when it comes to severe life-threatening anaphylactic reactions just about any allergen could trigger a fatal response in some highly-allergic people. peanuts do it. beestings do it. i guess it is possible that cat dander could do it too but i have never heard of a case. have your doctor or allergies order a blood test for cat dander (rast test) and see how high the reaction might be.
can children die from a cat allergy