Also it is highly recommended to NOT touch other rats in the petshop without first washing your hands and taking a shower before playing with the rats you have at home. SDA is a VERY HIGHLY CONTAGIOUS disease which can spread via air and also contact with mucous and secretions etc. Do not take your rats to the petstore with you. If there happens to be a sick ratty there your rat can be infected just by breathing the same air, which is why breeders quarantine new rats in seperate households with a seperate air supply. It could be a MYCO flare up also. ALL rats are born with MYCO, however not all show symptoms. It usually shows itself when there is stress in their environment, new ratties, a trip etc.