Morbidity in a microsurgical rat training model.

In a prospective study with 24 growing Wistar rats, with a mean body weight of 300 gram, microsurgery was trained. Patency as well as morbidity of the animals was assessed. There were 110 vascular anastomoses, constructed with various techniques. Of these, 104 were rendered for evaluation. The caliber of the vessels varied from 0.4 to 2.0 mm. On an average, the rats were operated two times, during which operations at least four anastomoses were created. Patency was related to caliber and flow rate of the vessel and varied between 50 and 100%. Mortality and weight increase, used to reflect morbidity were evaluated. Six animals died during or shortly after operation, three of them because of anaesthesia alone. Mean postoperative daily weight increase was 1 gram approximately. In the control group the weight increase was tripled. The rats needed two weeks after operation rats to regain their original weight. Analysis of results demonstrated highly significant difference between operated and non-operated rats. The study suggests, that morbidity of rats submitted to microsurgery will be reduced, if two weeks of recovery before other experiments are awaited. This may provide a standard for future experiments.