In "Not In Kansas Anymore" there is no sign of Doris' allergy as she cuddles her Aunt's dog. I guess most of that episode takes place in a dream so we should discount that however at the start of the episode, when we are in reality, Doris is carrying the dog wrapped up, in her arms. She tells the others that the dog is staying with her family for a week and she couldn't bare to leave him home alone. Surely someone with such an extreme allergy wouldn't want a dog in the house?