Slug-rats were indigenous to Ruten, and were considered by the inhabitants of that world to be the most disgusting creatures on the planet. In addition to simply being distasteful, slug-rats were prone to biting, and they were usually rabid. Slug-rats resembled furless, four-legged rodents with slimy slug-like bodies. The creatures bred at a rapid rate, frustrating attempts to exterminate them.
In one notable incident, Governor Bursthed of Ruten hosted a pet show, in which a slug-rat had been secretly introduced by agents opposed to his rule in the hopes of humiliating him. During the pet show, Bursthed placed his hand into the opaque cage which was supposed to hold his own entry in the show, a rare Glittering Mynock. Bursthed was surprised to have his hand attacked by a slug-rat which had been placed in the cage in place of his mynock.