 Because R. norvegicus and related species are seen as pests , their intentional import into foreign countries is often regulated . For example , the importation of foreign rodents is prohibited in Australia , and so various coat types , colors , and varieties have been bred separately from foreign lines , or are just not obtainable within that country ( for example , hairless and dumbo @-@ eared fancy rats do not exist in Australia ) . In other areas , like the Canadian province of Alberta , which is considered rat @-@ free , the ownership of domestic fancy rats outside of schools , laboratories , and zoos is illegal . 
