collected from six dogs which had closed-cervix pyometra (n = 3) and opened- cervix pyometra (n = 3). Healthy dogs in diestrus (n = 3) and anestrus (n=3) were used as controls. Tissues were histologically prepared and stained with hematoxylin and eosin. Biochemistry (IHC) and western blot analysis for the PTGFR and CRP were used to verify the protein expressions. Leukocyte infiltration was markedly presented in some layers of the uterine and cervical tissues of closed- and opened-cervix pyometra. Closed-cervix pyometra had a distinct severity of muscular layers of the uterus compared with opened-cervix pyometra. Plasma cell infiltration was significantly increased in both uterine and cervical pyometra tissues when compared with the controls (P < 0.0001). Western blot analysis confirmed the expression of PTGFR and CRP in normal and pyometra tissues. In the uterus and cervix, the positive CRP reactivity was weakly expressed (T score = 1.00-2.37). The expression of CRP as well as PTGFR reactivity did not significantly differ among the groups (P > 0.05). Inflammatory responses, pathological changes, and PTGFR expression did not correlate with CRP accumulation in uterine and cervical tissue of closed- and opened-cervix pyometra.