Canine Uterine Infection and the Expression of Toll-like Receptor 2 and 4 in Canine Uterus

Abstract

EXP. 1 aimed to identify the bacterial species in the vagina and uterus healthy bitches and bitches with closed-cervix and opened-cervix pyometra. Various bacterial species were found from the vagina and uterus of bitches in this study. No healthy bitches had a relationship between bacterial species in vagina and uterus and in 13 bitches with closed-cervix pyometra, the bacterial species of 10 bitches (76.92%) were not related between vagina and uterus. Meanwhile, in 20 bitches with opened-cervix pyometra, the bacterial species between vagina and uterus in 6 bitches (30%) had no relationship. Bacteria found in the vagina may not be an initial cause of uterine infection in bitches with closed-cervix pyometra. Bacterial species in the vagina of bitches with opened-cervix pyometra may be a cause of uterine infection or can be the result of uterine drainage. EXP. 2 aimed to investigate the number of leukocytes in the horn, body and cervix of the uterus in healthy dogs during the estrous cycle. The leukocytes that found from this study were lymphocytes, macrophages, neutrophils, and plasma cells. And lymphocytes were the most common leukocytes found in the uterus. In the endometrial stroma, the total leukocytes (P < 0.05) and the number of macrophages (P < 0.01) were significantly increased in anestrous dogs compared to other stages. The number of total leukocytes in the surface epithelium of the uterine horn significantly decreased at estrus (P < 0.01) but significantly decreased at anestrous stage in the cervix compared to other stages (P < 0.05). From this study, the number of leukocytes varied in a different tissue layers and different regions of the uterus at different stages of the estrous cycle which indicated the different role in the uterine immune surveillance protecting the host from the pathogen invasion. EXP. 3 aimed to investigate the expression of TLR2and TLR4 in canine uterus during the estrous cycle and in pyometra. The expression of TLR4 in the endometrial surface epithelium was significantly higher in dogs with pyometra compared with all other groups (P < 0.01). While, the expression of TLR2 in the surface epithelium of the uterine body was significantly decreased in pyometra dogs (P < 0.05). Interestingly, TLR2 was expressed in endometrial epithelium but absent in the endometrial stroma of healthy dogs at all stages. In dogs suffering from pyometra, when compared between the uterine regions, the expression of TLR4 was significantly more intensely in the surface epithelium and stroma of the uterine horn compared to the uterine body and the cervix (P < 0.01). Conversely, the expression of TLR2 in the surface epithelium of the cervix was significantly higher than the uterine horn and body (P < 0.01). From this study, the different levels of TLR2 and TLR4 expression related to distinct cell types of uterus, leukocytes populations and sex hormones.