Yeah , you should get stool tests done for all three of them . My vet charges me for just one test , and I take samples from all the rats . Giardia is a bit odd , some rats will have symptoms , and other rats will be asymptomatic carriers . You ' ll need to get an antiparasitic . I ' m using panacur , 2 courses of 4 days on and 10 days off . You test again a month after their last dose . It ' ll probably take a couple of months to kick it entirely , and you ' ll need to completely sanitize their cage and all toys very frequently until they test clean . I ' ve been doing physical scrubs , a bleach sanitizing solution , and washing their hammocks a lot . You should start seeing an improvement in the smell issues by the 2 nd course of antiparasitics .