Study On Characteristics Of Microflora In Canine Uterus And Its Correlation With Pyometra

Pyometra is a common and high incidence reproductive system disease in female dogs.It is characterized by acute or chronic suppurative bacterial infection in the uterus and the accumulation of inflammatory exudates in the uterine cavity.At present,it is believed that bacteria and hormones work together to cause pyometra in dogs,and the specific mechanism is not completely clear.With the in-depth study of flora,the hypothesis of "sterile uterus" has been challenged.Human medical research has found that there are flora in the uterus.However,it has not been reported whether there are bacteria in the normal uterus of companion dogs and whether the pyometra in the uterus is related to the abnormal changes of these bacteria.In this project,we investigated the incidence of pyometra cases in four cities of Jilin Province from January 2020 to December 2020,and performed 16 S r RNA gene sequencing analysis and metabonomics analysis on the endometrial tissues of 30 healthy dogs and 41 pyometra affected dogs,to study the characteristics of the flora in the uterus of healthy dogs and pyometra affected dogs,and to screen and analyze the key differential flora and metabolites,To further reveal the role and mechanism of abnormal intrauterine flora in the occurrence and development of pyometra,and to provide a new idea for the microbiological prevention and treatment of uterine diseases.From January 2020 to December 2020,the incidence of pyometra in dogs was investigated in Changchun City,Jilin City,Songyuan City and Yanbian Korean Autonomous Region of Jilin Province.Through the medical system and doctor's case records of the four regional animal hospitals,317 cases of pyometra were found.The results of the investigation on the size,breed,age,seasonal distribution of the disease and whether there were complications of the tumor were as follows: 1)the proportion of small dogs was 65.93%,including 30.60% of VIP dogs,9.78% of Pomeranian dogs,5.99% of Schnauzer dogs,4.73% of Chihuahua dogs and 3.79% of Bichon dogs;Medium sized dogs 19.8%,among which Samoye dogs 4.73%;Large dogs accounted for 14.19%,of which golden retrievers accounted for 9.78%.2)The minimum age of onset was 2 years old,and the maximum age of onset was 16 years old.94.00% of the cases had pyometra after 5 years old.3)Pyometra occurred in dogs in all seasons,including 28.39% in spring,26.81% in summer,22.08% in autumn and 22.71% in winter.4)14.51% of the patients had pyometra in uterus,2.21% had skin tumor,1.58% had vaginal tumor and 0.63% had lipoma.In this study,16 S r RNA gene sequencing was performed in 30 healthy dogs and41 dogs with pyometra.Healthy dogs and dogs with pyometra were determined by blood routine examination,biochemical examination,C-reactive protein(CRP),progesterone test,vaginal smear,B-ultrasonic examination,uterine appearance and histopathological examination.16 S r RNA gene sequencing analysis showed that bacteria were present in the uterus of both healthy dogs and dogs with pyometra.The main microflora of healthy dogs were Pseudomonas(21.85%),Vibrio(7.81%),Ralstonia(8.78%),Pseudoalteromonas(2.13%),Methylversatilis(2.75%)and Shigella(2.03%);Among Firmicutes,Staphylococcus(3.43%),Streptococcus(1.58%),Lactobacillus(1.56%),blautia(1.20%),etc;Bacteroides(2.12%)in Bacteroidetes,etc.Compared with the bacterial abundance in the endometrium of healthy dogs,the bacterial abundance in the endometrium of dogs with pyometra was significantly lower(P < 0.05).Lefse analysis showed that there were 21 different species in the uterus of healthy dogs and dogs with pyometra.Among them,Escherichia?shigella,Haemophilus,Mycoplasma,Enterococcus and Pseudomonas?aeruginosa were significantly enriched in the endometrium of dogs with pyometra.In order to further verify the correlation between the intrauterine flora and pyometra,and to screen and analyze the key metabolites and metabolic pathways between the two groups,the endometrial tissues of 15 healthy dogs and 15 dogs with pyometra were analyzed by non targeted LC-MS metabolome.The study found that there were significant differences in the metabolites of endometrial tissue between healthy dogs and dogs with pyometra.There were 275 different metabolites between the two groups,of which 180 were significantly up-regulated metabolites such as kynurenic acid(P < 0.05),and 95 were significantly down regulated metabolites such as prostaglandin H2(P < 0.05).The enrichment analysis of differential metabolites KEGG showed that the differential metabolites of the two groups were mainly related to the pathway of nicotinate and nicotinamide metabolism,arachidonic acid metabolism,prolactinic synapse and tryptophan metabolism.The results showed that kynurenic acid,2-aminoacetophenone and estrone played a key role in the occurrence of uterine abscess.In conclusion,there are specific flora and metabolites in the endometrium of healthy dogs and dogs with pyometra.The results showed that: 1)Shigella,Haemophilus,mycoplasma,Enterococcus and pseudomonas?aeruginosa are important flora in the occurrence and development of pyometra;2)Kynurenic acid,2-aminoacetophenone,estrone and other metabolites play a key role.3)Tryptophan metabolism,prolactin signaling pathway and other metabolic pathways participate in the related processes.