Hi Jane,   There really is no way for anyone at this end to know for sure what your son is allergic to. Certainly, you've picked up a couple of possible clues. But you will probably need to watch for future reactions (or lack of them) to get a better idea of what he's sensitive to.   Also, sensitization is sometimes a slow process. Even if he has never reacted before to the cat or cat's saliva, he could just have been getting sensitized, and now is finally reacting.   You could talk to your pediatrician about allergy skin testing, which can be used in children and infants, though results in kids under the age of 2 years are not always quite as reliable.   To your health, Kathi