| Objective:The incidence of anal fistula in China is not as high as that in foreign countries,but it still has a large proportion in all anorectal diseases.It is possible that the anal sphincter is vulnerable to the anal sphincter injury for the large wound and the long wound healing time after the operation.For many years,people have been looking for effective drugs and treatments to cure anal fistula,so it is necessary to establish an animal model which is repeatable,simple,economical and close to the clinical.The purpose of this study is to provide a reliable animal model for the clinical research by filling the anal fistula model of the rabbits through a rubber band hanging method to fill the blank of taking the rabbit as the anal fistula model.The establishment of the rabbit anal fistula model provides a basis for the treatment and pathology study of anal fistula.Methods:Fifteen healthy adult rabbits weighing 2-4 kg were randomly divided into two groups.Among them,10 rabbits are in the experimental group and 5 rabbits are in the control group,of which there was no significant difference in the weight,sex,health and other general data in two groups of rabbits(P > 0.05),which was comparable.Rabbits can start modeling after one week of normal diet.The experimental group established 20 anal fistula ducts under the general anesthesia using the rubber band hanging method.In the control group,10 anal fistula ducts were established with the artificial injury under the general anesthesia.After the model started,the temperature of the anus of each rabbit would be measured for 7 consecutive days and the secretion would be observed.After 20 days,in the experimental group were taken out of the rubber band,all rabbits underwent MRI examination,ultrasound examination,and probe examination under the general anesthesia.Histopathological examinations were performed after the clinical evaluation and sacrifice of animals.Results:After the modeling,the anus temperature of the experimental group and the control group increased to varying degrees,but the anus temperature of the experimental group was higher than that of the control group from the first to the third days after modeling.For the perianal secretion,the experimental group started from the third days to the tenth days,and the perianal secretion increased gradually and then decreased gradually,while the anus secretions in the control group changed little in most of the time.In the experimental group,15 anal fistulas were formed by the clinical evaluation,14 anal fistulas were detected by the perianal color ultrasonography,and 12 anal fistulas were detected by MRI,and 15 anal fistulas were formed by probe examination.The number of anal fistulas formed by histopathology was 15,and the success rate of the model establishment was 75%.In the control group,2 anal fistulas were formed by the clinical evaluation,and 2 anal fistulas were detected by the perianal color ultrasonography.Anal fistula was measured by MRI as one.There were 2 anal fistulas formed by the probe examination,and 2 anal fistulas were formed by the histopathological examination.The success rate of the model establishment was 20%.The success rate of the model establishment was significantly higher in the experimental group than that in the control group(P<0.05),and the difference was statistically significant.Conclusion:The use of anal thread-hanging method to make the rabbit anal fistula model has plasticity,repeatability and stability.The clinical evaluation and probe examination can clearly identify the internal and external orifices.Fresh granulation tissue and luminal and vessel wall formation can be seen under MRI and perianal ultrasound,and a large number of the inflammatory cells can be seen in the histopathological examination.Therefore,it is worthy of further promotion and the research to make the rabbit anal fistula model by anal thread-hanging method provides a certain basis for the treatment of the clinical anal fistula. |
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