Development of a special catheterbag to enable artificial organ evaluation in conscious, unrestrained pigs: technical note.

Pigs are widely used as models for a variety of human diseases, because many of their physiological functions closely resemble those of humans. However, information on instrumentation techniques is still scarce. In particular, experiments in conscious pigs focused on extracorporeal circuits are connected to a variety of methodical problems with respect to the handling of the animals. Usually, pigs are placed in restraint-slings during the application of an extracorporeal system. However, this method of restraint may lead to excessive mental distress even in trained animals. The latter might influence the results and certainly affects principles of animal welfare. Our own experiences with instrumented, conscious, but unrestrained dogs encouraged us to modify methods used for the fixation of in-dwelling central venous catheters in dogs with special regard to the species specific behaviour and phenotype of pigs. A cord retractable leash (CRL) was used for maintaining a safe distance between the animal and the outer ends of the catheters. To prevent dehiscences of the required fixation sutures a new catheter bag (CB) was designed to counteract tension forces caused by the CRL's spring-mechanism. The combination of both the CRL and CB enabled us to conduct safe experiments with conscious, unrestrained pigs. We alleviated the mental distress these animals were exposed to in comparison to former methods based on restraint of the animals.